Description
Integrated pest management (IPM), also known as Integrated Pest Control (IPC) is a broad-based approach that integrates a range of practices for economic control of pests. IPM aims to suppress pest populations below the economic injury level (EIL).
1
Integrated Pest Management for Grain Elevators that
Supply the Breakfast Cereal Industry:
Case Studies and Economic Analysis
By
Thomas W. Phillips
1
, Ronald T. Noyes
2
and Brian D. Adam
3
1
Department of Entomology and Plant Pathology,
2
Department of Biosystems and Agricultural Engineering
3
Department of Agricultural Economics
Oklahoma State University
Stillwater, OK
Final Report
June 2002
Sponsored by the Grocery Manufacturers of America, Washing ton. D.C. and funded
through the National Foundation for Integrated Pest Management Education, Austin, TX
Corresponding author:
Thomas W. Phillips
Dept. of Entomology and Plant Pathology
127 Noble Research Center
Oklahoma State University
Stillwater, OK 74078
Phone (405) 744-9408
FAX (405) 744-6039
e-mail: [email protected]
2
Preface
This report marks the culmination of a project that spanned several years and
involved numerous individuals. Prior to 1998 the Stored Grain IPM Committee of
Oklahoma State University, under the direction of Dr. Gerrit Cuperus, joined with the
Grocery Manufacturers of America and the Foundation for Integrated Pest Management
Education to deliver educational programs on integrated pest management IPM to grain
elevators throughout the grain-growing regions of the U.S. That educational program
resulted in the concept for the current project to document IPM practices at grain
elevators, and was initially led by Dr. Phil Kenkel of the Department of Agricultural
Economics at Oklahoma State University. Direction of the project since 2000 was by
Drs. Phillips, Noyes and Adam, the current report authors. The authors are grateful to
their co-investigators, Gerrit Cuperus and Phil Kenkel, for providing significant inputs
throughout the course of the project. Dirk Maier and Linda Mason, co-investigators at
Purdue University, helped in designing the project and in making valuable contacts with
industry participants. Ronda Danley and Tamara Lukens, both graduate students in the
Department of Agricultural Economics, provided valuable information on fumigation
practices and costs of IPM used in this report. The authors are very grateful to the
companies and elevator managers who participated in this study and allowed us to use
their valuable time to collect information. We particularly appreciate Mr. Fred Hegele,
General Mills, Inc., who shared his knowledge of the food industry and was a steady
source of help and encouragement throughout this work. Financial support of the
National Foundation of IPM Education during the course of this study was greatly
appreciated.
3
Table of Contents
Preface 2
Introduction 4
Approach and Methods 5
Findings and Recommendations from Facility Visits 7
Elevator 1: Wheat, Corn and Barley 7
Elevator 2: Oats 19
Elevator 3: Oats, Corn and Wheat 34
Elevator 4: Corn 40
Elevator 5: Corn 43
Elevator 6: Wheat 45
Elevator 7: Wheat 49
Elevator 8: Wheat 52
Costs and Benefits of IPM 54
Conclusions 68
References 69
Appendices
A. Ideal Elevator Checklist and Audit Form 70
B. IPM Characterization Survey for Grain Elevators 75
C. Procedures for Cost Analysis 81
D. Costs and Evaluation of Fumigation Monitoring Equipment 86
E. Template for Fumigation Management Plan 87
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Introduction
Safety of food products in the United States relies in part on effective pest
management and cautious use of chemical pesticides during storage and processing of
post-harvest commodities. The breakfast cereal industry is particularly sensitive to both
insect contamination and pesticide residues, and thus is faced with serious challenges for
effective pest control in raw commodities and in finished products. Integrated pest
management (IPM) is a process whereby information about the pest, the environment and
the infested crop (or commodity in this case) are assessed and decisions made about use
of one or more pest control methods (cultural, biological, genetic, chemical, etc.) to
prevent or reduce unacceptable levels of pest damage by the most economical means and
with the least negative impacts to human health, safety, property or the environment
(Phillips et al. 2000). Management of stored grain has the potential for excessive use of
chemical insecticides at one extreme, and proactive use of preventive measures with no
use of chemicals at the other extreme. Principals of IPM can be applied to grain storage
through vigilant preventive measures, regular monitoring for pests and product quality
loss, and targeted controls when needed.
This project investigated current practices and potential for use of IPM in grain
elevators that provide raw commodities to the breakfast cereal industry. The general
objectives of this project were as follows.
1. Assess the present knowledge of IPM by managers and determine the use of
ecologically-based IPM at a minimum of six demonstration facilities, two each
that store corn, oats and wheat.
2. Make recommendations for these facilities, where needed, on methods to improve
IPM practices.
3. Determine the costs incurred and benefits obtained for the adoption of post-
harvest IPM practices in representative facilities.
This report summarizes work conducted between 1998 and 2001 in which eight
grain elevator facilities meeting project criteria were visited by a team of researchers and
information was collected on IPM-related practices at each. In some cases there were
substantial engineering recommendations made for resolving IPM problems as well as
general elevator problems. Data from other facilities were used directly in development
of an economic model for implementation of IPM at grain elevators. The model provides
a conceptual basis for understanding costs and benefits of IPM, and how implementation
of IPM may impact facilities with given characteristics. The breadth of variation among
facilities assessed in this study, including differences in geography, commodity stored
and production activities, allows for the results of this work to be broadly applied to the
North American grain and food industry.
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Approach and Methods
Criteria for selection of grain elevators to study were well defined at the outset.
Elevators needed to receive and store grain that would ultimately be used in the
production of breakfast cereals. The project targeted three cereal grains: oats, wheat and
corn. Our goal was to observe and characterize a total of six elevators comprised of two
for each of the targeted cereal grains. Eight elevators were ultimately used because one
“wheat” company had two separate elevator facilities that each provided different
operations (giving a total of three for wheat) and one elevator in the western U.S. had a
mixture of several grains, none of which predominated, and thus did not fit the “norm”
for the other facilities. Six of the facilities were co-located with their mills that generated
a specific product for manufacture of breakfast cereal. We adhered strictly to the
breakfast cereal requirement; none of the elevators studied would be considered to be in
the marketing chain for bread-making, desert products or snack foods. We hoped for,
and succeeded in, sampling elevators from a broad geographic range. Thus we visited
companies from the great Lakes to the Rocky Mountains, and from the northern to
southern parts of the mid-west. Securing the few participants we had in the study proved
challenging. Not surprisingly, many companies we contacted were reluctant to openly
discuss pest infestation or other sanitation issues that may point to their product as being
less than wholesome. GMA members were helpful in securing study sites in some cases,
and in others we were fortunate to acquire study sites through past professional contacts.
Data for this project were collected through personal interviews conducted during
site visits by two or three PIs to a participating elevator. A typical visit would last a half-
day to 1 and half days and was usually hosted by a facility manager who was
knowledgeable in commodity handling, storage and conveying equipment, sanitation and
pest control carried out at his company. Typically, other company staff members with
expertise in one or more of these areas would join the interview. Interviews and data-
gathering were facilitated by administration of the survey instrument titled “Ideal
Elevator Checklist and Audit Form” (Appendix A). The IPM checklist presented the
facility manager with a series of practices organized under broad categories of grain
elevator IPM, and required that the manager perform a self-assessment of how important
the practice (e.g. critical vs non-critical) was to his/her company, and report their level of
accomplishment on that practice (e.g., on a 1-10 scale, with 10 being a high level of
accomplishment). The IPM checklist was roughly modeled after a HACCP (hazard
analysis critical control point) document such that each facility needed to determine for
themselves how important, or critical, specific IPM “points” were to their operation. The
IPM practices were grouped under the following categories: sanitation, in which cleaning
spilled product or empty bins is done to prevent residual pest build-up; receiving,
referring to decisions regarding how grain is received and handled upon receipt; aeration,
the use of ambient air to cool grain masses and inhibit pest population growth;
monitoring, by which managers sample or inspect grain and structures for insects,
temperatures, grain quality, or other features; pesticide use, in which managers were
surveyed about chemicals used for pest control; and safety and education opportunities
for workers and managers that relate to pest control and IPM practices. On a few
occasions an additional survey vehicle, the “IPM Characterization Survey for Grain
6
Elevators,” (Appendix B) was completed that collected technical details of facility
beyond those generally known to the manager being interviewed
The quantity and quality of information collected among facilities was not
consistent throughout the study. The IPM checklist was quantitatively completed in
some of the cases, and was more descriptively addressed in others. Thus some reports
below have numerical scores for IPM practices while others have more thorough verbal
descriptions of the company’s practice. Through the course of administering surveys the
managers would generally share information of particular concern that we documented.
Sharing of specific problems and concerns varied greatly among elevators, perhaps
reflecting the “comfort level” of the manager in revealing such concern. Hence certain
reports address problems and proposed solutions at length while others reveal few
problems and are more directly related just to the survey vehicles. Site visits always
included a tour of the physical plant along with the office interview. Plant tours focused
on grain storage structures, conveying equipment, monitoring equipment, grounds in
general, and occasionally mills and other processing and storage areas.
An economic model for partial budgeting of IPM in grain elevators was
developed and elaborated during this study. Costs of several IPM strategies, with and
without certain levels of insecticide use, were calculated. Economic data at various
levels of detail were collected at participating facilities throughout the study, and data
from two companies in particular were subjected to the model to determine the actual
costs of their IPM systems.
7
Findings and Recommendations from Facility Visits
Elevator 1: Wheat, Corn and Barley
Three principal investigators visited this facility in Idaho in May, 1998 and again in
March, 1999. Meetings were with the facility manager and the company’s regional
manager. During the initial meeting, the OSU team discussed the physical facilities,
methods of operation and IPM practices, and filled in the OSU IPM Checklist and
Facility Audit with the manager. The checklist allows the manager to decide if each item
is critical to his operation or a good management practice (GMP).
Facility Description
This facility was formerly used for processing sugar beets, so the large welded steel tanks
were converted sugar storage tanks. One attribute of the welded steel tanks are that the
roofs have less slope than bolted corrugated grain bins so there is more headspace in all
these bins.
One elevator leg and dump pit station serviced two 100,000 bu concrete silos. Another
large elevator leg and a small leg plus several drag conveyors were used to fill and unload
ten welded steel bins which give the Lincoln Elevator a combined storage capacity of 1.8
million bushels.
The breakdown of the to welded steel storage tanks and silos are as follows:
Tank #1 = 400,000 bu
Tank #2 = 270,000 bu
Tank #3 = 200,000 bu
Tanks #8 & #9 = 35,000 bu/tank
Tank # 10 = 5,000 bu
Tanks #11& #12 = Two 100,000 bu concrete silos
Commodities Stored
This part of the northern Rocky Mountains is an excellent agricultural production area,
with a relatively mild climate with sufficient moisture for dry land farming. Irrigation is
responsible for much grain production. The combination of the six welded steel storage
tanks of variable size and the two silos with four elevator legs at three separate grain
receiving and shipping locations is ideal for handling a variety of grain types. Grain
crops handled were hard red winter and hard red spring wheat, malting barley, feed grade
barley, and corn.
IPM grain storage practices
The facility provides an excellent example of a commercial grain facility that manages a
diverse range of stored grain products with virtually no pesticides and very low pest
8
related losses. In general, no pesticides were used at this elevator due excellent
sanitation, short storage to aeration time period and cold winters.
Overview of Stored Grain Management System
Sanitation
Two men worked full time at this elevator. Both times we visited the facility there was
very little spilled grain lying around. The grounds were relatively bare of vegetation.
Tank roof vent louvers on some tanks were crusted up and were not closing completely,
but these were not an insect proof seal, just a weather shield of vent outlets. No insects
were detected around bin entry points during May, 1998 or March, 1999 visits.
Initially, aeration ducts were trenches in the floor with flush-floor perforated duct covers.
They filled in the duct trenches and replaced the in-floor ducts with round on-floor ducts.
During grain shipping, after gravity flow of grain from tanks is complete, bobcat loaders
are used to move grain to unload drag conveyor or U-trough auger hoppers in the floor.
Duct sections are removed as unloading progresses, cleaned and stacked outside. After
all grain is removed, grain dust and fines are swept up, vacuumed and hauled to the
dump.
Bin floors and walls (up approximately 20 ft from the floor) are treated inside and outside
with Reldan residual pesticide spray. The outside of the bin bases are sealed with a
rubberized or elastomeric sealing paint annually, as needed. Bins are carefully checked
for water leaks as part of pre-filling inspection. Then the round floor aeration ducts are
then repositioned and anchored with grain in preparation for filling bins with new harvest
grain. Leg boot pits are cleaned prior to harvest and periodically as needed during the
year.
In the concrete silo facility, the hopper bottom self-unloading floors in the two 100,000
bu silos are swept out when emptied. Aeration ducts are vacuumed to remove residual
fine and grain particles. All spilled grain in and around the facility is swept up any time
there is a spill or leak. The elevator leg boot pits are cleaned once monthly. Standing
water that forms pools on the relatively flat ground across the facility are pumped out to
ditches to minimize ground water leaks into bin bases.
Weekly sanitation inspections are conducted. All grain spillage and other sanitation
problems are noted and corrected. Signs of rodent activity are also monitored during
these facility walk-arounds. Rodent traps are monitored weekly and trap catches are
recorded.
Receiving and Handling
Incoming grain is received by truck. All loads are probe-sampled at the elevator for
insects, moisture, dockage and protein. In-house grading is used on all in-bound
truckloads. Federal Grain Inspection Service (FGIS) grades are checked on all out-bound
truck and rail shipments. Any loads with marginally high moisture is transferred to
holding bins at a nearby company elevator for blending or shipping. No grain above 13
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% is stored at the study facility. A truck-load is rejected if 1 live insect is found. For
outbound shipments, a probe sample from each truck-load is submitted to a grain
inspection service near the elevator for official FGIS grades.
The grain peaks are also pulled down by "coring" the center of the bin to lower the peak
for improved aeration. Grain quality of outbound truck and rail shipments is controlled
through samples tested at a local testing laboratory. Grain from this facility to be rail
shipped is dumped at the main company elevator nearby and then loaded directly on rail
cars or held temporarily in silos.
Aeration
All grain tanks and the two silos are equipped with aeration fans, on-floor round
perforated aeration ducts, and roof vents. The aeration systems in the three large steel
tanks consisted of several centrifugal fans (fan HP proportional to tank size) per tank
positioned symmetrically around each tank. Tank #1 had a total of 110 HP in eight base
fans plus a 20 HP roof exhauster. Tank #2 and Tank #3 had six 10-HP base fans and one
10 HP roof exhauster. Base fans are connected to round perforated steel ducts positioned
radially toward the center of the tank. Each of these tanks had louvered exhaust vents
and one roof exhaust fan that appeared to be adequate to provide satisfactory exhaust air.
The roof exhauster was operated for a period of time after the aeration fans were shut off
to expel high humidity air.
Airflow rates is approximately 1/10
th
cfm/bu on Tanks #1, #2, #3, at or near full depth for
wheat and barley and about 1/6
th
cfm/bu fully loaded with corn, and when 2/3 full of
wheat and barley. At 1/10
th
cfm/bu airflow rates, wheat and barley could be cooled in
about 150-175 hours of cumulative fan operation in peaked grain. Tanks filled with corn
were cooled in 90-100 hours. The concrete silo aeration is powered by two 30-HP high
pressure centrifugal fans each, with an airflow rate of about 1/12th cfm/bu when filled
with wheat or 1/7th cfm/bu with corn.
Aeration is started as soon as air temperatures are 15-20
o
F below grain temperatures in
mid-to-late-September. All tanks have pressure, or up-flow aeration systems. Large tanks
have four louvered vents located symmetrically around the roof about 6-8 feet from the
edge of the roof with a powered roof exhaust fan near the center.
Because of the local power company restriction of a high peak demand charge on electric
power, not all tanks and silos could be aerated simultaneously. When elevator legs and
drag conveyors were being used for grain transfers, aeration fans were not operated. To
avoid increased peak power load charges, only about 1/3 of the tanks and silos could have
been aerated per day when grain handling was in progress, or half of the aeration
operated on alternate days when grain was not being transferred.
In actual practice, all aeration fans are manually operated at night by the two elevator
grain managers who typically turn part or most of the fans on as they leave work at 5:00
PM and turn them off when the return to the elevator at 8:00 AM. So, aeration had to be
scheduled when (pending suitable weather) grain was not being handled, and then
cooling was still limited to half of the tanks being aerated at night during the workers off-
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duty hours. At best, each of the large tanks could only receive about two days of aeration
per week. This system of manually operated alternate night aeration was able to lower
the temperature of the grain mass in the warmest grain below 70
o
F by the end of October.
The goal of the aeration program was to cool the grain of 40
o
F in all bins by December.
Once cooled, all grain is left at these cool temperatures until load-out.
The aeration systems on Tanks #8, 9 and 10 were poorly designed. Each tank had only
one old 5-HP 30-inch diameter Buffalo Forge axial fan. The transition consisted of a flat
steel back plate with an 18-inch diameter hole cut at the bottom of the plate to blow air
into an 18-inch diameter transition and aeration duct on each tank. This system was
totally ineffective on all crops. It is doubtful that this fan would deliver more than 30-
40% of its potential air delivery when aerating full tanks of corn, and far less on wheat.
Roof venting was also poorly designed. These aeration systems on Tanks #8 and #9
should be replaced immediately using a 10-HP low speed centrifugal fan similar to those
used on Tanks #2 and #3. The aeration duct system for these tanks, estimated at about 42
ft dia x 30 ft grain depth should be patterned similar to the same size bolted steel bin
ducts. A 1-2 HP vane axial fan with proper floor duct and roof vent should be suitable
for Tank #10.
Monitoring
This facility was used for sugar beet processing and to store liquid sugar until about 1994,
so the welded steel tanks were originally liquid tight from roof to base. The site around
the tanks was relatively bare of vegetation and natural habitat. Thus, stored grain insect
populations had not built up in the surrounding fields and creeks around the elevator site.
Probe samples from in-bound trucks are checked in-house for insects, moisture, dockage
and protein when processed at the neaby company headquarters. Loads are rejected for
moisture above 13% or if 1 or more live insects are found. The average moisture content
of grain received was bout 11%. If probe samples are found acceptable at the
headquarters, then trucks are routed to the subject facility for dumping. Grain between
12-13% and/or marginal dockage is diverted to concrete storage where it can be shipped
out easier.
Grain is dumped into the various tanks according to type, grade and moisture. Grain is
visually inspected in tanks at the surface about every two to three weeks. Although all
tanks have thermocouple cables, which are read through a Rolfes Hot Spot manual
temperature instrument, grain temperature monitoring was erratic. However, due to the
excellent climate, short time between harvest and cooling, and excellent sanitation, few
insect problems were encountered at this elevator. Individual tanks were fumigated if an
insect problem was detected in them, but only one or a few cases were reported t ooccur
in the four years of grain storage.
Anytime grain is removed form storage, samples are pulled at 2-minute intervals from the
moving grain stream. All samples are sieved and checked for insect activity.
Periodically during the season, a 400-500 bu truck load is transferred from each tank or
silo and sampled intensively. By taking numerous samples from each truck load and
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sieving all of the sampled grain for insect presence and damage, a good representation of
the center core of each grain mass is obtained.
The grain surface is also inspected monthly for roof leaks and insect or mold problems.
Shallow trier probe samples from various locations across the grain surface are obtained
and carefully inspected for insect presence or damage. These surface inspections are
discontinued for safety reasons when enough grain has been removed to form a
substantial inverted cone in the center. All outbound loads are officially sampled and
graded. Quality specifications on out-bound loads are no live insects and less than 3 IDK
(insect damaged kernels) per 100 gram sample.
Grain temperatures are monitored weekly. Temperature readings in all bins are recorded
weekly until all the grain mass in each bin reaches the target temperature (approximately
40F). A log of aeration timing and outside air temperatures is maintained during
aeration. If a hot spot is detected, the bin is inspected for leaks, insect activity or mold
problems. The bin is sampled by probing the surface, deep cup probing and power
probing the grain mass, and core samples are pulled using the unload system.
Maintenance and Safety
A full preventive maintenance program is in place at this elevator. All bearings are
greased and gearbox oil levels and quality are checked at pre-scheduled time and usage
intervals. A walk-around inspection of bearings on equipment located inside structures is
conducted at the end of each day's operation. An outside company is contracted to make
regular inspections of fire extinguishers. Outside resources are also used to conduct fit-
testing of personal protective equipment (PPE) and specialized safety training annually.
Results
For the four year period in which the facility has been under current management for
grain storage, approximately 1.5-2.0 million bushels of grain have been handled each
year without fumigation. Grain quality has been maintained with low shrinkage (less than
1/4 percent). Out-bound loads have consistently met high quality standards of below 3
IDK and zero live insects.
Facility Modifications
When this elevator came under current management only 50% of the thermocouples on
cables in all grain bins were functional. Some bins had aeration fans connected to bins,
but no ducts were installed inside the bins. In addition to resolving these facility
temperature monitoring and aeration duct deficiencies, all bin foundations were sealed
with a flexible rubberized material, roof exhaust fans were install on the three largest
steel tanks to provide positive exhaust of headspace moisture. Subfloor aeration duct
trenches were filled in and removable perforated tubular aeration ducts were install on the
bin floor surface in all steel bins.
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Critical IPM Factors
The facility manager participated in filling out the OSU Critical IPM Check-Point
Management Audit. As indicated above, grain managers identify two levels of grain
management practices related to IPM, those that they designate to be "Critical IPM
management factors" (CIPM) for their elevator storage, and another group that are
considered to be just "Good management practices" (GMP). GMPs are activities that are
part of their grain storage management system, but are not considered absolutely critical
to success or a corner-stone of their program.
The Critical IPM Practices identified at this facility were:
Sanitation
* Complete clean-out prior to filling
* Spraying down empty bins prior to filling
* Cleaning spilled grain and fines around bins, dump pits and drive
* Sealing bin bases and openings to prevent moisture leaks
Receiving/Handling
* Sampling incoming grain for moisture, insects and other factors
* Rejecting infested grain
* Leveling bins prior to aeration by removing center core
Aeration
* Bins equipped with adequate airflow
* Lowering grain temperatures below 60 degrees as soon as possible
* Monitoring temperature forecasts and operating fans to take advantage of cool nights
Monitoring
* Checking grain temperature weekly
* Sampling center-core of each bin at least monthly by removing a truck load of grain
and intensively sampling the load
Costs of IPM Practices
Pesticide Cost
The major pesticide cost is the cost of spraying empty bins with residual pesticide
(Reldan) to eliminate potential carry-over insect populations. An outside contractor was
used for the treatment at a total cost of approximately $700 (about 0.1c/bu). Temperature
management was achieved with an average of 100 fan hours/year with electrical cost of
about 0.5c/bu for aeration. Sanitation and monitoring activities involves 2 employees
with an average time spent of 10 hours each, or 20 man-hours/week. Labor costs were
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approximately $10,000/year or 0.6c/bu. Grain inventory records indicated an average
shrinkage of 1/4 % per year or slightly less than 1 c/bu. Total cost of the storage system
was estimated at 2.2 c/bu.
Demonstrational IPM Elevator #1
Costs Associated with Storage
Category Total Cost Cost/Bu Stored
Aeration $3,500-7,000 0.2 - 0.4 c/bu
Labor $10,000 0.6c/bu
Empty bin treatments $2,100 0.1c/bu
Grain shrinkage $18,000 1.0c/bu
Total Storage Costs including Shrinkage 1.9-2.1 c/bu
General Assessment of IPM
The grain managers at this facility are doing an excellent job of grain management, even
under serious electric power restrictions imposed by the local public utility. Excellent
facility sanitation and handling practices, good in-bound grain quality, and periodic
visual monitoring of grain in all tanks qualifies this elevator as a low risk, high quality
sustainable IPM grain elevator facility. The aeration fan systems on the concrete silos
and large steel tanks were excellent. The high level of cleanliness, particularly the lack
of old grain residues in and around storage and conveying structures, with concurrent
endemic insect problems that typically occur with grain residues, is likely due in part to
the relatively short history of grain storage (only four years) at this location. This
inherent low risk or having a brief grain storage history is certainly enhanced by the level
of understanding and attention to preventive IPM by the staff.
Recommendations for improvement of grain and elevator operations
The physical facility at this elevaotr was generally in good condition. However, the local
power utility’s policy at for this facility was extremely restrictive, which seriously
inhibited optimum grain storage management. The demand charges are so high that the
facility had to be continually micro-managed to maintain reasonable electrical power
costs. It is highly unusual to have such restrictive power control that the elevator is
required to use a three-day aeration schedule rotation when moving grain. Even though
the elevator is well managed, several improvements that could further enhance grain
storage management are: elaborated here.
1. Seal aeration fans and unload conveyors when not in the aeration season.
Sealing aeration fans blocks access to insect entry into the bottom of the storage units
keeps cold air from draining out of the tank and pulling warm air into the upper grain
mass, and keeps convection currents from moving through the grain, warming grain
and removing grain moisture and market weight. Unload conveyors should also be
sealed until time for use.
14
2. Core tanks for improved cooling uniformity and reduced aeration time.
Even though aeration was cooling the grain, it was a slow process due to power
company limitations on peak power load. Coring the steel tanks and concrete silos to
reduce the peak height by 1/4 to 1/3 shortens the air path, removes some fines and
foreign material from the core of fines that forms under fill spouts and lowers static
pressure. The aeration fans move more air with lower static pressure and shorter air
paths. Not cooling the peak will shorten aeration time by 10-15%, reducing the
power bills and minimizing marketable moisture removal due to longer cooling times.
Lower static pressures will lower pressure fan "heat of compression" which increases
the cooling air temperature by 5
o
F to 10
o
F.
3. Install an automatic aeration controller to pinpoint desired cooling air
temperatures.
Note that aeration controllers should be set lower to account for pressure fan "heat of
compression" temperature rise to cool the grain to a desired temperature such as 60
o
F
initially, and 50
o
F by end of the aeration period for winter storage. If the target grain
temperature is 50
o
F, and a thermometer stuck through a hole drilled in fan transition
ducts shows an air temperature rise of 7
o
F, the automatic aeration controller
temperature set point should be 43
o
F.
4. Monitor grain temperature at 2 week intervals.
Grain temperature monitoring is a similar practice to that of a physician checking a
patient's temperature and blood pressure. Grain temperatures give the elevator
manager a continuous picture of what's happening inside the grain mass. Grain
should be monitored at 2-week intervals so the elevator manager has a continuous
record from year to year of grain conditions for each tank. Reviewing temperatures
twice monthly will allow the manager to spot spontaneous heating problems that
indicate a moisture or insect problem before it becomes excessively costly.
5. Change aeration fans, ducts and vents on tanks #8, 9, 10
The 5-HP Buffalo Forge fans on tanks #8, 9, and 10 are poorly designed and should
be replaced with Tiernan fans (or similar) like those used on the other tanks and silos.
Check roof vents and perforated aeration ducts for adequate capacity.
6. Check all louvered roof vents on large steel tanks and silos.
At least two of the four-roof edge exhaust louvers on the very large Tank #1 were
sticking closed or partially closed when we inspected the tanks in May, 1998.
Sticking louvers minimize exhaust area, increase static pressure in the head space
placing and on the fans, reducing airflow and increasing "heat of compression"
temperature rise of the cooling air. Check exhaust louvers on other tanks for free
movement of gravity louvers. Headspace static pressures should not exceed 1/16 to
1/8 inch water column on pressure aeration systems. Exhaust louver air velocities of
1,000 fpm are desired but should not exceed 1,500 fpm. This is a function of total
15
roof duct cross-section area. Example: Tank #2 at 270,000 bu. with an airflow of
27,000 cfm at 0.1 cfm/bu should have 27,000/1,000 = 27 sq. ft of vent exhaust area.
Thus, each of the four vents should have a cross-section area of about 7 sq ft x 4 = 28
sq ft, or about 2 ft 8 inches square.
7. Heat of compression temperature rise on pressure aeration fans
Check heat of compression temperature rise on fans of all large tanks, and especially
Tanks #11 and #12 (two tall silos). To check temperature rise, drill a small hole (3/16
to 1/4 inch) in the transition between the fan and the tank just large enough to insert a
grain thermometer or digital thermometer thermocouple. Check the fan inlet air
temperature, then the fan outlet air temperature; the difference is the heat from the fan
compressing the air. Seal hole in fan transition with metal screw, bolt or duct tape.
All pressure fans add heat to cooling air. The 30 HP fans on silo #11 and silo #12
will have the highest temperature rise, probably 10-12
o
F, with big steel tank aeration
fan temperature increases of 6-8
o
F.
8. Develop an automatic controller aeration fan start-up sequence control system
Aeration fans and roof exhausters on Tanks #1, 2, 3, 8, 9, 10, 11, 12 should be started
using an automatic aeration controller using an 8-10 second time delay between fans
to allow each fan to reach full speed before another fan is energized. This will
minimize locked rotor amperage of all fans starting simultaneously. Motors should
be started in a selected sequence to minimize startup inrush current. A sequence
starting system could also be designed to minimize shutoff voltage spikes on
shutdown but let's concentrate on inrush control initially. (See Power Management
Schedule (Draft) Options at Lincoln Elevator below.)
9. Check with local power utility about getting the excessive peak demand charges
changed.
Because of the unreasonably high peak demand charges, in which the utility charged
for the entire year based on the highest monthly peak load, the aeration system
operation was very fragmented. Aeration fans on all tanks should have been operated
simultaneously to cool the grain. Dr. Noyes discussed this situation several times
with the maanger, urging him to contact the utility company and ask them to review
their peak demand policy for this elevaotr.
The manager made a successful contact with the power company and discovered that
his elevator should have been on a commercial account without a demand charge,
instead of an industrial account with peak demand charges. The power utility
switched the electrical policy, dropping the peak power demand charge. The power
company made the change retroactive for several months previous to the correction.
This resulted in a reimbursement of $3-4,000 and an electric power savings of about
$9-10,000 annually.
Before the power utility corrected their error for the power account of this elevaotr,
several options were developed by Dr. Noyes to help reduce the excessive peak
16
demand power costs and improve operational efficiency of the elevator. The
following recommendations, now a moot issue, were developed as initial
recommendations for this elevator and presented here as examples of alternative
approaches to improving efficiency of power use.
10. Study motor operating times to minimize peak demand load
If the power company had not changed the type of power account for this elevaotr, it
would have been beneficial to develop a history of motor operation sequences (time
and date when motors are turned ON and OFF) by tracking motor on/off events to
gain a better understanding of the peak demand problem here. A simple, economical
method of tracking motor stop/start sequence data is by attaching a small electro-
magnetic field sensor ("HOBO" is one brand) to each conveyor motor and one
aeration fan motor on each bin. Studying the pattern of running motors by date and
time could be used to fine tune grain handling and aeration operations.
11. Reducing motor starting inrush loads to improve critical power situations
When a peak load demand charge is assessed to elevators like this one, management
should consider installing reduced current starters on motors that are 20-25 HP and
larger to minimize peak load locked-rotor amperage on large motors. Ronk Electric
Company, Nokomis, IL is a leading manufacturer of reduced current starters (RCS).
RCS reduce inrush current by about 40% through capacitor banks, while maintaining
normal line voltage, which keeps starting torque higher for RCS than reduced voltage
starters (RVS). While Dr. Noyes was Chief Engineer at Beard Industries, Frankfort,
IN, Ronk prototyped several RCS's for 50 to 200 HP blower motors for them in the
1970's. The RCS capacitor kit is installed on the existing motor starter, at
substantially lower costs than major brand RVS's.
12. Power management schedule options
Aeration Motors:
Tank #1 1 @ 20 HP (roof exhauster), 6@15 HP, 2 @ 10 HP = 130 HP
Tank #2 1 @ 10 HP (roof exhauster - est.), 6@10 HP = 70 HP
Tank #3 1 @ 10 HP (roof exhauster - est.), 6@10 HP = 70 HP
Tank #8 1 @ 5 HP = 5 HP
Tank #9 1 @ 5 HP = 5 HP
Tank #10 1 @ 5 HP = 5 HP
Tank #11 2 @ 30 HP = 60 HP
Tank #12 2 @ 30 HP = 60 HP
Total Aeration HP = 405 HP
Managers Estimate of Conveyor Motor Powe:
Four legs @ 50 HP = 200 HP
Six Drags @ 25 HP = 150 HP
Two U-troughs @ 20 HP = 40 HP
17
Nine Augers @ 15 HP = 90 HP
Total Conveyor HP = 480 HP
Total HP = 885 HP
Start-up: If possible, always start largest motors first, then the next larger, etc in
descending size sequence (if possible) to minimize peak demand power.
Demand Meter System: We recommend that the manager discuss how the demand
meter works with a power company service representative. From a peak demand
situation, it might be less expensive to let elevator legs run continuously during grain
handling months, rather than shut them off daily. However, this may not be acceptable
when the site is unattended.
Power Sequencing
There appears to be as much potential for power to be used at a particular time during the
day when transferring grain as during aeration, based on the power table above with 480
HP on conveyors and 405 HP on aeration fans. Although there are four legs, it is likely
that only two legs and their associated conveyors would be operating at one time, such as
receiving grain at two pits, or receiving grain at one pit and loading out trucks or cars at
another leg site. So, 200-250 HP could be operating in grain movement. That is as much
as half the aeration system, but due to peak loading, usually no more than half the
aeration capacity was operated at one time when transferring grain.
Alternative grain handling vs aeration motor operating recommendations: To
minimize peak electrical current demand, several alternative motor power operating
schedules were outlined as recommendations.
Four Day Schedule (Grain Transfer + Aeration)
Day 1: (Grain Transfer + Aeration)
Leg @ 50 HP, drag @ 25 HP, u-trough @ 20 HP, auger @ 15 HP = 110 HP
Tank #11 @ 60 HP; Tank #12 @ 60 HP = 120 HP
Total Day 1 = 230 HP
Day 2: (Grain Transfer + Aeration)
Leg @ 50 HP, drag @ 25 HP, u-trough @ 20 HP, auger @ 15 HP = 110 HP
Tank #2 @ 70 HP; Tank #3 @ 70 HP; Tank #8, #9 & #10 @ 15 HP = 155 HP
Total Day 2 = 265 HP
Day 3: (Heavy Grain Transfer- - no aeration)
Leg @ 50 HP, drag @ 25 HP, u-trough @ 20 HP, auger @ 15 HP = 110 HP
Leg @ 50 HP, 2 drags @ 50 HP, 2 augers @ 30 HP = 130 HP
Total Day 3 = 240 HP
Day 4: (Grain Transfer + Aeration)
Leg @ 50 HP, drag @ 25 HP, u-trough @ 20 HP, auger @ 15 HP = 110 HP
Tank #1 @ 130 HP = 130 HP
18
Total Day 4 = 240 HP
Three Day Schedule (Light Aeration)
Day 1: Tank #11 @ 60 HP; Tank #12 @ 60 HP =120 HP
Day 2: Tank #2 @ 70 HP; Tank #3 @ 70 HP =140 HP
Day 3: Tank #1 @ 130 HP; Tank #8, #9 & # 10 @15 HP= 145 HP
Two Day Schedule (Heavy Aeration)
Day 1:
Tank #2 @ 70 HP; Tank #11 @ 60 HP; Tank #12 @ 60 HP; Tank #10 @ 5 HP = 195 HP
Day 2:
Tank #1 @ 130 HP; Tank #3 @ 70 HP; Tank #8 & #9 @10 HP = 210 HP
19
Elevator 2: Oats
Three principal investigators visited this elevator in Minnesota in March 16, 1999. The
facility stored only oats and was co-located with an oat flour milling facility. The PIs
met with a company management team composed of the elevator manager, the flour mill
manager, the company’s technical grain manager, a merchandiser and an individual from
the quality and regulatory operations division.
Facility Description
The primary grain storage facilities at this 5 million bushel elevator consisted of a 2
million bu concrete head-house facility with concrete silo annex, plus four each 750,000
bu bolted steel flat bottom bins constructed in line adjacent their concrete facility on a
site where two flat storage units were previously removed. These large steel bins are
rated for 750,000 bushels on oats and 500,000 bu for wheat due to soil bearing pressure
limitations. Due to their large diameter, contraction and expansion of the bins between
summer and winter seasons makes it difficult to seal the base against water leaks.
Handling rates from the receiving system and concrete facility is 15-20,000 bu/hr.
Concrete Elevator
The 2,000,000 bu. concrete silo system capacity had no temperature monitoring system.
Sanitation was the primary management practice for on-site pest control in the concrete
facility. However, a rigorous plan of quality control during contracting and shipment of
oats from Canada or Scandinavian countries was implemented by management through
contract requirements to sample each oat shipment in at the rail shipping point in
Manitoba. The same process was used at the barge unloading/105 car unit train loading
facility at the company receiving elevator on Lake Superior. Each railcar was sampled
and graded before being allowed to ship. This provided management with a critical IPM
checkpoint.
In addition to sampling for insects, other contract grade factors were dockage, test
weight, moisture content and foreign material. A moisture content of 14.0-14.5% wet
basis was the upper limit accepted for storage. At the time of receiving, oats with
variations in test weight, moisture content and other grade factors were segregated into
silos containing oats of similar characteristics. Oats were then cleaned and blended to
provide the desired characteristic for the oat milling process as oats were transferred from
the steel bins were unloaded and transferred back to the concrete facility. The elevator
manager estimated that 0.5% of their bulk grain mass was removed during cleaning as
scalpings which were land-filled.
One area of concern at the concrete elevator facility was the rail car staging and dump pit
area where spilled grain that was not immediately cleaned up provided attraction to birds,
rodents and insects.
20
Steel Bins
The four 750,000 bushel bolted steel oat Butler bins, constructed in 1990, were built in-
line perpendicular to the concrete silos and rail tracks. The steel bins were 105 ft.
diameter with 60 feet sidewalls and 90 ft. peak height. Filling was done by a 15-20,000
bph elevator leg from the truck or rail dump pit receiving leg to horizontal drag
conveyors across the top which discharged into the four steel bins.
A second horizontal drag conveyor from the concrete facility was designed to discharge
into the drag conveyors that filled the four steel bins allowed transfer of grain from the
rail dump pit in the concrete facility train receiving station to the steel bins. Return flow
from the steel bins to the concrete facility was achieved by elevating grain from the under
floor drag conveyors, elevating via bucket elevator, then transfer to the concrete house by
discharging the grain into the drag conveyor which was reversed to carry the grain to the
drag conveyor across the top of the concrete facility which distributed the grain to the
selected silo(s).
Lower moisture (12-13%) grain was placed in the steel bins for long term storage while
grain with higher moisture (13.5-14.5%) was stored in the short-term storage concrete
facilities and was used first. Although the company preferred to receive oats at 13-14%,
Canadian oats received in 1998 typically ranged from 10.5-12.0%.
Grain transferred into the steel bins was not cleaned during receiving before loading into
bins. No distributors or spreaders were used in the bins, therefore a core of fines and
trash that accumulated under the fill point down the center of the bins was a serious
problem when aerating the bins in fall and winter. According to the elevator manager,
the drier particles and light weight trash tended to slide along the surface to the outside,
while wet, heavier broken kernels and fines formed a core near the middle of the bin.
This is the pattern found often in most steel storage bins in the U.S. when grain spreaders
or distributors are not used.
No distributors or grain spreaders are used due to the high receiving rate, thus the oats,
which have 2-3% beginning foreign material (FM), are difficult to aerate due to high
concentration of FM in the center. Coring was attempted but caused a short circuit of air
through the center. The entire concrete and steel elevator facility was operated by just 7
men due to a high level of automation of conveying systems.
Overview of Stored Grain Management System
Sanitation
After gravity flow of grain unloaded from bins is complete, sweep augers are used to
finish loadout of the steel bins. Then bins are swept out and any wet or moldy grain
remaining on floors and lower walls are removed. The bins are inspected inside and
outside for moisture problems around the base. Then floors and the bottom 10 ft of
sidewalls are sprayed with the residual insecticide Tempo
TM.
21
Receiving/Handling
Incoming grain is received by both truck and rail. All loads are checked for insects. A
load is rejected if one or more live insects is found. Grain quality of inbound rail
shipments is controlled through submitted FGIS samples. In-house grades are used on in-
bound truck shipments. Grain is segregated by end-use characteristics. Oats with
unacceptable end-use or storage properties are channeled back into the commodity feed
market. Grain is typically received at 12-13% moisture. During years in which Canada
experiences a wet harvest, moisture content may be higher (14-14.5% maximum
moisture). Grain temperatures on in-bound oats typically ranges from 50-80
o
F.
Oats that are expected to be stored more than 4-5 months are cleaned before storing. The
grain managers at this facility attempt to move uncleaned oats out of storage within 4-5
months. The oats typically have a beginning FM content of 2-3%. Cleaning is done
through a Carter-Day Screenerator
TM
, which results in an ending FM content of 0.1-
0.2%. Approximately 4-5% of total material is removed during the cleaning process.
Dockage and other fine material is disposed of in a landfill. FM is channeled into feed
market uses and smaller oats (stub oats) that are aspirated out during cleaning are
marketed in the feed oats market. All oats are cleaned or re-cleaned prior to transfer to
the flour mill.
Management experimented with “coring” bins, in which sufficient grain is unloaded to
draw down, remove and re-distribute the center core that contains a disproportionate
amount of fine material. However, their coring experiences resulted in a lower-resistance
airflow path up through the center, which short-circuited air to other parts of the bin
during aeration. Hand-leveling bins was tried, but each bin required 3 days for 7 men (21
man-days) to level a bin which was considered impractical.
Aeration
Cooling is started in October and finished in November when evening temperatures drop
below 50
o
F. Estimated cooling cycle time was 10-18 days. Target grain temperatures
were 40-45
o
F. Two bins were equipped with aeration controllers, but when the
controllers operated the fans during 2-3 days of early cool weather, moisture problems
were created when cooling could not be completed because of a lengthy period of warm
weather. Powered roof exhausters are operated on each bin when aeration fans operate.
Aeration fans are sealed when not in use. Cold grain is not re-warmed during summer
months.
Monitoring
Each in-bound load is monitored for insects and quality. Loads are rejected if 1 live
insect is found. Grain quality of in-bound rail shipments is controlled through submitted
FGIS graded samples. In house grades are used on in-bound truck shipments. Trucks are
probed as they enter the north side of the elevator property and queue until grain samples
are graded and approved for dumping. In storage, grain surfaces are checked at least
once monthly for insects and other quality problems.
22
Vacuum and pneumatic drill samples are also used to check grain condition in the top 25
ft of the grain mass. (Note: Deep probe technology now available at the time of this
report should allow easy sampling of the entire grain mass, surface to floor, including the
90 ft depth at peaks.) Grain is also sampled for insects and quality each time grain is
transferred from bins. Quick withdrawal samples by short operating the unload
conveyors for a few minutes allow sampling of grain quality near the floor as well as the
surface. These samples provide a periodic profile of grain conditions in bins.
Accomplishments
Grain managers have successfully eliminated the practice of or need for direct residual
pesticide application to bulk grain in storage. During the 8 years prior to OSU Team’s
visit, no infested loads of outbound grain were detected. This management system
provides an excellent example of how an increased emphasis on facility sanitation, grain
cleaning, monitoring and aeration can facilitate the elimination of chemical inputs to
grain. Their use of grain cleaning as a final safeguard against insect presence in grain
used in flour processing is particularly important to recognize.
Major Grain Storage Problems Reported in Steel Bins:
The facility storage structure and surrounding environment and weather conditions
present several management challenges. Itemized in the list below are the most serious
physical problems that were related to grain management. Many of these problems are
related to the extremely large bin sizes of the steel tanks, both in bin diameter and grain
depth. Each problem group is then analyzed from an engineering standpoint with
recommended solutions listed.
1. Moisture leaking into the bins at the floor level along the south side of the walls.
2. Fines, trash and dockage in center core of bin under spout line blocks aeration.
3. Fines and foreign material cause 60-65 degree grain slope on unload cone after
gravity flow stops during unloading.
4. Aeration fans inadequate - -cooling too slow and irregular.
5. Aeration floor duct system inadequate.
6. Roof venting system inadequate - - 6 x 0.5 HP roof exhausters vs 80 HP pressure
aeration fans at base - - moisture condensation on surface grain.
7. No automatic control of aeration fan system on bins 53 and 54.
8. Roof exhausters create nuisance noise problems – need to be muffled.
9. Temperature cable breakage and lack of center thermocouple cable.
10. Sweep unloader wall clearance leaves grain around wall.
Problem #1 - - Moisture leakage into bin at bases
The elevator manager said the four 105 ft. diameter, 750,000 bu bins were too large.
Large temperature fluctuations from summer to winter are extreme. South and north
sidewall temperatures varied 30-40
o
F at mid-day in winter. Air temperatures vary from
over 100
o
F in mid-summer to –35
o
F in mid-winter. With solar absorption on southern
exposure galvanized sidewalls, steel base rings varied by 150
o
F from summer to winter.
Between summer and winter, the diameter of the steel base ring contracted by about 12
23
inches on the concrete base. With this amount of movement, the bin wall to base junction
could not be kept sealed.
Snow drifts 4 to 6 feet deep around the bins. Solar radiation on the steel sidewalls on
southern exposures melts snow around the base during the day. The water from snow-
melt freezes at night. This cyclic condition plus the movement of the steel base ring
causes water to seep under the wall into the grain causing spoilage along 30-40% of the
base along east, south and southwest sides of the bins.
Recommendations to help resolve problem:
1. Use wall steel base ring to concrete base “L” shaped anchor brackets mounted
about 2 ft up the base ring sidewall sheet with an I-bolt type turnbuckle connected to
the concrete base anchor bolt. The purpose of bin-base anchor systems are to hold the
bin on the concrete base against wind forces when bins are empty and to keep the bin
“centered” on the concrete base.
2. The base anchor bolts circle should be 8-10 inches from the bin wall flange during
cold weather so there is adequate room for the bin diameter to expand during hot
weather. This long anchor bolt assembly will allow the steel base ring to slide on the
concrete base as it expands and contracts without inducing shear forces to anchor
bolts.
3. Seal the wall/foundation joint with flexible elastomeric roofing paint using a
nylon mesh filler to bridge gaps of more than 1/8 inch. Seal in mid-summer, then re-
seal late in the fall before first snowfall or after clearing the first snow away from the
base and concrete is dry.
4. Clean snow away from southern exposed walls ASAP the snowfall or drift
buildup to avoid ice-dams against the wall on sides exposed to the sun.
5. Two or three times (monthly) during the winter, remove a small volume (3-5,000
bushels) of grain from each of the bin unload gates across the bin width and recycle
the grain back to the same bin to relieve compression stresses or pressure on the
sidewall steel caused by contraction of steel wall rings due to extreme temperature
drops during the winter.
Problem #2 - - Core of fines and dockage in cylindrical column in center of each bin
A buildup of grain fines, FM and trash as grain is discharged from the overhead drag
conveyor during filling creates serious problems when the bins are unloaded. During
filling, dockage, grain fines and trash segregate. Broken kernels, dockage, weed seeds
and other small material settle between the larger kernels within a few feet of the fill
point, plugging the kernel interstice air gap between kernels, forming a dense vertical
cylindrical column that restricts or blocks aeration airflow. This dense column can be
eliminated by mechanically spreading the fines.
24
These bins were too large and fill rate too high for low powered commercial grain
spreaders. Powered slingers used to fill ship holds or build large bulk piles of grain or
bunkers could handle the flow rate and distribute the fines fairly well across the 52.5 ft
radius, but these units are very heavy. They’re too expensive to install in each bin and
too bulky to transfer from bin to bin.
Recommendations to help resolve problem:
1. Fabricate and install a simple, large inverted cone shaped spreader constructed of
abrasion resistant (AR) steel or cold rolled steel, such as that depicted in Figure 1.
This spreader is light weight and will break up the fines pattern and reduce peak
height for improved aeration.
2. As an alternative to Item 1., “core” bins to reduce peak height for improved
aeration by operating the unload conveyor using the center unload gate after each
days fill or after complete filling of bin, to form an inverted cone about 1/4 for daily
coring and 1/3 of the bin diameter for the final cone. Coring removes fines which
restrict airflow and reduces airflow distance from floor to grain surface for more
uniform air velocities to all parts of the bin.
The surface slope or angle of repose for clean oats ranges from 32 to 35 degrees.
Oats with foreign material, dockage and trash may have a surface angle of repose of
40 to 45 degrees. The elevator manager reported inverted cone surface slopes of 60
to 65 degrees. Because of steeper slopes and deeper cone bottoms than other grain,
smaller cones must be used for oats.
Assuming 35 degree grain surface slope with a 55 ft grain depth at sidewalls, peak
height is 35-36 ft; center grain depth is about 90 ft. To avoid short-circuiting of
airflow, the bottom of the inverted cone should not extend below the sidewall
intercept of the grain slope. If the inverted cone surface slope is 45 degrees, the
inverted cone with base diameter of 1/3 the bin diameter (35 ft.) has a ridge height of
24 ft. above the sidewall and depth of 17.5 ft. The bottom is 6.5 ft above the sidewall
intercept. This is acceptable.
When slopes of the grain peak and inverted cone surfaces are not known, use a
drawdown cone of about 25-30 ft. A 30 ft cone requires unloading 5,000 bu. from
each bin. Although coring the bin once after complete filling is beneficial, coring
daily will remove more fines. Daily coring of 3-4,000 bu (10-15 minutes of
unloading daily) is especially beneficial if the cored grain can be cleaned and cycled
back into the bin as it fills. An alternative is to transfer the grain to a bin for clean
grain.
25
Bin Roof
Structure
Spreader Support
Rod
Grain Collector
Funnel Suspended
from Conveyor
Discharge
Adjustable Height
Secondary Grain
Spreader
45 degree 8 ft. diam.
Figure 1. Gravity Grain Spreader for Large Bins
26
Problem #3 - - Fines and foreign material cause 60-65 degree grain slope on unload cone
when gravity flow stops during unloading.
Dockage and foreign material tends to sift down through the surface layer of oats as it
flows down the inverted cone during unloading. This gradually causes an increased
surface resistance to sliding friction, causing the cone surface angle of repose to increase
as the grain cone enlarges and the grain draws down.
Recommendation to help resolve problem:
1. Core bins once per day during loading to remove and clean the oats from the peak
by drawing out grain to about 1/3 of the bin diameter, or 35 ft. Assuming a grain
surface slope for oats of 35 degrees and a draw-down cone grain slope of 45 degrees,
the grain volume on a 35 ft diameter cone would be about 9,000-10,000 bu/day or 25-
30 minutes unloading.
2. If each bin receives 150,000 bu/day, and is loaded in 7 days, this would involve
unloading about 5-6% of the grain per day, but would recycle grain and capture an
estimated 30-40% of the f.m. and dockage in the entire bin, which could be
transferred and cleaned out during night, and transferred back into an empty bin,
placing cleaner grain in the last bin to be filled. This process should sharply reduce
the steep slopes of grain remaining in the bin after gravity flow stops.
Problem #4 - - Aeration fans inadequate -- cooling slow and irregular
The aeration fans on these bins were designed with either two 40-HP Chicago Blower
Corp. Model SQB or two 40-HP Rolfes C3D40 BH discharge low speed (1750 RPM)
centrifugal fans supplying air to two 750,000 bu. oat bins. Two sets of blower
specification sheets were supplied by the company, so the fan source is not certain, but
both fans have similar performance.
This was a poor aeration design and practice as grain in all four bins should be aerated
simultaneously with a minimum of 1/10th cfm/bu in all bins. Management modified the
aeration fan system by installing two of the four 40 HP fans each on Bins 51 and 52.
They installed two 50 HP on each of Bins 53 and 54. Continuous aeration of all bins is
much better, but is still underpowered with two 40-HP fans servicing Bin 51 and 52.
The two 40-HP fans will provide only about 1/17th cfm/bu when both 40-HP fans are
applied to one bin - - 21,500 cfm x 2 = 43,000 cfm/750,000 bu = 0.057 (1/17.4) cfm/bu.
The two 50 HP fans should deliver about 15% more airflow or about 50,000 cfm at about
8 inches static pressure, compared to the 40 HP fans operating at 6-7 inches static
pressure. This would provide approximately 50,000/750,000 = 0.067 (1/15
th
) cfm/bu.
The elevator manager said the current 80-HP fan system cools the grain 20
o
F in 10-18
days, or about 240-430 hours of continuous fan time. He said he would like to cool 20
o
F
in 4-5 days using two 75-HP fans delivering for a total to deliver about 75,000 cfm (0.1
cfm/bu).
27
Aeration required to provide 1/10th cfm/bu using two centrifugal fans connected in
parallel on aeration floor ducts in a 105-ft diameter bin with an average depth of 75 feet
of oats will have an estimated static pressure of 9.24 inches w.c and require 126 HP.
Without significant changes in the present aeration duct system (recommended below),
adding another 50 HP to Bins 53 and 54 for a total of 150 HP would probably not achieve
0.1 cfm/bu.
Recommendations to help resolve problems:
1. Completely change the present aeration fan transition airflow system. Substantial
static pressure is lost in the current aeration distribution design by reversing the
airflow from its natural scroll discharge profile, bending the high speed air stream
backwards to turn 90 degrees down, then another 90 degrees to enter one or the other
ducts.
The eight centrifugal fans are designed as bottom horizontal (B-H) discharge which is
good. The 40-HP fans deliver about 20-22,000 cfm through a 22 x 33 inch vertical
rectangular outlet, about 5. 0 sq. ft. of discharge area. The average discharge air
velocity is about 4,000-4,200 ft/min, but the airflow along the outside of the scroll
will be about 5,000 fpm while the air coming off next to the fan wheel will be close to
3,000 fpm.
2. Mount each fan directly in line with one of the two main ducts. Design a new
blower base mount so fan discharge slopes down at 30 degrees from horizontal,
pointed at one of the two main transition ducts. Develop a new transition duct that
makes a 30 degree turn straight into one of the main ducts.
3. Mount a third 50-HP, BH discharge centrifugal fan per bin between the two ducts
and split the airflow so that 50% of the air flows into the side of the transition from
the two current fans. Use the same 30 degree downward slope blower mount so fan
discharge ducts are parallel and airflow is combined smoothly. This will provide 130-
HP aeration per bin on Bins 51 and 52, and 150 HP on Bins 53 and 54. With the
recommended spreaders added to spread fines away from bin centers to "level the
surface", or with cleaning some grain and peak removed by developing a 30 ft dia
inverted cone during coring and improved aeration duct area, the combined
technology changes should provide aeration close to 0.1 cfm/bu, and cool grain in
about 120-150 hrs (5-7 days) in the fall.
4. Make the transition shape change from the 22 inch x 33 inch (40 HP fans) vertical
rectangular fan outlet to the shallow horizontal rectangular duct entry cross-section as
smooth as possible. Allow as much space as economically and physically practical
from fan discharge to bin duct entry to allow the air to stabilize and equalize in
velocity, minimize fan static pressure loss and result in higher airflow through the
grain.
28
Problem #5. - - Aeration floor duct system inadequate.
The ducting system in each bin consists of two 72 ft long by 4.5 ft wide perforated ducts
that parallel the unload tunnel in each bin. Each 72 ft duct supplies a parallel 42 ft long x
2.5 ft wide duct through a cross duct at center (Figure 1). This layout pattern does not
provide enough distribution duct surface area or place the air in the right location for
uniformity of airflow. The 72 ft and 42 ft ducts are too short and the 42 ft ducts are too
far from the wall.
A 16 ft perforated cross duct connects 72 ft and 42 ft ducts. Assuming the 16 ft duct
perforated width is 2.5 ft, the existing aeration duct design has a total perforated exhaust
area of 938 sq ft. To provide 0.1 cfm/bu, minimum recommended U.S. standard aeration
design for steel bins, the duct system should deliver 75,000 cfm at a recommended design
entrance velocity of 30 fpm into the grain, which would require a total perforated duct
surface area of 75,000/30 = 2,500 sq ft. Using 40 fpm design air entrance velocity, the
duct surface area is 75,000/40 = 1875 sq ft -- double the available duct area. At 50 fpm
entrance velocity, the duct area will be 1500 sq ft.
Recommendations to help resolve problem:
1. Increase length of 72 ft ducts by extending the perforated duct by 12 ft on each
end, making them 96 ft of perforated length. Increase the length of the 42 ft side
ducts by adding 15 ft of duct to each end, to make these ducts 72 ft overall length.
2. Add two new 30 ft long parallel ducts about 12-13 ft center lines from 42 ft (72 ft)
ducts to place air closer to the sidewalls, filling in a weak airflow zone in the
current design.
3. Increase the width of the secondary side ducts from 2.5 ft to 4.5 ft of perforated
width by laying/attaching corrugated perforated duct sections across the original duct
trench. This will allow air to travel another foot laterally each way under the
corrugations and into the grain.
4. Total perforated duct length would now 448 ft. Perforated duct area would be 448 ft
x 4.5 ft width = 2016 sq ft of duct surface area. This would provide an average
airflow entry velocity of 75,000/2016 = 37 ft/min. Acceptable.
5. If secondary perforated ducts remained at 2.5 ft width, the total perforated area
would be 194 x 4.5 + ( 448-194) x 2.5 = 873 + 635 = 1508 sq ft. The air velocity
entering the grain would be 75,000/1508 = 49.7 or about 50 ft/min. Although a
higher pressure drop would occur at this velocity, it would probably still work
satisfactorily, when compared to current system of 43,000/938 = 45.9 fpm on Bins
51/52, and 50,000/938 = 53.3 fpm in Bins 53/54.
6. Another recommendation is to change all perforated duct surface from the
existing corrugated duct surface with 13.5% open area to a material with about 25-
30% perforated area using 3/32 inch (0.094 inch) diameter perforations.
29
7. Cutting aeration duct planks (typically at 25-30% perforated area with 0.094 ID
perforations) from formed interlocking drying floor materials such as SUKUP or GSI
drying bin flooring is recommended. This will allow easy removal for vacuuming
fines from aeration duct trenches for improved IPM and sanitation.
Problem #6. - - Roof venting system with six 0.5 HP roof exhausters/bin inadequate.
The roof venting system is totally inadequate to keep warm moist air from
condensing on the cold under side of the steel roof where it condenses moisture on
the grain, causing high moisture zones, surface crusting, mold and heating. This
condition is very conducive to insect infestation since several secondary grain insects
are mold feeders.
Each bin has fifteen (15) roof vents, each with a cross-section area of 1.78 sq ft. This
provides a total of 26.7 sq ft. Bins 51 and 52, vent air velocity is 43,000/26.7 = 1610
ft/min, 61% higher than recommended vent velocities of 1,000 ft/min for pressure
exhaust Bins 53 and 54 roof exhaust velocity without roof exhausters is now about
50,000/26.7 = 1872 fpm, 87% higher than recommended.
Existing roof exhausters provide some additional powered venting area, which helps
reduce the exhaust velocity of the vents, but they are not performing as they should be.
Roof exhausters should be sized to exhaust all air coming through the grain plus at least
the same amount of air being pulled in through the roof vents. These should probably be
six 5 HP units, not 0.5 HP exhausters and the number of roof vents should be increased as
outlined below.
Recommendations to help resolve problem:
1. There was no data provided on the handling capacity of the six 0.5 HP exhausters per
roof but 3 HP per bin is totally ineffective. Roof exhaust fans should deliver at least
twice as much airflow as the aeration fans. At present, with two 40-HP fans
delivering about 43,000 cfm, and the recommendation to add a third 40 HP fan to
each of the two west bins, or a total of about 65,000 cfm, roof exhausters should be
installed that can deliver 130,000 cfm (Bins 51 and 52) to 150,000 cfm (Bins 53 and
54) to provide double the airflow for blending of dry ambient air with warm moist
exhaust air.
2. Since the roof exhausters should draw fresh air into the roof cavity to blend with high
humidity air exiting the grain, the vents will be handling suction or inflow of air, so
the vents should be designed with a total area that would provide about 800 ft/min, or
65,000/800 = 81 sq ft of vent space for Bins 51 and 52. At present the vent area is
26.7 sq ft. so the roof vent area should be increased by 54 sq ft for Bins 51 and 52.
Bins 53 and 54 need 75,000/800 = 93.7 sq ft. so another 67 sq ft of vent area is
needed. .
30
3. Larger vents with cross-section areas of 4 to 8 sq ft can be used to reduce the number
of vents as long as the required amount of total vent area is provided.
4. An alternative to minimize cost of roof venting would be to retain the existing roof
exhausters, but oversize the roof vent area as outlined in Item 2, operate the present
underpowered roof exhausters anytime the aeration fans run, but develop a time delay
system to continue their operation for an hour or two after the aeration fans are shut
off to remove moist air from the headspace and dry the under bin roof surfaces to
minimize dripping and condensation.
Problem #7. - - No automatic control of aeration fan system on Bins 53 and 54
Automatic aeration control is a must for large commercial storage. Busy managers
cannot begin to compete with a preset temperature sensing thermostat that is properly set
to start the large fans in sequence and control the temperature within a bracketed
temperature range, such as 60
o
F upper setpoint and 35
o
F lower set point.
The aeration controller should also be set to operate the roof exhausters to run 1-2 hours
after aeration fans stop to exhaust moist air from the bin headspace and dry the grain
surface.
Recommendations to help resolve problem:
1. Design and install a “slave” control box to operate the aeration fans and roof
exhausters on Bins 53 and 54. Connect the “slave” controls to the automatic aeration
control system that operates the aeration system on Bins 51 and 52. Roof exhausters
should be set to run 1-2 hours after aeration fans shut off to evacuate excess moisture
from bin head space.
Problem #8. - - Roof exhausters create nuisance noise problems – need to be
muffled.
Although this problem may not seem like an IPM related problem, the roof exhaust fan
system is in fact an integral part of the overall IPM through its use during aeration. The
noisy aeration roof exhaust fan on Bin 54 was high above ground level pointing
southeastward toward a residual area. An attempt had been made to redirect or turn the
sound by putting a sheet metal extension on the roof exhaust fan outlet, but this did not
appear to resolve the customer complaint.
Recommendations to help resolve problem:
1. Take sound level readings (dBA scale is closest to the sound received by human
ears) at the property boundary on line with the complainers home, and at the
complainers property boundary in line between the noisy bin roof exhauster and the
home before any further changes.
2. Invite the complainer to listen to the sound level with the fan running and have
them observe the dBA meter reading as it is being recorded on a data sheet.
31
3. Have someone turn off just the noisy bin roof exhauster and take another
“background” sound reading of all other fans operating except the noisy roof
exhauster. Have the complainer listen and observe the reduced sound level as it is
recorded on the data sheet.
4. Remove the noisy/offending roof exhaust fan and install a new roof vent in place of
the roof exhaust fan.
5. Move the roof exhauster to the north side of the bin, as directly opposite of the
home of the complainer as possible, but not pointing toward the adjacent bin roof.
If the fan exhaust is point toward Bin 53 roof, move the bin a few degrees farther
around the roof and point it toward the grain probe station to avoid bouncing sound
waves from the adjacent bin back toward the complainers home.
6. Take a new set of dBA sound level readings at property boundary and complainers
property boundaries with all fans operating. Make sure the person complaining
observes the new dBA readings with the offending noisy fan operating on the
opposite side and pointing away from the complainers location. The sound levels at
this time should be very close to the background sound reading, Step 3.
7. If the sound level is still higher than the baseline background sound reading in Step
3, add a duct from the exhaust of the noisy fan (still high in the air and bouncing
sound off of other structures) down the bin roof slope to the edge of the roof and
aim the sound diagonally toward the ground near the truck probe station.
8. The noisy roof exhaust fan noise maybe a function of roof vibration due to an
unbalanced exhaust fan rotor that is shaking the fan and increasing noise due to roof
vibration. Check all roof exhausters and aeration fan wheels and blades for mud
dobber wasp deposits that can cause an unbalance and vibration in fans at high
speed.
Problem #9 - - Temperature cable breakage and lack of center thermocouple cable.
One thermocouple (T/C) temperature cable problem observed that was causing cables to
break was that the cables had a formed loop of about 2 inches length secured by a small
saddle clamp. The cable end was frayed. These loops had twine tied to them used to
anchor the cable temporarily to a bolt anchored in the floor to hold the cables in position
until the grain was around the bottom of the cable to keep the cable hanging straight
down.
Any bulky object clamped to a temperature cable will cause a very large increase in grain
loading and tension in the cable. This is due to the diagonal shearing forces of the grain
against the clamped object as grain settles.
32
Recommendations to help resolve problem:
1. Remove all turnbuckles and straighten cable ends. Overlap the twine on the last 2
feet of the smooth end of the temperature cable. Tape the twine to the smooth end
of the cable with high quality air conditioning tape or duct tape to form a strong
connection, which will allow a few feet of grain to build up and anchor the cable.
Smooth taped ends add far less bulk to the cable than the doubled cable with
frayed end and saddle clamp. This will reduce the tension on cables by 3-4 X or
more, and should eliminate cable breakage.
2. Add a center cable to each bin, or move one of the four inner circle cables to the
center and form a triangular pattern on the existing inner cable circle.
3. If the cable system needs to be replaced due to many faulty or broken
thermocouples, consider replacing the entire thermocouple temperature
monitoring system with the OPI GIMAC temperature monitoring and fan control
system. OPI uses thermistors which are more accurate and require only a 4-wire
transfer cable system from the bins to the computer in the office. Thus, one does
not have to run hundreds of T/C wires through junction and switch boxes several
hundred feet back to the office - - only 4 wires. OPI GIMAC can also be
instrumented to sense humidity, insect movement through the USDA developed
EGPIK system, and other functions. If part of the thermocouple system is in good
condition, OPI GIMAC can adapt to current T/Cs, handling a blend of thermistors
and T/Cs.
Problem #10 - - Sweep unloader wall clearance leaves grain around wall.
The bin sweep system was a gear reducer driven unit that used a cogged wheel running in
a matching circular floor track for positive movement around the bin. Because of the bin
base ring movement between temperature extremes of summer and winter, and the
possible “ob-round” configuration of the bin, the powered bin sweep drive wheel was
spaced away from the wall. Thus, when the bin was swept, a ring of grain approximately
12 to 18 inches from the wall remained, requiring bin-entry by a work crew to move this
volume of grain to the unload conveyor slide gates along the unload tunnel.
Recommendations to help resolve problem:
1. Operate the sweep unloader with the bin empty, just after normal cleanout.
Monitor the minimum distance to the wall from the end of the loader shaft or
support wheel. Modify the sweep unloader by adding a short extension to close
the gap to within 2-3 inches of the closest point. Repeat for all four bins as this
minimum clearance distance will likely vary between bins.
2. After checking the closest distance from end of sweep unloader for each bin,
develop an attachment to mount on the end of the sweep by brackets that will
“plow” the grain over to the sweep. This blade should extend forward of the end
mounting of the sweep at a 45 to 60 degree angle to minimize loading. This
33
“grain plow” should be made of 3/16 inch or heavier steel with a floor clearance
of 1 inch. A stiff rubber belting material may be added to extend closer to
“sweep” the floor and the wall, but should have enough flexibility that it will bend
back or deform over bolt heads and other projections.
34
Elevator 3: Oats; Corn and Wheat
Two PIs traveled to this elevator and its co-located oat mill in Missouri in
February 2000. The OSU team met with the site manager of the elevator, the facility
sanitarian who was in charge of pest control, and an individual from the company’s main
office who was involved with product safety and scientific affair.
Facility Description
There was a total of 4.25 million bu. capacity at the site. The largest storage
capacity is in 4 ea 500 bu., 107 ft. diameter round bolted steel bins, two of which have
standard in-floor aeration duct designs at approximately 0.1 cfm/bu and two of which
have PM-Luft pneumatic clean-out floor and aeration systems, each with two 60HP high
pressure centrifugal fans. The remaining 2.25 million bu are in a concrete elevator with
48 ea 97 ft tall by 25 ft diam. silos at 37,000 bu each and 32 interstice bins making up
the balance. The 800,000 bu concrete storage annex is equipped with high speed push-
pull aeration at about 0.1 cfm/bu. Raw commodity for the mill is always available from
the elevator. All grain cleaning took place in the mill, not in the elevator. No spreading
or leveling equipment was used in the steel bins at the facility. This created problems
with aeration, especially cooling grain peaks that contain proportionally higher levels of
dockage and fine material than the outer portions of the grain mass.
Commodities
The objective of our visit was to study a primary oat storage facility, but other
grains were handled in this elevator in addition to oats. The sequence of grains, based on
harvest times, and amounts handled in a year are as follows: wheat (2 M bu), oats (8 M
bu) and white corn (3 M bu). So, this 4.35 million bu facility handled about 13 million
bu of grain annually for a turn-over rate of about 3:1.
All incoming grain had to have official grades provided by the shipper. Additionally, the
company performed their own grading thorough grain inspections. The company does
not accept grain shipments with live insects, though we were lead to believe they would
tolerate the presence of dead insects (i.e. those from a recent fumigation).
The minimum test weight the company accepted for oats was 38 lbs/bu, although the
FGIS standard is 32 lbs/bu. Oats in some loads were as high as 47 lbs/bu. The company
would tolerate only 2 insect damaged kernals (IDK) per 100 g or less. They reported
using X-ray analysis to determine internal infesting insect load if IDK is high. The
company was very concerned about aflatoxin contamination and subjected samples of all
incoming corn to the simple black-light test followed the wet chemistry “mini-table”
analysis for suspect samples. The company had a threshold for acceptance of 10 ppm on
aflatoxin, even though the government threshold is 20 ppm. Oats were stored up to 12
months (to accommodate year-round milling), wheat was stored for 60 days and white
corn was stored up to 6 months. A protocol was in place to perform pesticide screenings
on certain samples as part of the company quality assurance.
35
Accomplishments
The manager successfully developed an IPM program that essentially eliminated direct
residual insecticide application to bulk grain in storage. Some top dressing is still
practiced on certain type of grain at specific high risk times of the year. During the past
decade, several key improvements were put in place to enhance grain management and
elevator operation. Two of the 500,000 bu bin aeration systems were modified to include
self cleaning floors using fluidized ducts in shallow hoppers between floor ridges. Prior
to this, one man worked two weeks with the sweep unloader system to finish cleanout of
the 100,000 bu inverted cone remaining in the bin after gravity cleanout. With the
fluidized grain unloading system, two men can cleanup the residual dust in less than 1-
day. This greatly reduces risks from insect pests.
Fro at least the past eight years there were no infestations detected loads of outbound
grain. This management system provides an excellent example of how an increased
emphasis on facility sanitation, grain cleaning, monitoring and aeration can facilitate the
elimination of chemical inputs to grain. Their use of grain cleaning as a final safeguard
against insect presence in grain used in flour processing is particularly important to
recognize.
Sanitation
The company used a regular (weekly or bi-weekly) sanitation checklist, and
indicated this was a critical IPM point for them (score=10). They felt empty bin cleaning
was critical, but admitted to not doing as much as they would like to do (score=7).
Workers were sometimes sent into bins on boatswain’s chairs to sweep down or blow
down the walls of empty bins. Although considered critical, walls of empty bins were
not sprayed with residuals; only fogging (probably of pyrethroids) was done in bins
(score=7). Cleaning spilled grain was considered critical, but was not performed at the
best level in the company’s opinion (score=8). Weed control was also critical, but
performed at a minimal level (score=6). Rodent and bird control programs were
considered critical and done at high levels (scores=9 for each, birds and rodents). Sealing
of side walls and bin bases was considered a good management practice, but was
performed minimally (score=5). Sealing of fan and conveyor inlets and outlets was
considered a good management practice, but the company indicated as “Not Applicable”
for the facility. The overall sanitation score for CIPM points was 8.0.
The company sanitarian said that Indianmeal moth laid eggs behind and inside electrical
boxes. She wanted to install screens over open man-holes to exclude insects when
manholes were open during bin loading. She checks grain from silos monthly by opening
R&P slide gates to drop just enough grain on the belt to clear spouts of existing grain
before pulling samples.
Receiving and Handling Grain
When the manager started work at this facility the truck-receiving rate was 100-
150 truck per 12 hour day. After adding remote controlled hydraulic probe stations
which reduced total time to grade samples and other grain receiving improvements, the
36
receiving rate increased to 300-400 trucks per day. Unit train sizes from 27 to 54 cars
can now be loaded at the facility.
All grain was received on contract from “preferred suppliers”, except for some
amounts of locally-produced corn (CIPM=10). The company reported that sampling
incoming grain for insects and moisture, as well as the policy to reject or fumigate
infested loads, were critical points that they performed very well (CIPM=10 for each).
Maintenance of safe moisture for long-term storage was listed as a good management
practice, and the company reported good adherence (GMP=8). Moisture was probably
most important for corn, which they dried to at least 15.5% mc before storage, and
presumably would dry slightly during aeration after binning. Neither spreading,
leveling, nor coring were practiced by the company (GMP=NA). The average CIPM
score for loading and receiving was 10.0; the average GMP score was 8.0.
Two of the 500,000 bu bin aeration systems were modified to include self
cleaning floors using fluidized ducts in shallow hoppers between floor ridges to eliminate
a serious handling problem. Prior to this, one man worked two weeks with the sweep
unloader system to finish cleanout of the 100,000 bu inverted cone remaining in each
500,000 bu bin after gravity cleanout was completed.
With the fluidized grain unloading system, two men can clean up residual grain
and dust , which is only around the center unload hopper in less than 1 hour. This system
greatly reduces risks of working in a confined space while unloading oats, which have a
much higher surface angle of repose (45-60 degrees from horizontal, depending on
dockage and f.m.) in inverted cones than most other grains. High cost of the self-
cleaning aeration floors prevented installing them in the other two 500,000 bu bins.
Aeration
The four steel bins and some of the concrete structures were equipped with
aeration. The company made a point of storing all their corn in aerated silos, presumably
because of its higher purchase and storage moisture content, so it could be cooled with
some additional moisture loss during aeration for safe storage. Steel bin aeration in the
two conventional aeration systems was approximately 01. cfm/bu. The two bins with
PM-Luft Kanal System floors had two 60 HP fans with 6 manifold valves/fan for
cleanout of the bin in 12 sections of the floor. For aeration, all valves are opened for
uniform distribution of air. The aeration airflow rate for this system is about 1/7-1/8
cfm/bu.
Twenty five concrete silos have excellent aeration systems. A variety of fan HP and
arrangements are used. Five bins have a roof mounted 35 HP suction fan for upflow
suction aeration. Four silos have a 25 HP centrifugal base mounted pressure fan plus a
10 HP centrifugal roof mounted suction fan on each silo. Sixteen silos each have a 15 HP
centrifugal base mounted pressure fan plus a 10 HP centrifugal roof mounted suction fan.
So, between 25 and 35 HP per 37,000 bu silo is used to produce about 1/5-1/6 cfm/bu,
which provides excellent cooling rates.
37
While completing in the Ideal IPM Elevator Checklist and Facility Audit form, the
manager indicated it was critical to use proper aeration when available (CIPM=10), cool
below 65
o
F for storage from winter through April (CIPM=10), and check the cooling
zone with thermocouples (CIPM=10). These three aeration section factors were
reportedly done as often as possible. Roof exhausters (CIPM=8), adequate roof venting
(CIPM=10), and other means to reduce condensation during aeration were considered
critical and were rated by the company as a good score. Use of aeration controllers was
considered a critical management practice (CIPM=8), although they did not report having
them. The company reported operating fans for 4-8 hrs a night during cool weather when
aerating. Average CIPM score for aeration was 9.6; the average GMP score was 8.0
Monitoring
All concrete bins had one temperature cable each and the large steel bins each had
seven cables. Grain temperature monitoring was considered critical and was reportedly
performed at the highest level by recording thermocouple readings of all stored grain
temperatures weekly or bi-weekly (CIPM=10).
Monitoring activities for insects and structural problems were not considered
critical, but were practiced to some degree (GMP=NA). The company sanitarian reported
taking bin-bottom samples of grain from every bin between July and December and
inspecting them for insects (GMP=NA). She also reported opening the tops of all bins
and looking inside for any obvious pest problems. Multiple bottom samples were taken if
initial samples revealed insects. The company reported using pheromone-baited sticky
traps for Indianmeal moth in both the basement and tops of the concrete silos; they also
trapped for dermestid beetles (e.g. the warehouse beetle).
Traps for many other insects were used in the milling sections. The company was
familiar with grain probe traps, but did not use them (GMP=NA). Storage structures
were checked regularly for leaks (GMP=9), and walls and other water sources were
monitored for rodent activity regularly (GMP=9). The average CIPM score for
monitoring was 10.0; the average GMP score was 9.0.
Overall IPM Score CIPM=9.4, GMP=7.5
(Note: numerical scores were not recorded for the practices below.)
Pesticide Use and Practices
Although the company allowed receipt of grain with residual pesticides below tolerance
levels, they reported that they did not add any residual grain protectants directly on the
grain. Top dressing of grain bulks with materials such as Reldan
TM
, Actellic
TM
or DE
(diatomaceous earth) was practiced on occasion. Crack and crevice spray treatments
outside and near bins was performed with Tempo
TM
. Fogging with Vapona
TM
and
pyrethroids (product not specified) was performed in bin headspaces to control
Indianmeal moths. Fumigation with phosphine was performed 1-2 times a year on corn,
“sometimes” on oats and never (or rarely) on wheat. Aluminum phosphide pellets were
38
applied at the rate of one flask per interstice bin and four flasks per round concrete bin;
rates on the large steel bins were not recorded, but were expected to be between the
middle and maximum label rate for steel bins. Application methods of pellets included
probing in from the top, “coring down” the pellets while withdrawing and recycling grain
to the same bin. Pellets were applied to concrete silos by automatic pellet dispenser for
uniform distribution in the grain while turning. Dosage levels in 37,000 bu concrete silos
were 4 flasks, or 180 pellets per 1,000 bu. Their target was to maintain 200-400 ppm
during the fumigaton.
Safety and Education
The company reported having 2-3 certified fumigators on staff and reported “yes” to all
questions about safety procedures. Phosphine detection tubes were used regularly for
worker safety and to test concentrations for levels to sustain efficacy during fumigation.
Both face mask with canisters and SCBA respirators were available for worker safety
use, especially when retrieving phosphide sachets. Managers and key employees attend
at least one pesticide training workshop a year and hold regular in-house safety meetings
at monthly intervals. The company maintained their own written standard operating
procedures for using pesticides. The company had staff specifically trained in grain
grading and sampling. The company reported that some training was provided to
producers and suppliers on the subjects of stored grain management and IPM.
Grain Storage Problem in Steel Bins:
The facility storage structure was well organized and maintained. The primary problem
observed at this elevator was the long cleanout time of these huge steel bins after gravity
flow of grain stopped. Two of the four 500,000 bu, 107 ft diameter bolted steel bins were
converted from flush floor aeration with sweep unloaders to pneumatic powered self-
cleaning floors using PM-Luft Kanal System floors. These floor systems worked very
well at this plant but were too expensive to install in all four steel bins at the same time.
The manager would like to convert the other two bins, but would prefer a much less
expensive alternative, which is not available at this time.
Major Problem
The primary problem experienced by the manager at this time is the 20% of the bin
volume in the 107 ft. diameter bins that does not drain out. This requires operating the
bin sweep to make 4-5 passes around the bin, followed by two men working 2 weeks to
do the final cleanout of the large floor in each bin (no access for bobcat unloader).
The problem is exacerbated by fines, trash and dockage in center core of bin under spout
line, and additional dockage and fines in the grain that sifts down below the slope during
gravity unloading. This material causes the inverted cone grain surface to become
steeper than the peak surface of the grain (about 35 degrees) as the bin was filled.
39
Possible Partial Solution to Problem
1. Cleaning the grain before loading the two conventional aeration and sweep
cleanout bins may reduce the slope angle of the remaining grain, reducing the volume of
grain that remains in the bin after gravity cleanout through the multiple floor hoppers that
create a V shaped grain slope. Cleaning will also improve aeration and storability for
oats which is held for up to 6 months.
2. The true solution is to install pneumatic self-cleaning aeration floors in these two
bins so they perform like the two bins with the PM-Luft Kanal Systems. A plan might be
developed with PM-Luft to install one floor each year for two years, or set up a plan to
pay the cost of the floors out over multiple years.
40
Elevator 4: Corn
Two PIs visited this elevator in Illinois in March 10, 2000. The individual hosting our
visit was very familiar with commodity handling and pest management at this facility.
We also met with the company sanitarian who is in charge of the day-to-day pest control
and fumigation when needed.
Facility Description
This facility is committed entirely to corn dry milling and has approximately 1
million bushels of total storage capacity, all in 24 concrete silos that are up to 110 feet
tall; 12 of which with a capacity of 75,000 bu each and the remainder ranging from 2500
to 27,000 bu.. The silos are served by 4 interior elevator legs. Areas around the silos are
paved; all driveways are paved and is one set of railroad tracks serving the facility. This
location is one of two main processing plants for the company, the other being in a
neighboring state. The company owns 10 country elevators across two states that supply
the processing plants.
Commodities Stored
Corn is the only commodity stored. The firm takes in corn of unconfirmed varieties, but
also maintains a list of 12 (at the time of our survey) specific varieties for identity
preserved (IP) storage and use. Growers are fully educated on the IP varieties by the
company and are stewarded by the company through production to delivery. IP varieties
can be worth $0.20 to $0.25 more per bushel to producers than regular corn. Only
country elevators with more than one elevator leg will receive IP corn for the company.
The company has a strict no-GMO (genetically modified organisms) policy, thus none of
the IP varieties used were GMO. At the time of this survey the company was aware that
19% of all corn in Indiana and 43% of corn in Illinois was genetically modified for
containing the gene for the insecticidal protein of the B.t. bacterium. The company
performed immunological and genetic (PCR) testing on IP varieties taken in to confirm
they were GMO-free. The company indicated that although they historically provided
most of their products to the breakfast cereal industry, that snack and convenience food
uses were beginning to dominate the end-uses of their products.
Sanitation
The company decided that use of a sanitation checklist was their only critical IPM point,
and that other sanitation factors were considered good manufacturing practices. The
company maintained weekly use of a sanitation/housekeeping checklist, which was based
on a master sanitation schedule that was developed for them by AIB (American Institute
of Baking); they assigned a CIPM=9 on use of a checklist. They reported doing regular
empty bin cleaning prior to filling (GMP=9); cleaning spilled trash and grain from around
bins (GMP=8); controlling weeds around silos where applicable (GMP=9); repairing
water leaks and other structural defects regularly (GMP=7); and sealing fan and conveyor
outlets when not in use (GMP=7). Blow-down and sweeping (not vacuuming) of dust
41
and debris around machinery and structures was practiced regularly as part of
housekeeping. There was no use of residual insecticidal sprays or fumigant application to
empty bins before loading, but such practices were done at their country locations. A
rodent control program was operated by an outside contractor (GMP=10) and some
attention was given to bird and rodent-proofing of the facility (GMP=5). Average GMP
score for sanitation was 7.9 and the one CIPM score was 9.0.
Loading and Receiving
Receiving grain from preferred supplier was considered a key factor in controlling
product quality, and indirectly for preventing pest problems, (CIPM=10). As indicated
above, all or nearly all grain delivered was from contract growers who were delivering
specified varieties that were fully documented. All grain is sampled upon receipt for
insects, moisture and other factors (CIPM=10). The company maintained a zero
tolerance policy for any insect found in a grain sample, whether dead or alive, and reject
(rather than fumigate) any shipment found to have an insect (CIPM=10). Long-term
storage of grain at safe moisture levels was considered simply a good manufacturing
practice (GMP=9) because grain was not stored very long at this site due to the rapid
turnover with the mill. High moisture grain was always used first, and that stored longer
was usually at 13% mc. Coring and leveling of grain bins at time of filling was not
practiced by this facility, but many of the country locations reportedly do this (GMP=7).
Average scores for loading and receiving were 10.0 for CIPM points and 8.0 for GMP
points.
Aeration
Aeration is used at all the facilities; down-flow aeration is used on the concrete silos in
this location and up-flow aeration was used on steel structures in the country elevators.
The company claimed that aeration was important, but placed airflow requirements (0.1
cfm/bu) in the good management practices and gave this point GMP=7. Cooling grain to
below 40 F (rather than 65 F) was a company goal, and progress of the cooling front is
checked with thermocouples (CIPM=10 for each). Automatic aeration controllers were
not used and the company reported that they achieved the target temperature by using
fans only at night. Engineering bins for minimization of condensation was considered
and important practice (GMP=7), as was the use of adequate roof venting (GMP=9). The
average scores for aeration were CIPM=10.0 and GMP=7.6.
Monitoring
The company put a high priority on checking grain temperatures in bins on a regular
basis (CIPM=9). There was no active monitoring for insects, either through simple
observations or through trapping, in stored grain. Grain samples were taken bi-weekly in
May from every bin to check for moisture and insects (GMP=9). All storage structures
are checked regularly for leaks (GMP=7) and areas were monitored for rodent activity
(GMP=8). Indian meal moth pheromone traps are deployed in the basement and gallery
of the concrete silo system to monitor this insect in the summer time (GMP=8). Average
score for monitoring was GMP=8.6 and CIPM=9 (for temperature cables only).
42
Overall IPM Score: The average overall score given by the company for critical IPM
points (CIPM) was 9.5, though this was based on only a few points. The average self-
assessment for good management practices (GMP) was 7.9.
Pesticide Use Practices
The company had a strong policy against the use of residual pesticides on grain, and they
also rejected or refused receipt of grain that had any known chemical residue. They
claimed a GMP sore of 10 for each of these practices. The respondents gave themselves
a GMP=2 for use of DE applied as an empty bin or crack and crevice treatment. They
claimed to be very judicious in the use of fumigation in the grain, with a GMP=9 and
purportedly no more than one fumigation per year. Re-circulation or closed-loop
fumigation was not used. The company reported using fogging treatments of pyrethrins
and Gentrol (an insect growth regulator) in the basement and gallery sections of the
concrete elevator, and they gave themselves a GMP=10 for this.
Safety and Education
Safety was a very high priority for this company. They responded with a score of “10” to
all GMP points related to safety (certified applicators on staff, air samples taken before
re-entry to a fumigated area, PPE available for any worker needing it, fit-testing for
respirators done, written safety plan implemented, written emergency action plan in
place, and use of a contractor orientation program for safety education). The company
reported that key employees attended at least one grain management or IPM workshop
each year (GMP=9) an he company reported giving such workshops to suppliers
(GMP=9). Company grain graders were trained in sampling and grading (GMP=9).
Employees reportedly received monthly safety and/or pesticide handling training
(GMP=10) and the managers and supervisors were required to attend such classes for
their performance review (GMP=10). The overall score for pesticide use, safety and
education was an average GMP=9.3.
43
Elevator 5: Corn
Two PIs visited Lauhoff Grain Co. this second corn milling company in March, 2000.
Our host was the company’s director of technical services. We were joined at times by
the manager of grain storage, and by his assistant manager. Reportedly one third of the
company’s products go into breakfast cereals, one third into the brewing industry, and the
remaining third into numerous food products or specialty material uses.
Facility Description
The main elevator facility is concrete with 5 interior elevator legs serving 114 concrete
silos. The large concrete silos were 32 ft in diameter and 129 ft tall with a capacity of
48,117 bushels of corn. A unique rhombohedron flat storage with a capacity of
4,000,000 bu was on site, but reportedly was used just for beans and it was not
considered in this analysis There were several interstice bins of various dimensions.
There were two very large round steel bins on site that were used mostly for beans. Each
of these was 133 ft in diameter and 113 feet tall for a capacity of 1 million bushels. All
roads and driveways were paved, some had gravel on top and others in the truck staging
lot were oiled. The bucket elevators operated at 7500 bu/hr and all had accessible boot
clean-outs. One large drag conveyor was used for horizontal movement.
Commodities
The primary commodity of interest is white or yellow dent corn. Soybeans are also taken
and stored, but beans are strictly segregated from corn to avoid soy protein contamination
of corn products. Soy products can cause allergies in some people and also affect
oganoleptic characteristics of corn products.
Sanitation
Three practices were considered critical IPM points. They were the use of a weekly or
biweekly sanitation/housekeeping checklist (CIPM=8), attending to spilled grain and
accumulation of fines around the facility (CIPM=7), and having a rodent-control program
(CIPM=9). Self-assessments on good management practices were: empty bin clean-out
prior to filling, GMP=5; empty bin spray or fumigation prior to filling, GMP=7; weed
control, GMP=9; seal bin bases and side-walls for leaks, GMP=9; sealing aeration fans
when not in use, GMP=8; bird and rodent control practiced in facility, GMP=9. The
company reported the additional sanitation activity of using a central vacuum cleaning
system to clean the gallery floor every 2-3 days (GMP=8). Average score for critical
IPM points in sanitation was 8.0, and the average score for good management practices
was 7.7.
Loading and Receiving
This company did not use preferred or contracted suppliers. However, most suppliers
were local and known to the company. The company placed a high priority on sampling
incoming grain (CIPM=9). No incoming grain was fumigated. The company rejected
44
grain that had more than one live insect or more than two dead insects found in any
sample (CIPM=9). All grain for long-term storage was stored at 14-15% moisture
content (GMP=9). The company was attendant to formation of spout lines in bin cores
and routinely practiced coring of bins; no spreaders were used (GMP=8). The company
also reported using rare-earth magnets on incoming grain. Overall scores for receiving
were CIPM=9.0 and GMP=8.5.
Aeration
All bins reportedly had aeration fans. The large round steel bins each had a single large
at 75 hp that was connected to a sub-floor system of aeration ducts. Concrete silos were
equipped with down-flow aeration. The company scored itself as GMP=9 for adequate
aeration. The company’s objective was to cool grain to below 50 F as soon as possible
after loading (CIPM=9) and the cooling zone was always monitored with thermocouples
(CIPM=10). The two large steel bins each had 26 thermocouple cables that each had 17
sensing points. The concrete silos had one cable in the center of each that had 17
thermocouples at 7-foot spacing. The manager did not consider condensation at roof
spouts a big issue, so engineering to minimize this was not stressed (GMP=4).
Nevertheless, adequate roof venting was provided for all bins (GMP=9). Automatic fan
controllers were not used. Overall scores for aeration were CIPM=9.5 and GMP=7.3.
Monitoring
The company reported that monitoring grain temperatures, reportedly daily
(presumably with electronic data acquisition) was extremely important, and they gave
themselves a CIPM=10 for this practice. Bin cores were not checked for insects or
moisture, and grain probe traps were not used. Grain surfaces and the insides of bins
were apparently checked on some periodic basis for moisture or pest problems, but the
company assessed themselves at only GMP=6 for each of these. Inspections for rodents
were considered critical, but the company reported only a CIP=7 for this.
Pesticide Use
The company reported that fumigants were rarely used, thus no re-circulation
systems were not in place; only emergency situations would elicit the use of phosphine.
The only residual insecticide reported was the use of Actellic on the inside surface of
empty bins following a yearly cleaning of the bin tops.
Safety and Education
The company gave themselves a score of “10” for all safety practices and safety
training queried. Managers and key employees would attempt to attend at least one IPM
workshop a year; grain graders were routinely trained in sampling and grading, and the
company was religious in having monthly safety training for employees. Although no
formal training in IPM and storage methods were given to grain suppliers, the company
has regular contact with all suppliers and transfers relevant information on a regular,
though informal, basis.
45
Elevator 6: Wheat
Three PIs visited this wheat storage and milling facility in western Michigan. Much of
this flour is sold for use in breakfast cereal products. The firm consists of two major
operations, a grain receiving and storage facility and a flour mill. Our interview with the
senior vice president focused primarily on the grain receiving and storage part of the
business.
Facility Description.
Grain storage capacity currently is approximately 2.8M bushels. A concrete elevator
holds 1M bu. and the remaining 1.8 M bu is in round steel bins. The steel bins are
composed of 4 ea. 35K bu. bins (w/1 leg), 6 ea. 150K bu. bins (w/ 3 legs), and 2 ea. 500K
bu. bins (w/one leg).
Commodities Stored
All grain purchased and stored is wheat, mostly soft white and soft red. Some hard red
(e.g. from Nebraska and Kansas) and dark northern spring (or the equivalent) from
Canada is railed in on the basis of federal grades to blend in to meet buyers’ protein
specifications. All of the firm’s facilities are at this location.
Sanitation
A full-time staff person is in charge of sanitation at the facility. All bins are cleaned
before the new crop is stored at harvest time (CIPM=9). In most years, most of the bins
are empty before the next harvest. This permits cleaning the bins before harvest, and also
means that only a small amount of grain is carried over, and this small amount may be
stored up to 15 months. Each of the 250K bu bins requires 3 people about 1 week to
clean and to do normal repair/maintenance prior to storage. The company brings
scaffolding into each bin to be able to sweep down the sides. Steel bins are cleaned more
thoroughly since the sides are corrugated and bottoms are not sloped as the concrete tanks
are. The manager reported using a regular housekeeping checklist (CIPM=8). In the
early to mid-1980s the company made an explicit decision to avoid pesticides to the
extent possible, presumably even if non-pesticide practices were more expensive. Thus
spray-down of empty bins with residual insecticides was not routinely practiced, though
the manager indicated it occurs in some instances. Cleaning of spills, control of grass
and weeds, repair of bin leaks and security of fan an conveyor transitions were all
regarded as critical IPM points by the manager (CIPM=9 for each). The company uses a
contracted rodent control service for inside and outside treatment (CIPM=9), but admitted
that bird and rodent-proofing the facility was a concern, but not always achievable
(GMP=9). The company reported and additional practice of cleaning elevator boots on a
monthly schedule (CIPM=9). Average CIPM score was 8.9 and GMP was 9.0.
46
Loading and Receiving
The firm religiously samples all incoming grain for insects moisture and other factors
(CIPM=10). All incoming truck-loads are sampled with a minimum of 5 manual probe
samples. Samples are tested for dockage, moisture, insects, and other grade factors. The
company rejects any truck in which one or more insects, whether dead or alive, is found
(CIPM=10). All received grain must be a safe storage moisture levels (CIPM=10). They
reject grain that is more than 18% moisture, and pay on a 13.5% moisture basis and
charge a drying fee. Wet grain is consequently dried down to about 13.5% moisture.
This company does not have preferred suppliers because they find that most suppliers
know that the load will be rejected if it doesn’t meet standards. However, they have
identified a small number of producers/elevators who have not been reliable suppliers and
would probably not purchase grain from them. The company specifies in purchase
contracts that no residual pesticides are to be used on grain. This is checked randomly by
sending samples out to a lab. The company reportedly uses no grain spreading, leveling
or coring methods to reduce fine material in spout lines. The average CIPM score for
loading and receiving was 10.0.
Aeration
All bins but one are equipped with down-flow aeration systems; the company reported
adequate aeration on the whole facility and considered this a critical point (CIPM=10).
Aeration fans run from mid-August to mid November with a target for grain cooling of
60 F as soon as possible after storage (CIPM=10). They don’t cool much below 60 F
because colder wheat will not mill as well (tempering doesn’t work as well with grain
cooler than this). Automatic aeration controllers are not used. The fans run continuously
in the fall unless the weather becomes warm. The manager estimated 2.5 months of fan
use at 30 days/month and 24 hours/day. Thermocouples are checked regularly to
monitoring the cooling front (CIPM=10). All bin roofs have adequate venting
(CIPM=10). Average CIPM score was 10.0.
Monitoring
Grain temperatures are monitoring bi-weekly during the aeration cooling period in the
fall, and then temperatures are given spot checks after that (CIPM=9). The company
reported doing no sampling, trapping or other kinds of monitoring for insects. The
manager reported monitoring grain quality (e.g., grade factors) on a regular basis
throughout the year.
Overall IPM Score: The average score for critical IPM (CIPM) points by this company
was 9.5. Only bird and rodent-proofing was a GMP (9.0), and this was due to do a
concern, but inability, to follow through as a critical point. The company prides itself in
storing and producing high quality products, and clearly puts a lot of effort into
preventive IPM practices such as sanitation, receipt of high quality grain and attention to
rapid and effective grain cooling.
47
Pesticide Use Practices
As indicated above, the company maintains an essentially insecticide-free policy for grain
management. The do not use residual insecticide sprays except in one old bin that is not
sealed as well as it should be because of structural problems. The company reports never
using fumigants on their stored grain. Methyl bromide was used in the flour mill
approximately 3-4 times in the last 8-9 years. Prior to 1984 the company used methyl
bromide on a regular basis, as many mills do presently. At one time the facility was
certified organic, but the market was too small to be worth it, and they couldn’t guarantee
supplier practices. Nevertheless, they strive for chemical and residue-free commodity
with effective insect suppression through preventive IPM.
Safety and Education
Pesticide safety issues reported were all related to the flour mill and not the grain storage
department. Two certified fumigant applicators are on staff in the mill (GMP=10). They
report obtaining safe air samples prior to entry following a fumigation (GMP=10), and
they have all appropriate personal protection equipment; an SCBA (self-contained
breathing apparatus) is on site (GMP=10). Fit testing for respiratory equipment is
conducting annually and appropriate safety plans and emergency action plans are in
place. Managers and key employees reportedly attend two grain management or
pesticide training workshops a year, such as those offered by private educators like
Association of Operative Millers or Fumigation Services and Supply. In-house safety
meetings for employees are conducted two or more times a year. The company does not
provide any formal educational programs to its grain suppliers. Company grain graders
are professionally trained.
Observations and Additional Comments
1) Cleanliness around steel bins was good, but the manager admitted it could be
improved. Workers were cleaning out one 250K bin at the time of the interview.
Grain in this bin smelled sour, perhaps because of water leak. That part of the state
had received a lot of rain recently. Puddles were observed around base of bins, and
water was observed in below ground areas such as loading pits.
2) This year and last year vomitoxin has been a problem. This facility tests each source
of grain for vomitoxin. Testing required that a truck wait to unload for the 20-45
minutes the test takes; after a pattern of low vomitoxin levels is established by a
particular supplier the company may allow truck to unload before test is completed
until another load tests positive.
3) Aeration systems are not cleaned every year before the new harvest unless problems
are obvious, such as a buildup of grain under the floor.
48
4) Some savings in electricity would likely be possible if fan capacity was increased,
and if automatic temperature controllers were used to only run fans when outside air
is cooler than grain.
5) Electricity provider bases prices for year on peak load at any time in previous year.
To save electricity costs the facility keeps aeration fans off until harvest-time
electricity loads are over.
6) Cost data on labor, overall sanitation, and electricity were generously provided by the
manager and used in the economic analysis below.
49
Elevator 7: Wheat
Three PIs conducted this IPM assessment at two locations owned by one company
in eastern Michigan. The first location (Elevator 7) was the grain elevator and flour mill
at the company headquarters. The second location (Elevator 8, described below) was a
country elevator located just 4-5 miles north of the main office. We learned that the
company owns several mills and supplies food grade wheat flour to several breakfast
cereal and pastry manufacturers. Specific wheat components such as bran and germ are
isolated and sold to specialty markets. The mill also cleans and prepares whole wheat
(unmilled) berries to sell for breakfast cereal use, such as for flakes. We met with the
head miller and worked through the IPM checklist with him.
Facility Description
The total storage capacity was approximately 450,000 bu. All storage is in concrete silos
comprised of one large silo at 260,000 bu, 9 silos of medium size at about 15,000 bu each
and a series of eight small silos totaling 60,000 bu. All the storage serves the mill
operation and no grain stays in storage longer than one to a few months. Thus no bins at
this location were considered to be “long-term” storage. The mill was planning on not
taking in harvest wheat this year (and typically took in very little at past harvests) and
they relied on nearby elevators for obtaining wheat throughout the year. The large silo
could supply the mill operation for about one month. Most wheat received would go to
the big silo, though it seemed that some wheat with special qualities, either good (e.g.,
size or protein) or bad (presence of vomitoxin) was segregated into the complex of nine
15K bu concrete silos. Wheat from the large silo moved to a preliminary cleaning
process and then was stored in the small silos for a period of a few days before it was
further cleaned then tempered and milled.
Commodities Stored
All grain stored and milled by this company is winter wheat, with 95% being soft white
and about 5% soft red. The flour that is not sent to their major customers is packaged and
sold for pastries, cake flour, etc.
Sanitation
The manager reported that they did a weekly sanitation inspection as part of a SOP and
that the results of an inspection were recorded monthly (CIPM=7). They have a
company-wide food safety committee composed of 5 people that inspect the 5 mills in the
U.S. on a rotating schedule. He reported doing an annual clean-out of all bins (CIPM=9)
and a clean-out of the aeration systems every other year. This cleaning requires 20 man-
hours for cleaning in off-year for the big silo, but only 10 man-hours during alternate
years when they don’t pull gratings up. Residual sprays were used in empty bins prior to
loading (CIPM=9). Bin floors at 4 feet from the sides, and walls 4 feet from the floor
were treated with a residual spray of Tempo. Clean-ups are made of trash spills as they
occur (CIPM=8). Most areas around bins are paved, but grass and weed control is done
50
in all cases that apply (CIPM=10). Leaks in bins and in transitions for fans and
conveyors are repaired following regular inspection (CIPM=9 for each). An in-house
rodent control program is in place that uses approximately 100 traps and bait stations
(CIPM=9). The company attends to bird and rodent-proofing with screens, hardware
cloth and door seals (CIPM=9). The company reported cleaning elevator boots monthly
and sprays then with a mold inhibitor (CIPM=7). Dump pits are cleaned as needed and
dust control is used. The average IPM score for sanitation was 8.5.
Loading and Receiving
The company does not have a formal system of using preferred suppliers, but they plan to
start doing inspections of bigger suppliers due partly to pressure from their customers to
have preferred supplier list (GMP=5). Thus they are working toward a guaranteed
suppliers list. Incoming wheat is inspected for various factors (CIPM=9).
Approximately 5 min. is needed to take a sample and conduct the inspection. The
company is beginning a program of holding a sample for 13 months so that they can trace
any problems that show up later. They don’t tell farmers who supply them what to grow
or how to grow, but they do know which producers supply consistently high quality or
consistently low quality wheat. If 1 live or 2 dead insects are detected, the load is
rejected (CIPM=10). No fumigation is done at this mill-elevator facility, so they can not
accept any grain with insects. All grain taken for storage must be at 13.8% moisture
content or less (CIPM=10). Cleaning with a clipper device is done at load-out to the mill,
but the company did not report any special methods to avoid fines in spout-lines of
storage bins (GMP=7). The overall loading and receiving scores were CIPM=9.7 and
GMP=6.0.
Aeration
The company reported that all bins have adequate aeration and that fans are used to cool
grain appropriately (CIPM=8). At country elevator receiving sites the incoming grain
after harvest is cooled down to 65-70 degrees F initially, then fumigated, and then cool
down to 50 degrees F for longer term storage (CIPM=9). Thermocouples are checked
every two weeks to monitoring the cooling zone movement (CIPM=9). Bins are properly
engineered for avoiding condensation, but this is rarely an issue because they use down-
flow aeration (CIPM=10). Bin roofs are adequately vented (CIPM-9) and automatic
aeration controllers are in use on only some of the bins (GMP=6). Average scores for
loading a receiving were CIPM=9.7 and GMP=6.0.
Monitoring
Grain temperatures in all bins are checked every two weeks throughout the whole year
(CIPM=8). Grain samples are taken from the tops of the small bins each month to check
for insects (CIPM=7). No other grain sampling or trapping is conducted for insect
monitoring. Monitoring for rodents is done on a regular basis by inspection of traps
(CIPM=9). Bins are checked monthly for water leaks (GMP=7). Samples of grain are
pulled from each bin every quarter and sent to a lab for analysis; presumably this is for
grain quality, but specific details of analysis were not obtained. Overall scores for
monitoring were CIPM=8.0 and GMP=7.0.
51
Overall IPM Score: The overall IPM scores for this facility were CIPM=8.8 and
GMP=6.3. The company seemed very attentive to important preventive IPM measures,
but it was clear that grain was not stored here very long before milling, so pest problems
rarely had time to manifest themselves.
Pesticide Use Practices
The company reported no use of residual pesticides on grain (CIPM=10) and they would
reject loads of incoming grain with known pesticide residues (CIPM=9). Fumigation is
done primarily at country elevators, but at this mill site the small silos are fumigated once
per year simply because the grain in them is stored for a longer time than in other silos
(CIPM=10). This fumigation is done by an outside contractor who uses a closed-loop
fumigation method (CIPM=10). DE is not used in any cases, and no top-dressing of any
kind is ever applied to any grain bins (GMP=10). Rail cars of outbound product are
fumigated only if this is specified by the customer; flour cars are typically well-sealed for
this purpose. When the small bins and the mill are fumigated the entire facility is closed
for 36 hrs. Grain fumigation reportedly cost less than 2 cents/bu from an outside
contractor. Although mill IPM was not the focus of this study, the manager volunteered
that they are considering the use of fogging (aerosol treatments) and targeted use of
ECO
2
FUME (cylinder-based phosphine) as alternative to methyl bromide in the future.
The manager indicated that (in the mill) the red flour beetle was the worst insect, with
some trouble from Indian meal moth.
Safety and Education
The company reported having four certified pesticide applicators on site (GMP=10). Air
samples during fumigation are monitored with Draeger tubes (CIPM=10). An SCBA
and other required personal protective equipment are available on site (CIPM=10).
Respiratory equipment fit testing and PPE training are conducted on some regular basis
(GMP=6). Written safety and emergency action plans are in use and available (GMP=8
for each). Managers and employees attend some outside education programs for either
grain management or pesticide use, but generally cannot obtain continuing education
credits and thus must re-take their certification tests every 3 years (GMP=5). The
elevator provides some sort of educational programs to their suppliers (GMP=7) and
company grain graders receive some training throughout the year (GMP=5). Regular
safety meetings for employees are offered (GMP=7).
52
Elevator 8: Wheat
This facility is the country elevator located 5 miles north of Elevator 7 that supplies that
elevator with most of its wheat needed for milling throughout the year. Elevators 7 and 8
are owned by the same milling company and were visited by the same team of three PIs.
Facility Description
Total storage capacity is about 1 million bushels, with 250,000 bu in a concrete elevator
and the remainder in 5 steel bins at capacities of 150,000 bu each. The facility goes
through about 2.5 complete volumes of grain a year. A 15-car train loading facility is on
site.
Commodities Stored
Of the 2.5 million bushels stored, 1 million bu are corn, 850,000 bu are wheat and the
remainder are soybeans and navy beans. The facility houses a small navy bean
processing plant with a throughput of 3,500 bu/hr. All the stored wheat stays with the
company (i.e., moved to the nearby Elevator 7), while the corn and soybeans are sold
outside to an ethanol plant in Canada, a feed mill in Canada and for livestock feed in the
U.S. Processed navy beans go primarily for export to the U.K.
Sanitation
For this section and others the manager of this facility chose to evaluate all practices as
Good Management Practices and did not feel that any practice could be considered a
critical point. A monthly sanitation inspection if conducted of the facility (GMP=8). All
empty bins are cleaned out prior to loading new grain (GMP=9). Empty steel bins are
given a spray with Tempo for residual insect control, and some concrete silos are treated
(GMP=9). Spilled grain is cleaned up and grass and weeds are controlled around bins
(GMP=9 for each). Holes in bins are sealed to prevent water and insect entry (GMP=9).
A monthly rodent control program is in place that uses traps and bait stations (GMP=7),
and the facility is protected from entry by birds and rodents (GMP=8). The company also
reported that they clean the elevator boots and dump bits, and wash these out with a
Chlorox solution. Average score for sanitation was GMP=8.5.
Loading and Receiving
Most grain is received from preferred supplies (GMP=9). Wheat is received at harvest
during the first week of July and most of it is moved out by October. Al incoming grain
is sampled and evaluated for grade factors at a rate of 2 minutes pre load (GMP=10).
Any load containing one or more live insects or two or more dead insects will be rejected
or treated before storage (GMP=10). Grain is stored only at safe moisture levels
(GMP=9). Wheat is segregated by moisture and will be dried dry if it is greater than
14.2%. Supplier will be charged for shrink plus a drying charge if over a particular level
(not specified in the interview). About 10% of all loads received need some drying.
53
Testing for vomitoxin is conducted in some cases. All bins are cored as part of a standard
practice after loading to reduce the fines in the spout line (GMP=9). Average score for
loading receiving was GMP=9.5.
Aeration
All bins are aerated to cool grain using down-flow aeration (GMP=10). Grain is cooled
to temperatures between 60 and 45 F (GMP=10) and the cooling zones are checked with
thermocouples (GMP=10). Cooling cycles take approximately 120 hours using 3 HP
motors. The company reported that bins are engineered to minimize condensation
(GMP=6), roof venting is adequate (GMP=7) and the automatic aeration controllers are
used (GMP=7) to some extent. However, a separate statement was made that no aeration
controllers are available. Average score for aeration was GMP=8.3.
Monitoring
Grain temperature in all bins are checked weekly throughout the entire year (GMP=10).
The surface of grain bins are checked monthly for insects and leaks (GMP=10). No bin
cores, trap or other forms of monitoring are used for insect detection. Grain is routinely
sampled upon load-out to check quality. Average score for monitoring was GMP=8.2.
Overall IPM Score: The average IPM score for this facility was GMP=8.6. This
elevator is typical of many northern grain elevators that keep their facility clean in that
they can prevent insect problems by routine sanitation and effective cooling of grain after
storage.
Pesticide Use and Practices
No residual insecticides are ever applied to grain (GMP=10) and no grain is received with
residues (GMP=10), though the company reported that they did not test for residues.
Fumigation is not conducted on a routine basis, but any carryover wheat is fumigated by
a contractor using re-circulation when needed (GMP=10). No DE or top-dresses of any
kind are used (GMP=10. Aside from empty bin sprays with Tempo, insecticide use is
minimal to non-existent at this facility.
Safety and Education
One employee, the manager, is certified in fumigation (GMP=10). No air samples are
taken due to the virtual non-use of fumigants. The company reported that all necessary
PPE is available on site (GMP=10) and that fit-testing of respiratory equipment is done
regularly (GMP=8). Written safety and emergency action plans are in use and available
(GMP=10). The company reported that employees attend outside training programs
(GMP=5) and that company grain graders receive specialized training (GMP=10). Safety
meetings are provided for employees approximately 14-18 times a year (GMP=10). The
elevator does not provide much training to suppliers regarding grain IPM (GMP=3).
54
Costs and Benefits of IPM in Grain Elevators
Businesses that handle stored grain products have economic incentives to control
insects. Traditional control measures, such as pesticides, have been cost-effective.
However, insect adaptation and resistance have reduced effectiveness of some pesticides,
and regulatory constraints have eliminated entire classes of pesticides. Also, consumers
are increasingly sensitive to the possibility of pesticide residues in food products.
Alternative Integrated Pest Management (IPM) measures that reduce use of pesticides are
being developed, but businesses often are reluctant to invest in the facilities and training
necessary to use new technology without better information on whether the expected
payoff will cover the costs of the investment.
A key factor in the adoption of IPM or any change in management systems is the
costs and benefits associated with the change. Cost-benefit analysis refers to the formal
process of comparing the costs and benefits of a proposed change. Simply put, a cost
reduces a decision-maker’s objective and a benefit contributes to the objective. In the
case of agribusiness managers, a major objective is to maximize net income. For this
reason, most cost-benefit analyses concentrate on how a proposed management change
will impact revenues and costs. Decision makers also have other objectives, such as
minimizing risks. These objectives can also be considered within the context of cost-
benefit analysis, although they often are more difficult to quantify.
Studies on the economic evaluation of IPM strategies and practices have been
reviewed by Norton and Mullen (1994). In general, implementing stored grain IPM
programs typically involves increased costs for sanitation, monitoring and, in some cases,
facility modifications to improve sanitation and grain temperature monitoring and to
facilitate effective fumigations when needed. Benefits include: potentially lower pest
damage costs, particularly where insects have developed resistance to traditional
pesticides or where some pesticides have been eliminated by regulatory authorities;
reduced costs for grain turning and pesticides; reduced risk of pesticide residues; reduced
risk of worker injury; and reduced environmental damage. IPM systems may also open
up market opportunities and/or maintain access to existing market outlets which are
increasingly concerned about grain quality, insect presence and pesticide residues. In
addition, IPM strategies are more management intensive and require more information.
They may also require more labor for monitoring and sanitation. Also, some decision
makers may believe that use of IPM strategies may have greater risk of failing to control
insects, compared to conventional strategies such as routine fumigation.
Reduced Insect Damage and “Infested” Grain
One of the major objectives of a manger is to reduce insect damage costs and
loads rejected for infestation. Insects reduce grain value by lowering grade and triggering
discounts or rejected loads. U.S. Grade standards for wheat include the percentage of
damaged kernels that include insect damaged kernels (IDK) as well as other types of
storage and field damage. Wheat with more than 32 IDK per 100-gram sample does not
meet the standards for any of the numerical grades and is designated “U.S. Sample
55
Grade”. Sample grade wheat must be used for non-food uses at substantially lower value.
Domestic and international buyers typically include much more stringent standards for
IDK on grain contracts.
Wheat containing two or more insects injurious to stored grain per sample
receives the special designation of “infested”. In addition to examining for insects the
grain samples that are obtained for grain grading purposes, many buyers are initiating
separate samples for insects. One common practice is to “crack” the hopper slide gates of
grain carriers over top of a tarp. Many food processors reject loads if a single live insect
is detected in the grain from the hopper bottom. Terminal elevators and export elevators
are rapidly moving toward a zero tolerance. In the past, country elevators often accepted
infested grain with a market discount; often the discount was essentially a charge for
fumigating the grain. Historically, market penalties for delivering “infested” wheat to
Kansas elevators ranged from $0.00 to $0.60 per bushel (Reed et al., 1989). Anecdotal
evidence suggests that penalties may have increased in recent years.
The cost of a rejected load can be a substantial percentage (10-20%) of the value
of a lot of grain. A single insect-infested sample can cause rejection of an entire
truckload, trainload or barge of grain. If rejected, the grain must be either transported to
another market outlet with less stringent standards or to a location where it can be legally
fumigated. The economic impact depends on the relative price at other market outlets
and the transportation and fumigation costs involved. The cost of rejected loads are the
single most important pest risk factor for most elevator grain managers. A well-designed
IPM program can reduce the occurrence of rejected loads without the high cost of routine
“preventive” fumigations.
Reduced Pesticide Costs
Fumigation costs can often be reduced or, in some cases, even eliminated by
using nonchemical pest management methods. The total cost of fumigation includes the
cost of the actual fumigant, materials used to seal the bins, safety placards, air monitoring
tubes and other materials. The labor costs for sealing, applying fumigant, air monitoring,
unsealing and deplacarding are also major costs of fumigation. Overhead costs such as
the ownership costs of respiratory protection and other personal protection equipment
should also be considered as a cost of fumigation. Fumigation costs can be 8–13% of an
elevator’s total grain handling and storage income.
Other Benefits
Other benefits are more subjective and difficult to quantify for an individual
manager. Increased adoption of IPM practices likely will lead to less resistance by
insects to remaining pesticides, increased worker safety, and lower risk of insect damage
and infestation in the long run. Also, there is a lower likelihood of detectable pesticide
residues. Substantial proportions of grain exported from the U.S. contain detectable
levels of insecticides such as Malathion and Reldan (e.g. over 50-70% of wheat samples
with these, USDA AMS 1998), thus foreign buyers may pay premiums for residue-free
grain.
56
IPM Implementation Costs
Implementing stored grain IPM often requires facility modifications to improve
sanitation, grain temperature monitoring and control, and to improve the effectiveness of
fumigation. The adoption of an IPM-based management system also involves increased
costs for sanitation, labor and/or electricity to level bins after filling, labor and material
costs for more intensive insect monitoring and the energy costs of grain aeration. In most
cases elevators have adopted IPM without hiring additional personnel, but rather have
redirected existing personnel. Recurring costs that tend to decrease as the degree of IPM
adoption increases include the costs of fumigation and grain turning.
Facility Modification
In some cases, adopting IPM will require facility modification to improve
sanitation, measurement and control of grain temperature and the effectiveness of
fumigation. Modifications that enhance sanitation would include the replacement of open
belts with enclosed conveyors for dust control, addition of dust control systems for some
enclosed areas of the facility and modification of aeration floors to allow removal and
cleaning.
Modifications related to temperature control include the installation of
thermocouple and remote read-outs, installation and upgrading of aeration systems, use
of automatic aeration controllers, and when appropriate, the use of grain chillers.
Modifications to improve fumigation include bin sealing, modifications to roof vents,
aeration ducts, and grain distributors to facilitate easy sealing or removal and the
installation of re-circulation fumigation systems. The adoption of re-circulation
fumigation systems can be particularly important for concrete storage facilities.
Although they typically are fumigated using pellet dispensers while turning grain, the re-
circulation system allows the manager to separate the timing of the fumigation from the
timing of grain turning.
Economic Analysis of IPM Strategies for Insects in Stored Products
This section describes calculation of costs of alternative strategies for control of
insects in the grain storage section of food processing facilities. In particular, costs of
IPM strategies are compared with those of conventional pest control strategies, including
routine fumigation. Components of the strategies considered include sampling,
monitoring, aeration, fumigation, sanitation, and use of protectants (e.g., Malathion,
Reldan). Specific costs considered include electricity (for aeration and turning), labor
(for sampling, monitoring, fumigation, and sanitation), material costs for fumigant and/or
protectant, equipment (for sampling, fumigation monitoring, and fumigation), and
management costs.
The approach used here is a versatile one that can be adapted to a variety of firm
situations by changing model parameters. Data used are those assumed to represent
conditions applicable to a typical firm. Two implications of this are: first, since the
analysis calculates costs for firm-level practices, societal costs of pesticide residues or
societal benefits of reducing pesticide applications are not considered here, except to the
57
extent that they affect the firm. For example, costs of EPA monitoring requirements for
phosphine fumigations are included in the cost of fumigation. Or, if a regulatory agency
imposed a tax on fumigants for societal goals (reducing insect resistance, for example),
the effect on the firm would be reflected in this approach by raising the cost of the
fumigant in the calculations. Second, because benefits of reducing pesticide use vary
greatly by firms, benefit calculations are not included here. Each firm should estimate
the benefits it would receive from a particular strategy that reduces pesticide use, and
subtract the costs for that strategy calculated here to get an estimated net benefit.
A later section applies this general methodology of calculating costs to two
specific firms, using empirical data gathered from the firms themselves and considering
only strategies actually employed by the firms. These firms did not provide data on
benefits to their firms of reducing chemical use, but had made the business decision to
pursue chemical-reducing strategies.
For the general approach, the particular strategies considered are:
(1) Routine fumigation (fumigation at a fixed period of time after receipt of grain),
assuming that grain must be turned for effective fumigation
(2) Routine fumigation as in (1), but with a closed-loop system
(3) Controlled aeration of grain (aeration only when outside temperatures are cooler than
grain), plus sanitation. (assumes that # of fan hours can be reduced by half to
achieve same level of cooling – benefits of lower shrinkage than with manual
aeration are not included in calculations because it is assumed that the grain is
processed in house rather than sold)
(4) Controlled aeration, plus sanitation, plus 1 sampling in which 10 samples are drawn
from various depths of each bin in which grain is stored using a PowerVac.
(5) Strategy (4), assuming that the insect sampling indicates that ½ of the bins need to be
fumigated
(6) Routine manual aeration in evening hours plus grain protectant (Reldan, at a cost of
$0.022/bu. as per Kenkel et al.)
(7) Strategy (6), except that fan hours are reduced through temperature controllers
(controlled aeration)
(8) Controlled aeration plus sanitation, plus two insect samplings several months apart
(9) Controlled aeration plus sanitation, plus one insect sampling, assuming that insect
sampling indicates that ½ of the bins need to be fumigated (using closed-loop)
(10) Controlled aeration plus sanitation, closed-loop fumigation of all bins, plus
application of a protectant.
(11) Mechanical cleaning for better aeration and insect control (in place of protectants),
plus aeration, plus sanitation
For those strategies involving fumigation, cost of sealing bins is included in labor
costs of fumigation. The cost of empty bin treatment is very low relative to other costs
(e.g. $0.000009/bu. for Malathion and $0.000076/bu. for Reldan), so it is not included
here.
58
Cost-Benefit Analysis
Figure 1 shows the annual cost of several IPM and conventional strategies in a
storage system with total capacity of 250,000 bushels. Costs considered include
equipment, chemicals, sanitation, turning, aeration, and labor. Pest control strategies
considered are the eleven strategies listed above. The lower portion of each bar (strategy)
measures labor cost. Since a significant portion of IPM costs are related to sampling, the
sampling-based IPM strategies have the highest labor costs. However, if sampling is
done upon receipt of grain, and grain is stored for less than one year (as was the case in
all subject elevators studied) much of this cost can be avoided.
The second component is aeration costs, composed primarily of electricity costs.
Aerating upon receipt of grain is less effective than aerating after outside temperatures
drop, so electricity cost is higher for the same amount of cooling. Savings can be
achieved if aeration fans are shut off when outside temperatures are higher than the grain
temperature, and turned on only when outside temperatures are lower than grain
temperature. This can be done manually, but perhaps more economically and effectively
using temperature controllers.
The third component is turning cost, composed of electricity, labor, and shrink.
Grain is emptied from one silo and transported on a moving belt to another silo within the
facility. Fumigation can be done while turning by inserting phosphine pellets or tablets
into the moving grain flow. Turning is often done in concrete silos in order to fumigate
when closed loop fumigation is not used. Turning may also be done as part of other
management practices such as blending for particular quality characteristics, to break up
sections of “fines” or “hot spots” to prevent grain infestation or spoilage.
The fourth component is sanitation, composed primarily of labor costs. This
practice includes cleaning out empty bins, elevator legs and boots, and areas surrounding
bins.
The fifth component is cost of chemicals. For both an IPM sampling strategy in
which not all of the bins are fumigated, and a closed loop fumigation which requires less
fumigant for the same level of effectiveness, fumigant costs are lower than with routine
fumigation. Closed loop fumigation would typically require 1/3 less fumigant to achieve
the same level of effectiveness, and would not require turning of the grain. Also included
in chemical costs is the cost of protectant used. Here, Reldan is assumed to be the
protectant used, at a cost of $.022/bu.
The sixth component is equipment. It is assumed for IPM strategies that sampling
equipment is required (a Power-Vac sampler is specified here), and for fumigation
strategies that fumigation equipment is needed. For closed loop fumigation, amortized
installation costs of the closed loop system are included in this cost. For IPM strategies
that do not require additional sampling while grain is in storage, this cost could be
reduced. However, both fumigation and sampling equipment costs are included where
Power-Vac sampling has determined that fumigation is needed. Also, note that once the
choice is made to acquire fumigation or sampling equipment, this cost should not be
considered when choosing among strategies.
59
It is assumed here that all strategies considered are equally effective. However,
firm managers should recognize that some strategies may be more effective than others in
their particular situations. (Little published research is available that compares
effectiveness of IPM and chemical-based strategies under a range of environmental
conditions. Work in progress by this report’s authors together with colleagues from other
institutions is evaluating effectiveness and economic risk of these and other insect
management practices.) Also, firm managers should consider and evaluate any subjective
costs. For example, fumigation may be associated with worker safety concerns, while use
of protectants may have associated concerns about residues on food products. Other
benefits of IPM strategies not quantified here include worker health safety, improved
environmental conditions, and a decline of insect resistance due to excessive use of
fumigants.
60
Costs of Pest Management Strategies
0.0000
0.0050
0.0100
0.0150
0.0200
0.0250
0.0300
0.0350
0.0400
0.0450
0.0500
Fumigation
(with
turning)
Fumigation-
Closed
Loop
Controlled
aeration,
sanitation
Controlled
aeration,
sanitation,
1 sampling
Controlled
aeration,
sanitation,
1 sampling,
1/2 of bins
f umigated
Manual
aeration in
evening
hours,
sanitation,
protectant
Controlled
aeration,
sanitation,
protectant
Controlled
aeration,
sanitation,
closed-
loop
f umigation
twice
Controlled
aeration,
sanitation,
2
samplings
Controlled
aeration,
sanitation,
1 sampling,
1/2 of bins
f umigated
closed-
loop
Controlled
aeration,
sanitation,
closed-
loop
f umigation,
protectant
Mechanical
cleaning,
controlled
aeration,
sanitation
Strategy
C
o
s
t
(
$
/
b
u
.
)
Equipment
Chemicals
Sanitation
Turning
Aeration
Labor
61
Table 1: Costs of Pest Management Strategies Shown in Figure 1
Labor Aeration Turning Sanitation Chemicals Equipment Total
Cost
Fumigation (with turning) 0.0040 0.0000 0.0134 0.0000 0.0051 0.0040 0.0266
Fumigation- Closed Loop 0.0040 0.0001 0.0000 0.0000 0.0034 0.0073 0.0149
Controlled aeration, sanitation 0.0018 0.0048 0.0000 0.0050 0.0000 0.0000 0.0116
Controlled aeration, sanitation, 1 sampling 0.0078 0.0048 0.0000 0.0050 0.0000 0.0084 0.0260
Controlled aeration, sanitation, 1 sampling, 1/2 of bins
fumigated
0.0108 0.0048 0.0058 0.0050 0.0026 0.0124 0.0414
Manual aeration in evening hours, sanitation, protectant 0.0018 0.0059 0.0000 0.0050 0.0220 0.0000 0.0346
Controlled aeration, sanitation, protectant 0.0018 0.0048 0.0000 0.0050 0.0220 0.0000 0.0336
Controlled aeration, sanitation, closed-loop fumigation
twice
0.0096 0.0048 0.0000 0.0050 0.0069 0.0073 0.0337
Controlled aeration, sanitation, 2 samplings 0.0151 0.0048 0.0000 0.0050 0.0000 0.0084 0.0333
Controlled aeration, sanitation, 1 sampling, 1/2 of bins
fumigated closed-loop
0.0080 0.0048 0.0000 0.0050 0.0017 0.0157 0.0352
Controlled aeration, sanitation, closed-loop fumigation,
protectant
0.0058 0.0048 0.0000 0.0050 0.0254 0.0073 0.0484
Mechanical cleaning, controlled aeration, sanitation 0.0018 0.0048 0.0000 0.0050 0.0000 0.0200 0.0316
62
Fumigation (with turning) costs just over 2.5¢/bu. The biggest cost component is turning
the grain for effective dispersion of the fumigant. Although it has a higher equipment
cost, closed-loop fumigation, the second bar on the graph, avoids this cost as well as
reducing chemical cost by about 1/3. It does have higher equipment cost, though. Its
cost is about 1.4¢/bu.
The third bar is controlled aeration combined with sanitation. No chemicals are
used in this strategy. Its cost is about 1.2¢/bu. The fourth bar adds to this strategy a
sampling for insects and other quality factors after grain has been in storage for a time.
This practice is expensive because it requires specialized equipment (e.g., a PowerVac)
and requires typically two workers who take several samples at various depths in each
storage bin. The cost of the fourth strategy is 2.6¢/bu. If sampling indicates that an
economic threshold of insect infestation has occurred, other treatment practices would be
utilized. These other practices could include chemical treatments such as fumigation.
Thus, the strategy represented by the fifth bar assumes that sampling has
determined that in half of the bins sampled, there is an insect infestation that requires
fumigation. This is one of the more expensive strategies because of the cost of
equipment for both sampling and fumigation, cost of turning, and labor for all of the
practices. The cost of this strategy is 4.2¢/bu. It should be noted here that comparisons
of these strategies assume that cost of appropriate equipment is part of the consideration.
If equipment has already been purchased, however, the equipment portion of these costs
should be ignored in comparisons since no additional equipment costs would be incurred.
The sixth bar represents a strategy in which aeration fans are turned on in mid-fall
as temperatures become cool and are run most evenings. Also, sanitation is practiced and
a protectant is applied. The protectant is the biggest cost component of this strategy,
amounting to more than 60% of the nearly 3.5¢/bu. The seventh bar replaces the manual
aeration with controlled aeration, running the fans only when outside temperatures are
cooler than the grain being cooled. This practice is assumed to require only half the fan
hours by more efficiently cooling the grain, reducing the cost slightly to 3.4¢/bu.
The eighth bar represents the cost of controlled aeration, sanitation, and two
samplings for insects of grain already in storage (for example, if the grain has been in
storage for longer than expected or if environmental conditions have been favorable to
insect growth, the firm may wish to sample for insects again 2-3 months after the first
sample). Note that the cost of this strategy is slightly less than the previous one,
replacing the cost of protectant with sampling costs. Similarly, the ninth bar shows
controlled aeration, sanitation, one sampling for insects, and closed-loop fumigation for
½ of the bins. The cost of this strategy is almost the same as that of the previous three
bars.
The tenth bar represents a chemically-intensive strategy that also uses some IPM
practices. Controlled aeration and sanitation are combined with closed-loop fumigation
of all bins and a protectant applied to all grain. This is the most expensive strategy
considered here, costing 4.75¢/bu. Finally, the eleventh (right-most) bar represents a
63
strategy in which the firm mechanically cleans grain before storing it, removing fines and
most foreign material in which insects thrive in an attempt to avoid use of chemicals, and
conducts controlled aeration and sanitation practices. This strategy costs 3.2¢/bu.
Observations
It is clear that a wide range of stored product management strategies is available.
Even the large number considered here does not represent all that are available.
However, several patterns emerge. First, comparing the first bar with the second bar, it is
clear that for firms that fumigate, closed-loop fumigation is more economical than non-
closed-loop fumigation, even after accounting for installation costs. Because less
fumigant is needed (about 1/3 less), chemical costs are lower, and any environmental
effects will be reduced. The biggest cost savings with closed-loop fumigation compared
with conventional fumigation is that closed-loop fumigation does not require turning of
grain, saving energy and labor costs. Moreover, because workers do not need to be in the
facility while fumigant is applied, worker safety is greatly enhanced. Also, closed-loop
fumigation is likely more effective in controlling insects because of the sustained
concentration of gas in the facility.
Second, strategies using grain protectant (bars 6, 7, and 10) are among the more
expensive strategies, since protectant itself (assuming Reldan is used) costs about 2.2¢/bu
(Kenkel et al.). Costs of IPM strategies compare quite favorably with those of strategies
using a protectant, even in a situation where insect infestation reaches the point where
partial fumigation is needed to supplement the IPM practices. For example, the seventh
strategy – Controlled aeration, sanitation, protectant – costs about the same as the ninth
strategy – Controlled aeration, sanitation, 1 sampling, ½ of bins fumigated using closed-
loop. Using a grain protectant also has potential to leave chemical residue, though this
cost is not considered here.
Third, effective, accurate sampling is labor-intensive, making it the most costly of
IPM practices considered. However, if grain is not to be stored long and if other IPM
practices such as sanitation and aeration for cooling are followed, sampling may not be
required as part of an effective IPM strategy. If in-storage sampling is not required,
sampling equipment and labor for sampling is not required, so costs of IPM strategies are
likely to be lower than those of conventional strategies.
For many IPM strategies, however, it is important that effective monitoring be
implemented as a part of the grain management program. As noted earlier, a major cost
of managing stored grain is the potential rejection of a load because of insect infestation.
Effective monitoring can detect problems before they become severe. This monitoring
does not necessarily require the extensive sampling included in the cost calculations here.
Labor costs may range from 50% to 100% of those calculated here, and sampling
equipment cost would be much lower. Of the eight elevators evaluated from site visits,
none utilized extensive sampling of grain in bins, yet had very successful IPM programs
through rigorous prevention and sanitation practices.
64
Case Studies
This methodology is applied to two specific firms analyzed as part of this project.
These firms supply product to the cereal manufacturing industry. Rather than measuring
costs of potential strategies these firms might use, the cost of these firms’ actual
strategies was estimated using data provided by the firms. These two firms were
implementing many of the practices recommended as part of an IPM approach. The
tables below indicate the major categories of pest management costs considered: Grain
Sampling, Sanitation, Aeration, Monitoring & Management of IPM, and, when needed,
cost of fumigation.
Grain Sampling
Both firms sampled grain upon receipt and tested for quality factors as well as
insects. (Thus, in-bin grain sampling could legitimately be excluded from cost of IPM for
these elevators, but it is included here for completeness.) One of the firms rejected grain
that had one or more live or dead insect. The other rejected any load that had one live or
two or more dead insects. Since these firms typically kept very little grain in storage for
more than one year (only grain that was expected to be used in processing that year was
stored), no sampling was done after grain was in storage. Sampling costs are measured
as # of samples x time per sample x wage rate of people sampling (including benefits),
divided by total number of bushels stored.
Sanitation
Both firms had regular sanitation practices. These costs are calculated as # of
hours spent on sanitation x wage rate of people performing these duties (including
benefits), divided by total number of bushels stored.
Aeration
Both firms attempted to cool grain down to approximately 65°F as soon as outside
temperatures permitted in order to slow insect activity, using aeration fans. The
electricity usage of each fan on each bin was measured using the formula ((Volts/1,000) x
Amps)/70% efficiency, and this was multiplied by the number of fans on each bin and by
the number of hours the fans were typically operated to cool the grain (as reported by the
firm). (Alternatively, to measure electricity usage of each fan, hp/fan was divided by
0.748.) This result was multiplied by the average electricity cost per kwh. For one firm,
our team observed that the fans likely were being run at times when the outside
temperature was too high for effective cooling, requiring the fans to run too long. The
table for this firm includes a column indicating the expected cost of aeration for this firm
if it were to only run fans when the outside temperature is cooler than the grain, using
aeration temperature controllers for example.
65
Monitoring & Management
The labor hours (reported by the firms) spent monitoring and managing the grain
for insect and other pest control and cleanliness is multiplied by the wage/salary rate
(including benefits) for the persons performing these duties.
Fumigation Costs
One of the firms reported fumigating only those storage facilities that stored grain
for more than several months (a small proportion of total storage). The cost of fumigation
was reported by the firm as the cost of hiring an outside contractor who used closed-loop
fumigation.
Tables 2 and 3 summarize the costs incurred by these two firms to implement their IPM
practices. As table 2 indicates, Firm 1 reported spending a large number of man-hours on
cleaning elevator boots and trash spills, a highly-recommended IPM sanitation practice.
In addition, they conducted a weekly sanitation inspection and a bi-weekly temperature
inspection. These costs brought their annual IPM costs to $0.036 per bushel.
Fumigation, when needed, would add $0.018/bu. to their pest management costs for that
portion of the grain that required fumigation.
Table 3 indicates that Firm 2 spent less hours in cleaning, even though their total storage
capacity was much higher. And, instead of paying an hourly wage for sanitation
inspection and temperature checks, they hired a Sanitation Manager on an annual salary.
Their annual IPM implementation costs summed to $0.025/bu. This facility was
somewhat less clean than Firm 1, suggesting that the lower number of hours spent in
sanitation had some consequence. This firm had lower overall IPM costs, however,
primarily because it could spread its cost over more bushels.
In spite of its lower IPM costs, though, it is likely that this firm could reduce those
costs even further with no sacrifice in effectiveness. The engineer on this project noted
that the firm was likely running its aeration fans far more hours than needed for effective
temperature control. The firm reported that it ran its aeration fans continuously from
August through mid-November. Using temperature controllers to only run fans when
outside temperatures are colder than the grain would greatly reduce required fan hours,
which would in turn reduce aeration costs from about $0.016/bu. to $0.002/bu., an 85%
reduction. This would reduce its IPM costs by 40% to about $0.01/bu. (It is possible that
the firm overstated its use of aeration fans, by saying that they ran the fans continuously
when in fact they only ran the fans in, say, the evening hours. In that case, these potential
savings are overestimated.)
66
Table 2: Costs of IPM Practices Currently Used by Firm #1
Cost Category
Man-hours Bin Size
(bu)
Cooling
hours
#
fans
Volts/
fan
Amps/
fan
hp/
fan
Annual Cost
($/bu)
Sanitation
Cleaning Bins 20 160,000 $0.0028
Cleaning elevator boots, trash spills 160 $0.0078
Aeration
electricity 260,000 200 1 100 $0.0123
15,000 150
Grain Sampling
5 minutes per load x 2 samples per load 0.167 $0.0041
Monitoring & Management of IPM
weekly sanitation inspection 104 $0.0051
check temperature every 2 weeks 78 $0.0038
IPM Cost/bu
$0.0359
Fumigation (when needed) 0.018
Parameters
Electricity Cost ($/kwh) $0.12
Labor Cost ($/hr) $22.00
Total Capacity (bu) 450,000
truckload (bu.) 900
67
Table 3: Costs of IPM Practices Currently Used by Firm 2
Cost Category
Man-hours Bin Size
(bu)
Cooling
hours
#
fans
Volts/
fan
Amps/
fan
hp/
fan
Annual
Cost
($/bu)
Potential
Cost
($/bu)
Sanitation
Cleaning Bins 40 250,000 $0.00352
60 500,000 $0.00264
Cleaning elevator boots, trash spills 0 $0.00000
Aeration
could be
Electricity 150,000 1,800 2 460 12.8 10 $0.01615 $0.0022
500,000 1,800 4 460 21.6 20 $0.01635 $0.0027
Grain Sampling
3 minutes per load x 2 samples per load 0.1000 $0.00244
Monitoring & Management of IPM
Sanitation Manager $0.00218
($47K/yr + benefits)
IPM Cost ($/bu)
$0.02450
Parameters
Electricity Cost ($/kwh) $0.08
Labor Cost ($/hr) $22.00 (for sanitation)
Total Capacity (bu) 28,000,000
truckload (bu) 900
68
Conclusions
• All facilities studied were considered very good to excellent in current pest
management practices. Therefore, they provided excellent case studies for
general U.S. elevator adoption and use of IPM.
• Prevention–based IPM was practiced almost exclusively, with very little
monitoring for pests. However, most elevators maintained an excellent
surveillance program for insect and moisture problems, using temperature
monitoring and aeration as major IPM tools.
• Essentially all facilities rejected incoming grain that contained either live or dead
stored grain insects. Most received grain from providers of known reliable
quality, or in some cases from contracted providers.
• Very little chemical insecticide use was recorded throughout the study, typically
only as a surface treatment to empty bins. No direct admixture of grain
protectants was reported. Fumigants were used more in southern locations
(Illinois and Missouri) compared to very little fumigant use in the north
(Michigan, Minnesota and Idaho).
• Cooling grain with aeration was key to successful grain storage at all facilities,
and was easier to effectively practice at more northern locations. Effective
aeration of extremely large bins proved problematic due to inadequate grain
spreading (avoiding the “spout-line” of fines) and aeration capacity, and should be
addressed with given engineering recommendations from the case studies of two
sites.
• The cost of using IPM can be relatively low or high depending on the given
situation. For example, sanitation plus aeration was the cheapest scenario, but
this may not be effective given a poorly engineered facility in a southern location.
In the south, more attention to insect monitoring and timely fumigation followed
by controlled aeration will be needed.
• The tangible benefits of IPM are clearly the avoidance of costs that might occur
with insect infestation and the resulting loss of grain quality. Since such benefits
may be on an economic par with chemical-based pest controls, the more
intangible and perhaps greater benefits of IPM accrue from low chemical input in
some market advantage, improved consumer perception, or potential societal
benefits, which are beyond the scope if this study.
• Successful elevators that directly supply the breakfast food industry clearly are
maintaining a very high level of sanitation and pest management to deliver high
quality product and maintain market presence.
69
References
Danley, Ronda. Choosing Among Phosphine Monitoring Devices: An Economic and
Qualitative Analysis, M.S. Thesis in progress, Oklahoma State University.
Kenkel, P., J. T. Criswell, G. Cuperus, R. T. Noyes, K. Anderson, W.S> Fargo, K.
Shelton, W. P. Morrison and B. Adam. 1994. Current Managemetn Practices and
Impact on Pesticide Loss in the Hard Red Winter Wheat Post-harvest System.
Oklhoma Cooperative Extension Service Publ. E-930. Stilwlater, OK.
Krischik, V., G. Cuperus and D. Galliart. 1995. Stored Product Management.
Oklahoma Cooperative Extension Service Publ. E-912. Stillwater, OK.
Norton, G. W. and J. Mullen. 1994. Economic evaluation of integrated pest management
programs. Virginia Cooperative Extension Publication 448-120, Virginia Tech,
Blacksburg, VA.
Phillips, T. W., R. C. Berberet and G. W. Cuperus. 2000. Post-Harvest Integrated Pest
Management. pp. 2690-2701 In: Francis, F. J., ed. “Encyclopedia of Food
Science and Technology, 2
nd
Edition.” John Wiley and Sons, Inc. New York
Rulon, Rodney A., Dirk E. Maier, and Mike D. Boehlje. “A post-harvest economic
model to evaluate grain chilling as an IPM technology.” Journal of Stored
Product Research 35(1999):369-83.
Rulon, Rodney Alexander. In-Bin Conditioning and Pest Management of Popcorn Using
Chilled Aeration, M.S.Thesis, Purdue University, May 1996.
USDA Agricultural Marketing Service. 1998. Pesticide Data Program, Annual
Summary Calendar Year 1997.
70
Appendices
Appendix A. Following is the “Ideal IPM Elevator Checklist and Facility Audit” form
that was used as the primary data gathering vehicle at all study elevators. Additional
information was gathered through personal interviews that initially centered around the
checklist
71
IPM Checklist and Facility Audit
Instructions:
For each management area decide whether it is a Critical IPM Point or a Good
Management Practice. Critical IPM Points are the key aspects of your stored grain
system. Most facilities will have 3-5 Critical IPM points per management category. Good
Management Practices are the areas which may be important but are not the cornerstone of
successful grain management in your storage environment.
For each practice rate your elevator on a scale of 1 to 10 (with 1 being poor and 10 being
ideal) in the appropriate column. If the practice or management area does not apply to your
situation, leave it blank.
When you are finished, average your scores for each column. You may also want to
calculate your average score for each sub-category (Sanitation, Loading, Aeration,
Monitoring, Pesticide Use, and Education).
Date:
Location
Storage Volume
Steel
Concrete
Flat
Practice
Score 1 to 10 (10=ideal)
Critical
IPM Point
Good
Management
Practice
Sanitation
Weekly/Biweekly Sanitation/housekeeping checklist
Complete bin/silo clean out prior to filing (at least annually)
Control residual insect populations in empty bins prior to
filling (spray down or fumigate)
Keep trash/spilled grain and fines accumulation cleaned
around bins/dumps/drives--overall facility clean
Control grass/weeds around bins/silos
Base and sidewall openings sealed for water leaks
Aeration fans sealed when not in use
Rodent control program in place
Facility bird and rodent proofed to eliminate grain
contamination
72
Other (specify)
Average Score for Sanitation
Receiving
Receive from a preferred supplier
Sample incoming grain for insect, moisture and other factors
Policy to Reject or Fumigate Infested Grain
All grain for long-term storage is at safe moisture levels.
Fines in spout lines eliminated through Acoring@, leveling or
use of grain spreader.
Other (specify):
Average Score for Receiving
Aeration
Bins have aeration with adequate airflow (at least .1 cfm/bu
for steel bins. .05 cfm/bu for concrete)
Grain cooled to below 65
o
F within 120 days
Cooling zone movement checked with thermocouples
Bins engineered to minimize condensation (spouts temporarily
sealed or gravity flap valves installed, or roof exhausters)
Adequate roof venting (1.5 sq. Ft./fan HP installed)
Automatic controllers installed and used
Other (specify):
Average Score for Aeration
Monitoring
Grain temperature checked every week until cooled, (bi-
weekly thereafter)
Grain surface in bins sampled for insects every 2-4 weeks
73
Bin cores checked monthly for insects and moisture (deep cup
probes, sampling moving grain etc.)
Insect probe traps in surface grain monitored weekly
Bin checked monthly for leaks, condensation, etc.
Walls and sources of water monitored for rodent sign monthly
Other (specify):
Average Score for Monitoring
OVERALL AVERAGE SCORE FOR IPM
Pesticide Use
No residual pesticides applied to grain
Fumigation based on insect action thresholds (not calender
based)
Grain quality maintained with no more than one
fumigation/year
Recirculation fumigation used to achieve maximum control
with minimum dosage
Other (specify):
Average Score for Pesticide Use
Safety
At least two fumigant applicators trained and certified
Safe air samples obtained prior to de-placarding and
bin/facility entry
Appropriate personal respiratory protection
available/maintained
Annual fit-testing and training for respiratory protection
Written safety plan in use (hot work, lock-out, tag-out, bin
entry etc.)
Written emergency action program in place
74
Other (specify):
Average Score for Safety
Education
Managers and key employees attend two grain management,
fumigation or IPM workshops per year
Grain graders trained in sampling and grading
Elevator provides IPM/Stored grain training to
producers/suppliers
Monthly safety training of employees
Other (specify):
Average Score for Education
75
Appendix B. The following survey instrument was used infrequently for information
gathering at study elevators. It is included here to indicate the breadth if information that
can be collected about an elevator facility that is relevant to IPM.
IPM CHARACTERIZATION SURVEY
FOR GRAIN ELEVATORS
by
Ronald T. Noyes, Ext. Agricultural Engineer
Philip A. Kenkel, Extension Economist
Tom Phillips, Stored Grain Research Entomologist
Oklahoma State University
Integrated pest management (IPM) is a sustainable approach to pest control that
integrates biological, cultural, physical and chemical control into systems which minimize
economic, environmental, and social risks. While elevator practices may vary by
geographic location, certain facility and equipment components are generally common to
most country and terminal grain elevators. Goals of an IPM program typically include
reducing pesticide input, reducing insect pest numbers and maintaining high grain quality.
The purpose of this checklist is to provide a standardized method of documenting
the facilities, equipment and practices that are in place or in use at an elevator at a specific
time. This listing will allow this elevator to be compared with other elevators based on use
and location for comparison of capacities, functions and management practices. An
elevator's characterization can be useful as a tool when evaluating the IPM practices and
IPM qualifications of an elevator.
The following survey lists major functions of a grain elevator. Some sections, such
as grain drying, aeration systems or grain cleaning, may not be applicable to all elevators.
Other sections, like storage structures, conveying equipment, sanitation/housekeeping
should be applicable to all elevators that are interested in using IPM.
While all elevator functions and practices are not "IPM" activities, their use may
affect or support IPM. Since the overall goal of this program is to evaluate costs vs
benefits of IPM, any key elevator function that has a major cost/benefit impact will be
reviewed and listed. Since the purpose of this sheet involves appraising a food grain
elevator for use in IPM evaluation, significant portions of this checklist and outline were
adapted from Appraising an Existing Elevator, Jan/Feb 1998 Grain Journal.
MAJOR PHYSICAL ACTIVITIES/DIVISIONS OF GRAIN ELEVATORS
Physical IPM functions of grain elevators that will be reviewed in the Elevator IPM
Characterization Survey form are:
Overall Facility
Transportation
Conveying/Blending
Cleaning/Aspiration
76
Drying/Moisture Control
Storage Systems
Temperature Control/Management
Insect Control/Management
Fumigation Systems
Sanitation/Housekeeping
IPM Record Keeping
ELEVATOR IPM CHARACTERIZATION SURVEY
Name of elevator or mill _________________________________ Date
________
Location of facility _____________________________________________________
Evaluators ____________________________________________________________
OVERALL FACILITY
The primary activity of this elevator facility is (what the elevator does):________________
Main elevator facility headhouse concrete or steel? _________________________________
_____ No. of interior elevator legs and pits? _____ No. of exterior elevator legs and pits?
Drives paved _____ or gravel _____ ? Weeds/grass mowed _____ ft from bins, silos, flats?
Area around bins, silos, flats paved or graveled ______ ft for insect habitat barrier.
Trash or moldy grain laying around the facility? ________
Fumigation supplies maintained stored in facility under lock/key_______________________
Fumigation equipment well maintained and serviceable?_____________________________
Written Sanitation/Housekeeping Plan posted for employee use?_________________
Grain sample power probe system?________________________________________
TRANSPORTATION
Rail System No. of tracks ________
Tracks paved so spilt grain can be easily cleaned up? ________________________
Loadout sidings clean and no weeds or trash? _____________________________
Dump pits clean? _____
Pit conveyors clean? ____
General track, loading and pit areas clean ?_______
Trash and spilled grain cleaned up?
____________________________________
Road/Driveway System
Roads/Drives Paved ______ Gravel ________ Dusty _____ Oiled
_________
Dump pits clean? _____
Pit conveyors clean? ____
General truck loading and pit areas clean ? _____________________
77
Surrounding area, grass and weeds mowed or graveled? ________________
Trash and spilled grain cleaned up? ____________________________________
CONVEYING
Bucket elevators -- No. of Legs _______
Leg #1 Ht.____ ft., ____ bu/hr, ____ HP;
Leg #2 Ht. ____ ft., _____ bu/hr, ___ HP;
Leg #3 Ht.____ ft., _____ bu/hr;
Leg #4 Ht. ___ ft., _____bu/hr , ____ HP;
Leg boot cleanouts accessible ________________________________________
Boots cleaned between different grains __________________________________
Conveyors -- No. U-Troughs ________; No. Augers ______; No. Drags _______
Do conveyors clean out? _______ Can conveyors be cleaned? ___________
CLEANING
No. Grain cleaners _______;
Type/brand of cleaners _________________________________________________
Are cleaners cleaned out between grains? ________________________________
DUST ASPIRATION SYSTEMS (DAS)
No. of Dust Aspiration systems ___; DAS#1 ___ HP ; DAS#2 ___ HP; DAS#3 __
HP
How often are DAS cleaned? _________________________________________
Drying/Moisture Control
No. Grain Dryers ______; make/model/type of grain dryers ___________________
_______________________________________________________________;
Dryer #1 ____ HP ;Dryer #2 ____ HP ; Dryer #3 ____ HP ;
_____________________________________________
Are dryers/conveyors cleaned out between drying operations? ________________
No. wet holding tanks (WHT) feeding dryers? _____________________
WHT cleaned between grains? _____________________
Is grain dried below 13% MC before storing? ____; If NO, what MC? _____
STORAGE SYSTEMS
Round Storage
No. round units -- Steel ___________________ Concrete __________________
Diameter _______________________________________________
Sidewall height_______________________________________________
Overall height _______________________________________________
Bushel volume_______________________________________________
Type bottom _______________________________________________
Year built _______________________________________________
78
Aeration systems _______________________________________________
Thermocouples _______________________________________________
Clean? _______________________________________________
Other description ___________________________________________________
STEEL TANKS:
Exterior: Down spouts sealable during fumigation? __________ Eaves sealed? ______;
Roof fans vibrate? _____ Roof leaks? ______
Base/sidewall junction caulked/sealed with flexible, UV resistant material? _____________
Aeration fans, blowers, transition ducts sealed except during use? ___________________
Base doors, sample points, bolt openings sealed to exclude moisture and insects? ________
Conveyors clean? ____________ Conveyor exteriors sealed to exclude insects? _______
Recirculation or closed loop fumigation (CLF) system installed/used? ____ Blower; ___HP?
Interior: Moldy grain evidence of base moisture leaks? __________________________
Galvanizing corroded on interior walls? _____
Holes visible through roof panels during daylight? ______
Down spout condensation from aeration? ________
Grain "cored" to lower peak/level surface? _____
Aeration ducts cleaned yearly? _____
Interior vertical wall stiffeners cleaned during or after bin unloading? _________________
Grain dust cleaned out of bin roof corrugations at fill cap, openings foam sealed? ________
CONCRETE SILOS AND TANKS:
Exterior: Cracks in sidewalls? ________
Down spouts sealable during fumigation? ____
Aeration ? __________ What HP? _______ Airflow rate? _________
Upflow or down flow aeration? _________________________
Aeration fans, blowers, transition ducts sealed base manhole doors, sealed to exclude
moisture and insects except during use? ____
Aeration fans on roof (upflow system)? ______
Recirculation or closed loop fumigation (CLF) system installed/used? ____; Blower ___HP?
Discharge spout outlets cleaned out each time after silo unloaded? __________________
FLAT STORAGE:
Size: Length _____ ft; width _____ft; sidewall height _____ ft., Peak height _____ ft.
Fill: Leg/down spout ____; U-trough ___ or drag ___ conveyor in peak @ ____ ft.;
Unload: Tunnel belt ___ ft. ; In-floor u-trough ___ ft.; front loader ___; Other _________
79
Aeration fans: ___ No. of ____ HP ___ axial; ___ centrifugal blowers @ _____ ft centers
Aeration ducts: ____ No. ducts ___ in-floor; ____ on-floor; ___ round; ____ half
round.
Duct pattern ___________________________________________________________
Head space ventilation fans/louvered vents in gables? _____ Fan size ___ x ___ inches; Fan
_____ HP ; Louver size ___ x ___ inches;
TEMPERATURE CONTROL/MANAGEMENT
Grain Temperature Management
Grain storage thermocouple system in place,? _____ ; maintained/used?
__________
Type of thermocouple system? ____ plugin/readout; _____ computerized to
office?
Temperatures read ___ weekly; ___ bi-weekly; ___ monthly; ____________
other.
Target grain temperatures: steel tanks ____
o
F; concrete silos ____
o
F; flats
____
o
F;
Other critical temperature points monitored?
_____________________________
Aeration Systems
No. fans on steel tanks ______ ; HP/fan ______; Total fan HP _____
No. roof vents on steel tanks ___ ; Size/vent ______; Total vent area _____
sq ft
No. fans on concrete silos ______ ; HP/fan ______; Total fan HP _____
No. roof vents on concrete silos ___ ; Size/vent ______; Total vent area
_____ sq ft
No. fans on flat storage ______ ; HP/fan ______; Total fan HP _____
No. roof vents on flat storage ___ ; Size/vent ______; Total vent area _____
sq ft
Aeration duct plan, steel tanks (Lgth/ area)
_______________________________
Aeration duct plan, concrete silos (Lgth/ area)
_____________________________
Aeration duct plan, flat storage (Lgth/ area)
______________________________
Aeration controller type/model?
80
_______________________________________
HOUSEKEEPING/SANITATION
Written housekeeping plan posted ________
Shop vacs used in open drives and well ventilated floors? ______________________
Adequate housekeeping tools? _____
IPM RECORD KEEPING
IPM Files/Record System in Place covering:
Insect monitoring program ______________________________________________
Fumigation program ___________________________________________________
Aeration operation details ______________________________________________
Grain temperature management __________________________________________
Residual pesticide use, where/when/what/amounts ____________________________
Oil dust control ______________________________________________________
Aspiration dust control _________________________________________________
Electrical utilities -- cost/benefit of IPM management changes
____________________
Other ______________________________________________________________
81
Appendix C. Protocol for estimating and assigning costs to various practices
The cost analysis is based on a framework provided by Rulon’s study on pest
management in popcorn (Rulon; Rulon et al.). A spreadsheet is used to calculate the
costs of managing stored grain for alternative insect control strategies. The spreadsheet is
divided into six worksheets. In the first worksheet, the user specifies information about
the facility. Worksheets two through five calculate insect sampling costs, aeration costs,
fumigation costs and turning costs. The sixth worksheet computes the annual operating
cost of each scenario in dollars per bushel. The first column of each worksheet contains
field names, the second column contains the numbers and costs associated with the field
names, and the third column contains an explanation of the number entered or the
formula used.
The base model computes costs for an elevator with 10 concrete silos, each with a
capacity of 26,000 bushels of grain. Each silo currently contains 25,000 bushels, totaling
250,000 bushels. The base model assumes a wheat price of $3.75/bu.
Costs are calculated on a per-bushel basis. Specific costs considered are
electricity, labor, fumigant and other insecticides, and capital costs for equipment.
Electricity costs are calculated as cooling hours per fan x number of fans used x
(horsepower per fan / efficiency of the fans) x electricity cost in $/kwh, all divided by the
number of bushels cooled.
Labor costs per task are calculated as hourly labor cost (including employee
wages, taxes and benefits paid by employer) x employee hours per task. For the base
case, a labor cost of $16/hr. (including benefits) was assumed for full- time employees
with minimal management responsibilities.
Fumigant costs are calculated as cost per tablet (pellet) x number of tablets
(pellets) used. There are 500 tablets (1,660 pellets) per flask, and 14 flasks per case (21
flasks of pellets per case), for a total of 7,000 tablets (34,860 pellets) per case. The base
price is $300 per case of tablets or pellets, or $0.043 per tablet ($0.0086 per pellet). A
minimum dosage consistent with the label would be 40 tablets (200 pellets) per 1,000
bushels of grain; a more reasonable dosage of 120 tablets (600 pellets) per 1,000 bushels
for typical bulk storage facilities, also consistent with the label, is used here. However, if
closed loop fumigation is used, the base dosage is set at 80 tablets (400 pellets) per 1000
bushels.
Capital costs for equipment are calculated by dividing the total investment cost by
a present value interest factor, PVIFA
1
, to amortize the equipment cost over its useful
1
The Present Value Interest Factor, or PVIFA, for an annuity of n years at i
percent interest, and is calculated as:
82
life, assumed to be 10 years. In addition, an annual insurance cost of 15% of the initial
equipment cost, and an annual maintenance cost of 10% of the initial equipment costs are
assumed.
Cost of fumigation monitoring devices are included in equipment costs for all
strategies using fumigation. The highest-ranking instrument (based on costs as well as
other considerations) from Danley’s study is assumed to be used here. This particular
device is an electronic monitor, and requires at least annual recalibration. That cost is
also included. Labor costs for fumigation monitoring are considered separately.
Calculation Details
In the first worksheet (Facility Description), initial equipment costs are entered,
along with their expected life, maintenance, insurance, and salvage values. The
equipment used includes the PowerVac, a machine used to sample stored grain for
insects; fumigation equipment, which includes safety and application devices; and the
closed loop fumigation equipment, if applicable, in the elevator bin. As noted above, a
fumigation monitoring device is included in equipment costs. All equipment is assumed
to have a life of 10 years with a salvage value of zero.
This sheet also contains the fan horsepower for the fans used during aeration; the
centrifugal fan horsepower for facilities with closed loop systems; the fan efficiency,
which is assumed to be 80 percent; electricity costs expressed in dollars per kilowatt
hours; and hourly labor costs. The fumigant type and costs are specified in this
worksheet. The fumigant cost is calculated by using an if-statement in the cell containing
the formula for the calculation of the final cost of fumigant. Grain protectant costs can
also be entered, if the facility uses it.
The second worksheet (Insect Sampling) contains the number of samples typically
required to effectively monitor the insects in stored product; labor hours, which are the
amount of time required to go to a bin, probe for the required samples, sieve the grain,
remove the insects and count and identify the insects; the time it takes to set up and take
down the vacuum probe and inclined sieves; and the number of people it takes to do the
job. The equipment setup step is done only once for each elevator. Our base model
assumes 3 samplers taking 10 insect samples, using 0.08 labor hours each, and a total of 3
hours in setting up the sampling equipment. Insect sampling labor charges and sampling
equipment costs are expressed in dollars per bushel, and calculated as
( ) ( )
ored bushels st
r cost ourly labo samplers*h * setup time mples hours*# sa abor sampling l
r Charges pling Labo Insect Sam
#
+
=
i
n
i
PVIFA
(
(
¸
(
¸
|
.
|
\
|
?
?
=
1
1
1
83
and,
( ) ( )
ored bushels st
cost/year insurance r e cost/yea maintenanc
PVIFA
t WERVAC cos initial PO
osts quipment C Sampling E
|
|
.
|
\
|
+ + |
.
|
\
|
=
The third worksheet (Aeration and Conditioning) contains data on moisture
samples, the number of samples typically required during the summer storage season to
effectively monitor the condition of the stored product; sampling labor hours (the amount
of time it takes to go to a bin, probe for the required samples, test moisture and record
results) and conditioning labor hours (the amount of time spent during the summer
storage season to monitor moisture sampling results, ambient conditions and supervise
operation of aeration fans); the number of samplers; and the fan hours, which are the
number of hours a fan runs on a bin during the summer storage season for conditioning,
dependent on temperature and moisture. The base model uses 40 fan hours at 0.3 cfm,
which is the optimal amount of time needed for medium aeration for a grain depth of
50ft. during the fall storage season (Stored Product Management, table 6, pg.78). The
base model uses 10 moisture samples taken by 2 workers using 0.1 hours of sampling
labor and 0.75 hours of conditioning labor. These samples are not needed if insect
sampling is conducted as part of the strategy.
The worksheet contains a shrink factor, which is the amount of shrink observed
during the summer storage season in a bin under aeration and conditioning, and it is used
in the calculation of a shrink loss charge. The shrink loss charge is the shrink factor x the
grain price.
Calculations for sampling labor, conditioning labor and electricity charges follow.
These costs are calculated as:
( )
ed units stor
ers ost*#sampl ly labor c hours*hour bor ampling la samples*s
e abor Charg Sampling L Moisture
#
=
( )
s stored total unit
ost*#bins ly labor c hours*hour ng labor conditioni
harge ng Labor C Conditioni
=
( )
ed units stor
in $/kwh ty cost *electrici n of the fa efficiency per fan horsepower per fan* urs cooling ho
ost Electric c
) / (
=
(Alternatively, the term horsepower per fan / efficiency of the fan can be replaced with
the term ((Volts/1000) x Amps) /efficiency.)
The fourth worksheet (Fumigation) allows the user to specify whether or not the
elevator has a closed loop system in its bins. A binary variable is used to choose between
closed loop fumigation (1), and a conventional type of fumigation (0). The number of
fumigations is also included. Another binary variable is used to indicate whether or not a
bin will be fumigated just prior to unloading to prevent insects from entering the
processing facility: 0=No, 1=Yes. The proportion of the bins to be fumigated is entered
well, recognizing that sampling may indicate that only some bins are at risk of damaging
84
infestation. This is important because IPM strategies use fumigation only when sampling
indicates it is needed.
The fumigant cost is recalled from the facility sheet for calculation purposes. The
base model uses 3 employees per crew, each requiring an hour of training. The number
of training hours represents the hours required per employee on a fumigation crew per
year for certification, continuing education, and safety training. Two crew hours per
fumigation are required to seal bin, administer fumigant, check concentrations, and aerate
the bin. A liability insurance cost expressed in dollars per bushel is included in this
worksheet, which is associated with fumigation and includes worker and environmental
safety. The base model uses a liability insurance cost of $0.0001/bu.
The amount of blower hours to distribute fumigant gas evenly throughout the bin
can be specified in this worksheet if the facility uses closed loop systems. For this case,
48 blower hours are considered. This number is used in the calculation of the closed loop
system blower charge, expressed in dollars per bushel. The formula is as follows:
ed units stor
ions of fumigat ty cost*# *electrici efficiency blower HP rs* blower hou ) / (
charge blower . L . C =
An if–statement is used in the cell containing the formula to let the program know
whether to calculate the blower charge: if there is a closed loop system in the facility, the
program calculates the charge using the formula above. Otherwise, the program enters a
zero in the cell.
If a chemical grain protectant is used, its cost calculated in dollars per bushel is
included in the cost of chemicals. The worksheet specifies Actellic for corn and allows
selection of either Malathion or Reldan for wheat. The cost for Malathion is $0.002/bu.
and for Reldan/Actellic is $0.022/bu. (Kenkel et al.).
Calculations for fumigation labor, fumigation training, fumigant charges, and
fumigation equipment follow. Costs for closed loop facilities are also included. All costs
are expressed in dollars per bushel. The cost formulas are:
ored bushels st
s cost*# bin rly labor n crew*hou fumigatio loyees per ation* emp per fumig crew hours
ge labor char Fumigation =
stored bushels
cost urly labor mployee*ho training/e
charge training fumigation =
( ) ( )
ored bushels st
cost/year insurance r e cost/yea maintenanc
PVIFA
st uipment co initial eq
Costs Equipment Fumigation
|
|
.
|
\
|
+ + |
.
|
\
|
=
( ) ( )
ored bushels st
cost/year insurance r e cost/yea maintenanc
PVIFA
st uipment co initial eq
Costs Equipment p Closed Loo
|
|
.
|
\
|
+ + |
.
|
\
|
=
85
The fifth worksheet (Turning) allows the manager to specify if the grain is turned
while fumigating or not. A binary variable depicts the decision, using 1 and 0
respectively. The base model uses 3 hours of labor for turning the grain, and is calculated
as
ored bushels st
gations # of fumi abor cost* * hourly l bor hours turning la
bor Charge Turning La =
The base model assumes electric costs for turning the grain are $0.004/bu.(Stored Product
Management, table 2, p. 154). There is also a shrink factor of 0.003 is associated to
turning the grain. The shrink cost is
rice r* grain p rink facto turning sh rink cost turning sh = .
The final sheet calculates the annual per-bushel cost for each strategy considered.
For example,
k loss ning shrin charge+tur
tricity rning elec e+grain tu abor charg +turning l
arge tectant ch +grain pro insurance +liability
nt on equipme f fumigati st erating co +annual op
harge fumigant c
harge+ training c + ge labor char t equipment urning) (w/grain t migation Routine Fu
o
cos + =
e tant charg ain protec surance+gr ability in systems+li
on p fumigati closed loo of ing cost ual operat charge+ann +fumigant
harge L blower c g charge+C ge+trainin labor char t equipment on p Fumigati Closed Loo
cos + =
cos
ipment mpling equ cost of sa
erating annual op r charge pling labo insect sam
ss charge shrink lo ty charge electrici
harge ng labor c conditioni
e abor charg sampling l t equipment sampling ear) ling per y gy (1 samp IPM Strate
+
+ + +
+ + =
86
Appendix D.
Costs and Evaluation of Fumigation Monitoring Equipment
abstracted from Ronda Danley’s MS thesis
Summary
Aluminum/magnesium phosphide is an important tool in keeping commodity
grain free of insects. This fumigant is important to many Oklahoma grain elevators.
However, there is a lack of knowledge about whether or not their facilities are gas-tight.
The only way to know for sure if a facility is gas-tight is by monitoring areas around the
facility while it is under fumigation. This is accomplished by a phosphine gas monitoring
device. These devices are expensive and require training so it is important for each
facility to pick a device that is optimal for them. A way to determine which is optimal is
to list all costs and benefits of each device that they are considering. This study lists the
costs and benefits for five phosphine gas monitoring devices. A Multiple Criteria
Decision Model is then used to evaluate each of the costs and benefits (both quantitative
and subjective) in order of importance.
For example, one weighting scheme used was to weight the costs at 80% (35%
initial equipment cost, 25% additional equipment cost, and 10% recalibration costs) and
the subjective attributes at 20% (5% for user-friendliness, 5% for convenience, 5% for
ruggedness, and 5% for worker safety). Assuming a labor cost of $8/hr. and a fumigation
length of 24 days, the results showed that the devices ranked 1) Draeger Pac III; 2)
Lumidor MicroMax; 3) ATI PortaSensII; 4) Draeger MiniWarn; 5) MSA Tube. This
scenario shows that the tube-type devices, represented by the MSA Tube, ranked below
the electronic-type devices when costs are weighted more heavily than benefits.
When costs are instead weighted at 35% (20% for initial equipment costs, 5% for
additional equipment costs, 5% for recalibration costs, and 5% for labor costs) and the
subjective attributes are weighted at 65% (50% for worker safety, 5% for ruggedness, 5%
for convenience, and 5% for user-friendliness), the results change somewhat. Valuing
worker safety at the higher level leads to a ranking of: 1) Draeger Pac III; 2) Lumidor
MicroMax; 3) MSA Tube; 4) ATI PortaSensII; 5) Draeger MiniWarn. The tube-type
device ranks near the middle of the group when worker safety and other benefits are
weighted more heavily than costs.
87
Appendix E.
Guidance for Preparation of a Fumigation Management Plan
The following are the required parts in creating a Fumigation Management Plan
Purpose
A Checklist Guide
Preliminary Planning and Preparation
Personnel
Monitoring
Sealing Procedures
Application Procedures and Fumigation Period
Post-Application Operations
FUMIGATION MANAGEMENT PLAN
The certified applicator is responsible for working with the owners and/or responsible
employees of the site to be fumigated to develop a Fumigation Management Plan (FMP).
The FMP is intended to ensure a safety and effective fumigation. The FMP must address
characterization of the site, and include appropriate monitoring and notification
requirements, consistent with, but not limited to, the following:
1. Inspect the site to determine its suitability for fumigation.
2. When sealing is required, consult previous records for any changes to the structure,
seal leaks, and monitor any occupied adjacent buildings to ensure safety.
3. Prior to each fumigation, review any existing FMP, MSDS, Applicators Manual and
other relevant safety procedures with company officials and appropriate employees.
4. Consult company officials in the development of procedures and appropriate safety
measures for nearby workers that will be in and around the area during application and
aeration.
5. Consult with company officials to develop an appropriate monitoring plan that will
confirm that nearby workers and bystanders are not exposed to levels above the allowed
limits during application/aeration. This plan must also demonstrate that nearby residents
will not be exposed to concentrations above the allowable limits.
6. Consult with company officials to develop procedures for local authorities to notify
nearby residents in the event of an emergency.
7. Confirm the placement of placards to secure entrance into any area under fumigation.
8. Confirm the required safety equipment is in place and the necessary manpower is
available to complete a safety effective fumigation.
88
These factors should be considered in putting a FMP together. It is important to note that
some plans will be more comprehensive than others. All plans should reflect the
experience and expertise of the applicator and circumstances at and around the site.
In addition to the plan, the applicator must read the entire label and follow its directions
carefully. If the applicator has any questions about the development of a FMP, contact
DEGESCH AMERICA, INC. for further assistance.
The FMP and related documentation, including monitoring records, must be maintained
for a minimum of 2 years.
GUIDANCE FOR PREPARATION OF A FUMIGATION MANAGEMENT PLAN
Purpose
A Fumigation Management Plan (FMP) is an organized, written description of the
required steps involved to help ensure a safe, legal, and effective fumigation. It will also
assist you and others in complying with pesticide product label requirements. The
guidance that follows is designed to help assist you in addressing all the necessary factors
involved in preparing for and fumigating a site.
This guidance is intended to help you organize any fumigation that you might perform
PRIOR TO ACTUAL TREATMENT. It is meant to be somewhat prescriptive, yet
flexible enough to allow the experience and expertise of the fumigator to make changes
based on circumstances which may exist in the field. By following a step-by-step
procedure, yet allowing for flexibility, safe and effective fumigation can be performed.
Before any fumigation begins, carefully read and review the label and the Applicator's
Manual. This information must also be given to the appropriate company officials
(supervisors, foreman, safety officer, etc.) in charge of the site. Preparation is the key to
any successful fumigation. If the type of fumigation that you are to perform is not listed
in this Guidance Document you will want to construct a similar set of procedures.
Finally, before any fumigation begins you must be familiar with and comply with all
applicable state and local laws. The success and future of fumigation are not only
dependent on your ability to do your job but also by carefully following all rules,
regulations, and procedures required by governmental agencies.
A CHECKLIST GUIDE FOR A FUMIGATION MANAGEMENT PLAN
This checklist is provided to help you take into account factors that must be addressed
prior to performing all fumigations. It emphasizes safety steps to protect people and
property. The checklist is general in nature and cannot be expected to apply to all types of
fumigation situations. It is to be used as a guide to prepare the required plan. Each item
must be considered, however, it is understood that each fumigation is different and not all
items will be necessary for each fumigation site.
A. PRELIMINARY PLANNING AND PREPARATION
89
1. Determine the purpose of the fumigation.
a. Elimination of insect infestation
b. Elimination of rodent infestation
c. Plant pest quarantine
2. Determine the type of fumigation, for example
a. Space; tarp, mill, warehouse, food plant
b. Vehicle; railcar, truck, van, container
c. Commodity; raw agricultural or processed foods
d. Grain; vertical silo, farm storage, flat storage
e. Vessels; ship or barge. In addition to the Applicator's Manual, read the U.S. Coast
Guard Regulations 46CFR 147A.
3. Fully acquaint yourself with the site and commodity to be fumigated, including
a. The general structure layout, construction (materials, design, age, maintenance) of the
structure, fire or combustibility hazards, connecting structures and escape routes, above
and below ground, and other unique hazards or structure characteristics. Prepare, with the
owner/operator/person in charge. Draw or have a drawing or sketch of structure to be
fumigated, delineating features, hazards, and other structural issues.
b. The number and identification of persons who routinely enter the area to be fumigated
(i.e. Employees, visitors,customers, etc.)
c. The specific commodity to be fumigated, its mode of storage, and its condition.
d. The previous treatment history of the commodity, if available.
e. Accessibility of utility service connections.
f. Nearest telephone or other means of communication, and mark the location of these
items on the drawing/sketch.
g. Emergency shut-off stations for electricity water and gas. Mark the location of these
items on the drawing/sketch.
h. Current emergency telephone numbers of local Health, Fire, Police, Hospital, and
Physician responders.
i. Name and phone number (both day and night) of appropriate company officials.
90
j. Check, mark and prepare the points of fumigation application locations if the job
involves entry into the
structure for fumigation.
k. Review labeling
l. Exposure time considerations.
1. Fumigant to be used.
2. Minimum fumigation period, as defined and described by the label use directions.
3. Down time required to be available
4. Aeration requirements
5. Cleanup requirements, including dry or wet deactivation methods, equipment, and
personnel needs,
if necessary.
6. Measured and recorded commodity temperature and moisture.
m. Determination of dosage
1. Cubic footage or other appropriate space/location calculations.
2. Structure sealing capability and methods.
3. Label recommendations
4. Temperature, humidity, wind
5. Commodity/space volume
6. Past history of fumigation of structure
7. Exposure time
B. PERSONNEL
1. Confirm in writing that all personnel in and around the area to be fumigated have been
notified prior to application of the fumigant. Consider using a checklist each one initials
indicating they have been notified.
2. Instruct all fumigation personnel about the hazards that may be encountered; and about
the selection of personal protection devices, including detection equipment.
3. Confirm that all personnel are aware of and know how to proceed in case of an
emergency situation.
91
4. Instruct all personnel on how to report any accident and/or incidents related to
fumigant exposure. Provide a telephone number for emergency response reporting.
5. Instruct all personnel to report to proper authorities any theft of fumigant and/or
equipment related to fumigation.
6. Establish a meeting area for all personnel in case of emergency.
C. MONITORING
1. Safety
a. Monitoring must be conducted in areas to prevent excessive exposure and to determine
where exposure may occur. Document where monitoring will occur.
b. Keep a log or manual of monitoring records for each fumigation site. This log must, at
a minimum, contain the timing, number of readings taken and level of concentrations
found in each location.
c. When monitoring log records, document there is no phosphine present above the safe
levels, subsequent monitoring is not routinely required. However, spot checks should be
made occasionally, especially if conditions significantly change.
d. Monitoring must be conducted during aeration and corrective action taken if gas levels
exceed the allowed levels in an area where bystanders and/or nearby residents may be
exposed.
2. Efficacy
a. Gas readings should be taken from within the fumigated structure to insure proper gas
concentrations. If the phosphine levels have fallen below the targeted level the
fumigators, following proper entry procedures, may reenter the structure and add
additional product.
b. Document readings.
D. NOTIFICATION
1. Confirm all local authorities (fire departments, police departments, etc.) have been
notified as per label instructions, local ordinances if applicable, or instructions of the
client.
2. Prepare written procedure ("Emergency Response Plan") which contains explicit
instructions, names, and telephone numbers so as to be able to notify local authorities if
phosphine levels are exceeded in an area that could be dangerous to bystanders.
E. SEALING PROCEDURES
1. Sealing must be complete.
92
2. If the site has been fumigated before, review the previous FMP for previous sealing
information.
3. Make sure that construction/remodeling has not changed the building.
4. Warning placards must be placed on every possible entrance to the fumigation site.
F. APPLICATION PROCEDURES & FUMIGATION PERIOD
1. Plan carefully and apply all fumigants in accordance with the registrants label
requirements.
2. When entering into the area under fumigation, always work with two or more people
under the direct supervision of a certified applicator wearing appropriate respirators.
3. Apply fumigant from the outside where appropriate.
4. Provide watchmen when a fumigation site cannot otherwise be made secure from entry
by unauthorized persons.
5. When entering structures, always follow OSHA rules for confined spaces.
6. Document that the receiver of in-transit fumigation has been notified and is trained to
receive commodity under fumigation.
G. POST-APPLICATION OPERATIONS
1. Provide watchmen when you cannot secure the fumigation site from entry by
unauthorized persons during the aeration process.
2. Ventilate and aerate in accordance with structural limitations.
3. Turn on ventilating or aerating fans where appropriate.
4. Use a suitable gas detector before reentry to determine fumigant concentration.
5. Keep written records of monitoring to document completion of aeration.
6. Consider temperature when aerating.
7. Insure aeration is complete before moving vehicle into public roads.
8. Remove warning placards when aeration is complete.
9. Inform business/client that employees/other persons may return to work or otherwise
be allowed to reenter.
APPLICATION PROCEDURES
A FMP must be devised for application, aeration and disposal of the fumigant so as to
keep to a minimum any exposures to hydrogen phosphide and to help assure adequate
control of the insect pests.
93
The following instructions are intended to provide general guidelines for typical
fumigations. These instructions are not intended to cover every type of situation nor are
they meant to be restrictive. Other procedures may be used if they are safe, effective and
consistent with the properties of aluminum phosphide products.
FLAT STORAGES
Treatment of these types of storages often require considerable physical effort. Therefore,
sufficient manpower should be available to complete the work rapidly enough to prevent
excessive exposure to hydrogen phosphide gas. Vent flasks outside the storage, conduct
fumigations during cooler periods, and employ other work practices to minimize
exposures. It is likely that respiratory protection will be required during application of
fumigant to flat storages. Refer to the sections on Applicator and Worker Exposure and
Respiratory Protection.
1. Inspect the site to determine its suitability for fumigation.
2. Determine if the structure is in an area where leakage during fumigation or aeration
would adversely effect nearby workers or bystanders if concentrations were above the
permitted exposure levels.
3. Develop an appropriate Fumigation Management Plan. (Refer to FMP guidelines.)
4. Consult previous records for any changes to the structure. Seal vents, cracks and other
sources of leaks.
5. Apply tablets or pellets by surface application, shallow probing, deep probing or
uniform addition as the bin is filled. Storages requiring more than 24 hours to fill should
not be treated by addition of fumigant to the commodity stream as large quantities of
hydrogen phosphide may escape before the bin is completely sealed.
Probes should be inserted vertically at intervals along the length and width of the flat
storage. Pellets or tablets may be dropped into the probe at intervals as it is withdrawn.
Surface application may be used if the bin can be made sufficiently gas tight to contain
the fumigant gas long enough for it to penetrate the commodity. In this instance, it is
advisable to place about 25 percent of the dosage in the floor level aeration ducts. Check
the ducts prior to addition of PHOSTOXIN® to make sure that they contain no liquid
water.
6. Placement of plastic tarp over the surface of the commodity is often advisable,
particularly if the overhead of the storage cannot be well sealed.
7. Lock all entrances to the storage and post fumigation warning placards.
VERTICAL STORAGES (concrete upright bins and other silos in which grain can be
rapidly transferred)
1. Inspect the site to determine its suitability for fumigation.
94
2. Determine if the structure is in an area where leakage during fumigation or aeration
would expose nearby workers or bystanders to concentrations above the permitted levels.
3. Develop an appropriate Fumigation Management Plan. (Refer to FMP guidelines.)
4. Consult previous records for any changes to the structure. Close openings and seal
cracks to make the structure as airtight as possible. Prior to the fumigation, seal the vents
near the bin top which connect to adjacent bins.
5. Pellets or tablets may be applied continuously by hand or by an automatic dispenser on
the headhouse/gallery belt or into the fill opening as the commodity is loaded into the bin.
An automatic dispenser may also be used to add PHOSTOXIN® into the commodity
stream in the up leg of the elevator.
6. Seal the bin deck openings after the fumigation has been completed.
7. Bins requiring more than 24 hours to fill should not be fumigated by continuous
addition into the commodity stream. These bins may be fumigated by probing, surface
application, or other appropriate means. Exposure periods should be lengthened to allow
for diffusion of gas to all parts of the bin if PHOSTOXIN® has not been applied
uniformly throughout the commodity mass.
8. Place warning placards on the discharge gate and on all entrances.
doc_245901605.pdf
Integrated pest management (IPM), also known as Integrated Pest Control (IPC) is a broad-based approach that integrates a range of practices for economic control of pests. IPM aims to suppress pest populations below the economic injury level (EIL).
1
Integrated Pest Management for Grain Elevators that
Supply the Breakfast Cereal Industry:
Case Studies and Economic Analysis
By
Thomas W. Phillips
1
, Ronald T. Noyes
2
and Brian D. Adam
3
1
Department of Entomology and Plant Pathology,
2
Department of Biosystems and Agricultural Engineering
3
Department of Agricultural Economics
Oklahoma State University
Stillwater, OK
Final Report
June 2002
Sponsored by the Grocery Manufacturers of America, Washing ton. D.C. and funded
through the National Foundation for Integrated Pest Management Education, Austin, TX
Corresponding author:
Thomas W. Phillips
Dept. of Entomology and Plant Pathology
127 Noble Research Center
Oklahoma State University
Stillwater, OK 74078
Phone (405) 744-9408
FAX (405) 744-6039
e-mail: [email protected]
2
Preface
This report marks the culmination of a project that spanned several years and
involved numerous individuals. Prior to 1998 the Stored Grain IPM Committee of
Oklahoma State University, under the direction of Dr. Gerrit Cuperus, joined with the
Grocery Manufacturers of America and the Foundation for Integrated Pest Management
Education to deliver educational programs on integrated pest management IPM to grain
elevators throughout the grain-growing regions of the U.S. That educational program
resulted in the concept for the current project to document IPM practices at grain
elevators, and was initially led by Dr. Phil Kenkel of the Department of Agricultural
Economics at Oklahoma State University. Direction of the project since 2000 was by
Drs. Phillips, Noyes and Adam, the current report authors. The authors are grateful to
their co-investigators, Gerrit Cuperus and Phil Kenkel, for providing significant inputs
throughout the course of the project. Dirk Maier and Linda Mason, co-investigators at
Purdue University, helped in designing the project and in making valuable contacts with
industry participants. Ronda Danley and Tamara Lukens, both graduate students in the
Department of Agricultural Economics, provided valuable information on fumigation
practices and costs of IPM used in this report. The authors are very grateful to the
companies and elevator managers who participated in this study and allowed us to use
their valuable time to collect information. We particularly appreciate Mr. Fred Hegele,
General Mills, Inc., who shared his knowledge of the food industry and was a steady
source of help and encouragement throughout this work. Financial support of the
National Foundation of IPM Education during the course of this study was greatly
appreciated.
3
Table of Contents
Preface 2
Introduction 4
Approach and Methods 5
Findings and Recommendations from Facility Visits 7
Elevator 1: Wheat, Corn and Barley 7
Elevator 2: Oats 19
Elevator 3: Oats, Corn and Wheat 34
Elevator 4: Corn 40
Elevator 5: Corn 43
Elevator 6: Wheat 45
Elevator 7: Wheat 49
Elevator 8: Wheat 52
Costs and Benefits of IPM 54
Conclusions 68
References 69
Appendices
A. Ideal Elevator Checklist and Audit Form 70
B. IPM Characterization Survey for Grain Elevators 75
C. Procedures for Cost Analysis 81
D. Costs and Evaluation of Fumigation Monitoring Equipment 86
E. Template for Fumigation Management Plan 87
4
Introduction
Safety of food products in the United States relies in part on effective pest
management and cautious use of chemical pesticides during storage and processing of
post-harvest commodities. The breakfast cereal industry is particularly sensitive to both
insect contamination and pesticide residues, and thus is faced with serious challenges for
effective pest control in raw commodities and in finished products. Integrated pest
management (IPM) is a process whereby information about the pest, the environment and
the infested crop (or commodity in this case) are assessed and decisions made about use
of one or more pest control methods (cultural, biological, genetic, chemical, etc.) to
prevent or reduce unacceptable levels of pest damage by the most economical means and
with the least negative impacts to human health, safety, property or the environment
(Phillips et al. 2000). Management of stored grain has the potential for excessive use of
chemical insecticides at one extreme, and proactive use of preventive measures with no
use of chemicals at the other extreme. Principals of IPM can be applied to grain storage
through vigilant preventive measures, regular monitoring for pests and product quality
loss, and targeted controls when needed.
This project investigated current practices and potential for use of IPM in grain
elevators that provide raw commodities to the breakfast cereal industry. The general
objectives of this project were as follows.
1. Assess the present knowledge of IPM by managers and determine the use of
ecologically-based IPM at a minimum of six demonstration facilities, two each
that store corn, oats and wheat.
2. Make recommendations for these facilities, where needed, on methods to improve
IPM practices.
3. Determine the costs incurred and benefits obtained for the adoption of post-
harvest IPM practices in representative facilities.
This report summarizes work conducted between 1998 and 2001 in which eight
grain elevator facilities meeting project criteria were visited by a team of researchers and
information was collected on IPM-related practices at each. In some cases there were
substantial engineering recommendations made for resolving IPM problems as well as
general elevator problems. Data from other facilities were used directly in development
of an economic model for implementation of IPM at grain elevators. The model provides
a conceptual basis for understanding costs and benefits of IPM, and how implementation
of IPM may impact facilities with given characteristics. The breadth of variation among
facilities assessed in this study, including differences in geography, commodity stored
and production activities, allows for the results of this work to be broadly applied to the
North American grain and food industry.
5
Approach and Methods
Criteria for selection of grain elevators to study were well defined at the outset.
Elevators needed to receive and store grain that would ultimately be used in the
production of breakfast cereals. The project targeted three cereal grains: oats, wheat and
corn. Our goal was to observe and characterize a total of six elevators comprised of two
for each of the targeted cereal grains. Eight elevators were ultimately used because one
“wheat” company had two separate elevator facilities that each provided different
operations (giving a total of three for wheat) and one elevator in the western U.S. had a
mixture of several grains, none of which predominated, and thus did not fit the “norm”
for the other facilities. Six of the facilities were co-located with their mills that generated
a specific product for manufacture of breakfast cereal. We adhered strictly to the
breakfast cereal requirement; none of the elevators studied would be considered to be in
the marketing chain for bread-making, desert products or snack foods. We hoped for,
and succeeded in, sampling elevators from a broad geographic range. Thus we visited
companies from the great Lakes to the Rocky Mountains, and from the northern to
southern parts of the mid-west. Securing the few participants we had in the study proved
challenging. Not surprisingly, many companies we contacted were reluctant to openly
discuss pest infestation or other sanitation issues that may point to their product as being
less than wholesome. GMA members were helpful in securing study sites in some cases,
and in others we were fortunate to acquire study sites through past professional contacts.
Data for this project were collected through personal interviews conducted during
site visits by two or three PIs to a participating elevator. A typical visit would last a half-
day to 1 and half days and was usually hosted by a facility manager who was
knowledgeable in commodity handling, storage and conveying equipment, sanitation and
pest control carried out at his company. Typically, other company staff members with
expertise in one or more of these areas would join the interview. Interviews and data-
gathering were facilitated by administration of the survey instrument titled “Ideal
Elevator Checklist and Audit Form” (Appendix A). The IPM checklist presented the
facility manager with a series of practices organized under broad categories of grain
elevator IPM, and required that the manager perform a self-assessment of how important
the practice (e.g. critical vs non-critical) was to his/her company, and report their level of
accomplishment on that practice (e.g., on a 1-10 scale, with 10 being a high level of
accomplishment). The IPM checklist was roughly modeled after a HACCP (hazard
analysis critical control point) document such that each facility needed to determine for
themselves how important, or critical, specific IPM “points” were to their operation. The
IPM practices were grouped under the following categories: sanitation, in which cleaning
spilled product or empty bins is done to prevent residual pest build-up; receiving,
referring to decisions regarding how grain is received and handled upon receipt; aeration,
the use of ambient air to cool grain masses and inhibit pest population growth;
monitoring, by which managers sample or inspect grain and structures for insects,
temperatures, grain quality, or other features; pesticide use, in which managers were
surveyed about chemicals used for pest control; and safety and education opportunities
for workers and managers that relate to pest control and IPM practices. On a few
occasions an additional survey vehicle, the “IPM Characterization Survey for Grain
6
Elevators,” (Appendix B) was completed that collected technical details of facility
beyond those generally known to the manager being interviewed
The quantity and quality of information collected among facilities was not
consistent throughout the study. The IPM checklist was quantitatively completed in
some of the cases, and was more descriptively addressed in others. Thus some reports
below have numerical scores for IPM practices while others have more thorough verbal
descriptions of the company’s practice. Through the course of administering surveys the
managers would generally share information of particular concern that we documented.
Sharing of specific problems and concerns varied greatly among elevators, perhaps
reflecting the “comfort level” of the manager in revealing such concern. Hence certain
reports address problems and proposed solutions at length while others reveal few
problems and are more directly related just to the survey vehicles. Site visits always
included a tour of the physical plant along with the office interview. Plant tours focused
on grain storage structures, conveying equipment, monitoring equipment, grounds in
general, and occasionally mills and other processing and storage areas.
An economic model for partial budgeting of IPM in grain elevators was
developed and elaborated during this study. Costs of several IPM strategies, with and
without certain levels of insecticide use, were calculated. Economic data at various
levels of detail were collected at participating facilities throughout the study, and data
from two companies in particular were subjected to the model to determine the actual
costs of their IPM systems.
7
Findings and Recommendations from Facility Visits
Elevator 1: Wheat, Corn and Barley
Three principal investigators visited this facility in Idaho in May, 1998 and again in
March, 1999. Meetings were with the facility manager and the company’s regional
manager. During the initial meeting, the OSU team discussed the physical facilities,
methods of operation and IPM practices, and filled in the OSU IPM Checklist and
Facility Audit with the manager. The checklist allows the manager to decide if each item
is critical to his operation or a good management practice (GMP).
Facility Description
This facility was formerly used for processing sugar beets, so the large welded steel tanks
were converted sugar storage tanks. One attribute of the welded steel tanks are that the
roofs have less slope than bolted corrugated grain bins so there is more headspace in all
these bins.
One elevator leg and dump pit station serviced two 100,000 bu concrete silos. Another
large elevator leg and a small leg plus several drag conveyors were used to fill and unload
ten welded steel bins which give the Lincoln Elevator a combined storage capacity of 1.8
million bushels.
The breakdown of the to welded steel storage tanks and silos are as follows:
Tank #1 = 400,000 bu
Tank #2 = 270,000 bu
Tank #3 = 200,000 bu
Tanks #8 & #9 = 35,000 bu/tank
Tank # 10 = 5,000 bu
Tanks #11& #12 = Two 100,000 bu concrete silos
Commodities Stored
This part of the northern Rocky Mountains is an excellent agricultural production area,
with a relatively mild climate with sufficient moisture for dry land farming. Irrigation is
responsible for much grain production. The combination of the six welded steel storage
tanks of variable size and the two silos with four elevator legs at three separate grain
receiving and shipping locations is ideal for handling a variety of grain types. Grain
crops handled were hard red winter and hard red spring wheat, malting barley, feed grade
barley, and corn.
IPM grain storage practices
The facility provides an excellent example of a commercial grain facility that manages a
diverse range of stored grain products with virtually no pesticides and very low pest
8
related losses. In general, no pesticides were used at this elevator due excellent
sanitation, short storage to aeration time period and cold winters.
Overview of Stored Grain Management System
Sanitation
Two men worked full time at this elevator. Both times we visited the facility there was
very little spilled grain lying around. The grounds were relatively bare of vegetation.
Tank roof vent louvers on some tanks were crusted up and were not closing completely,
but these were not an insect proof seal, just a weather shield of vent outlets. No insects
were detected around bin entry points during May, 1998 or March, 1999 visits.
Initially, aeration ducts were trenches in the floor with flush-floor perforated duct covers.
They filled in the duct trenches and replaced the in-floor ducts with round on-floor ducts.
During grain shipping, after gravity flow of grain from tanks is complete, bobcat loaders
are used to move grain to unload drag conveyor or U-trough auger hoppers in the floor.
Duct sections are removed as unloading progresses, cleaned and stacked outside. After
all grain is removed, grain dust and fines are swept up, vacuumed and hauled to the
dump.
Bin floors and walls (up approximately 20 ft from the floor) are treated inside and outside
with Reldan residual pesticide spray. The outside of the bin bases are sealed with a
rubberized or elastomeric sealing paint annually, as needed. Bins are carefully checked
for water leaks as part of pre-filling inspection. Then the round floor aeration ducts are
then repositioned and anchored with grain in preparation for filling bins with new harvest
grain. Leg boot pits are cleaned prior to harvest and periodically as needed during the
year.
In the concrete silo facility, the hopper bottom self-unloading floors in the two 100,000
bu silos are swept out when emptied. Aeration ducts are vacuumed to remove residual
fine and grain particles. All spilled grain in and around the facility is swept up any time
there is a spill or leak. The elevator leg boot pits are cleaned once monthly. Standing
water that forms pools on the relatively flat ground across the facility are pumped out to
ditches to minimize ground water leaks into bin bases.
Weekly sanitation inspections are conducted. All grain spillage and other sanitation
problems are noted and corrected. Signs of rodent activity are also monitored during
these facility walk-arounds. Rodent traps are monitored weekly and trap catches are
recorded.
Receiving and Handling
Incoming grain is received by truck. All loads are probe-sampled at the elevator for
insects, moisture, dockage and protein. In-house grading is used on all in-bound
truckloads. Federal Grain Inspection Service (FGIS) grades are checked on all out-bound
truck and rail shipments. Any loads with marginally high moisture is transferred to
holding bins at a nearby company elevator for blending or shipping. No grain above 13
9
% is stored at the study facility. A truck-load is rejected if 1 live insect is found. For
outbound shipments, a probe sample from each truck-load is submitted to a grain
inspection service near the elevator for official FGIS grades.
The grain peaks are also pulled down by "coring" the center of the bin to lower the peak
for improved aeration. Grain quality of outbound truck and rail shipments is controlled
through samples tested at a local testing laboratory. Grain from this facility to be rail
shipped is dumped at the main company elevator nearby and then loaded directly on rail
cars or held temporarily in silos.
Aeration
All grain tanks and the two silos are equipped with aeration fans, on-floor round
perforated aeration ducts, and roof vents. The aeration systems in the three large steel
tanks consisted of several centrifugal fans (fan HP proportional to tank size) per tank
positioned symmetrically around each tank. Tank #1 had a total of 110 HP in eight base
fans plus a 20 HP roof exhauster. Tank #2 and Tank #3 had six 10-HP base fans and one
10 HP roof exhauster. Base fans are connected to round perforated steel ducts positioned
radially toward the center of the tank. Each of these tanks had louvered exhaust vents
and one roof exhaust fan that appeared to be adequate to provide satisfactory exhaust air.
The roof exhauster was operated for a period of time after the aeration fans were shut off
to expel high humidity air.
Airflow rates is approximately 1/10
th
cfm/bu on Tanks #1, #2, #3, at or near full depth for
wheat and barley and about 1/6
th
cfm/bu fully loaded with corn, and when 2/3 full of
wheat and barley. At 1/10
th
cfm/bu airflow rates, wheat and barley could be cooled in
about 150-175 hours of cumulative fan operation in peaked grain. Tanks filled with corn
were cooled in 90-100 hours. The concrete silo aeration is powered by two 30-HP high
pressure centrifugal fans each, with an airflow rate of about 1/12th cfm/bu when filled
with wheat or 1/7th cfm/bu with corn.
Aeration is started as soon as air temperatures are 15-20
o
F below grain temperatures in
mid-to-late-September. All tanks have pressure, or up-flow aeration systems. Large tanks
have four louvered vents located symmetrically around the roof about 6-8 feet from the
edge of the roof with a powered roof exhaust fan near the center.
Because of the local power company restriction of a high peak demand charge on electric
power, not all tanks and silos could be aerated simultaneously. When elevator legs and
drag conveyors were being used for grain transfers, aeration fans were not operated. To
avoid increased peak power load charges, only about 1/3 of the tanks and silos could have
been aerated per day when grain handling was in progress, or half of the aeration
operated on alternate days when grain was not being transferred.
In actual practice, all aeration fans are manually operated at night by the two elevator
grain managers who typically turn part or most of the fans on as they leave work at 5:00
PM and turn them off when the return to the elevator at 8:00 AM. So, aeration had to be
scheduled when (pending suitable weather) grain was not being handled, and then
cooling was still limited to half of the tanks being aerated at night during the workers off-
10
duty hours. At best, each of the large tanks could only receive about two days of aeration
per week. This system of manually operated alternate night aeration was able to lower
the temperature of the grain mass in the warmest grain below 70
o
F by the end of October.
The goal of the aeration program was to cool the grain of 40
o
F in all bins by December.
Once cooled, all grain is left at these cool temperatures until load-out.
The aeration systems on Tanks #8, 9 and 10 were poorly designed. Each tank had only
one old 5-HP 30-inch diameter Buffalo Forge axial fan. The transition consisted of a flat
steel back plate with an 18-inch diameter hole cut at the bottom of the plate to blow air
into an 18-inch diameter transition and aeration duct on each tank. This system was
totally ineffective on all crops. It is doubtful that this fan would deliver more than 30-
40% of its potential air delivery when aerating full tanks of corn, and far less on wheat.
Roof venting was also poorly designed. These aeration systems on Tanks #8 and #9
should be replaced immediately using a 10-HP low speed centrifugal fan similar to those
used on Tanks #2 and #3. The aeration duct system for these tanks, estimated at about 42
ft dia x 30 ft grain depth should be patterned similar to the same size bolted steel bin
ducts. A 1-2 HP vane axial fan with proper floor duct and roof vent should be suitable
for Tank #10.
Monitoring
This facility was used for sugar beet processing and to store liquid sugar until about 1994,
so the welded steel tanks were originally liquid tight from roof to base. The site around
the tanks was relatively bare of vegetation and natural habitat. Thus, stored grain insect
populations had not built up in the surrounding fields and creeks around the elevator site.
Probe samples from in-bound trucks are checked in-house for insects, moisture, dockage
and protein when processed at the neaby company headquarters. Loads are rejected for
moisture above 13% or if 1 or more live insects are found. The average moisture content
of grain received was bout 11%. If probe samples are found acceptable at the
headquarters, then trucks are routed to the subject facility for dumping. Grain between
12-13% and/or marginal dockage is diverted to concrete storage where it can be shipped
out easier.
Grain is dumped into the various tanks according to type, grade and moisture. Grain is
visually inspected in tanks at the surface about every two to three weeks. Although all
tanks have thermocouple cables, which are read through a Rolfes Hot Spot manual
temperature instrument, grain temperature monitoring was erratic. However, due to the
excellent climate, short time between harvest and cooling, and excellent sanitation, few
insect problems were encountered at this elevator. Individual tanks were fumigated if an
insect problem was detected in them, but only one or a few cases were reported t ooccur
in the four years of grain storage.
Anytime grain is removed form storage, samples are pulled at 2-minute intervals from the
moving grain stream. All samples are sieved and checked for insect activity.
Periodically during the season, a 400-500 bu truck load is transferred from each tank or
silo and sampled intensively. By taking numerous samples from each truck load and
11
sieving all of the sampled grain for insect presence and damage, a good representation of
the center core of each grain mass is obtained.
The grain surface is also inspected monthly for roof leaks and insect or mold problems.
Shallow trier probe samples from various locations across the grain surface are obtained
and carefully inspected for insect presence or damage. These surface inspections are
discontinued for safety reasons when enough grain has been removed to form a
substantial inverted cone in the center. All outbound loads are officially sampled and
graded. Quality specifications on out-bound loads are no live insects and less than 3 IDK
(insect damaged kernels) per 100 gram sample.
Grain temperatures are monitored weekly. Temperature readings in all bins are recorded
weekly until all the grain mass in each bin reaches the target temperature (approximately
40F). A log of aeration timing and outside air temperatures is maintained during
aeration. If a hot spot is detected, the bin is inspected for leaks, insect activity or mold
problems. The bin is sampled by probing the surface, deep cup probing and power
probing the grain mass, and core samples are pulled using the unload system.
Maintenance and Safety
A full preventive maintenance program is in place at this elevator. All bearings are
greased and gearbox oil levels and quality are checked at pre-scheduled time and usage
intervals. A walk-around inspection of bearings on equipment located inside structures is
conducted at the end of each day's operation. An outside company is contracted to make
regular inspections of fire extinguishers. Outside resources are also used to conduct fit-
testing of personal protective equipment (PPE) and specialized safety training annually.
Results
For the four year period in which the facility has been under current management for
grain storage, approximately 1.5-2.0 million bushels of grain have been handled each
year without fumigation. Grain quality has been maintained with low shrinkage (less than
1/4 percent). Out-bound loads have consistently met high quality standards of below 3
IDK and zero live insects.
Facility Modifications
When this elevator came under current management only 50% of the thermocouples on
cables in all grain bins were functional. Some bins had aeration fans connected to bins,
but no ducts were installed inside the bins. In addition to resolving these facility
temperature monitoring and aeration duct deficiencies, all bin foundations were sealed
with a flexible rubberized material, roof exhaust fans were install on the three largest
steel tanks to provide positive exhaust of headspace moisture. Subfloor aeration duct
trenches were filled in and removable perforated tubular aeration ducts were install on the
bin floor surface in all steel bins.
12
Critical IPM Factors
The facility manager participated in filling out the OSU Critical IPM Check-Point
Management Audit. As indicated above, grain managers identify two levels of grain
management practices related to IPM, those that they designate to be "Critical IPM
management factors" (CIPM) for their elevator storage, and another group that are
considered to be just "Good management practices" (GMP). GMPs are activities that are
part of their grain storage management system, but are not considered absolutely critical
to success or a corner-stone of their program.
The Critical IPM Practices identified at this facility were:
Sanitation
* Complete clean-out prior to filling
* Spraying down empty bins prior to filling
* Cleaning spilled grain and fines around bins, dump pits and drive
* Sealing bin bases and openings to prevent moisture leaks
Receiving/Handling
* Sampling incoming grain for moisture, insects and other factors
* Rejecting infested grain
* Leveling bins prior to aeration by removing center core
Aeration
* Bins equipped with adequate airflow
* Lowering grain temperatures below 60 degrees as soon as possible
* Monitoring temperature forecasts and operating fans to take advantage of cool nights
Monitoring
* Checking grain temperature weekly
* Sampling center-core of each bin at least monthly by removing a truck load of grain
and intensively sampling the load
Costs of IPM Practices
Pesticide Cost
The major pesticide cost is the cost of spraying empty bins with residual pesticide
(Reldan) to eliminate potential carry-over insect populations. An outside contractor was
used for the treatment at a total cost of approximately $700 (about 0.1c/bu). Temperature
management was achieved with an average of 100 fan hours/year with electrical cost of
about 0.5c/bu for aeration. Sanitation and monitoring activities involves 2 employees
with an average time spent of 10 hours each, or 20 man-hours/week. Labor costs were
13
approximately $10,000/year or 0.6c/bu. Grain inventory records indicated an average
shrinkage of 1/4 % per year or slightly less than 1 c/bu. Total cost of the storage system
was estimated at 2.2 c/bu.
Demonstrational IPM Elevator #1
Costs Associated with Storage
Category Total Cost Cost/Bu Stored
Aeration $3,500-7,000 0.2 - 0.4 c/bu
Labor $10,000 0.6c/bu
Empty bin treatments $2,100 0.1c/bu
Grain shrinkage $18,000 1.0c/bu
Total Storage Costs including Shrinkage 1.9-2.1 c/bu
General Assessment of IPM
The grain managers at this facility are doing an excellent job of grain management, even
under serious electric power restrictions imposed by the local public utility. Excellent
facility sanitation and handling practices, good in-bound grain quality, and periodic
visual monitoring of grain in all tanks qualifies this elevator as a low risk, high quality
sustainable IPM grain elevator facility. The aeration fan systems on the concrete silos
and large steel tanks were excellent. The high level of cleanliness, particularly the lack
of old grain residues in and around storage and conveying structures, with concurrent
endemic insect problems that typically occur with grain residues, is likely due in part to
the relatively short history of grain storage (only four years) at this location. This
inherent low risk or having a brief grain storage history is certainly enhanced by the level
of understanding and attention to preventive IPM by the staff.
Recommendations for improvement of grain and elevator operations
The physical facility at this elevaotr was generally in good condition. However, the local
power utility’s policy at for this facility was extremely restrictive, which seriously
inhibited optimum grain storage management. The demand charges are so high that the
facility had to be continually micro-managed to maintain reasonable electrical power
costs. It is highly unusual to have such restrictive power control that the elevator is
required to use a three-day aeration schedule rotation when moving grain. Even though
the elevator is well managed, several improvements that could further enhance grain
storage management are: elaborated here.
1. Seal aeration fans and unload conveyors when not in the aeration season.
Sealing aeration fans blocks access to insect entry into the bottom of the storage units
keeps cold air from draining out of the tank and pulling warm air into the upper grain
mass, and keeps convection currents from moving through the grain, warming grain
and removing grain moisture and market weight. Unload conveyors should also be
sealed until time for use.
14
2. Core tanks for improved cooling uniformity and reduced aeration time.
Even though aeration was cooling the grain, it was a slow process due to power
company limitations on peak power load. Coring the steel tanks and concrete silos to
reduce the peak height by 1/4 to 1/3 shortens the air path, removes some fines and
foreign material from the core of fines that forms under fill spouts and lowers static
pressure. The aeration fans move more air with lower static pressure and shorter air
paths. Not cooling the peak will shorten aeration time by 10-15%, reducing the
power bills and minimizing marketable moisture removal due to longer cooling times.
Lower static pressures will lower pressure fan "heat of compression" which increases
the cooling air temperature by 5
o
F to 10
o
F.
3. Install an automatic aeration controller to pinpoint desired cooling air
temperatures.
Note that aeration controllers should be set lower to account for pressure fan "heat of
compression" temperature rise to cool the grain to a desired temperature such as 60
o
F
initially, and 50
o
F by end of the aeration period for winter storage. If the target grain
temperature is 50
o
F, and a thermometer stuck through a hole drilled in fan transition
ducts shows an air temperature rise of 7
o
F, the automatic aeration controller
temperature set point should be 43
o
F.
4. Monitor grain temperature at 2 week intervals.
Grain temperature monitoring is a similar practice to that of a physician checking a
patient's temperature and blood pressure. Grain temperatures give the elevator
manager a continuous picture of what's happening inside the grain mass. Grain
should be monitored at 2-week intervals so the elevator manager has a continuous
record from year to year of grain conditions for each tank. Reviewing temperatures
twice monthly will allow the manager to spot spontaneous heating problems that
indicate a moisture or insect problem before it becomes excessively costly.
5. Change aeration fans, ducts and vents on tanks #8, 9, 10
The 5-HP Buffalo Forge fans on tanks #8, 9, and 10 are poorly designed and should
be replaced with Tiernan fans (or similar) like those used on the other tanks and silos.
Check roof vents and perforated aeration ducts for adequate capacity.
6. Check all louvered roof vents on large steel tanks and silos.
At least two of the four-roof edge exhaust louvers on the very large Tank #1 were
sticking closed or partially closed when we inspected the tanks in May, 1998.
Sticking louvers minimize exhaust area, increase static pressure in the head space
placing and on the fans, reducing airflow and increasing "heat of compression"
temperature rise of the cooling air. Check exhaust louvers on other tanks for free
movement of gravity louvers. Headspace static pressures should not exceed 1/16 to
1/8 inch water column on pressure aeration systems. Exhaust louver air velocities of
1,000 fpm are desired but should not exceed 1,500 fpm. This is a function of total
15
roof duct cross-section area. Example: Tank #2 at 270,000 bu. with an airflow of
27,000 cfm at 0.1 cfm/bu should have 27,000/1,000 = 27 sq. ft of vent exhaust area.
Thus, each of the four vents should have a cross-section area of about 7 sq ft x 4 = 28
sq ft, or about 2 ft 8 inches square.
7. Heat of compression temperature rise on pressure aeration fans
Check heat of compression temperature rise on fans of all large tanks, and especially
Tanks #11 and #12 (two tall silos). To check temperature rise, drill a small hole (3/16
to 1/4 inch) in the transition between the fan and the tank just large enough to insert a
grain thermometer or digital thermometer thermocouple. Check the fan inlet air
temperature, then the fan outlet air temperature; the difference is the heat from the fan
compressing the air. Seal hole in fan transition with metal screw, bolt or duct tape.
All pressure fans add heat to cooling air. The 30 HP fans on silo #11 and silo #12
will have the highest temperature rise, probably 10-12
o
F, with big steel tank aeration
fan temperature increases of 6-8
o
F.
8. Develop an automatic controller aeration fan start-up sequence control system
Aeration fans and roof exhausters on Tanks #1, 2, 3, 8, 9, 10, 11, 12 should be started
using an automatic aeration controller using an 8-10 second time delay between fans
to allow each fan to reach full speed before another fan is energized. This will
minimize locked rotor amperage of all fans starting simultaneously. Motors should
be started in a selected sequence to minimize startup inrush current. A sequence
starting system could also be designed to minimize shutoff voltage spikes on
shutdown but let's concentrate on inrush control initially. (See Power Management
Schedule (Draft) Options at Lincoln Elevator below.)
9. Check with local power utility about getting the excessive peak demand charges
changed.
Because of the unreasonably high peak demand charges, in which the utility charged
for the entire year based on the highest monthly peak load, the aeration system
operation was very fragmented. Aeration fans on all tanks should have been operated
simultaneously to cool the grain. Dr. Noyes discussed this situation several times
with the maanger, urging him to contact the utility company and ask them to review
their peak demand policy for this elevaotr.
The manager made a successful contact with the power company and discovered that
his elevator should have been on a commercial account without a demand charge,
instead of an industrial account with peak demand charges. The power utility
switched the electrical policy, dropping the peak power demand charge. The power
company made the change retroactive for several months previous to the correction.
This resulted in a reimbursement of $3-4,000 and an electric power savings of about
$9-10,000 annually.
Before the power utility corrected their error for the power account of this elevaotr,
several options were developed by Dr. Noyes to help reduce the excessive peak
16
demand power costs and improve operational efficiency of the elevator. The
following recommendations, now a moot issue, were developed as initial
recommendations for this elevator and presented here as examples of alternative
approaches to improving efficiency of power use.
10. Study motor operating times to minimize peak demand load
If the power company had not changed the type of power account for this elevaotr, it
would have been beneficial to develop a history of motor operation sequences (time
and date when motors are turned ON and OFF) by tracking motor on/off events to
gain a better understanding of the peak demand problem here. A simple, economical
method of tracking motor stop/start sequence data is by attaching a small electro-
magnetic field sensor ("HOBO" is one brand) to each conveyor motor and one
aeration fan motor on each bin. Studying the pattern of running motors by date and
time could be used to fine tune grain handling and aeration operations.
11. Reducing motor starting inrush loads to improve critical power situations
When a peak load demand charge is assessed to elevators like this one, management
should consider installing reduced current starters on motors that are 20-25 HP and
larger to minimize peak load locked-rotor amperage on large motors. Ronk Electric
Company, Nokomis, IL is a leading manufacturer of reduced current starters (RCS).
RCS reduce inrush current by about 40% through capacitor banks, while maintaining
normal line voltage, which keeps starting torque higher for RCS than reduced voltage
starters (RVS). While Dr. Noyes was Chief Engineer at Beard Industries, Frankfort,
IN, Ronk prototyped several RCS's for 50 to 200 HP blower motors for them in the
1970's. The RCS capacitor kit is installed on the existing motor starter, at
substantially lower costs than major brand RVS's.
12. Power management schedule options
Aeration Motors:
Tank #1 1 @ 20 HP (roof exhauster), 6@15 HP, 2 @ 10 HP = 130 HP
Tank #2 1 @ 10 HP (roof exhauster - est.), 6@10 HP = 70 HP
Tank #3 1 @ 10 HP (roof exhauster - est.), 6@10 HP = 70 HP
Tank #8 1 @ 5 HP = 5 HP
Tank #9 1 @ 5 HP = 5 HP
Tank #10 1 @ 5 HP = 5 HP
Tank #11 2 @ 30 HP = 60 HP
Tank #12 2 @ 30 HP = 60 HP
Total Aeration HP = 405 HP
Managers Estimate of Conveyor Motor Powe:
Four legs @ 50 HP = 200 HP
Six Drags @ 25 HP = 150 HP
Two U-troughs @ 20 HP = 40 HP
17
Nine Augers @ 15 HP = 90 HP
Total Conveyor HP = 480 HP
Total HP = 885 HP
Start-up: If possible, always start largest motors first, then the next larger, etc in
descending size sequence (if possible) to minimize peak demand power.
Demand Meter System: We recommend that the manager discuss how the demand
meter works with a power company service representative. From a peak demand
situation, it might be less expensive to let elevator legs run continuously during grain
handling months, rather than shut them off daily. However, this may not be acceptable
when the site is unattended.
Power Sequencing
There appears to be as much potential for power to be used at a particular time during the
day when transferring grain as during aeration, based on the power table above with 480
HP on conveyors and 405 HP on aeration fans. Although there are four legs, it is likely
that only two legs and their associated conveyors would be operating at one time, such as
receiving grain at two pits, or receiving grain at one pit and loading out trucks or cars at
another leg site. So, 200-250 HP could be operating in grain movement. That is as much
as half the aeration system, but due to peak loading, usually no more than half the
aeration capacity was operated at one time when transferring grain.
Alternative grain handling vs aeration motor operating recommendations: To
minimize peak electrical current demand, several alternative motor power operating
schedules were outlined as recommendations.
Four Day Schedule (Grain Transfer + Aeration)
Day 1: (Grain Transfer + Aeration)
Leg @ 50 HP, drag @ 25 HP, u-trough @ 20 HP, auger @ 15 HP = 110 HP
Tank #11 @ 60 HP; Tank #12 @ 60 HP = 120 HP
Total Day 1 = 230 HP
Day 2: (Grain Transfer + Aeration)
Leg @ 50 HP, drag @ 25 HP, u-trough @ 20 HP, auger @ 15 HP = 110 HP
Tank #2 @ 70 HP; Tank #3 @ 70 HP; Tank #8, #9 & #10 @ 15 HP = 155 HP
Total Day 2 = 265 HP
Day 3: (Heavy Grain Transfer- - no aeration)
Leg @ 50 HP, drag @ 25 HP, u-trough @ 20 HP, auger @ 15 HP = 110 HP
Leg @ 50 HP, 2 drags @ 50 HP, 2 augers @ 30 HP = 130 HP
Total Day 3 = 240 HP
Day 4: (Grain Transfer + Aeration)
Leg @ 50 HP, drag @ 25 HP, u-trough @ 20 HP, auger @ 15 HP = 110 HP
Tank #1 @ 130 HP = 130 HP
18
Total Day 4 = 240 HP
Three Day Schedule (Light Aeration)
Day 1: Tank #11 @ 60 HP; Tank #12 @ 60 HP =120 HP
Day 2: Tank #2 @ 70 HP; Tank #3 @ 70 HP =140 HP
Day 3: Tank #1 @ 130 HP; Tank #8, #9 & # 10 @15 HP= 145 HP
Two Day Schedule (Heavy Aeration)
Day 1:
Tank #2 @ 70 HP; Tank #11 @ 60 HP; Tank #12 @ 60 HP; Tank #10 @ 5 HP = 195 HP
Day 2:
Tank #1 @ 130 HP; Tank #3 @ 70 HP; Tank #8 & #9 @10 HP = 210 HP
19
Elevator 2: Oats
Three principal investigators visited this elevator in Minnesota in March 16, 1999. The
facility stored only oats and was co-located with an oat flour milling facility. The PIs
met with a company management team composed of the elevator manager, the flour mill
manager, the company’s technical grain manager, a merchandiser and an individual from
the quality and regulatory operations division.
Facility Description
The primary grain storage facilities at this 5 million bushel elevator consisted of a 2
million bu concrete head-house facility with concrete silo annex, plus four each 750,000
bu bolted steel flat bottom bins constructed in line adjacent their concrete facility on a
site where two flat storage units were previously removed. These large steel bins are
rated for 750,000 bushels on oats and 500,000 bu for wheat due to soil bearing pressure
limitations. Due to their large diameter, contraction and expansion of the bins between
summer and winter seasons makes it difficult to seal the base against water leaks.
Handling rates from the receiving system and concrete facility is 15-20,000 bu/hr.
Concrete Elevator
The 2,000,000 bu. concrete silo system capacity had no temperature monitoring system.
Sanitation was the primary management practice for on-site pest control in the concrete
facility. However, a rigorous plan of quality control during contracting and shipment of
oats from Canada or Scandinavian countries was implemented by management through
contract requirements to sample each oat shipment in at the rail shipping point in
Manitoba. The same process was used at the barge unloading/105 car unit train loading
facility at the company receiving elevator on Lake Superior. Each railcar was sampled
and graded before being allowed to ship. This provided management with a critical IPM
checkpoint.
In addition to sampling for insects, other contract grade factors were dockage, test
weight, moisture content and foreign material. A moisture content of 14.0-14.5% wet
basis was the upper limit accepted for storage. At the time of receiving, oats with
variations in test weight, moisture content and other grade factors were segregated into
silos containing oats of similar characteristics. Oats were then cleaned and blended to
provide the desired characteristic for the oat milling process as oats were transferred from
the steel bins were unloaded and transferred back to the concrete facility. The elevator
manager estimated that 0.5% of their bulk grain mass was removed during cleaning as
scalpings which were land-filled.
One area of concern at the concrete elevator facility was the rail car staging and dump pit
area where spilled grain that was not immediately cleaned up provided attraction to birds,
rodents and insects.
20
Steel Bins
The four 750,000 bushel bolted steel oat Butler bins, constructed in 1990, were built in-
line perpendicular to the concrete silos and rail tracks. The steel bins were 105 ft.
diameter with 60 feet sidewalls and 90 ft. peak height. Filling was done by a 15-20,000
bph elevator leg from the truck or rail dump pit receiving leg to horizontal drag
conveyors across the top which discharged into the four steel bins.
A second horizontal drag conveyor from the concrete facility was designed to discharge
into the drag conveyors that filled the four steel bins allowed transfer of grain from the
rail dump pit in the concrete facility train receiving station to the steel bins. Return flow
from the steel bins to the concrete facility was achieved by elevating grain from the under
floor drag conveyors, elevating via bucket elevator, then transfer to the concrete house by
discharging the grain into the drag conveyor which was reversed to carry the grain to the
drag conveyor across the top of the concrete facility which distributed the grain to the
selected silo(s).
Lower moisture (12-13%) grain was placed in the steel bins for long term storage while
grain with higher moisture (13.5-14.5%) was stored in the short-term storage concrete
facilities and was used first. Although the company preferred to receive oats at 13-14%,
Canadian oats received in 1998 typically ranged from 10.5-12.0%.
Grain transferred into the steel bins was not cleaned during receiving before loading into
bins. No distributors or spreaders were used in the bins, therefore a core of fines and
trash that accumulated under the fill point down the center of the bins was a serious
problem when aerating the bins in fall and winter. According to the elevator manager,
the drier particles and light weight trash tended to slide along the surface to the outside,
while wet, heavier broken kernels and fines formed a core near the middle of the bin.
This is the pattern found often in most steel storage bins in the U.S. when grain spreaders
or distributors are not used.
No distributors or grain spreaders are used due to the high receiving rate, thus the oats,
which have 2-3% beginning foreign material (FM), are difficult to aerate due to high
concentration of FM in the center. Coring was attempted but caused a short circuit of air
through the center. The entire concrete and steel elevator facility was operated by just 7
men due to a high level of automation of conveying systems.
Overview of Stored Grain Management System
Sanitation
After gravity flow of grain unloaded from bins is complete, sweep augers are used to
finish loadout of the steel bins. Then bins are swept out and any wet or moldy grain
remaining on floors and lower walls are removed. The bins are inspected inside and
outside for moisture problems around the base. Then floors and the bottom 10 ft of
sidewalls are sprayed with the residual insecticide Tempo
TM.
21
Receiving/Handling
Incoming grain is received by both truck and rail. All loads are checked for insects. A
load is rejected if one or more live insects is found. Grain quality of inbound rail
shipments is controlled through submitted FGIS samples. In-house grades are used on in-
bound truck shipments. Grain is segregated by end-use characteristics. Oats with
unacceptable end-use or storage properties are channeled back into the commodity feed
market. Grain is typically received at 12-13% moisture. During years in which Canada
experiences a wet harvest, moisture content may be higher (14-14.5% maximum
moisture). Grain temperatures on in-bound oats typically ranges from 50-80
o
F.
Oats that are expected to be stored more than 4-5 months are cleaned before storing. The
grain managers at this facility attempt to move uncleaned oats out of storage within 4-5
months. The oats typically have a beginning FM content of 2-3%. Cleaning is done
through a Carter-Day Screenerator
TM
, which results in an ending FM content of 0.1-
0.2%. Approximately 4-5% of total material is removed during the cleaning process.
Dockage and other fine material is disposed of in a landfill. FM is channeled into feed
market uses and smaller oats (stub oats) that are aspirated out during cleaning are
marketed in the feed oats market. All oats are cleaned or re-cleaned prior to transfer to
the flour mill.
Management experimented with “coring” bins, in which sufficient grain is unloaded to
draw down, remove and re-distribute the center core that contains a disproportionate
amount of fine material. However, their coring experiences resulted in a lower-resistance
airflow path up through the center, which short-circuited air to other parts of the bin
during aeration. Hand-leveling bins was tried, but each bin required 3 days for 7 men (21
man-days) to level a bin which was considered impractical.
Aeration
Cooling is started in October and finished in November when evening temperatures drop
below 50
o
F. Estimated cooling cycle time was 10-18 days. Target grain temperatures
were 40-45
o
F. Two bins were equipped with aeration controllers, but when the
controllers operated the fans during 2-3 days of early cool weather, moisture problems
were created when cooling could not be completed because of a lengthy period of warm
weather. Powered roof exhausters are operated on each bin when aeration fans operate.
Aeration fans are sealed when not in use. Cold grain is not re-warmed during summer
months.
Monitoring
Each in-bound load is monitored for insects and quality. Loads are rejected if 1 live
insect is found. Grain quality of in-bound rail shipments is controlled through submitted
FGIS graded samples. In house grades are used on in-bound truck shipments. Trucks are
probed as they enter the north side of the elevator property and queue until grain samples
are graded and approved for dumping. In storage, grain surfaces are checked at least
once monthly for insects and other quality problems.
22
Vacuum and pneumatic drill samples are also used to check grain condition in the top 25
ft of the grain mass. (Note: Deep probe technology now available at the time of this
report should allow easy sampling of the entire grain mass, surface to floor, including the
90 ft depth at peaks.) Grain is also sampled for insects and quality each time grain is
transferred from bins. Quick withdrawal samples by short operating the unload
conveyors for a few minutes allow sampling of grain quality near the floor as well as the
surface. These samples provide a periodic profile of grain conditions in bins.
Accomplishments
Grain managers have successfully eliminated the practice of or need for direct residual
pesticide application to bulk grain in storage. During the 8 years prior to OSU Team’s
visit, no infested loads of outbound grain were detected. This management system
provides an excellent example of how an increased emphasis on facility sanitation, grain
cleaning, monitoring and aeration can facilitate the elimination of chemical inputs to
grain. Their use of grain cleaning as a final safeguard against insect presence in grain
used in flour processing is particularly important to recognize.
Major Grain Storage Problems Reported in Steel Bins:
The facility storage structure and surrounding environment and weather conditions
present several management challenges. Itemized in the list below are the most serious
physical problems that were related to grain management. Many of these problems are
related to the extremely large bin sizes of the steel tanks, both in bin diameter and grain
depth. Each problem group is then analyzed from an engineering standpoint with
recommended solutions listed.
1. Moisture leaking into the bins at the floor level along the south side of the walls.
2. Fines, trash and dockage in center core of bin under spout line blocks aeration.
3. Fines and foreign material cause 60-65 degree grain slope on unload cone after
gravity flow stops during unloading.
4. Aeration fans inadequate - -cooling too slow and irregular.
5. Aeration floor duct system inadequate.
6. Roof venting system inadequate - - 6 x 0.5 HP roof exhausters vs 80 HP pressure
aeration fans at base - - moisture condensation on surface grain.
7. No automatic control of aeration fan system on bins 53 and 54.
8. Roof exhausters create nuisance noise problems – need to be muffled.
9. Temperature cable breakage and lack of center thermocouple cable.
10. Sweep unloader wall clearance leaves grain around wall.
Problem #1 - - Moisture leakage into bin at bases
The elevator manager said the four 105 ft. diameter, 750,000 bu bins were too large.
Large temperature fluctuations from summer to winter are extreme. South and north
sidewall temperatures varied 30-40
o
F at mid-day in winter. Air temperatures vary from
over 100
o
F in mid-summer to –35
o
F in mid-winter. With solar absorption on southern
exposure galvanized sidewalls, steel base rings varied by 150
o
F from summer to winter.
Between summer and winter, the diameter of the steel base ring contracted by about 12
23
inches on the concrete base. With this amount of movement, the bin wall to base junction
could not be kept sealed.
Snow drifts 4 to 6 feet deep around the bins. Solar radiation on the steel sidewalls on
southern exposures melts snow around the base during the day. The water from snow-
melt freezes at night. This cyclic condition plus the movement of the steel base ring
causes water to seep under the wall into the grain causing spoilage along 30-40% of the
base along east, south and southwest sides of the bins.
Recommendations to help resolve problem:
1. Use wall steel base ring to concrete base “L” shaped anchor brackets mounted
about 2 ft up the base ring sidewall sheet with an I-bolt type turnbuckle connected to
the concrete base anchor bolt. The purpose of bin-base anchor systems are to hold the
bin on the concrete base against wind forces when bins are empty and to keep the bin
“centered” on the concrete base.
2. The base anchor bolts circle should be 8-10 inches from the bin wall flange during
cold weather so there is adequate room for the bin diameter to expand during hot
weather. This long anchor bolt assembly will allow the steel base ring to slide on the
concrete base as it expands and contracts without inducing shear forces to anchor
bolts.
3. Seal the wall/foundation joint with flexible elastomeric roofing paint using a
nylon mesh filler to bridge gaps of more than 1/8 inch. Seal in mid-summer, then re-
seal late in the fall before first snowfall or after clearing the first snow away from the
base and concrete is dry.
4. Clean snow away from southern exposed walls ASAP the snowfall or drift
buildup to avoid ice-dams against the wall on sides exposed to the sun.
5. Two or three times (monthly) during the winter, remove a small volume (3-5,000
bushels) of grain from each of the bin unload gates across the bin width and recycle
the grain back to the same bin to relieve compression stresses or pressure on the
sidewall steel caused by contraction of steel wall rings due to extreme temperature
drops during the winter.
Problem #2 - - Core of fines and dockage in cylindrical column in center of each bin
A buildup of grain fines, FM and trash as grain is discharged from the overhead drag
conveyor during filling creates serious problems when the bins are unloaded. During
filling, dockage, grain fines and trash segregate. Broken kernels, dockage, weed seeds
and other small material settle between the larger kernels within a few feet of the fill
point, plugging the kernel interstice air gap between kernels, forming a dense vertical
cylindrical column that restricts or blocks aeration airflow. This dense column can be
eliminated by mechanically spreading the fines.
24
These bins were too large and fill rate too high for low powered commercial grain
spreaders. Powered slingers used to fill ship holds or build large bulk piles of grain or
bunkers could handle the flow rate and distribute the fines fairly well across the 52.5 ft
radius, but these units are very heavy. They’re too expensive to install in each bin and
too bulky to transfer from bin to bin.
Recommendations to help resolve problem:
1. Fabricate and install a simple, large inverted cone shaped spreader constructed of
abrasion resistant (AR) steel or cold rolled steel, such as that depicted in Figure 1.
This spreader is light weight and will break up the fines pattern and reduce peak
height for improved aeration.
2. As an alternative to Item 1., “core” bins to reduce peak height for improved
aeration by operating the unload conveyor using the center unload gate after each
days fill or after complete filling of bin, to form an inverted cone about 1/4 for daily
coring and 1/3 of the bin diameter for the final cone. Coring removes fines which
restrict airflow and reduces airflow distance from floor to grain surface for more
uniform air velocities to all parts of the bin.
The surface slope or angle of repose for clean oats ranges from 32 to 35 degrees.
Oats with foreign material, dockage and trash may have a surface angle of repose of
40 to 45 degrees. The elevator manager reported inverted cone surface slopes of 60
to 65 degrees. Because of steeper slopes and deeper cone bottoms than other grain,
smaller cones must be used for oats.
Assuming 35 degree grain surface slope with a 55 ft grain depth at sidewalls, peak
height is 35-36 ft; center grain depth is about 90 ft. To avoid short-circuiting of
airflow, the bottom of the inverted cone should not extend below the sidewall
intercept of the grain slope. If the inverted cone surface slope is 45 degrees, the
inverted cone with base diameter of 1/3 the bin diameter (35 ft.) has a ridge height of
24 ft. above the sidewall and depth of 17.5 ft. The bottom is 6.5 ft above the sidewall
intercept. This is acceptable.
When slopes of the grain peak and inverted cone surfaces are not known, use a
drawdown cone of about 25-30 ft. A 30 ft cone requires unloading 5,000 bu. from
each bin. Although coring the bin once after complete filling is beneficial, coring
daily will remove more fines. Daily coring of 3-4,000 bu (10-15 minutes of
unloading daily) is especially beneficial if the cored grain can be cleaned and cycled
back into the bin as it fills. An alternative is to transfer the grain to a bin for clean
grain.
25
Bin Roof
Structure
Spreader Support
Rod
Grain Collector
Funnel Suspended
from Conveyor
Discharge
Adjustable Height
Secondary Grain
Spreader
45 degree 8 ft. diam.
Figure 1. Gravity Grain Spreader for Large Bins
26
Problem #3 - - Fines and foreign material cause 60-65 degree grain slope on unload cone
when gravity flow stops during unloading.
Dockage and foreign material tends to sift down through the surface layer of oats as it
flows down the inverted cone during unloading. This gradually causes an increased
surface resistance to sliding friction, causing the cone surface angle of repose to increase
as the grain cone enlarges and the grain draws down.
Recommendation to help resolve problem:
1. Core bins once per day during loading to remove and clean the oats from the peak
by drawing out grain to about 1/3 of the bin diameter, or 35 ft. Assuming a grain
surface slope for oats of 35 degrees and a draw-down cone grain slope of 45 degrees,
the grain volume on a 35 ft diameter cone would be about 9,000-10,000 bu/day or 25-
30 minutes unloading.
2. If each bin receives 150,000 bu/day, and is loaded in 7 days, this would involve
unloading about 5-6% of the grain per day, but would recycle grain and capture an
estimated 30-40% of the f.m. and dockage in the entire bin, which could be
transferred and cleaned out during night, and transferred back into an empty bin,
placing cleaner grain in the last bin to be filled. This process should sharply reduce
the steep slopes of grain remaining in the bin after gravity flow stops.
Problem #4 - - Aeration fans inadequate -- cooling slow and irregular
The aeration fans on these bins were designed with either two 40-HP Chicago Blower
Corp. Model SQB or two 40-HP Rolfes C3D40 BH discharge low speed (1750 RPM)
centrifugal fans supplying air to two 750,000 bu. oat bins. Two sets of blower
specification sheets were supplied by the company, so the fan source is not certain, but
both fans have similar performance.
This was a poor aeration design and practice as grain in all four bins should be aerated
simultaneously with a minimum of 1/10th cfm/bu in all bins. Management modified the
aeration fan system by installing two of the four 40 HP fans each on Bins 51 and 52.
They installed two 50 HP on each of Bins 53 and 54. Continuous aeration of all bins is
much better, but is still underpowered with two 40-HP fans servicing Bin 51 and 52.
The two 40-HP fans will provide only about 1/17th cfm/bu when both 40-HP fans are
applied to one bin - - 21,500 cfm x 2 = 43,000 cfm/750,000 bu = 0.057 (1/17.4) cfm/bu.
The two 50 HP fans should deliver about 15% more airflow or about 50,000 cfm at about
8 inches static pressure, compared to the 40 HP fans operating at 6-7 inches static
pressure. This would provide approximately 50,000/750,000 = 0.067 (1/15
th
) cfm/bu.
The elevator manager said the current 80-HP fan system cools the grain 20
o
F in 10-18
days, or about 240-430 hours of continuous fan time. He said he would like to cool 20
o
F
in 4-5 days using two 75-HP fans delivering for a total to deliver about 75,000 cfm (0.1
cfm/bu).
27
Aeration required to provide 1/10th cfm/bu using two centrifugal fans connected in
parallel on aeration floor ducts in a 105-ft diameter bin with an average depth of 75 feet
of oats will have an estimated static pressure of 9.24 inches w.c and require 126 HP.
Without significant changes in the present aeration duct system (recommended below),
adding another 50 HP to Bins 53 and 54 for a total of 150 HP would probably not achieve
0.1 cfm/bu.
Recommendations to help resolve problems:
1. Completely change the present aeration fan transition airflow system. Substantial
static pressure is lost in the current aeration distribution design by reversing the
airflow from its natural scroll discharge profile, bending the high speed air stream
backwards to turn 90 degrees down, then another 90 degrees to enter one or the other
ducts.
The eight centrifugal fans are designed as bottom horizontal (B-H) discharge which is
good. The 40-HP fans deliver about 20-22,000 cfm through a 22 x 33 inch vertical
rectangular outlet, about 5. 0 sq. ft. of discharge area. The average discharge air
velocity is about 4,000-4,200 ft/min, but the airflow along the outside of the scroll
will be about 5,000 fpm while the air coming off next to the fan wheel will be close to
3,000 fpm.
2. Mount each fan directly in line with one of the two main ducts. Design a new
blower base mount so fan discharge slopes down at 30 degrees from horizontal,
pointed at one of the two main transition ducts. Develop a new transition duct that
makes a 30 degree turn straight into one of the main ducts.
3. Mount a third 50-HP, BH discharge centrifugal fan per bin between the two ducts
and split the airflow so that 50% of the air flows into the side of the transition from
the two current fans. Use the same 30 degree downward slope blower mount so fan
discharge ducts are parallel and airflow is combined smoothly. This will provide 130-
HP aeration per bin on Bins 51 and 52, and 150 HP on Bins 53 and 54. With the
recommended spreaders added to spread fines away from bin centers to "level the
surface", or with cleaning some grain and peak removed by developing a 30 ft dia
inverted cone during coring and improved aeration duct area, the combined
technology changes should provide aeration close to 0.1 cfm/bu, and cool grain in
about 120-150 hrs (5-7 days) in the fall.
4. Make the transition shape change from the 22 inch x 33 inch (40 HP fans) vertical
rectangular fan outlet to the shallow horizontal rectangular duct entry cross-section as
smooth as possible. Allow as much space as economically and physically practical
from fan discharge to bin duct entry to allow the air to stabilize and equalize in
velocity, minimize fan static pressure loss and result in higher airflow through the
grain.
28
Problem #5. - - Aeration floor duct system inadequate.
The ducting system in each bin consists of two 72 ft long by 4.5 ft wide perforated ducts
that parallel the unload tunnel in each bin. Each 72 ft duct supplies a parallel 42 ft long x
2.5 ft wide duct through a cross duct at center (Figure 1). This layout pattern does not
provide enough distribution duct surface area or place the air in the right location for
uniformity of airflow. The 72 ft and 42 ft ducts are too short and the 42 ft ducts are too
far from the wall.
A 16 ft perforated cross duct connects 72 ft and 42 ft ducts. Assuming the 16 ft duct
perforated width is 2.5 ft, the existing aeration duct design has a total perforated exhaust
area of 938 sq ft. To provide 0.1 cfm/bu, minimum recommended U.S. standard aeration
design for steel bins, the duct system should deliver 75,000 cfm at a recommended design
entrance velocity of 30 fpm into the grain, which would require a total perforated duct
surface area of 75,000/30 = 2,500 sq ft. Using 40 fpm design air entrance velocity, the
duct surface area is 75,000/40 = 1875 sq ft -- double the available duct area. At 50 fpm
entrance velocity, the duct area will be 1500 sq ft.
Recommendations to help resolve problem:
1. Increase length of 72 ft ducts by extending the perforated duct by 12 ft on each
end, making them 96 ft of perforated length. Increase the length of the 42 ft side
ducts by adding 15 ft of duct to each end, to make these ducts 72 ft overall length.
2. Add two new 30 ft long parallel ducts about 12-13 ft center lines from 42 ft (72 ft)
ducts to place air closer to the sidewalls, filling in a weak airflow zone in the
current design.
3. Increase the width of the secondary side ducts from 2.5 ft to 4.5 ft of perforated
width by laying/attaching corrugated perforated duct sections across the original duct
trench. This will allow air to travel another foot laterally each way under the
corrugations and into the grain.
4. Total perforated duct length would now 448 ft. Perforated duct area would be 448 ft
x 4.5 ft width = 2016 sq ft of duct surface area. This would provide an average
airflow entry velocity of 75,000/2016 = 37 ft/min. Acceptable.
5. If secondary perforated ducts remained at 2.5 ft width, the total perforated area
would be 194 x 4.5 + ( 448-194) x 2.5 = 873 + 635 = 1508 sq ft. The air velocity
entering the grain would be 75,000/1508 = 49.7 or about 50 ft/min. Although a
higher pressure drop would occur at this velocity, it would probably still work
satisfactorily, when compared to current system of 43,000/938 = 45.9 fpm on Bins
51/52, and 50,000/938 = 53.3 fpm in Bins 53/54.
6. Another recommendation is to change all perforated duct surface from the
existing corrugated duct surface with 13.5% open area to a material with about 25-
30% perforated area using 3/32 inch (0.094 inch) diameter perforations.
29
7. Cutting aeration duct planks (typically at 25-30% perforated area with 0.094 ID
perforations) from formed interlocking drying floor materials such as SUKUP or GSI
drying bin flooring is recommended. This will allow easy removal for vacuuming
fines from aeration duct trenches for improved IPM and sanitation.
Problem #6. - - Roof venting system with six 0.5 HP roof exhausters/bin inadequate.
The roof venting system is totally inadequate to keep warm moist air from
condensing on the cold under side of the steel roof where it condenses moisture on
the grain, causing high moisture zones, surface crusting, mold and heating. This
condition is very conducive to insect infestation since several secondary grain insects
are mold feeders.
Each bin has fifteen (15) roof vents, each with a cross-section area of 1.78 sq ft. This
provides a total of 26.7 sq ft. Bins 51 and 52, vent air velocity is 43,000/26.7 = 1610
ft/min, 61% higher than recommended vent velocities of 1,000 ft/min for pressure
exhaust Bins 53 and 54 roof exhaust velocity without roof exhausters is now about
50,000/26.7 = 1872 fpm, 87% higher than recommended.
Existing roof exhausters provide some additional powered venting area, which helps
reduce the exhaust velocity of the vents, but they are not performing as they should be.
Roof exhausters should be sized to exhaust all air coming through the grain plus at least
the same amount of air being pulled in through the roof vents. These should probably be
six 5 HP units, not 0.5 HP exhausters and the number of roof vents should be increased as
outlined below.
Recommendations to help resolve problem:
1. There was no data provided on the handling capacity of the six 0.5 HP exhausters per
roof but 3 HP per bin is totally ineffective. Roof exhaust fans should deliver at least
twice as much airflow as the aeration fans. At present, with two 40-HP fans
delivering about 43,000 cfm, and the recommendation to add a third 40 HP fan to
each of the two west bins, or a total of about 65,000 cfm, roof exhausters should be
installed that can deliver 130,000 cfm (Bins 51 and 52) to 150,000 cfm (Bins 53 and
54) to provide double the airflow for blending of dry ambient air with warm moist
exhaust air.
2. Since the roof exhausters should draw fresh air into the roof cavity to blend with high
humidity air exiting the grain, the vents will be handling suction or inflow of air, so
the vents should be designed with a total area that would provide about 800 ft/min, or
65,000/800 = 81 sq ft of vent space for Bins 51 and 52. At present the vent area is
26.7 sq ft. so the roof vent area should be increased by 54 sq ft for Bins 51 and 52.
Bins 53 and 54 need 75,000/800 = 93.7 sq ft. so another 67 sq ft of vent area is
needed. .
30
3. Larger vents with cross-section areas of 4 to 8 sq ft can be used to reduce the number
of vents as long as the required amount of total vent area is provided.
4. An alternative to minimize cost of roof venting would be to retain the existing roof
exhausters, but oversize the roof vent area as outlined in Item 2, operate the present
underpowered roof exhausters anytime the aeration fans run, but develop a time delay
system to continue their operation for an hour or two after the aeration fans are shut
off to remove moist air from the headspace and dry the under bin roof surfaces to
minimize dripping and condensation.
Problem #7. - - No automatic control of aeration fan system on Bins 53 and 54
Automatic aeration control is a must for large commercial storage. Busy managers
cannot begin to compete with a preset temperature sensing thermostat that is properly set
to start the large fans in sequence and control the temperature within a bracketed
temperature range, such as 60
o
F upper setpoint and 35
o
F lower set point.
The aeration controller should also be set to operate the roof exhausters to run 1-2 hours
after aeration fans stop to exhaust moist air from the bin headspace and dry the grain
surface.
Recommendations to help resolve problem:
1. Design and install a “slave” control box to operate the aeration fans and roof
exhausters on Bins 53 and 54. Connect the “slave” controls to the automatic aeration
control system that operates the aeration system on Bins 51 and 52. Roof exhausters
should be set to run 1-2 hours after aeration fans shut off to evacuate excess moisture
from bin head space.
Problem #8. - - Roof exhausters create nuisance noise problems – need to be
muffled.
Although this problem may not seem like an IPM related problem, the roof exhaust fan
system is in fact an integral part of the overall IPM through its use during aeration. The
noisy aeration roof exhaust fan on Bin 54 was high above ground level pointing
southeastward toward a residual area. An attempt had been made to redirect or turn the
sound by putting a sheet metal extension on the roof exhaust fan outlet, but this did not
appear to resolve the customer complaint.
Recommendations to help resolve problem:
1. Take sound level readings (dBA scale is closest to the sound received by human
ears) at the property boundary on line with the complainers home, and at the
complainers property boundary in line between the noisy bin roof exhauster and the
home before any further changes.
2. Invite the complainer to listen to the sound level with the fan running and have
them observe the dBA meter reading as it is being recorded on a data sheet.
31
3. Have someone turn off just the noisy bin roof exhauster and take another
“background” sound reading of all other fans operating except the noisy roof
exhauster. Have the complainer listen and observe the reduced sound level as it is
recorded on the data sheet.
4. Remove the noisy/offending roof exhaust fan and install a new roof vent in place of
the roof exhaust fan.
5. Move the roof exhauster to the north side of the bin, as directly opposite of the
home of the complainer as possible, but not pointing toward the adjacent bin roof.
If the fan exhaust is point toward Bin 53 roof, move the bin a few degrees farther
around the roof and point it toward the grain probe station to avoid bouncing sound
waves from the adjacent bin back toward the complainers home.
6. Take a new set of dBA sound level readings at property boundary and complainers
property boundaries with all fans operating. Make sure the person complaining
observes the new dBA readings with the offending noisy fan operating on the
opposite side and pointing away from the complainers location. The sound levels at
this time should be very close to the background sound reading, Step 3.
7. If the sound level is still higher than the baseline background sound reading in Step
3, add a duct from the exhaust of the noisy fan (still high in the air and bouncing
sound off of other structures) down the bin roof slope to the edge of the roof and
aim the sound diagonally toward the ground near the truck probe station.
8. The noisy roof exhaust fan noise maybe a function of roof vibration due to an
unbalanced exhaust fan rotor that is shaking the fan and increasing noise due to roof
vibration. Check all roof exhausters and aeration fan wheels and blades for mud
dobber wasp deposits that can cause an unbalance and vibration in fans at high
speed.
Problem #9 - - Temperature cable breakage and lack of center thermocouple cable.
One thermocouple (T/C) temperature cable problem observed that was causing cables to
break was that the cables had a formed loop of about 2 inches length secured by a small
saddle clamp. The cable end was frayed. These loops had twine tied to them used to
anchor the cable temporarily to a bolt anchored in the floor to hold the cables in position
until the grain was around the bottom of the cable to keep the cable hanging straight
down.
Any bulky object clamped to a temperature cable will cause a very large increase in grain
loading and tension in the cable. This is due to the diagonal shearing forces of the grain
against the clamped object as grain settles.
32
Recommendations to help resolve problem:
1. Remove all turnbuckles and straighten cable ends. Overlap the twine on the last 2
feet of the smooth end of the temperature cable. Tape the twine to the smooth end
of the cable with high quality air conditioning tape or duct tape to form a strong
connection, which will allow a few feet of grain to build up and anchor the cable.
Smooth taped ends add far less bulk to the cable than the doubled cable with
frayed end and saddle clamp. This will reduce the tension on cables by 3-4 X or
more, and should eliminate cable breakage.
2. Add a center cable to each bin, or move one of the four inner circle cables to the
center and form a triangular pattern on the existing inner cable circle.
3. If the cable system needs to be replaced due to many faulty or broken
thermocouples, consider replacing the entire thermocouple temperature
monitoring system with the OPI GIMAC temperature monitoring and fan control
system. OPI uses thermistors which are more accurate and require only a 4-wire
transfer cable system from the bins to the computer in the office. Thus, one does
not have to run hundreds of T/C wires through junction and switch boxes several
hundred feet back to the office - - only 4 wires. OPI GIMAC can also be
instrumented to sense humidity, insect movement through the USDA developed
EGPIK system, and other functions. If part of the thermocouple system is in good
condition, OPI GIMAC can adapt to current T/Cs, handling a blend of thermistors
and T/Cs.
Problem #10 - - Sweep unloader wall clearance leaves grain around wall.
The bin sweep system was a gear reducer driven unit that used a cogged wheel running in
a matching circular floor track for positive movement around the bin. Because of the bin
base ring movement between temperature extremes of summer and winter, and the
possible “ob-round” configuration of the bin, the powered bin sweep drive wheel was
spaced away from the wall. Thus, when the bin was swept, a ring of grain approximately
12 to 18 inches from the wall remained, requiring bin-entry by a work crew to move this
volume of grain to the unload conveyor slide gates along the unload tunnel.
Recommendations to help resolve problem:
1. Operate the sweep unloader with the bin empty, just after normal cleanout.
Monitor the minimum distance to the wall from the end of the loader shaft or
support wheel. Modify the sweep unloader by adding a short extension to close
the gap to within 2-3 inches of the closest point. Repeat for all four bins as this
minimum clearance distance will likely vary between bins.
2. After checking the closest distance from end of sweep unloader for each bin,
develop an attachment to mount on the end of the sweep by brackets that will
“plow” the grain over to the sweep. This blade should extend forward of the end
mounting of the sweep at a 45 to 60 degree angle to minimize loading. This
33
“grain plow” should be made of 3/16 inch or heavier steel with a floor clearance
of 1 inch. A stiff rubber belting material may be added to extend closer to
“sweep” the floor and the wall, but should have enough flexibility that it will bend
back or deform over bolt heads and other projections.
34
Elevator 3: Oats; Corn and Wheat
Two PIs traveled to this elevator and its co-located oat mill in Missouri in
February 2000. The OSU team met with the site manager of the elevator, the facility
sanitarian who was in charge of pest control, and an individual from the company’s main
office who was involved with product safety and scientific affair.
Facility Description
There was a total of 4.25 million bu. capacity at the site. The largest storage
capacity is in 4 ea 500 bu., 107 ft. diameter round bolted steel bins, two of which have
standard in-floor aeration duct designs at approximately 0.1 cfm/bu and two of which
have PM-Luft pneumatic clean-out floor and aeration systems, each with two 60HP high
pressure centrifugal fans. The remaining 2.25 million bu are in a concrete elevator with
48 ea 97 ft tall by 25 ft diam. silos at 37,000 bu each and 32 interstice bins making up
the balance. The 800,000 bu concrete storage annex is equipped with high speed push-
pull aeration at about 0.1 cfm/bu. Raw commodity for the mill is always available from
the elevator. All grain cleaning took place in the mill, not in the elevator. No spreading
or leveling equipment was used in the steel bins at the facility. This created problems
with aeration, especially cooling grain peaks that contain proportionally higher levels of
dockage and fine material than the outer portions of the grain mass.
Commodities
The objective of our visit was to study a primary oat storage facility, but other
grains were handled in this elevator in addition to oats. The sequence of grains, based on
harvest times, and amounts handled in a year are as follows: wheat (2 M bu), oats (8 M
bu) and white corn (3 M bu). So, this 4.35 million bu facility handled about 13 million
bu of grain annually for a turn-over rate of about 3:1.
All incoming grain had to have official grades provided by the shipper. Additionally, the
company performed their own grading thorough grain inspections. The company does
not accept grain shipments with live insects, though we were lead to believe they would
tolerate the presence of dead insects (i.e. those from a recent fumigation).
The minimum test weight the company accepted for oats was 38 lbs/bu, although the
FGIS standard is 32 lbs/bu. Oats in some loads were as high as 47 lbs/bu. The company
would tolerate only 2 insect damaged kernals (IDK) per 100 g or less. They reported
using X-ray analysis to determine internal infesting insect load if IDK is high. The
company was very concerned about aflatoxin contamination and subjected samples of all
incoming corn to the simple black-light test followed the wet chemistry “mini-table”
analysis for suspect samples. The company had a threshold for acceptance of 10 ppm on
aflatoxin, even though the government threshold is 20 ppm. Oats were stored up to 12
months (to accommodate year-round milling), wheat was stored for 60 days and white
corn was stored up to 6 months. A protocol was in place to perform pesticide screenings
on certain samples as part of the company quality assurance.
35
Accomplishments
The manager successfully developed an IPM program that essentially eliminated direct
residual insecticide application to bulk grain in storage. Some top dressing is still
practiced on certain type of grain at specific high risk times of the year. During the past
decade, several key improvements were put in place to enhance grain management and
elevator operation. Two of the 500,000 bu bin aeration systems were modified to include
self cleaning floors using fluidized ducts in shallow hoppers between floor ridges. Prior
to this, one man worked two weeks with the sweep unloader system to finish cleanout of
the 100,000 bu inverted cone remaining in the bin after gravity cleanout. With the
fluidized grain unloading system, two men can cleanup the residual dust in less than 1-
day. This greatly reduces risks from insect pests.
Fro at least the past eight years there were no infestations detected loads of outbound
grain. This management system provides an excellent example of how an increased
emphasis on facility sanitation, grain cleaning, monitoring and aeration can facilitate the
elimination of chemical inputs to grain. Their use of grain cleaning as a final safeguard
against insect presence in grain used in flour processing is particularly important to
recognize.
Sanitation
The company used a regular (weekly or bi-weekly) sanitation checklist, and
indicated this was a critical IPM point for them (score=10). They felt empty bin cleaning
was critical, but admitted to not doing as much as they would like to do (score=7).
Workers were sometimes sent into bins on boatswain’s chairs to sweep down or blow
down the walls of empty bins. Although considered critical, walls of empty bins were
not sprayed with residuals; only fogging (probably of pyrethroids) was done in bins
(score=7). Cleaning spilled grain was considered critical, but was not performed at the
best level in the company’s opinion (score=8). Weed control was also critical, but
performed at a minimal level (score=6). Rodent and bird control programs were
considered critical and done at high levels (scores=9 for each, birds and rodents). Sealing
of side walls and bin bases was considered a good management practice, but was
performed minimally (score=5). Sealing of fan and conveyor inlets and outlets was
considered a good management practice, but the company indicated as “Not Applicable”
for the facility. The overall sanitation score for CIPM points was 8.0.
The company sanitarian said that Indianmeal moth laid eggs behind and inside electrical
boxes. She wanted to install screens over open man-holes to exclude insects when
manholes were open during bin loading. She checks grain from silos monthly by opening
R&P slide gates to drop just enough grain on the belt to clear spouts of existing grain
before pulling samples.
Receiving and Handling Grain
When the manager started work at this facility the truck-receiving rate was 100-
150 truck per 12 hour day. After adding remote controlled hydraulic probe stations
which reduced total time to grade samples and other grain receiving improvements, the
36
receiving rate increased to 300-400 trucks per day. Unit train sizes from 27 to 54 cars
can now be loaded at the facility.
All grain was received on contract from “preferred suppliers”, except for some
amounts of locally-produced corn (CIPM=10). The company reported that sampling
incoming grain for insects and moisture, as well as the policy to reject or fumigate
infested loads, were critical points that they performed very well (CIPM=10 for each).
Maintenance of safe moisture for long-term storage was listed as a good management
practice, and the company reported good adherence (GMP=8). Moisture was probably
most important for corn, which they dried to at least 15.5% mc before storage, and
presumably would dry slightly during aeration after binning. Neither spreading,
leveling, nor coring were practiced by the company (GMP=NA). The average CIPM
score for loading and receiving was 10.0; the average GMP score was 8.0.
Two of the 500,000 bu bin aeration systems were modified to include self
cleaning floors using fluidized ducts in shallow hoppers between floor ridges to eliminate
a serious handling problem. Prior to this, one man worked two weeks with the sweep
unloader system to finish cleanout of the 100,000 bu inverted cone remaining in each
500,000 bu bin after gravity cleanout was completed.
With the fluidized grain unloading system, two men can clean up residual grain
and dust , which is only around the center unload hopper in less than 1 hour. This system
greatly reduces risks of working in a confined space while unloading oats, which have a
much higher surface angle of repose (45-60 degrees from horizontal, depending on
dockage and f.m.) in inverted cones than most other grains. High cost of the self-
cleaning aeration floors prevented installing them in the other two 500,000 bu bins.
Aeration
The four steel bins and some of the concrete structures were equipped with
aeration. The company made a point of storing all their corn in aerated silos, presumably
because of its higher purchase and storage moisture content, so it could be cooled with
some additional moisture loss during aeration for safe storage. Steel bin aeration in the
two conventional aeration systems was approximately 01. cfm/bu. The two bins with
PM-Luft Kanal System floors had two 60 HP fans with 6 manifold valves/fan for
cleanout of the bin in 12 sections of the floor. For aeration, all valves are opened for
uniform distribution of air. The aeration airflow rate for this system is about 1/7-1/8
cfm/bu.
Twenty five concrete silos have excellent aeration systems. A variety of fan HP and
arrangements are used. Five bins have a roof mounted 35 HP suction fan for upflow
suction aeration. Four silos have a 25 HP centrifugal base mounted pressure fan plus a
10 HP centrifugal roof mounted suction fan on each silo. Sixteen silos each have a 15 HP
centrifugal base mounted pressure fan plus a 10 HP centrifugal roof mounted suction fan.
So, between 25 and 35 HP per 37,000 bu silo is used to produce about 1/5-1/6 cfm/bu,
which provides excellent cooling rates.
37
While completing in the Ideal IPM Elevator Checklist and Facility Audit form, the
manager indicated it was critical to use proper aeration when available (CIPM=10), cool
below 65
o
F for storage from winter through April (CIPM=10), and check the cooling
zone with thermocouples (CIPM=10). These three aeration section factors were
reportedly done as often as possible. Roof exhausters (CIPM=8), adequate roof venting
(CIPM=10), and other means to reduce condensation during aeration were considered
critical and were rated by the company as a good score. Use of aeration controllers was
considered a critical management practice (CIPM=8), although they did not report having
them. The company reported operating fans for 4-8 hrs a night during cool weather when
aerating. Average CIPM score for aeration was 9.6; the average GMP score was 8.0
Monitoring
All concrete bins had one temperature cable each and the large steel bins each had
seven cables. Grain temperature monitoring was considered critical and was reportedly
performed at the highest level by recording thermocouple readings of all stored grain
temperatures weekly or bi-weekly (CIPM=10).
Monitoring activities for insects and structural problems were not considered
critical, but were practiced to some degree (GMP=NA). The company sanitarian reported
taking bin-bottom samples of grain from every bin between July and December and
inspecting them for insects (GMP=NA). She also reported opening the tops of all bins
and looking inside for any obvious pest problems. Multiple bottom samples were taken if
initial samples revealed insects. The company reported using pheromone-baited sticky
traps for Indianmeal moth in both the basement and tops of the concrete silos; they also
trapped for dermestid beetles (e.g. the warehouse beetle).
Traps for many other insects were used in the milling sections. The company was
familiar with grain probe traps, but did not use them (GMP=NA). Storage structures
were checked regularly for leaks (GMP=9), and walls and other water sources were
monitored for rodent activity regularly (GMP=9). The average CIPM score for
monitoring was 10.0; the average GMP score was 9.0.
Overall IPM Score CIPM=9.4, GMP=7.5
(Note: numerical scores were not recorded for the practices below.)
Pesticide Use and Practices
Although the company allowed receipt of grain with residual pesticides below tolerance
levels, they reported that they did not add any residual grain protectants directly on the
grain. Top dressing of grain bulks with materials such as Reldan
TM
, Actellic
TM
or DE
(diatomaceous earth) was practiced on occasion. Crack and crevice spray treatments
outside and near bins was performed with Tempo
TM
. Fogging with Vapona
TM
and
pyrethroids (product not specified) was performed in bin headspaces to control
Indianmeal moths. Fumigation with phosphine was performed 1-2 times a year on corn,
“sometimes” on oats and never (or rarely) on wheat. Aluminum phosphide pellets were
38
applied at the rate of one flask per interstice bin and four flasks per round concrete bin;
rates on the large steel bins were not recorded, but were expected to be between the
middle and maximum label rate for steel bins. Application methods of pellets included
probing in from the top, “coring down” the pellets while withdrawing and recycling grain
to the same bin. Pellets were applied to concrete silos by automatic pellet dispenser for
uniform distribution in the grain while turning. Dosage levels in 37,000 bu concrete silos
were 4 flasks, or 180 pellets per 1,000 bu. Their target was to maintain 200-400 ppm
during the fumigaton.
Safety and Education
The company reported having 2-3 certified fumigators on staff and reported “yes” to all
questions about safety procedures. Phosphine detection tubes were used regularly for
worker safety and to test concentrations for levels to sustain efficacy during fumigation.
Both face mask with canisters and SCBA respirators were available for worker safety
use, especially when retrieving phosphide sachets. Managers and key employees attend
at least one pesticide training workshop a year and hold regular in-house safety meetings
at monthly intervals. The company maintained their own written standard operating
procedures for using pesticides. The company had staff specifically trained in grain
grading and sampling. The company reported that some training was provided to
producers and suppliers on the subjects of stored grain management and IPM.
Grain Storage Problem in Steel Bins:
The facility storage structure was well organized and maintained. The primary problem
observed at this elevator was the long cleanout time of these huge steel bins after gravity
flow of grain stopped. Two of the four 500,000 bu, 107 ft diameter bolted steel bins were
converted from flush floor aeration with sweep unloaders to pneumatic powered self-
cleaning floors using PM-Luft Kanal System floors. These floor systems worked very
well at this plant but were too expensive to install in all four steel bins at the same time.
The manager would like to convert the other two bins, but would prefer a much less
expensive alternative, which is not available at this time.
Major Problem
The primary problem experienced by the manager at this time is the 20% of the bin
volume in the 107 ft. diameter bins that does not drain out. This requires operating the
bin sweep to make 4-5 passes around the bin, followed by two men working 2 weeks to
do the final cleanout of the large floor in each bin (no access for bobcat unloader).
The problem is exacerbated by fines, trash and dockage in center core of bin under spout
line, and additional dockage and fines in the grain that sifts down below the slope during
gravity unloading. This material causes the inverted cone grain surface to become
steeper than the peak surface of the grain (about 35 degrees) as the bin was filled.
39
Possible Partial Solution to Problem
1. Cleaning the grain before loading the two conventional aeration and sweep
cleanout bins may reduce the slope angle of the remaining grain, reducing the volume of
grain that remains in the bin after gravity cleanout through the multiple floor hoppers that
create a V shaped grain slope. Cleaning will also improve aeration and storability for
oats which is held for up to 6 months.
2. The true solution is to install pneumatic self-cleaning aeration floors in these two
bins so they perform like the two bins with the PM-Luft Kanal Systems. A plan might be
developed with PM-Luft to install one floor each year for two years, or set up a plan to
pay the cost of the floors out over multiple years.
40
Elevator 4: Corn
Two PIs visited this elevator in Illinois in March 10, 2000. The individual hosting our
visit was very familiar with commodity handling and pest management at this facility.
We also met with the company sanitarian who is in charge of the day-to-day pest control
and fumigation when needed.
Facility Description
This facility is committed entirely to corn dry milling and has approximately 1
million bushels of total storage capacity, all in 24 concrete silos that are up to 110 feet
tall; 12 of which with a capacity of 75,000 bu each and the remainder ranging from 2500
to 27,000 bu.. The silos are served by 4 interior elevator legs. Areas around the silos are
paved; all driveways are paved and is one set of railroad tracks serving the facility. This
location is one of two main processing plants for the company, the other being in a
neighboring state. The company owns 10 country elevators across two states that supply
the processing plants.
Commodities Stored
Corn is the only commodity stored. The firm takes in corn of unconfirmed varieties, but
also maintains a list of 12 (at the time of our survey) specific varieties for identity
preserved (IP) storage and use. Growers are fully educated on the IP varieties by the
company and are stewarded by the company through production to delivery. IP varieties
can be worth $0.20 to $0.25 more per bushel to producers than regular corn. Only
country elevators with more than one elevator leg will receive IP corn for the company.
The company has a strict no-GMO (genetically modified organisms) policy, thus none of
the IP varieties used were GMO. At the time of this survey the company was aware that
19% of all corn in Indiana and 43% of corn in Illinois was genetically modified for
containing the gene for the insecticidal protein of the B.t. bacterium. The company
performed immunological and genetic (PCR) testing on IP varieties taken in to confirm
they were GMO-free. The company indicated that although they historically provided
most of their products to the breakfast cereal industry, that snack and convenience food
uses were beginning to dominate the end-uses of their products.
Sanitation
The company decided that use of a sanitation checklist was their only critical IPM point,
and that other sanitation factors were considered good manufacturing practices. The
company maintained weekly use of a sanitation/housekeeping checklist, which was based
on a master sanitation schedule that was developed for them by AIB (American Institute
of Baking); they assigned a CIPM=9 on use of a checklist. They reported doing regular
empty bin cleaning prior to filling (GMP=9); cleaning spilled trash and grain from around
bins (GMP=8); controlling weeds around silos where applicable (GMP=9); repairing
water leaks and other structural defects regularly (GMP=7); and sealing fan and conveyor
outlets when not in use (GMP=7). Blow-down and sweeping (not vacuuming) of dust
41
and debris around machinery and structures was practiced regularly as part of
housekeeping. There was no use of residual insecticidal sprays or fumigant application to
empty bins before loading, but such practices were done at their country locations. A
rodent control program was operated by an outside contractor (GMP=10) and some
attention was given to bird and rodent-proofing of the facility (GMP=5). Average GMP
score for sanitation was 7.9 and the one CIPM score was 9.0.
Loading and Receiving
Receiving grain from preferred supplier was considered a key factor in controlling
product quality, and indirectly for preventing pest problems, (CIPM=10). As indicated
above, all or nearly all grain delivered was from contract growers who were delivering
specified varieties that were fully documented. All grain is sampled upon receipt for
insects, moisture and other factors (CIPM=10). The company maintained a zero
tolerance policy for any insect found in a grain sample, whether dead or alive, and reject
(rather than fumigate) any shipment found to have an insect (CIPM=10). Long-term
storage of grain at safe moisture levels was considered simply a good manufacturing
practice (GMP=9) because grain was not stored very long at this site due to the rapid
turnover with the mill. High moisture grain was always used first, and that stored longer
was usually at 13% mc. Coring and leveling of grain bins at time of filling was not
practiced by this facility, but many of the country locations reportedly do this (GMP=7).
Average scores for loading and receiving were 10.0 for CIPM points and 8.0 for GMP
points.
Aeration
Aeration is used at all the facilities; down-flow aeration is used on the concrete silos in
this location and up-flow aeration was used on steel structures in the country elevators.
The company claimed that aeration was important, but placed airflow requirements (0.1
cfm/bu) in the good management practices and gave this point GMP=7. Cooling grain to
below 40 F (rather than 65 F) was a company goal, and progress of the cooling front is
checked with thermocouples (CIPM=10 for each). Automatic aeration controllers were
not used and the company reported that they achieved the target temperature by using
fans only at night. Engineering bins for minimization of condensation was considered
and important practice (GMP=7), as was the use of adequate roof venting (GMP=9). The
average scores for aeration were CIPM=10.0 and GMP=7.6.
Monitoring
The company put a high priority on checking grain temperatures in bins on a regular
basis (CIPM=9). There was no active monitoring for insects, either through simple
observations or through trapping, in stored grain. Grain samples were taken bi-weekly in
May from every bin to check for moisture and insects (GMP=9). All storage structures
are checked regularly for leaks (GMP=7) and areas were monitored for rodent activity
(GMP=8). Indian meal moth pheromone traps are deployed in the basement and gallery
of the concrete silo system to monitor this insect in the summer time (GMP=8). Average
score for monitoring was GMP=8.6 and CIPM=9 (for temperature cables only).
42
Overall IPM Score: The average overall score given by the company for critical IPM
points (CIPM) was 9.5, though this was based on only a few points. The average self-
assessment for good management practices (GMP) was 7.9.
Pesticide Use Practices
The company had a strong policy against the use of residual pesticides on grain, and they
also rejected or refused receipt of grain that had any known chemical residue. They
claimed a GMP sore of 10 for each of these practices. The respondents gave themselves
a GMP=2 for use of DE applied as an empty bin or crack and crevice treatment. They
claimed to be very judicious in the use of fumigation in the grain, with a GMP=9 and
purportedly no more than one fumigation per year. Re-circulation or closed-loop
fumigation was not used. The company reported using fogging treatments of pyrethrins
and Gentrol (an insect growth regulator) in the basement and gallery sections of the
concrete elevator, and they gave themselves a GMP=10 for this.
Safety and Education
Safety was a very high priority for this company. They responded with a score of “10” to
all GMP points related to safety (certified applicators on staff, air samples taken before
re-entry to a fumigated area, PPE available for any worker needing it, fit-testing for
respirators done, written safety plan implemented, written emergency action plan in
place, and use of a contractor orientation program for safety education). The company
reported that key employees attended at least one grain management or IPM workshop
each year (GMP=9) an he company reported giving such workshops to suppliers
(GMP=9). Company grain graders were trained in sampling and grading (GMP=9).
Employees reportedly received monthly safety and/or pesticide handling training
(GMP=10) and the managers and supervisors were required to attend such classes for
their performance review (GMP=10). The overall score for pesticide use, safety and
education was an average GMP=9.3.
43
Elevator 5: Corn
Two PIs visited Lauhoff Grain Co. this second corn milling company in March, 2000.
Our host was the company’s director of technical services. We were joined at times by
the manager of grain storage, and by his assistant manager. Reportedly one third of the
company’s products go into breakfast cereals, one third into the brewing industry, and the
remaining third into numerous food products or specialty material uses.
Facility Description
The main elevator facility is concrete with 5 interior elevator legs serving 114 concrete
silos. The large concrete silos were 32 ft in diameter and 129 ft tall with a capacity of
48,117 bushels of corn. A unique rhombohedron flat storage with a capacity of
4,000,000 bu was on site, but reportedly was used just for beans and it was not
considered in this analysis There were several interstice bins of various dimensions.
There were two very large round steel bins on site that were used mostly for beans. Each
of these was 133 ft in diameter and 113 feet tall for a capacity of 1 million bushels. All
roads and driveways were paved, some had gravel on top and others in the truck staging
lot were oiled. The bucket elevators operated at 7500 bu/hr and all had accessible boot
clean-outs. One large drag conveyor was used for horizontal movement.
Commodities
The primary commodity of interest is white or yellow dent corn. Soybeans are also taken
and stored, but beans are strictly segregated from corn to avoid soy protein contamination
of corn products. Soy products can cause allergies in some people and also affect
oganoleptic characteristics of corn products.
Sanitation
Three practices were considered critical IPM points. They were the use of a weekly or
biweekly sanitation/housekeeping checklist (CIPM=8), attending to spilled grain and
accumulation of fines around the facility (CIPM=7), and having a rodent-control program
(CIPM=9). Self-assessments on good management practices were: empty bin clean-out
prior to filling, GMP=5; empty bin spray or fumigation prior to filling, GMP=7; weed
control, GMP=9; seal bin bases and side-walls for leaks, GMP=9; sealing aeration fans
when not in use, GMP=8; bird and rodent control practiced in facility, GMP=9. The
company reported the additional sanitation activity of using a central vacuum cleaning
system to clean the gallery floor every 2-3 days (GMP=8). Average score for critical
IPM points in sanitation was 8.0, and the average score for good management practices
was 7.7.
Loading and Receiving
This company did not use preferred or contracted suppliers. However, most suppliers
were local and known to the company. The company placed a high priority on sampling
incoming grain (CIPM=9). No incoming grain was fumigated. The company rejected
44
grain that had more than one live insect or more than two dead insects found in any
sample (CIPM=9). All grain for long-term storage was stored at 14-15% moisture
content (GMP=9). The company was attendant to formation of spout lines in bin cores
and routinely practiced coring of bins; no spreaders were used (GMP=8). The company
also reported using rare-earth magnets on incoming grain. Overall scores for receiving
were CIPM=9.0 and GMP=8.5.
Aeration
All bins reportedly had aeration fans. The large round steel bins each had a single large
at 75 hp that was connected to a sub-floor system of aeration ducts. Concrete silos were
equipped with down-flow aeration. The company scored itself as GMP=9 for adequate
aeration. The company’s objective was to cool grain to below 50 F as soon as possible
after loading (CIPM=9) and the cooling zone was always monitored with thermocouples
(CIPM=10). The two large steel bins each had 26 thermocouple cables that each had 17
sensing points. The concrete silos had one cable in the center of each that had 17
thermocouples at 7-foot spacing. The manager did not consider condensation at roof
spouts a big issue, so engineering to minimize this was not stressed (GMP=4).
Nevertheless, adequate roof venting was provided for all bins (GMP=9). Automatic fan
controllers were not used. Overall scores for aeration were CIPM=9.5 and GMP=7.3.
Monitoring
The company reported that monitoring grain temperatures, reportedly daily
(presumably with electronic data acquisition) was extremely important, and they gave
themselves a CIPM=10 for this practice. Bin cores were not checked for insects or
moisture, and grain probe traps were not used. Grain surfaces and the insides of bins
were apparently checked on some periodic basis for moisture or pest problems, but the
company assessed themselves at only GMP=6 for each of these. Inspections for rodents
were considered critical, but the company reported only a CIP=7 for this.
Pesticide Use
The company reported that fumigants were rarely used, thus no re-circulation
systems were not in place; only emergency situations would elicit the use of phosphine.
The only residual insecticide reported was the use of Actellic on the inside surface of
empty bins following a yearly cleaning of the bin tops.
Safety and Education
The company gave themselves a score of “10” for all safety practices and safety
training queried. Managers and key employees would attempt to attend at least one IPM
workshop a year; grain graders were routinely trained in sampling and grading, and the
company was religious in having monthly safety training for employees. Although no
formal training in IPM and storage methods were given to grain suppliers, the company
has regular contact with all suppliers and transfers relevant information on a regular,
though informal, basis.
45
Elevator 6: Wheat
Three PIs visited this wheat storage and milling facility in western Michigan. Much of
this flour is sold for use in breakfast cereal products. The firm consists of two major
operations, a grain receiving and storage facility and a flour mill. Our interview with the
senior vice president focused primarily on the grain receiving and storage part of the
business.
Facility Description.
Grain storage capacity currently is approximately 2.8M bushels. A concrete elevator
holds 1M bu. and the remaining 1.8 M bu is in round steel bins. The steel bins are
composed of 4 ea. 35K bu. bins (w/1 leg), 6 ea. 150K bu. bins (w/ 3 legs), and 2 ea. 500K
bu. bins (w/one leg).
Commodities Stored
All grain purchased and stored is wheat, mostly soft white and soft red. Some hard red
(e.g. from Nebraska and Kansas) and dark northern spring (or the equivalent) from
Canada is railed in on the basis of federal grades to blend in to meet buyers’ protein
specifications. All of the firm’s facilities are at this location.
Sanitation
A full-time staff person is in charge of sanitation at the facility. All bins are cleaned
before the new crop is stored at harvest time (CIPM=9). In most years, most of the bins
are empty before the next harvest. This permits cleaning the bins before harvest, and also
means that only a small amount of grain is carried over, and this small amount may be
stored up to 15 months. Each of the 250K bu bins requires 3 people about 1 week to
clean and to do normal repair/maintenance prior to storage. The company brings
scaffolding into each bin to be able to sweep down the sides. Steel bins are cleaned more
thoroughly since the sides are corrugated and bottoms are not sloped as the concrete tanks
are. The manager reported using a regular housekeeping checklist (CIPM=8). In the
early to mid-1980s the company made an explicit decision to avoid pesticides to the
extent possible, presumably even if non-pesticide practices were more expensive. Thus
spray-down of empty bins with residual insecticides was not routinely practiced, though
the manager indicated it occurs in some instances. Cleaning of spills, control of grass
and weeds, repair of bin leaks and security of fan an conveyor transitions were all
regarded as critical IPM points by the manager (CIPM=9 for each). The company uses a
contracted rodent control service for inside and outside treatment (CIPM=9), but admitted
that bird and rodent-proofing the facility was a concern, but not always achievable
(GMP=9). The company reported and additional practice of cleaning elevator boots on a
monthly schedule (CIPM=9). Average CIPM score was 8.9 and GMP was 9.0.
46
Loading and Receiving
The firm religiously samples all incoming grain for insects moisture and other factors
(CIPM=10). All incoming truck-loads are sampled with a minimum of 5 manual probe
samples. Samples are tested for dockage, moisture, insects, and other grade factors. The
company rejects any truck in which one or more insects, whether dead or alive, is found
(CIPM=10). All received grain must be a safe storage moisture levels (CIPM=10). They
reject grain that is more than 18% moisture, and pay on a 13.5% moisture basis and
charge a drying fee. Wet grain is consequently dried down to about 13.5% moisture.
This company does not have preferred suppliers because they find that most suppliers
know that the load will be rejected if it doesn’t meet standards. However, they have
identified a small number of producers/elevators who have not been reliable suppliers and
would probably not purchase grain from them. The company specifies in purchase
contracts that no residual pesticides are to be used on grain. This is checked randomly by
sending samples out to a lab. The company reportedly uses no grain spreading, leveling
or coring methods to reduce fine material in spout lines. The average CIPM score for
loading and receiving was 10.0.
Aeration
All bins but one are equipped with down-flow aeration systems; the company reported
adequate aeration on the whole facility and considered this a critical point (CIPM=10).
Aeration fans run from mid-August to mid November with a target for grain cooling of
60 F as soon as possible after storage (CIPM=10). They don’t cool much below 60 F
because colder wheat will not mill as well (tempering doesn’t work as well with grain
cooler than this). Automatic aeration controllers are not used. The fans run continuously
in the fall unless the weather becomes warm. The manager estimated 2.5 months of fan
use at 30 days/month and 24 hours/day. Thermocouples are checked regularly to
monitoring the cooling front (CIPM=10). All bin roofs have adequate venting
(CIPM=10). Average CIPM score was 10.0.
Monitoring
Grain temperatures are monitoring bi-weekly during the aeration cooling period in the
fall, and then temperatures are given spot checks after that (CIPM=9). The company
reported doing no sampling, trapping or other kinds of monitoring for insects. The
manager reported monitoring grain quality (e.g., grade factors) on a regular basis
throughout the year.
Overall IPM Score: The average score for critical IPM (CIPM) points by this company
was 9.5. Only bird and rodent-proofing was a GMP (9.0), and this was due to do a
concern, but inability, to follow through as a critical point. The company prides itself in
storing and producing high quality products, and clearly puts a lot of effort into
preventive IPM practices such as sanitation, receipt of high quality grain and attention to
rapid and effective grain cooling.
47
Pesticide Use Practices
As indicated above, the company maintains an essentially insecticide-free policy for grain
management. The do not use residual insecticide sprays except in one old bin that is not
sealed as well as it should be because of structural problems. The company reports never
using fumigants on their stored grain. Methyl bromide was used in the flour mill
approximately 3-4 times in the last 8-9 years. Prior to 1984 the company used methyl
bromide on a regular basis, as many mills do presently. At one time the facility was
certified organic, but the market was too small to be worth it, and they couldn’t guarantee
supplier practices. Nevertheless, they strive for chemical and residue-free commodity
with effective insect suppression through preventive IPM.
Safety and Education
Pesticide safety issues reported were all related to the flour mill and not the grain storage
department. Two certified fumigant applicators are on staff in the mill (GMP=10). They
report obtaining safe air samples prior to entry following a fumigation (GMP=10), and
they have all appropriate personal protection equipment; an SCBA (self-contained
breathing apparatus) is on site (GMP=10). Fit testing for respiratory equipment is
conducting annually and appropriate safety plans and emergency action plans are in
place. Managers and key employees reportedly attend two grain management or
pesticide training workshops a year, such as those offered by private educators like
Association of Operative Millers or Fumigation Services and Supply. In-house safety
meetings for employees are conducted two or more times a year. The company does not
provide any formal educational programs to its grain suppliers. Company grain graders
are professionally trained.
Observations and Additional Comments
1) Cleanliness around steel bins was good, but the manager admitted it could be
improved. Workers were cleaning out one 250K bin at the time of the interview.
Grain in this bin smelled sour, perhaps because of water leak. That part of the state
had received a lot of rain recently. Puddles were observed around base of bins, and
water was observed in below ground areas such as loading pits.
2) This year and last year vomitoxin has been a problem. This facility tests each source
of grain for vomitoxin. Testing required that a truck wait to unload for the 20-45
minutes the test takes; after a pattern of low vomitoxin levels is established by a
particular supplier the company may allow truck to unload before test is completed
until another load tests positive.
3) Aeration systems are not cleaned every year before the new harvest unless problems
are obvious, such as a buildup of grain under the floor.
48
4) Some savings in electricity would likely be possible if fan capacity was increased,
and if automatic temperature controllers were used to only run fans when outside air
is cooler than grain.
5) Electricity provider bases prices for year on peak load at any time in previous year.
To save electricity costs the facility keeps aeration fans off until harvest-time
electricity loads are over.
6) Cost data on labor, overall sanitation, and electricity were generously provided by the
manager and used in the economic analysis below.
49
Elevator 7: Wheat
Three PIs conducted this IPM assessment at two locations owned by one company
in eastern Michigan. The first location (Elevator 7) was the grain elevator and flour mill
at the company headquarters. The second location (Elevator 8, described below) was a
country elevator located just 4-5 miles north of the main office. We learned that the
company owns several mills and supplies food grade wheat flour to several breakfast
cereal and pastry manufacturers. Specific wheat components such as bran and germ are
isolated and sold to specialty markets. The mill also cleans and prepares whole wheat
(unmilled) berries to sell for breakfast cereal use, such as for flakes. We met with the
head miller and worked through the IPM checklist with him.
Facility Description
The total storage capacity was approximately 450,000 bu. All storage is in concrete silos
comprised of one large silo at 260,000 bu, 9 silos of medium size at about 15,000 bu each
and a series of eight small silos totaling 60,000 bu. All the storage serves the mill
operation and no grain stays in storage longer than one to a few months. Thus no bins at
this location were considered to be “long-term” storage. The mill was planning on not
taking in harvest wheat this year (and typically took in very little at past harvests) and
they relied on nearby elevators for obtaining wheat throughout the year. The large silo
could supply the mill operation for about one month. Most wheat received would go to
the big silo, though it seemed that some wheat with special qualities, either good (e.g.,
size or protein) or bad (presence of vomitoxin) was segregated into the complex of nine
15K bu concrete silos. Wheat from the large silo moved to a preliminary cleaning
process and then was stored in the small silos for a period of a few days before it was
further cleaned then tempered and milled.
Commodities Stored
All grain stored and milled by this company is winter wheat, with 95% being soft white
and about 5% soft red. The flour that is not sent to their major customers is packaged and
sold for pastries, cake flour, etc.
Sanitation
The manager reported that they did a weekly sanitation inspection as part of a SOP and
that the results of an inspection were recorded monthly (CIPM=7). They have a
company-wide food safety committee composed of 5 people that inspect the 5 mills in the
U.S. on a rotating schedule. He reported doing an annual clean-out of all bins (CIPM=9)
and a clean-out of the aeration systems every other year. This cleaning requires 20 man-
hours for cleaning in off-year for the big silo, but only 10 man-hours during alternate
years when they don’t pull gratings up. Residual sprays were used in empty bins prior to
loading (CIPM=9). Bin floors at 4 feet from the sides, and walls 4 feet from the floor
were treated with a residual spray of Tempo. Clean-ups are made of trash spills as they
occur (CIPM=8). Most areas around bins are paved, but grass and weed control is done
50
in all cases that apply (CIPM=10). Leaks in bins and in transitions for fans and
conveyors are repaired following regular inspection (CIPM=9 for each). An in-house
rodent control program is in place that uses approximately 100 traps and bait stations
(CIPM=9). The company attends to bird and rodent-proofing with screens, hardware
cloth and door seals (CIPM=9). The company reported cleaning elevator boots monthly
and sprays then with a mold inhibitor (CIPM=7). Dump pits are cleaned as needed and
dust control is used. The average IPM score for sanitation was 8.5.
Loading and Receiving
The company does not have a formal system of using preferred suppliers, but they plan to
start doing inspections of bigger suppliers due partly to pressure from their customers to
have preferred supplier list (GMP=5). Thus they are working toward a guaranteed
suppliers list. Incoming wheat is inspected for various factors (CIPM=9).
Approximately 5 min. is needed to take a sample and conduct the inspection. The
company is beginning a program of holding a sample for 13 months so that they can trace
any problems that show up later. They don’t tell farmers who supply them what to grow
or how to grow, but they do know which producers supply consistently high quality or
consistently low quality wheat. If 1 live or 2 dead insects are detected, the load is
rejected (CIPM=10). No fumigation is done at this mill-elevator facility, so they can not
accept any grain with insects. All grain taken for storage must be at 13.8% moisture
content or less (CIPM=10). Cleaning with a clipper device is done at load-out to the mill,
but the company did not report any special methods to avoid fines in spout-lines of
storage bins (GMP=7). The overall loading and receiving scores were CIPM=9.7 and
GMP=6.0.
Aeration
The company reported that all bins have adequate aeration and that fans are used to cool
grain appropriately (CIPM=8). At country elevator receiving sites the incoming grain
after harvest is cooled down to 65-70 degrees F initially, then fumigated, and then cool
down to 50 degrees F for longer term storage (CIPM=9). Thermocouples are checked
every two weeks to monitoring the cooling zone movement (CIPM=9). Bins are properly
engineered for avoiding condensation, but this is rarely an issue because they use down-
flow aeration (CIPM=10). Bin roofs are adequately vented (CIPM-9) and automatic
aeration controllers are in use on only some of the bins (GMP=6). Average scores for
loading a receiving were CIPM=9.7 and GMP=6.0.
Monitoring
Grain temperatures in all bins are checked every two weeks throughout the whole year
(CIPM=8). Grain samples are taken from the tops of the small bins each month to check
for insects (CIPM=7). No other grain sampling or trapping is conducted for insect
monitoring. Monitoring for rodents is done on a regular basis by inspection of traps
(CIPM=9). Bins are checked monthly for water leaks (GMP=7). Samples of grain are
pulled from each bin every quarter and sent to a lab for analysis; presumably this is for
grain quality, but specific details of analysis were not obtained. Overall scores for
monitoring were CIPM=8.0 and GMP=7.0.
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Overall IPM Score: The overall IPM scores for this facility were CIPM=8.8 and
GMP=6.3. The company seemed very attentive to important preventive IPM measures,
but it was clear that grain was not stored here very long before milling, so pest problems
rarely had time to manifest themselves.
Pesticide Use Practices
The company reported no use of residual pesticides on grain (CIPM=10) and they would
reject loads of incoming grain with known pesticide residues (CIPM=9). Fumigation is
done primarily at country elevators, but at this mill site the small silos are fumigated once
per year simply because the grain in them is stored for a longer time than in other silos
(CIPM=10). This fumigation is done by an outside contractor who uses a closed-loop
fumigation method (CIPM=10). DE is not used in any cases, and no top-dressing of any
kind is ever applied to any grain bins (GMP=10). Rail cars of outbound product are
fumigated only if this is specified by the customer; flour cars are typically well-sealed for
this purpose. When the small bins and the mill are fumigated the entire facility is closed
for 36 hrs. Grain fumigation reportedly cost less than 2 cents/bu from an outside
contractor. Although mill IPM was not the focus of this study, the manager volunteered
that they are considering the use of fogging (aerosol treatments) and targeted use of
ECO
2
FUME (cylinder-based phosphine) as alternative to methyl bromide in the future.
The manager indicated that (in the mill) the red flour beetle was the worst insect, with
some trouble from Indian meal moth.
Safety and Education
The company reported having four certified pesticide applicators on site (GMP=10). Air
samples during fumigation are monitored with Draeger tubes (CIPM=10). An SCBA
and other required personal protective equipment are available on site (CIPM=10).
Respiratory equipment fit testing and PPE training are conducted on some regular basis
(GMP=6). Written safety and emergency action plans are in use and available (GMP=8
for each). Managers and employees attend some outside education programs for either
grain management or pesticide use, but generally cannot obtain continuing education
credits and thus must re-take their certification tests every 3 years (GMP=5). The
elevator provides some sort of educational programs to their suppliers (GMP=7) and
company grain graders receive some training throughout the year (GMP=5). Regular
safety meetings for employees are offered (GMP=7).
52
Elevator 8: Wheat
This facility is the country elevator located 5 miles north of Elevator 7 that supplies that
elevator with most of its wheat needed for milling throughout the year. Elevators 7 and 8
are owned by the same milling company and were visited by the same team of three PIs.
Facility Description
Total storage capacity is about 1 million bushels, with 250,000 bu in a concrete elevator
and the remainder in 5 steel bins at capacities of 150,000 bu each. The facility goes
through about 2.5 complete volumes of grain a year. A 15-car train loading facility is on
site.
Commodities Stored
Of the 2.5 million bushels stored, 1 million bu are corn, 850,000 bu are wheat and the
remainder are soybeans and navy beans. The facility houses a small navy bean
processing plant with a throughput of 3,500 bu/hr. All the stored wheat stays with the
company (i.e., moved to the nearby Elevator 7), while the corn and soybeans are sold
outside to an ethanol plant in Canada, a feed mill in Canada and for livestock feed in the
U.S. Processed navy beans go primarily for export to the U.K.
Sanitation
For this section and others the manager of this facility chose to evaluate all practices as
Good Management Practices and did not feel that any practice could be considered a
critical point. A monthly sanitation inspection if conducted of the facility (GMP=8). All
empty bins are cleaned out prior to loading new grain (GMP=9). Empty steel bins are
given a spray with Tempo for residual insect control, and some concrete silos are treated
(GMP=9). Spilled grain is cleaned up and grass and weeds are controlled around bins
(GMP=9 for each). Holes in bins are sealed to prevent water and insect entry (GMP=9).
A monthly rodent control program is in place that uses traps and bait stations (GMP=7),
and the facility is protected from entry by birds and rodents (GMP=8). The company also
reported that they clean the elevator boots and dump bits, and wash these out with a
Chlorox solution. Average score for sanitation was GMP=8.5.
Loading and Receiving
Most grain is received from preferred supplies (GMP=9). Wheat is received at harvest
during the first week of July and most of it is moved out by October. Al incoming grain
is sampled and evaluated for grade factors at a rate of 2 minutes pre load (GMP=10).
Any load containing one or more live insects or two or more dead insects will be rejected
or treated before storage (GMP=10). Grain is stored only at safe moisture levels
(GMP=9). Wheat is segregated by moisture and will be dried dry if it is greater than
14.2%. Supplier will be charged for shrink plus a drying charge if over a particular level
(not specified in the interview). About 10% of all loads received need some drying.
53
Testing for vomitoxin is conducted in some cases. All bins are cored as part of a standard
practice after loading to reduce the fines in the spout line (GMP=9). Average score for
loading receiving was GMP=9.5.
Aeration
All bins are aerated to cool grain using down-flow aeration (GMP=10). Grain is cooled
to temperatures between 60 and 45 F (GMP=10) and the cooling zones are checked with
thermocouples (GMP=10). Cooling cycles take approximately 120 hours using 3 HP
motors. The company reported that bins are engineered to minimize condensation
(GMP=6), roof venting is adequate (GMP=7) and the automatic aeration controllers are
used (GMP=7) to some extent. However, a separate statement was made that no aeration
controllers are available. Average score for aeration was GMP=8.3.
Monitoring
Grain temperature in all bins are checked weekly throughout the entire year (GMP=10).
The surface of grain bins are checked monthly for insects and leaks (GMP=10). No bin
cores, trap or other forms of monitoring are used for insect detection. Grain is routinely
sampled upon load-out to check quality. Average score for monitoring was GMP=8.2.
Overall IPM Score: The average IPM score for this facility was GMP=8.6. This
elevator is typical of many northern grain elevators that keep their facility clean in that
they can prevent insect problems by routine sanitation and effective cooling of grain after
storage.
Pesticide Use and Practices
No residual insecticides are ever applied to grain (GMP=10) and no grain is received with
residues (GMP=10), though the company reported that they did not test for residues.
Fumigation is not conducted on a routine basis, but any carryover wheat is fumigated by
a contractor using re-circulation when needed (GMP=10). No DE or top-dresses of any
kind are used (GMP=10. Aside from empty bin sprays with Tempo, insecticide use is
minimal to non-existent at this facility.
Safety and Education
One employee, the manager, is certified in fumigation (GMP=10). No air samples are
taken due to the virtual non-use of fumigants. The company reported that all necessary
PPE is available on site (GMP=10) and that fit-testing of respiratory equipment is done
regularly (GMP=8). Written safety and emergency action plans are in use and available
(GMP=10). The company reported that employees attend outside training programs
(GMP=5) and that company grain graders receive specialized training (GMP=10). Safety
meetings are provided for employees approximately 14-18 times a year (GMP=10). The
elevator does not provide much training to suppliers regarding grain IPM (GMP=3).
54
Costs and Benefits of IPM in Grain Elevators
Businesses that handle stored grain products have economic incentives to control
insects. Traditional control measures, such as pesticides, have been cost-effective.
However, insect adaptation and resistance have reduced effectiveness of some pesticides,
and regulatory constraints have eliminated entire classes of pesticides. Also, consumers
are increasingly sensitive to the possibility of pesticide residues in food products.
Alternative Integrated Pest Management (IPM) measures that reduce use of pesticides are
being developed, but businesses often are reluctant to invest in the facilities and training
necessary to use new technology without better information on whether the expected
payoff will cover the costs of the investment.
A key factor in the adoption of IPM or any change in management systems is the
costs and benefits associated with the change. Cost-benefit analysis refers to the formal
process of comparing the costs and benefits of a proposed change. Simply put, a cost
reduces a decision-maker’s objective and a benefit contributes to the objective. In the
case of agribusiness managers, a major objective is to maximize net income. For this
reason, most cost-benefit analyses concentrate on how a proposed management change
will impact revenues and costs. Decision makers also have other objectives, such as
minimizing risks. These objectives can also be considered within the context of cost-
benefit analysis, although they often are more difficult to quantify.
Studies on the economic evaluation of IPM strategies and practices have been
reviewed by Norton and Mullen (1994). In general, implementing stored grain IPM
programs typically involves increased costs for sanitation, monitoring and, in some cases,
facility modifications to improve sanitation and grain temperature monitoring and to
facilitate effective fumigations when needed. Benefits include: potentially lower pest
damage costs, particularly where insects have developed resistance to traditional
pesticides or where some pesticides have been eliminated by regulatory authorities;
reduced costs for grain turning and pesticides; reduced risk of pesticide residues; reduced
risk of worker injury; and reduced environmental damage. IPM systems may also open
up market opportunities and/or maintain access to existing market outlets which are
increasingly concerned about grain quality, insect presence and pesticide residues. In
addition, IPM strategies are more management intensive and require more information.
They may also require more labor for monitoring and sanitation. Also, some decision
makers may believe that use of IPM strategies may have greater risk of failing to control
insects, compared to conventional strategies such as routine fumigation.
Reduced Insect Damage and “Infested” Grain
One of the major objectives of a manger is to reduce insect damage costs and
loads rejected for infestation. Insects reduce grain value by lowering grade and triggering
discounts or rejected loads. U.S. Grade standards for wheat include the percentage of
damaged kernels that include insect damaged kernels (IDK) as well as other types of
storage and field damage. Wheat with more than 32 IDK per 100-gram sample does not
meet the standards for any of the numerical grades and is designated “U.S. Sample
55
Grade”. Sample grade wheat must be used for non-food uses at substantially lower value.
Domestic and international buyers typically include much more stringent standards for
IDK on grain contracts.
Wheat containing two or more insects injurious to stored grain per sample
receives the special designation of “infested”. In addition to examining for insects the
grain samples that are obtained for grain grading purposes, many buyers are initiating
separate samples for insects. One common practice is to “crack” the hopper slide gates of
grain carriers over top of a tarp. Many food processors reject loads if a single live insect
is detected in the grain from the hopper bottom. Terminal elevators and export elevators
are rapidly moving toward a zero tolerance. In the past, country elevators often accepted
infested grain with a market discount; often the discount was essentially a charge for
fumigating the grain. Historically, market penalties for delivering “infested” wheat to
Kansas elevators ranged from $0.00 to $0.60 per bushel (Reed et al., 1989). Anecdotal
evidence suggests that penalties may have increased in recent years.
The cost of a rejected load can be a substantial percentage (10-20%) of the value
of a lot of grain. A single insect-infested sample can cause rejection of an entire
truckload, trainload or barge of grain. If rejected, the grain must be either transported to
another market outlet with less stringent standards or to a location where it can be legally
fumigated. The economic impact depends on the relative price at other market outlets
and the transportation and fumigation costs involved. The cost of rejected loads are the
single most important pest risk factor for most elevator grain managers. A well-designed
IPM program can reduce the occurrence of rejected loads without the high cost of routine
“preventive” fumigations.
Reduced Pesticide Costs
Fumigation costs can often be reduced or, in some cases, even eliminated by
using nonchemical pest management methods. The total cost of fumigation includes the
cost of the actual fumigant, materials used to seal the bins, safety placards, air monitoring
tubes and other materials. The labor costs for sealing, applying fumigant, air monitoring,
unsealing and deplacarding are also major costs of fumigation. Overhead costs such as
the ownership costs of respiratory protection and other personal protection equipment
should also be considered as a cost of fumigation. Fumigation costs can be 8–13% of an
elevator’s total grain handling and storage income.
Other Benefits
Other benefits are more subjective and difficult to quantify for an individual
manager. Increased adoption of IPM practices likely will lead to less resistance by
insects to remaining pesticides, increased worker safety, and lower risk of insect damage
and infestation in the long run. Also, there is a lower likelihood of detectable pesticide
residues. Substantial proportions of grain exported from the U.S. contain detectable
levels of insecticides such as Malathion and Reldan (e.g. over 50-70% of wheat samples
with these, USDA AMS 1998), thus foreign buyers may pay premiums for residue-free
grain.
56
IPM Implementation Costs
Implementing stored grain IPM often requires facility modifications to improve
sanitation, grain temperature monitoring and control, and to improve the effectiveness of
fumigation. The adoption of an IPM-based management system also involves increased
costs for sanitation, labor and/or electricity to level bins after filling, labor and material
costs for more intensive insect monitoring and the energy costs of grain aeration. In most
cases elevators have adopted IPM without hiring additional personnel, but rather have
redirected existing personnel. Recurring costs that tend to decrease as the degree of IPM
adoption increases include the costs of fumigation and grain turning.
Facility Modification
In some cases, adopting IPM will require facility modification to improve
sanitation, measurement and control of grain temperature and the effectiveness of
fumigation. Modifications that enhance sanitation would include the replacement of open
belts with enclosed conveyors for dust control, addition of dust control systems for some
enclosed areas of the facility and modification of aeration floors to allow removal and
cleaning.
Modifications related to temperature control include the installation of
thermocouple and remote read-outs, installation and upgrading of aeration systems, use
of automatic aeration controllers, and when appropriate, the use of grain chillers.
Modifications to improve fumigation include bin sealing, modifications to roof vents,
aeration ducts, and grain distributors to facilitate easy sealing or removal and the
installation of re-circulation fumigation systems. The adoption of re-circulation
fumigation systems can be particularly important for concrete storage facilities.
Although they typically are fumigated using pellet dispensers while turning grain, the re-
circulation system allows the manager to separate the timing of the fumigation from the
timing of grain turning.
Economic Analysis of IPM Strategies for Insects in Stored Products
This section describes calculation of costs of alternative strategies for control of
insects in the grain storage section of food processing facilities. In particular, costs of
IPM strategies are compared with those of conventional pest control strategies, including
routine fumigation. Components of the strategies considered include sampling,
monitoring, aeration, fumigation, sanitation, and use of protectants (e.g., Malathion,
Reldan). Specific costs considered include electricity (for aeration and turning), labor
(for sampling, monitoring, fumigation, and sanitation), material costs for fumigant and/or
protectant, equipment (for sampling, fumigation monitoring, and fumigation), and
management costs.
The approach used here is a versatile one that can be adapted to a variety of firm
situations by changing model parameters. Data used are those assumed to represent
conditions applicable to a typical firm. Two implications of this are: first, since the
analysis calculates costs for firm-level practices, societal costs of pesticide residues or
societal benefits of reducing pesticide applications are not considered here, except to the
57
extent that they affect the firm. For example, costs of EPA monitoring requirements for
phosphine fumigations are included in the cost of fumigation. Or, if a regulatory agency
imposed a tax on fumigants for societal goals (reducing insect resistance, for example),
the effect on the firm would be reflected in this approach by raising the cost of the
fumigant in the calculations. Second, because benefits of reducing pesticide use vary
greatly by firms, benefit calculations are not included here. Each firm should estimate
the benefits it would receive from a particular strategy that reduces pesticide use, and
subtract the costs for that strategy calculated here to get an estimated net benefit.
A later section applies this general methodology of calculating costs to two
specific firms, using empirical data gathered from the firms themselves and considering
only strategies actually employed by the firms. These firms did not provide data on
benefits to their firms of reducing chemical use, but had made the business decision to
pursue chemical-reducing strategies.
For the general approach, the particular strategies considered are:
(1) Routine fumigation (fumigation at a fixed period of time after receipt of grain),
assuming that grain must be turned for effective fumigation
(2) Routine fumigation as in (1), but with a closed-loop system
(3) Controlled aeration of grain (aeration only when outside temperatures are cooler than
grain), plus sanitation. (assumes that # of fan hours can be reduced by half to
achieve same level of cooling – benefits of lower shrinkage than with manual
aeration are not included in calculations because it is assumed that the grain is
processed in house rather than sold)
(4) Controlled aeration, plus sanitation, plus 1 sampling in which 10 samples are drawn
from various depths of each bin in which grain is stored using a PowerVac.
(5) Strategy (4), assuming that the insect sampling indicates that ½ of the bins need to be
fumigated
(6) Routine manual aeration in evening hours plus grain protectant (Reldan, at a cost of
$0.022/bu. as per Kenkel et al.)
(7) Strategy (6), except that fan hours are reduced through temperature controllers
(controlled aeration)
(8) Controlled aeration plus sanitation, plus two insect samplings several months apart
(9) Controlled aeration plus sanitation, plus one insect sampling, assuming that insect
sampling indicates that ½ of the bins need to be fumigated (using closed-loop)
(10) Controlled aeration plus sanitation, closed-loop fumigation of all bins, plus
application of a protectant.
(11) Mechanical cleaning for better aeration and insect control (in place of protectants),
plus aeration, plus sanitation
For those strategies involving fumigation, cost of sealing bins is included in labor
costs of fumigation. The cost of empty bin treatment is very low relative to other costs
(e.g. $0.000009/bu. for Malathion and $0.000076/bu. for Reldan), so it is not included
here.
58
Cost-Benefit Analysis
Figure 1 shows the annual cost of several IPM and conventional strategies in a
storage system with total capacity of 250,000 bushels. Costs considered include
equipment, chemicals, sanitation, turning, aeration, and labor. Pest control strategies
considered are the eleven strategies listed above. The lower portion of each bar (strategy)
measures labor cost. Since a significant portion of IPM costs are related to sampling, the
sampling-based IPM strategies have the highest labor costs. However, if sampling is
done upon receipt of grain, and grain is stored for less than one year (as was the case in
all subject elevators studied) much of this cost can be avoided.
The second component is aeration costs, composed primarily of electricity costs.
Aerating upon receipt of grain is less effective than aerating after outside temperatures
drop, so electricity cost is higher for the same amount of cooling. Savings can be
achieved if aeration fans are shut off when outside temperatures are higher than the grain
temperature, and turned on only when outside temperatures are lower than grain
temperature. This can be done manually, but perhaps more economically and effectively
using temperature controllers.
The third component is turning cost, composed of electricity, labor, and shrink.
Grain is emptied from one silo and transported on a moving belt to another silo within the
facility. Fumigation can be done while turning by inserting phosphine pellets or tablets
into the moving grain flow. Turning is often done in concrete silos in order to fumigate
when closed loop fumigation is not used. Turning may also be done as part of other
management practices such as blending for particular quality characteristics, to break up
sections of “fines” or “hot spots” to prevent grain infestation or spoilage.
The fourth component is sanitation, composed primarily of labor costs. This
practice includes cleaning out empty bins, elevator legs and boots, and areas surrounding
bins.
The fifth component is cost of chemicals. For both an IPM sampling strategy in
which not all of the bins are fumigated, and a closed loop fumigation which requires less
fumigant for the same level of effectiveness, fumigant costs are lower than with routine
fumigation. Closed loop fumigation would typically require 1/3 less fumigant to achieve
the same level of effectiveness, and would not require turning of the grain. Also included
in chemical costs is the cost of protectant used. Here, Reldan is assumed to be the
protectant used, at a cost of $.022/bu.
The sixth component is equipment. It is assumed for IPM strategies that sampling
equipment is required (a Power-Vac sampler is specified here), and for fumigation
strategies that fumigation equipment is needed. For closed loop fumigation, amortized
installation costs of the closed loop system are included in this cost. For IPM strategies
that do not require additional sampling while grain is in storage, this cost could be
reduced. However, both fumigation and sampling equipment costs are included where
Power-Vac sampling has determined that fumigation is needed. Also, note that once the
choice is made to acquire fumigation or sampling equipment, this cost should not be
considered when choosing among strategies.
59
It is assumed here that all strategies considered are equally effective. However,
firm managers should recognize that some strategies may be more effective than others in
their particular situations. (Little published research is available that compares
effectiveness of IPM and chemical-based strategies under a range of environmental
conditions. Work in progress by this report’s authors together with colleagues from other
institutions is evaluating effectiveness and economic risk of these and other insect
management practices.) Also, firm managers should consider and evaluate any subjective
costs. For example, fumigation may be associated with worker safety concerns, while use
of protectants may have associated concerns about residues on food products. Other
benefits of IPM strategies not quantified here include worker health safety, improved
environmental conditions, and a decline of insect resistance due to excessive use of
fumigants.
60
Costs of Pest Management Strategies
0.0000
0.0050
0.0100
0.0150
0.0200
0.0250
0.0300
0.0350
0.0400
0.0450
0.0500
Fumigation
(with
turning)
Fumigation-
Closed
Loop
Controlled
aeration,
sanitation
Controlled
aeration,
sanitation,
1 sampling
Controlled
aeration,
sanitation,
1 sampling,
1/2 of bins
f umigated
Manual
aeration in
evening
hours,
sanitation,
protectant
Controlled
aeration,
sanitation,
protectant
Controlled
aeration,
sanitation,
closed-
loop
f umigation
twice
Controlled
aeration,
sanitation,
2
samplings
Controlled
aeration,
sanitation,
1 sampling,
1/2 of bins
f umigated
closed-
loop
Controlled
aeration,
sanitation,
closed-
loop
f umigation,
protectant
Mechanical
cleaning,
controlled
aeration,
sanitation
Strategy
C
o
s
t
(
$
/
b
u
.
)
Equipment
Chemicals
Sanitation
Turning
Aeration
Labor
61
Table 1: Costs of Pest Management Strategies Shown in Figure 1
Labor Aeration Turning Sanitation Chemicals Equipment Total
Cost
Fumigation (with turning) 0.0040 0.0000 0.0134 0.0000 0.0051 0.0040 0.0266
Fumigation- Closed Loop 0.0040 0.0001 0.0000 0.0000 0.0034 0.0073 0.0149
Controlled aeration, sanitation 0.0018 0.0048 0.0000 0.0050 0.0000 0.0000 0.0116
Controlled aeration, sanitation, 1 sampling 0.0078 0.0048 0.0000 0.0050 0.0000 0.0084 0.0260
Controlled aeration, sanitation, 1 sampling, 1/2 of bins
fumigated
0.0108 0.0048 0.0058 0.0050 0.0026 0.0124 0.0414
Manual aeration in evening hours, sanitation, protectant 0.0018 0.0059 0.0000 0.0050 0.0220 0.0000 0.0346
Controlled aeration, sanitation, protectant 0.0018 0.0048 0.0000 0.0050 0.0220 0.0000 0.0336
Controlled aeration, sanitation, closed-loop fumigation
twice
0.0096 0.0048 0.0000 0.0050 0.0069 0.0073 0.0337
Controlled aeration, sanitation, 2 samplings 0.0151 0.0048 0.0000 0.0050 0.0000 0.0084 0.0333
Controlled aeration, sanitation, 1 sampling, 1/2 of bins
fumigated closed-loop
0.0080 0.0048 0.0000 0.0050 0.0017 0.0157 0.0352
Controlled aeration, sanitation, closed-loop fumigation,
protectant
0.0058 0.0048 0.0000 0.0050 0.0254 0.0073 0.0484
Mechanical cleaning, controlled aeration, sanitation 0.0018 0.0048 0.0000 0.0050 0.0000 0.0200 0.0316
62
Fumigation (with turning) costs just over 2.5¢/bu. The biggest cost component is turning
the grain for effective dispersion of the fumigant. Although it has a higher equipment
cost, closed-loop fumigation, the second bar on the graph, avoids this cost as well as
reducing chemical cost by about 1/3. It does have higher equipment cost, though. Its
cost is about 1.4¢/bu.
The third bar is controlled aeration combined with sanitation. No chemicals are
used in this strategy. Its cost is about 1.2¢/bu. The fourth bar adds to this strategy a
sampling for insects and other quality factors after grain has been in storage for a time.
This practice is expensive because it requires specialized equipment (e.g., a PowerVac)
and requires typically two workers who take several samples at various depths in each
storage bin. The cost of the fourth strategy is 2.6¢/bu. If sampling indicates that an
economic threshold of insect infestation has occurred, other treatment practices would be
utilized. These other practices could include chemical treatments such as fumigation.
Thus, the strategy represented by the fifth bar assumes that sampling has
determined that in half of the bins sampled, there is an insect infestation that requires
fumigation. This is one of the more expensive strategies because of the cost of
equipment for both sampling and fumigation, cost of turning, and labor for all of the
practices. The cost of this strategy is 4.2¢/bu. It should be noted here that comparisons
of these strategies assume that cost of appropriate equipment is part of the consideration.
If equipment has already been purchased, however, the equipment portion of these costs
should be ignored in comparisons since no additional equipment costs would be incurred.
The sixth bar represents a strategy in which aeration fans are turned on in mid-fall
as temperatures become cool and are run most evenings. Also, sanitation is practiced and
a protectant is applied. The protectant is the biggest cost component of this strategy,
amounting to more than 60% of the nearly 3.5¢/bu. The seventh bar replaces the manual
aeration with controlled aeration, running the fans only when outside temperatures are
cooler than the grain being cooled. This practice is assumed to require only half the fan
hours by more efficiently cooling the grain, reducing the cost slightly to 3.4¢/bu.
The eighth bar represents the cost of controlled aeration, sanitation, and two
samplings for insects of grain already in storage (for example, if the grain has been in
storage for longer than expected or if environmental conditions have been favorable to
insect growth, the firm may wish to sample for insects again 2-3 months after the first
sample). Note that the cost of this strategy is slightly less than the previous one,
replacing the cost of protectant with sampling costs. Similarly, the ninth bar shows
controlled aeration, sanitation, one sampling for insects, and closed-loop fumigation for
½ of the bins. The cost of this strategy is almost the same as that of the previous three
bars.
The tenth bar represents a chemically-intensive strategy that also uses some IPM
practices. Controlled aeration and sanitation are combined with closed-loop fumigation
of all bins and a protectant applied to all grain. This is the most expensive strategy
considered here, costing 4.75¢/bu. Finally, the eleventh (right-most) bar represents a
63
strategy in which the firm mechanically cleans grain before storing it, removing fines and
most foreign material in which insects thrive in an attempt to avoid use of chemicals, and
conducts controlled aeration and sanitation practices. This strategy costs 3.2¢/bu.
Observations
It is clear that a wide range of stored product management strategies is available.
Even the large number considered here does not represent all that are available.
However, several patterns emerge. First, comparing the first bar with the second bar, it is
clear that for firms that fumigate, closed-loop fumigation is more economical than non-
closed-loop fumigation, even after accounting for installation costs. Because less
fumigant is needed (about 1/3 less), chemical costs are lower, and any environmental
effects will be reduced. The biggest cost savings with closed-loop fumigation compared
with conventional fumigation is that closed-loop fumigation does not require turning of
grain, saving energy and labor costs. Moreover, because workers do not need to be in the
facility while fumigant is applied, worker safety is greatly enhanced. Also, closed-loop
fumigation is likely more effective in controlling insects because of the sustained
concentration of gas in the facility.
Second, strategies using grain protectant (bars 6, 7, and 10) are among the more
expensive strategies, since protectant itself (assuming Reldan is used) costs about 2.2¢/bu
(Kenkel et al.). Costs of IPM strategies compare quite favorably with those of strategies
using a protectant, even in a situation where insect infestation reaches the point where
partial fumigation is needed to supplement the IPM practices. For example, the seventh
strategy – Controlled aeration, sanitation, protectant – costs about the same as the ninth
strategy – Controlled aeration, sanitation, 1 sampling, ½ of bins fumigated using closed-
loop. Using a grain protectant also has potential to leave chemical residue, though this
cost is not considered here.
Third, effective, accurate sampling is labor-intensive, making it the most costly of
IPM practices considered. However, if grain is not to be stored long and if other IPM
practices such as sanitation and aeration for cooling are followed, sampling may not be
required as part of an effective IPM strategy. If in-storage sampling is not required,
sampling equipment and labor for sampling is not required, so costs of IPM strategies are
likely to be lower than those of conventional strategies.
For many IPM strategies, however, it is important that effective monitoring be
implemented as a part of the grain management program. As noted earlier, a major cost
of managing stored grain is the potential rejection of a load because of insect infestation.
Effective monitoring can detect problems before they become severe. This monitoring
does not necessarily require the extensive sampling included in the cost calculations here.
Labor costs may range from 50% to 100% of those calculated here, and sampling
equipment cost would be much lower. Of the eight elevators evaluated from site visits,
none utilized extensive sampling of grain in bins, yet had very successful IPM programs
through rigorous prevention and sanitation practices.
64
Case Studies
This methodology is applied to two specific firms analyzed as part of this project.
These firms supply product to the cereal manufacturing industry. Rather than measuring
costs of potential strategies these firms might use, the cost of these firms’ actual
strategies was estimated using data provided by the firms. These two firms were
implementing many of the practices recommended as part of an IPM approach. The
tables below indicate the major categories of pest management costs considered: Grain
Sampling, Sanitation, Aeration, Monitoring & Management of IPM, and, when needed,
cost of fumigation.
Grain Sampling
Both firms sampled grain upon receipt and tested for quality factors as well as
insects. (Thus, in-bin grain sampling could legitimately be excluded from cost of IPM for
these elevators, but it is included here for completeness.) One of the firms rejected grain
that had one or more live or dead insect. The other rejected any load that had one live or
two or more dead insects. Since these firms typically kept very little grain in storage for
more than one year (only grain that was expected to be used in processing that year was
stored), no sampling was done after grain was in storage. Sampling costs are measured
as # of samples x time per sample x wage rate of people sampling (including benefits),
divided by total number of bushels stored.
Sanitation
Both firms had regular sanitation practices. These costs are calculated as # of
hours spent on sanitation x wage rate of people performing these duties (including
benefits), divided by total number of bushels stored.
Aeration
Both firms attempted to cool grain down to approximately 65°F as soon as outside
temperatures permitted in order to slow insect activity, using aeration fans. The
electricity usage of each fan on each bin was measured using the formula ((Volts/1,000) x
Amps)/70% efficiency, and this was multiplied by the number of fans on each bin and by
the number of hours the fans were typically operated to cool the grain (as reported by the
firm). (Alternatively, to measure electricity usage of each fan, hp/fan was divided by
0.748.) This result was multiplied by the average electricity cost per kwh. For one firm,
our team observed that the fans likely were being run at times when the outside
temperature was too high for effective cooling, requiring the fans to run too long. The
table for this firm includes a column indicating the expected cost of aeration for this firm
if it were to only run fans when the outside temperature is cooler than the grain, using
aeration temperature controllers for example.
65
Monitoring & Management
The labor hours (reported by the firms) spent monitoring and managing the grain
for insect and other pest control and cleanliness is multiplied by the wage/salary rate
(including benefits) for the persons performing these duties.
Fumigation Costs
One of the firms reported fumigating only those storage facilities that stored grain
for more than several months (a small proportion of total storage). The cost of fumigation
was reported by the firm as the cost of hiring an outside contractor who used closed-loop
fumigation.
Tables 2 and 3 summarize the costs incurred by these two firms to implement their IPM
practices. As table 2 indicates, Firm 1 reported spending a large number of man-hours on
cleaning elevator boots and trash spills, a highly-recommended IPM sanitation practice.
In addition, they conducted a weekly sanitation inspection and a bi-weekly temperature
inspection. These costs brought their annual IPM costs to $0.036 per bushel.
Fumigation, when needed, would add $0.018/bu. to their pest management costs for that
portion of the grain that required fumigation.
Table 3 indicates that Firm 2 spent less hours in cleaning, even though their total storage
capacity was much higher. And, instead of paying an hourly wage for sanitation
inspection and temperature checks, they hired a Sanitation Manager on an annual salary.
Their annual IPM implementation costs summed to $0.025/bu. This facility was
somewhat less clean than Firm 1, suggesting that the lower number of hours spent in
sanitation had some consequence. This firm had lower overall IPM costs, however,
primarily because it could spread its cost over more bushels.
In spite of its lower IPM costs, though, it is likely that this firm could reduce those
costs even further with no sacrifice in effectiveness. The engineer on this project noted
that the firm was likely running its aeration fans far more hours than needed for effective
temperature control. The firm reported that it ran its aeration fans continuously from
August through mid-November. Using temperature controllers to only run fans when
outside temperatures are colder than the grain would greatly reduce required fan hours,
which would in turn reduce aeration costs from about $0.016/bu. to $0.002/bu., an 85%
reduction. This would reduce its IPM costs by 40% to about $0.01/bu. (It is possible that
the firm overstated its use of aeration fans, by saying that they ran the fans continuously
when in fact they only ran the fans in, say, the evening hours. In that case, these potential
savings are overestimated.)
66
Table 2: Costs of IPM Practices Currently Used by Firm #1
Cost Category
Man-hours Bin Size
(bu)
Cooling
hours
#
fans
Volts/
fan
Amps/
fan
hp/
fan
Annual Cost
($/bu)
Sanitation
Cleaning Bins 20 160,000 $0.0028
Cleaning elevator boots, trash spills 160 $0.0078
Aeration
electricity 260,000 200 1 100 $0.0123
15,000 150
Grain Sampling
5 minutes per load x 2 samples per load 0.167 $0.0041
Monitoring & Management of IPM
weekly sanitation inspection 104 $0.0051
check temperature every 2 weeks 78 $0.0038
IPM Cost/bu
$0.0359
Fumigation (when needed) 0.018
Parameters
Electricity Cost ($/kwh) $0.12
Labor Cost ($/hr) $22.00
Total Capacity (bu) 450,000
truckload (bu.) 900
67
Table 3: Costs of IPM Practices Currently Used by Firm 2
Cost Category
Man-hours Bin Size
(bu)
Cooling
hours
#
fans
Volts/
fan
Amps/
fan
hp/
fan
Annual
Cost
($/bu)
Potential
Cost
($/bu)
Sanitation
Cleaning Bins 40 250,000 $0.00352
60 500,000 $0.00264
Cleaning elevator boots, trash spills 0 $0.00000
Aeration
could be
Electricity 150,000 1,800 2 460 12.8 10 $0.01615 $0.0022
500,000 1,800 4 460 21.6 20 $0.01635 $0.0027
Grain Sampling
3 minutes per load x 2 samples per load 0.1000 $0.00244
Monitoring & Management of IPM
Sanitation Manager $0.00218
($47K/yr + benefits)
IPM Cost ($/bu)
$0.02450
Parameters
Electricity Cost ($/kwh) $0.08
Labor Cost ($/hr) $22.00 (for sanitation)
Total Capacity (bu) 28,000,000
truckload (bu) 900
68
Conclusions
• All facilities studied were considered very good to excellent in current pest
management practices. Therefore, they provided excellent case studies for
general U.S. elevator adoption and use of IPM.
• Prevention–based IPM was practiced almost exclusively, with very little
monitoring for pests. However, most elevators maintained an excellent
surveillance program for insect and moisture problems, using temperature
monitoring and aeration as major IPM tools.
• Essentially all facilities rejected incoming grain that contained either live or dead
stored grain insects. Most received grain from providers of known reliable
quality, or in some cases from contracted providers.
• Very little chemical insecticide use was recorded throughout the study, typically
only as a surface treatment to empty bins. No direct admixture of grain
protectants was reported. Fumigants were used more in southern locations
(Illinois and Missouri) compared to very little fumigant use in the north
(Michigan, Minnesota and Idaho).
• Cooling grain with aeration was key to successful grain storage at all facilities,
and was easier to effectively practice at more northern locations. Effective
aeration of extremely large bins proved problematic due to inadequate grain
spreading (avoiding the “spout-line” of fines) and aeration capacity, and should be
addressed with given engineering recommendations from the case studies of two
sites.
• The cost of using IPM can be relatively low or high depending on the given
situation. For example, sanitation plus aeration was the cheapest scenario, but
this may not be effective given a poorly engineered facility in a southern location.
In the south, more attention to insect monitoring and timely fumigation followed
by controlled aeration will be needed.
• The tangible benefits of IPM are clearly the avoidance of costs that might occur
with insect infestation and the resulting loss of grain quality. Since such benefits
may be on an economic par with chemical-based pest controls, the more
intangible and perhaps greater benefits of IPM accrue from low chemical input in
some market advantage, improved consumer perception, or potential societal
benefits, which are beyond the scope if this study.
• Successful elevators that directly supply the breakfast food industry clearly are
maintaining a very high level of sanitation and pest management to deliver high
quality product and maintain market presence.
69
References
Danley, Ronda. Choosing Among Phosphine Monitoring Devices: An Economic and
Qualitative Analysis, M.S. Thesis in progress, Oklahoma State University.
Kenkel, P., J. T. Criswell, G. Cuperus, R. T. Noyes, K. Anderson, W.S> Fargo, K.
Shelton, W. P. Morrison and B. Adam. 1994. Current Managemetn Practices and
Impact on Pesticide Loss in the Hard Red Winter Wheat Post-harvest System.
Oklhoma Cooperative Extension Service Publ. E-930. Stilwlater, OK.
Krischik, V., G. Cuperus and D. Galliart. 1995. Stored Product Management.
Oklahoma Cooperative Extension Service Publ. E-912. Stillwater, OK.
Norton, G. W. and J. Mullen. 1994. Economic evaluation of integrated pest management
programs. Virginia Cooperative Extension Publication 448-120, Virginia Tech,
Blacksburg, VA.
Phillips, T. W., R. C. Berberet and G. W. Cuperus. 2000. Post-Harvest Integrated Pest
Management. pp. 2690-2701 In: Francis, F. J., ed. “Encyclopedia of Food
Science and Technology, 2
nd
Edition.” John Wiley and Sons, Inc. New York
Rulon, Rodney A., Dirk E. Maier, and Mike D. Boehlje. “A post-harvest economic
model to evaluate grain chilling as an IPM technology.” Journal of Stored
Product Research 35(1999):369-83.
Rulon, Rodney Alexander. In-Bin Conditioning and Pest Management of Popcorn Using
Chilled Aeration, M.S.Thesis, Purdue University, May 1996.
USDA Agricultural Marketing Service. 1998. Pesticide Data Program, Annual
Summary Calendar Year 1997.
70
Appendices
Appendix A. Following is the “Ideal IPM Elevator Checklist and Facility Audit” form
that was used as the primary data gathering vehicle at all study elevators. Additional
information was gathered through personal interviews that initially centered around the
checklist
71
IPM Checklist and Facility Audit
Instructions:
For each management area decide whether it is a Critical IPM Point or a Good
Management Practice. Critical IPM Points are the key aspects of your stored grain
system. Most facilities will have 3-5 Critical IPM points per management category. Good
Management Practices are the areas which may be important but are not the cornerstone of
successful grain management in your storage environment.
For each practice rate your elevator on a scale of 1 to 10 (with 1 being poor and 10 being
ideal) in the appropriate column. If the practice or management area does not apply to your
situation, leave it blank.
When you are finished, average your scores for each column. You may also want to
calculate your average score for each sub-category (Sanitation, Loading, Aeration,
Monitoring, Pesticide Use, and Education).
Date:
Location
Storage Volume
Steel
Concrete
Flat
Practice
Score 1 to 10 (10=ideal)
Critical
IPM Point
Good
Management
Practice
Sanitation
Weekly/Biweekly Sanitation/housekeeping checklist
Complete bin/silo clean out prior to filing (at least annually)
Control residual insect populations in empty bins prior to
filling (spray down or fumigate)
Keep trash/spilled grain and fines accumulation cleaned
around bins/dumps/drives--overall facility clean
Control grass/weeds around bins/silos
Base and sidewall openings sealed for water leaks
Aeration fans sealed when not in use
Rodent control program in place
Facility bird and rodent proofed to eliminate grain
contamination
72
Other (specify)
Average Score for Sanitation
Receiving
Receive from a preferred supplier
Sample incoming grain for insect, moisture and other factors
Policy to Reject or Fumigate Infested Grain
All grain for long-term storage is at safe moisture levels.
Fines in spout lines eliminated through Acoring@, leveling or
use of grain spreader.
Other (specify):
Average Score for Receiving
Aeration
Bins have aeration with adequate airflow (at least .1 cfm/bu
for steel bins. .05 cfm/bu for concrete)
Grain cooled to below 65
o
F within 120 days
Cooling zone movement checked with thermocouples
Bins engineered to minimize condensation (spouts temporarily
sealed or gravity flap valves installed, or roof exhausters)
Adequate roof venting (1.5 sq. Ft./fan HP installed)
Automatic controllers installed and used
Other (specify):
Average Score for Aeration
Monitoring
Grain temperature checked every week until cooled, (bi-
weekly thereafter)
Grain surface in bins sampled for insects every 2-4 weeks
73
Bin cores checked monthly for insects and moisture (deep cup
probes, sampling moving grain etc.)
Insect probe traps in surface grain monitored weekly
Bin checked monthly for leaks, condensation, etc.
Walls and sources of water monitored for rodent sign monthly
Other (specify):
Average Score for Monitoring
OVERALL AVERAGE SCORE FOR IPM
Pesticide Use
No residual pesticides applied to grain
Fumigation based on insect action thresholds (not calender
based)
Grain quality maintained with no more than one
fumigation/year
Recirculation fumigation used to achieve maximum control
with minimum dosage
Other (specify):
Average Score for Pesticide Use
Safety
At least two fumigant applicators trained and certified
Safe air samples obtained prior to de-placarding and
bin/facility entry
Appropriate personal respiratory protection
available/maintained
Annual fit-testing and training for respiratory protection
Written safety plan in use (hot work, lock-out, tag-out, bin
entry etc.)
Written emergency action program in place
74
Other (specify):
Average Score for Safety
Education
Managers and key employees attend two grain management,
fumigation or IPM workshops per year
Grain graders trained in sampling and grading
Elevator provides IPM/Stored grain training to
producers/suppliers
Monthly safety training of employees
Other (specify):
Average Score for Education
75
Appendix B. The following survey instrument was used infrequently for information
gathering at study elevators. It is included here to indicate the breadth if information that
can be collected about an elevator facility that is relevant to IPM.
IPM CHARACTERIZATION SURVEY
FOR GRAIN ELEVATORS
by
Ronald T. Noyes, Ext. Agricultural Engineer
Philip A. Kenkel, Extension Economist
Tom Phillips, Stored Grain Research Entomologist
Oklahoma State University
Integrated pest management (IPM) is a sustainable approach to pest control that
integrates biological, cultural, physical and chemical control into systems which minimize
economic, environmental, and social risks. While elevator practices may vary by
geographic location, certain facility and equipment components are generally common to
most country and terminal grain elevators. Goals of an IPM program typically include
reducing pesticide input, reducing insect pest numbers and maintaining high grain quality.
The purpose of this checklist is to provide a standardized method of documenting
the facilities, equipment and practices that are in place or in use at an elevator at a specific
time. This listing will allow this elevator to be compared with other elevators based on use
and location for comparison of capacities, functions and management practices. An
elevator's characterization can be useful as a tool when evaluating the IPM practices and
IPM qualifications of an elevator.
The following survey lists major functions of a grain elevator. Some sections, such
as grain drying, aeration systems or grain cleaning, may not be applicable to all elevators.
Other sections, like storage structures, conveying equipment, sanitation/housekeeping
should be applicable to all elevators that are interested in using IPM.
While all elevator functions and practices are not "IPM" activities, their use may
affect or support IPM. Since the overall goal of this program is to evaluate costs vs
benefits of IPM, any key elevator function that has a major cost/benefit impact will be
reviewed and listed. Since the purpose of this sheet involves appraising a food grain
elevator for use in IPM evaluation, significant portions of this checklist and outline were
adapted from Appraising an Existing Elevator, Jan/Feb 1998 Grain Journal.
MAJOR PHYSICAL ACTIVITIES/DIVISIONS OF GRAIN ELEVATORS
Physical IPM functions of grain elevators that will be reviewed in the Elevator IPM
Characterization Survey form are:
Overall Facility
Transportation
Conveying/Blending
Cleaning/Aspiration
76
Drying/Moisture Control
Storage Systems
Temperature Control/Management
Insect Control/Management
Fumigation Systems
Sanitation/Housekeeping
IPM Record Keeping
ELEVATOR IPM CHARACTERIZATION SURVEY
Name of elevator or mill _________________________________ Date
________
Location of facility _____________________________________________________
Evaluators ____________________________________________________________
OVERALL FACILITY
The primary activity of this elevator facility is (what the elevator does):________________
Main elevator facility headhouse concrete or steel? _________________________________
_____ No. of interior elevator legs and pits? _____ No. of exterior elevator legs and pits?
Drives paved _____ or gravel _____ ? Weeds/grass mowed _____ ft from bins, silos, flats?
Area around bins, silos, flats paved or graveled ______ ft for insect habitat barrier.
Trash or moldy grain laying around the facility? ________
Fumigation supplies maintained stored in facility under lock/key_______________________
Fumigation equipment well maintained and serviceable?_____________________________
Written Sanitation/Housekeeping Plan posted for employee use?_________________
Grain sample power probe system?________________________________________
TRANSPORTATION
Rail System No. of tracks ________
Tracks paved so spilt grain can be easily cleaned up? ________________________
Loadout sidings clean and no weeds or trash? _____________________________
Dump pits clean? _____
Pit conveyors clean? ____
General track, loading and pit areas clean ?_______
Trash and spilled grain cleaned up?
____________________________________
Road/Driveway System
Roads/Drives Paved ______ Gravel ________ Dusty _____ Oiled
_________
Dump pits clean? _____
Pit conveyors clean? ____
General truck loading and pit areas clean ? _____________________
77
Surrounding area, grass and weeds mowed or graveled? ________________
Trash and spilled grain cleaned up? ____________________________________
CONVEYING
Bucket elevators -- No. of Legs _______
Leg #1 Ht.____ ft., ____ bu/hr, ____ HP;
Leg #2 Ht. ____ ft., _____ bu/hr, ___ HP;
Leg #3 Ht.____ ft., _____ bu/hr;
Leg #4 Ht. ___ ft., _____bu/hr , ____ HP;
Leg boot cleanouts accessible ________________________________________
Boots cleaned between different grains __________________________________
Conveyors -- No. U-Troughs ________; No. Augers ______; No. Drags _______
Do conveyors clean out? _______ Can conveyors be cleaned? ___________
CLEANING
No. Grain cleaners _______;
Type/brand of cleaners _________________________________________________
Are cleaners cleaned out between grains? ________________________________
DUST ASPIRATION SYSTEMS (DAS)
No. of Dust Aspiration systems ___; DAS#1 ___ HP ; DAS#2 ___ HP; DAS#3 __
HP
How often are DAS cleaned? _________________________________________
Drying/Moisture Control
No. Grain Dryers ______; make/model/type of grain dryers ___________________
_______________________________________________________________;
Dryer #1 ____ HP ;Dryer #2 ____ HP ; Dryer #3 ____ HP ;
_____________________________________________
Are dryers/conveyors cleaned out between drying operations? ________________
No. wet holding tanks (WHT) feeding dryers? _____________________
WHT cleaned between grains? _____________________
Is grain dried below 13% MC before storing? ____; If NO, what MC? _____
STORAGE SYSTEMS
Round Storage
No. round units -- Steel ___________________ Concrete __________________
Diameter _______________________________________________
Sidewall height_______________________________________________
Overall height _______________________________________________
Bushel volume_______________________________________________
Type bottom _______________________________________________
Year built _______________________________________________
78
Aeration systems _______________________________________________
Thermocouples _______________________________________________
Clean? _______________________________________________
Other description ___________________________________________________
STEEL TANKS:
Exterior: Down spouts sealable during fumigation? __________ Eaves sealed? ______;
Roof fans vibrate? _____ Roof leaks? ______
Base/sidewall junction caulked/sealed with flexible, UV resistant material? _____________
Aeration fans, blowers, transition ducts sealed except during use? ___________________
Base doors, sample points, bolt openings sealed to exclude moisture and insects? ________
Conveyors clean? ____________ Conveyor exteriors sealed to exclude insects? _______
Recirculation or closed loop fumigation (CLF) system installed/used? ____ Blower; ___HP?
Interior: Moldy grain evidence of base moisture leaks? __________________________
Galvanizing corroded on interior walls? _____
Holes visible through roof panels during daylight? ______
Down spout condensation from aeration? ________
Grain "cored" to lower peak/level surface? _____
Aeration ducts cleaned yearly? _____
Interior vertical wall stiffeners cleaned during or after bin unloading? _________________
Grain dust cleaned out of bin roof corrugations at fill cap, openings foam sealed? ________
CONCRETE SILOS AND TANKS:
Exterior: Cracks in sidewalls? ________
Down spouts sealable during fumigation? ____
Aeration ? __________ What HP? _______ Airflow rate? _________
Upflow or down flow aeration? _________________________
Aeration fans, blowers, transition ducts sealed base manhole doors, sealed to exclude
moisture and insects except during use? ____
Aeration fans on roof (upflow system)? ______
Recirculation or closed loop fumigation (CLF) system installed/used? ____; Blower ___HP?
Discharge spout outlets cleaned out each time after silo unloaded? __________________
FLAT STORAGE:
Size: Length _____ ft; width _____ft; sidewall height _____ ft., Peak height _____ ft.
Fill: Leg/down spout ____; U-trough ___ or drag ___ conveyor in peak @ ____ ft.;
Unload: Tunnel belt ___ ft. ; In-floor u-trough ___ ft.; front loader ___; Other _________
79
Aeration fans: ___ No. of ____ HP ___ axial; ___ centrifugal blowers @ _____ ft centers
Aeration ducts: ____ No. ducts ___ in-floor; ____ on-floor; ___ round; ____ half
round.
Duct pattern ___________________________________________________________
Head space ventilation fans/louvered vents in gables? _____ Fan size ___ x ___ inches; Fan
_____ HP ; Louver size ___ x ___ inches;
TEMPERATURE CONTROL/MANAGEMENT
Grain Temperature Management
Grain storage thermocouple system in place,? _____ ; maintained/used?
__________
Type of thermocouple system? ____ plugin/readout; _____ computerized to
office?
Temperatures read ___ weekly; ___ bi-weekly; ___ monthly; ____________
other.
Target grain temperatures: steel tanks ____
o
F; concrete silos ____
o
F; flats
____
o
F;
Other critical temperature points monitored?
_____________________________
Aeration Systems
No. fans on steel tanks ______ ; HP/fan ______; Total fan HP _____
No. roof vents on steel tanks ___ ; Size/vent ______; Total vent area _____
sq ft
No. fans on concrete silos ______ ; HP/fan ______; Total fan HP _____
No. roof vents on concrete silos ___ ; Size/vent ______; Total vent area
_____ sq ft
No. fans on flat storage ______ ; HP/fan ______; Total fan HP _____
No. roof vents on flat storage ___ ; Size/vent ______; Total vent area _____
sq ft
Aeration duct plan, steel tanks (Lgth/ area)
_______________________________
Aeration duct plan, concrete silos (Lgth/ area)
_____________________________
Aeration duct plan, flat storage (Lgth/ area)
______________________________
Aeration controller type/model?
80
_______________________________________
HOUSEKEEPING/SANITATION
Written housekeeping plan posted ________
Shop vacs used in open drives and well ventilated floors? ______________________
Adequate housekeeping tools? _____
IPM RECORD KEEPING
IPM Files/Record System in Place covering:
Insect monitoring program ______________________________________________
Fumigation program ___________________________________________________
Aeration operation details ______________________________________________
Grain temperature management __________________________________________
Residual pesticide use, where/when/what/amounts ____________________________
Oil dust control ______________________________________________________
Aspiration dust control _________________________________________________
Electrical utilities -- cost/benefit of IPM management changes
____________________
Other ______________________________________________________________
81
Appendix C. Protocol for estimating and assigning costs to various practices
The cost analysis is based on a framework provided by Rulon’s study on pest
management in popcorn (Rulon; Rulon et al.). A spreadsheet is used to calculate the
costs of managing stored grain for alternative insect control strategies. The spreadsheet is
divided into six worksheets. In the first worksheet, the user specifies information about
the facility. Worksheets two through five calculate insect sampling costs, aeration costs,
fumigation costs and turning costs. The sixth worksheet computes the annual operating
cost of each scenario in dollars per bushel. The first column of each worksheet contains
field names, the second column contains the numbers and costs associated with the field
names, and the third column contains an explanation of the number entered or the
formula used.
The base model computes costs for an elevator with 10 concrete silos, each with a
capacity of 26,000 bushels of grain. Each silo currently contains 25,000 bushels, totaling
250,000 bushels. The base model assumes a wheat price of $3.75/bu.
Costs are calculated on a per-bushel basis. Specific costs considered are
electricity, labor, fumigant and other insecticides, and capital costs for equipment.
Electricity costs are calculated as cooling hours per fan x number of fans used x
(horsepower per fan / efficiency of the fans) x electricity cost in $/kwh, all divided by the
number of bushels cooled.
Labor costs per task are calculated as hourly labor cost (including employee
wages, taxes and benefits paid by employer) x employee hours per task. For the base
case, a labor cost of $16/hr. (including benefits) was assumed for full- time employees
with minimal management responsibilities.
Fumigant costs are calculated as cost per tablet (pellet) x number of tablets
(pellets) used. There are 500 tablets (1,660 pellets) per flask, and 14 flasks per case (21
flasks of pellets per case), for a total of 7,000 tablets (34,860 pellets) per case. The base
price is $300 per case of tablets or pellets, or $0.043 per tablet ($0.0086 per pellet). A
minimum dosage consistent with the label would be 40 tablets (200 pellets) per 1,000
bushels of grain; a more reasonable dosage of 120 tablets (600 pellets) per 1,000 bushels
for typical bulk storage facilities, also consistent with the label, is used here. However, if
closed loop fumigation is used, the base dosage is set at 80 tablets (400 pellets) per 1000
bushels.
Capital costs for equipment are calculated by dividing the total investment cost by
a present value interest factor, PVIFA
1
, to amortize the equipment cost over its useful
1
The Present Value Interest Factor, or PVIFA, for an annuity of n years at i
percent interest, and is calculated as:
82
life, assumed to be 10 years. In addition, an annual insurance cost of 15% of the initial
equipment cost, and an annual maintenance cost of 10% of the initial equipment costs are
assumed.
Cost of fumigation monitoring devices are included in equipment costs for all
strategies using fumigation. The highest-ranking instrument (based on costs as well as
other considerations) from Danley’s study is assumed to be used here. This particular
device is an electronic monitor, and requires at least annual recalibration. That cost is
also included. Labor costs for fumigation monitoring are considered separately.
Calculation Details
In the first worksheet (Facility Description), initial equipment costs are entered,
along with their expected life, maintenance, insurance, and salvage values. The
equipment used includes the PowerVac, a machine used to sample stored grain for
insects; fumigation equipment, which includes safety and application devices; and the
closed loop fumigation equipment, if applicable, in the elevator bin. As noted above, a
fumigation monitoring device is included in equipment costs. All equipment is assumed
to have a life of 10 years with a salvage value of zero.
This sheet also contains the fan horsepower for the fans used during aeration; the
centrifugal fan horsepower for facilities with closed loop systems; the fan efficiency,
which is assumed to be 80 percent; electricity costs expressed in dollars per kilowatt
hours; and hourly labor costs. The fumigant type and costs are specified in this
worksheet. The fumigant cost is calculated by using an if-statement in the cell containing
the formula for the calculation of the final cost of fumigant. Grain protectant costs can
also be entered, if the facility uses it.
The second worksheet (Insect Sampling) contains the number of samples typically
required to effectively monitor the insects in stored product; labor hours, which are the
amount of time required to go to a bin, probe for the required samples, sieve the grain,
remove the insects and count and identify the insects; the time it takes to set up and take
down the vacuum probe and inclined sieves; and the number of people it takes to do the
job. The equipment setup step is done only once for each elevator. Our base model
assumes 3 samplers taking 10 insect samples, using 0.08 labor hours each, and a total of 3
hours in setting up the sampling equipment. Insect sampling labor charges and sampling
equipment costs are expressed in dollars per bushel, and calculated as
( ) ( )
ored bushels st
r cost ourly labo samplers*h * setup time mples hours*# sa abor sampling l
r Charges pling Labo Insect Sam
#
+
=
i
n
i
PVIFA
(
(
¸
(
¸
|
.
|
\
|
?
?
=
1
1
1
83
and,
( ) ( )
ored bushels st
cost/year insurance r e cost/yea maintenanc
PVIFA
t WERVAC cos initial PO
osts quipment C Sampling E
|
|
.
|
\
|
+ + |
.
|
\
|
=
The third worksheet (Aeration and Conditioning) contains data on moisture
samples, the number of samples typically required during the summer storage season to
effectively monitor the condition of the stored product; sampling labor hours (the amount
of time it takes to go to a bin, probe for the required samples, test moisture and record
results) and conditioning labor hours (the amount of time spent during the summer
storage season to monitor moisture sampling results, ambient conditions and supervise
operation of aeration fans); the number of samplers; and the fan hours, which are the
number of hours a fan runs on a bin during the summer storage season for conditioning,
dependent on temperature and moisture. The base model uses 40 fan hours at 0.3 cfm,
which is the optimal amount of time needed for medium aeration for a grain depth of
50ft. during the fall storage season (Stored Product Management, table 6, pg.78). The
base model uses 10 moisture samples taken by 2 workers using 0.1 hours of sampling
labor and 0.75 hours of conditioning labor. These samples are not needed if insect
sampling is conducted as part of the strategy.
The worksheet contains a shrink factor, which is the amount of shrink observed
during the summer storage season in a bin under aeration and conditioning, and it is used
in the calculation of a shrink loss charge. The shrink loss charge is the shrink factor x the
grain price.
Calculations for sampling labor, conditioning labor and electricity charges follow.
These costs are calculated as:
( )
ed units stor
ers ost*#sampl ly labor c hours*hour bor ampling la samples*s
e abor Charg Sampling L Moisture
#
=
( )
s stored total unit
ost*#bins ly labor c hours*hour ng labor conditioni
harge ng Labor C Conditioni
=
( )
ed units stor
in $/kwh ty cost *electrici n of the fa efficiency per fan horsepower per fan* urs cooling ho
ost Electric c
) / (
=
(Alternatively, the term horsepower per fan / efficiency of the fan can be replaced with
the term ((Volts/1000) x Amps) /efficiency.)
The fourth worksheet (Fumigation) allows the user to specify whether or not the
elevator has a closed loop system in its bins. A binary variable is used to choose between
closed loop fumigation (1), and a conventional type of fumigation (0). The number of
fumigations is also included. Another binary variable is used to indicate whether or not a
bin will be fumigated just prior to unloading to prevent insects from entering the
processing facility: 0=No, 1=Yes. The proportion of the bins to be fumigated is entered
well, recognizing that sampling may indicate that only some bins are at risk of damaging
84
infestation. This is important because IPM strategies use fumigation only when sampling
indicates it is needed.
The fumigant cost is recalled from the facility sheet for calculation purposes. The
base model uses 3 employees per crew, each requiring an hour of training. The number
of training hours represents the hours required per employee on a fumigation crew per
year for certification, continuing education, and safety training. Two crew hours per
fumigation are required to seal bin, administer fumigant, check concentrations, and aerate
the bin. A liability insurance cost expressed in dollars per bushel is included in this
worksheet, which is associated with fumigation and includes worker and environmental
safety. The base model uses a liability insurance cost of $0.0001/bu.
The amount of blower hours to distribute fumigant gas evenly throughout the bin
can be specified in this worksheet if the facility uses closed loop systems. For this case,
48 blower hours are considered. This number is used in the calculation of the closed loop
system blower charge, expressed in dollars per bushel. The formula is as follows:
ed units stor
ions of fumigat ty cost*# *electrici efficiency blower HP rs* blower hou ) / (
charge blower . L . C =
An if–statement is used in the cell containing the formula to let the program know
whether to calculate the blower charge: if there is a closed loop system in the facility, the
program calculates the charge using the formula above. Otherwise, the program enters a
zero in the cell.
If a chemical grain protectant is used, its cost calculated in dollars per bushel is
included in the cost of chemicals. The worksheet specifies Actellic for corn and allows
selection of either Malathion or Reldan for wheat. The cost for Malathion is $0.002/bu.
and for Reldan/Actellic is $0.022/bu. (Kenkel et al.).
Calculations for fumigation labor, fumigation training, fumigant charges, and
fumigation equipment follow. Costs for closed loop facilities are also included. All costs
are expressed in dollars per bushel. The cost formulas are:
ored bushels st
s cost*# bin rly labor n crew*hou fumigatio loyees per ation* emp per fumig crew hours
ge labor char Fumigation =
stored bushels
cost urly labor mployee*ho training/e
charge training fumigation =
( ) ( )
ored bushels st
cost/year insurance r e cost/yea maintenanc
PVIFA
st uipment co initial eq
Costs Equipment Fumigation
|
|
.
|
\
|
+ + |
.
|
\
|
=
( ) ( )
ored bushels st
cost/year insurance r e cost/yea maintenanc
PVIFA
st uipment co initial eq
Costs Equipment p Closed Loo
|
|
.
|
\
|
+ + |
.
|
\
|
=
85
The fifth worksheet (Turning) allows the manager to specify if the grain is turned
while fumigating or not. A binary variable depicts the decision, using 1 and 0
respectively. The base model uses 3 hours of labor for turning the grain, and is calculated
as
ored bushels st
gations # of fumi abor cost* * hourly l bor hours turning la
bor Charge Turning La =
The base model assumes electric costs for turning the grain are $0.004/bu.(Stored Product
Management, table 2, p. 154). There is also a shrink factor of 0.003 is associated to
turning the grain. The shrink cost is
rice r* grain p rink facto turning sh rink cost turning sh = .
The final sheet calculates the annual per-bushel cost for each strategy considered.
For example,
k loss ning shrin charge+tur
tricity rning elec e+grain tu abor charg +turning l
arge tectant ch +grain pro insurance +liability
nt on equipme f fumigati st erating co +annual op
harge fumigant c
harge+ training c + ge labor char t equipment urning) (w/grain t migation Routine Fu
o
cos + =
e tant charg ain protec surance+gr ability in systems+li
on p fumigati closed loo of ing cost ual operat charge+ann +fumigant
harge L blower c g charge+C ge+trainin labor char t equipment on p Fumigati Closed Loo
cos + =
cos
ipment mpling equ cost of sa
erating annual op r charge pling labo insect sam
ss charge shrink lo ty charge electrici
harge ng labor c conditioni
e abor charg sampling l t equipment sampling ear) ling per y gy (1 samp IPM Strate
+
+ + +
+ + =
86
Appendix D.
Costs and Evaluation of Fumigation Monitoring Equipment
abstracted from Ronda Danley’s MS thesis
Summary
Aluminum/magnesium phosphide is an important tool in keeping commodity
grain free of insects. This fumigant is important to many Oklahoma grain elevators.
However, there is a lack of knowledge about whether or not their facilities are gas-tight.
The only way to know for sure if a facility is gas-tight is by monitoring areas around the
facility while it is under fumigation. This is accomplished by a phosphine gas monitoring
device. These devices are expensive and require training so it is important for each
facility to pick a device that is optimal for them. A way to determine which is optimal is
to list all costs and benefits of each device that they are considering. This study lists the
costs and benefits for five phosphine gas monitoring devices. A Multiple Criteria
Decision Model is then used to evaluate each of the costs and benefits (both quantitative
and subjective) in order of importance.
For example, one weighting scheme used was to weight the costs at 80% (35%
initial equipment cost, 25% additional equipment cost, and 10% recalibration costs) and
the subjective attributes at 20% (5% for user-friendliness, 5% for convenience, 5% for
ruggedness, and 5% for worker safety). Assuming a labor cost of $8/hr. and a fumigation
length of 24 days, the results showed that the devices ranked 1) Draeger Pac III; 2)
Lumidor MicroMax; 3) ATI PortaSensII; 4) Draeger MiniWarn; 5) MSA Tube. This
scenario shows that the tube-type devices, represented by the MSA Tube, ranked below
the electronic-type devices when costs are weighted more heavily than benefits.
When costs are instead weighted at 35% (20% for initial equipment costs, 5% for
additional equipment costs, 5% for recalibration costs, and 5% for labor costs) and the
subjective attributes are weighted at 65% (50% for worker safety, 5% for ruggedness, 5%
for convenience, and 5% for user-friendliness), the results change somewhat. Valuing
worker safety at the higher level leads to a ranking of: 1) Draeger Pac III; 2) Lumidor
MicroMax; 3) MSA Tube; 4) ATI PortaSensII; 5) Draeger MiniWarn. The tube-type
device ranks near the middle of the group when worker safety and other benefits are
weighted more heavily than costs.
87
Appendix E.
Guidance for Preparation of a Fumigation Management Plan
The following are the required parts in creating a Fumigation Management Plan
Purpose
A Checklist Guide
Preliminary Planning and Preparation
Personnel
Monitoring
Sealing Procedures
Application Procedures and Fumigation Period
Post-Application Operations
FUMIGATION MANAGEMENT PLAN
The certified applicator is responsible for working with the owners and/or responsible
employees of the site to be fumigated to develop a Fumigation Management Plan (FMP).
The FMP is intended to ensure a safety and effective fumigation. The FMP must address
characterization of the site, and include appropriate monitoring and notification
requirements, consistent with, but not limited to, the following:
1. Inspect the site to determine its suitability for fumigation.
2. When sealing is required, consult previous records for any changes to the structure,
seal leaks, and monitor any occupied adjacent buildings to ensure safety.
3. Prior to each fumigation, review any existing FMP, MSDS, Applicators Manual and
other relevant safety procedures with company officials and appropriate employees.
4. Consult company officials in the development of procedures and appropriate safety
measures for nearby workers that will be in and around the area during application and
aeration.
5. Consult with company officials to develop an appropriate monitoring plan that will
confirm that nearby workers and bystanders are not exposed to levels above the allowed
limits during application/aeration. This plan must also demonstrate that nearby residents
will not be exposed to concentrations above the allowable limits.
6. Consult with company officials to develop procedures for local authorities to notify
nearby residents in the event of an emergency.
7. Confirm the placement of placards to secure entrance into any area under fumigation.
8. Confirm the required safety equipment is in place and the necessary manpower is
available to complete a safety effective fumigation.
88
These factors should be considered in putting a FMP together. It is important to note that
some plans will be more comprehensive than others. All plans should reflect the
experience and expertise of the applicator and circumstances at and around the site.
In addition to the plan, the applicator must read the entire label and follow its directions
carefully. If the applicator has any questions about the development of a FMP, contact
DEGESCH AMERICA, INC. for further assistance.
The FMP and related documentation, including monitoring records, must be maintained
for a minimum of 2 years.
GUIDANCE FOR PREPARATION OF A FUMIGATION MANAGEMENT PLAN
Purpose
A Fumigation Management Plan (FMP) is an organized, written description of the
required steps involved to help ensure a safe, legal, and effective fumigation. It will also
assist you and others in complying with pesticide product label requirements. The
guidance that follows is designed to help assist you in addressing all the necessary factors
involved in preparing for and fumigating a site.
This guidance is intended to help you organize any fumigation that you might perform
PRIOR TO ACTUAL TREATMENT. It is meant to be somewhat prescriptive, yet
flexible enough to allow the experience and expertise of the fumigator to make changes
based on circumstances which may exist in the field. By following a step-by-step
procedure, yet allowing for flexibility, safe and effective fumigation can be performed.
Before any fumigation begins, carefully read and review the label and the Applicator's
Manual. This information must also be given to the appropriate company officials
(supervisors, foreman, safety officer, etc.) in charge of the site. Preparation is the key to
any successful fumigation. If the type of fumigation that you are to perform is not listed
in this Guidance Document you will want to construct a similar set of procedures.
Finally, before any fumigation begins you must be familiar with and comply with all
applicable state and local laws. The success and future of fumigation are not only
dependent on your ability to do your job but also by carefully following all rules,
regulations, and procedures required by governmental agencies.
A CHECKLIST GUIDE FOR A FUMIGATION MANAGEMENT PLAN
This checklist is provided to help you take into account factors that must be addressed
prior to performing all fumigations. It emphasizes safety steps to protect people and
property. The checklist is general in nature and cannot be expected to apply to all types of
fumigation situations. It is to be used as a guide to prepare the required plan. Each item
must be considered, however, it is understood that each fumigation is different and not all
items will be necessary for each fumigation site.
A. PRELIMINARY PLANNING AND PREPARATION
89
1. Determine the purpose of the fumigation.
a. Elimination of insect infestation
b. Elimination of rodent infestation
c. Plant pest quarantine
2. Determine the type of fumigation, for example
a. Space; tarp, mill, warehouse, food plant
b. Vehicle; railcar, truck, van, container
c. Commodity; raw agricultural or processed foods
d. Grain; vertical silo, farm storage, flat storage
e. Vessels; ship or barge. In addition to the Applicator's Manual, read the U.S. Coast
Guard Regulations 46CFR 147A.
3. Fully acquaint yourself with the site and commodity to be fumigated, including
a. The general structure layout, construction (materials, design, age, maintenance) of the
structure, fire or combustibility hazards, connecting structures and escape routes, above
and below ground, and other unique hazards or structure characteristics. Prepare, with the
owner/operator/person in charge. Draw or have a drawing or sketch of structure to be
fumigated, delineating features, hazards, and other structural issues.
b. The number and identification of persons who routinely enter the area to be fumigated
(i.e. Employees, visitors,customers, etc.)
c. The specific commodity to be fumigated, its mode of storage, and its condition.
d. The previous treatment history of the commodity, if available.
e. Accessibility of utility service connections.
f. Nearest telephone or other means of communication, and mark the location of these
items on the drawing/sketch.
g. Emergency shut-off stations for electricity water and gas. Mark the location of these
items on the drawing/sketch.
h. Current emergency telephone numbers of local Health, Fire, Police, Hospital, and
Physician responders.
i. Name and phone number (both day and night) of appropriate company officials.
90
j. Check, mark and prepare the points of fumigation application locations if the job
involves entry into the
structure for fumigation.
k. Review labeling
l. Exposure time considerations.
1. Fumigant to be used.
2. Minimum fumigation period, as defined and described by the label use directions.
3. Down time required to be available
4. Aeration requirements
5. Cleanup requirements, including dry or wet deactivation methods, equipment, and
personnel needs,
if necessary.
6. Measured and recorded commodity temperature and moisture.
m. Determination of dosage
1. Cubic footage or other appropriate space/location calculations.
2. Structure sealing capability and methods.
3. Label recommendations
4. Temperature, humidity, wind
5. Commodity/space volume
6. Past history of fumigation of structure
7. Exposure time
B. PERSONNEL
1. Confirm in writing that all personnel in and around the area to be fumigated have been
notified prior to application of the fumigant. Consider using a checklist each one initials
indicating they have been notified.
2. Instruct all fumigation personnel about the hazards that may be encountered; and about
the selection of personal protection devices, including detection equipment.
3. Confirm that all personnel are aware of and know how to proceed in case of an
emergency situation.
91
4. Instruct all personnel on how to report any accident and/or incidents related to
fumigant exposure. Provide a telephone number for emergency response reporting.
5. Instruct all personnel to report to proper authorities any theft of fumigant and/or
equipment related to fumigation.
6. Establish a meeting area for all personnel in case of emergency.
C. MONITORING
1. Safety
a. Monitoring must be conducted in areas to prevent excessive exposure and to determine
where exposure may occur. Document where monitoring will occur.
b. Keep a log or manual of monitoring records for each fumigation site. This log must, at
a minimum, contain the timing, number of readings taken and level of concentrations
found in each location.
c. When monitoring log records, document there is no phosphine present above the safe
levels, subsequent monitoring is not routinely required. However, spot checks should be
made occasionally, especially if conditions significantly change.
d. Monitoring must be conducted during aeration and corrective action taken if gas levels
exceed the allowed levels in an area where bystanders and/or nearby residents may be
exposed.
2. Efficacy
a. Gas readings should be taken from within the fumigated structure to insure proper gas
concentrations. If the phosphine levels have fallen below the targeted level the
fumigators, following proper entry procedures, may reenter the structure and add
additional product.
b. Document readings.
D. NOTIFICATION
1. Confirm all local authorities (fire departments, police departments, etc.) have been
notified as per label instructions, local ordinances if applicable, or instructions of the
client.
2. Prepare written procedure ("Emergency Response Plan") which contains explicit
instructions, names, and telephone numbers so as to be able to notify local authorities if
phosphine levels are exceeded in an area that could be dangerous to bystanders.
E. SEALING PROCEDURES
1. Sealing must be complete.
92
2. If the site has been fumigated before, review the previous FMP for previous sealing
information.
3. Make sure that construction/remodeling has not changed the building.
4. Warning placards must be placed on every possible entrance to the fumigation site.
F. APPLICATION PROCEDURES & FUMIGATION PERIOD
1. Plan carefully and apply all fumigants in accordance with the registrants label
requirements.
2. When entering into the area under fumigation, always work with two or more people
under the direct supervision of a certified applicator wearing appropriate respirators.
3. Apply fumigant from the outside where appropriate.
4. Provide watchmen when a fumigation site cannot otherwise be made secure from entry
by unauthorized persons.
5. When entering structures, always follow OSHA rules for confined spaces.
6. Document that the receiver of in-transit fumigation has been notified and is trained to
receive commodity under fumigation.
G. POST-APPLICATION OPERATIONS
1. Provide watchmen when you cannot secure the fumigation site from entry by
unauthorized persons during the aeration process.
2. Ventilate and aerate in accordance with structural limitations.
3. Turn on ventilating or aerating fans where appropriate.
4. Use a suitable gas detector before reentry to determine fumigant concentration.
5. Keep written records of monitoring to document completion of aeration.
6. Consider temperature when aerating.
7. Insure aeration is complete before moving vehicle into public roads.
8. Remove warning placards when aeration is complete.
9. Inform business/client that employees/other persons may return to work or otherwise
be allowed to reenter.
APPLICATION PROCEDURES
A FMP must be devised for application, aeration and disposal of the fumigant so as to
keep to a minimum any exposures to hydrogen phosphide and to help assure adequate
control of the insect pests.
93
The following instructions are intended to provide general guidelines for typical
fumigations. These instructions are not intended to cover every type of situation nor are
they meant to be restrictive. Other procedures may be used if they are safe, effective and
consistent with the properties of aluminum phosphide products.
FLAT STORAGES
Treatment of these types of storages often require considerable physical effort. Therefore,
sufficient manpower should be available to complete the work rapidly enough to prevent
excessive exposure to hydrogen phosphide gas. Vent flasks outside the storage, conduct
fumigations during cooler periods, and employ other work practices to minimize
exposures. It is likely that respiratory protection will be required during application of
fumigant to flat storages. Refer to the sections on Applicator and Worker Exposure and
Respiratory Protection.
1. Inspect the site to determine its suitability for fumigation.
2. Determine if the structure is in an area where leakage during fumigation or aeration
would adversely effect nearby workers or bystanders if concentrations were above the
permitted exposure levels.
3. Develop an appropriate Fumigation Management Plan. (Refer to FMP guidelines.)
4. Consult previous records for any changes to the structure. Seal vents, cracks and other
sources of leaks.
5. Apply tablets or pellets by surface application, shallow probing, deep probing or
uniform addition as the bin is filled. Storages requiring more than 24 hours to fill should
not be treated by addition of fumigant to the commodity stream as large quantities of
hydrogen phosphide may escape before the bin is completely sealed.
Probes should be inserted vertically at intervals along the length and width of the flat
storage. Pellets or tablets may be dropped into the probe at intervals as it is withdrawn.
Surface application may be used if the bin can be made sufficiently gas tight to contain
the fumigant gas long enough for it to penetrate the commodity. In this instance, it is
advisable to place about 25 percent of the dosage in the floor level aeration ducts. Check
the ducts prior to addition of PHOSTOXIN® to make sure that they contain no liquid
water.
6. Placement of plastic tarp over the surface of the commodity is often advisable,
particularly if the overhead of the storage cannot be well sealed.
7. Lock all entrances to the storage and post fumigation warning placards.
VERTICAL STORAGES (concrete upright bins and other silos in which grain can be
rapidly transferred)
1. Inspect the site to determine its suitability for fumigation.
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2. Determine if the structure is in an area where leakage during fumigation or aeration
would expose nearby workers or bystanders to concentrations above the permitted levels.
3. Develop an appropriate Fumigation Management Plan. (Refer to FMP guidelines.)
4. Consult previous records for any changes to the structure. Close openings and seal
cracks to make the structure as airtight as possible. Prior to the fumigation, seal the vents
near the bin top which connect to adjacent bins.
5. Pellets or tablets may be applied continuously by hand or by an automatic dispenser on
the headhouse/gallery belt or into the fill opening as the commodity is loaded into the bin.
An automatic dispenser may also be used to add PHOSTOXIN® into the commodity
stream in the up leg of the elevator.
6. Seal the bin deck openings after the fumigation has been completed.
7. Bins requiring more than 24 hours to fill should not be fumigated by continuous
addition into the commodity stream. These bins may be fumigated by probing, surface
application, or other appropriate means. Exposure periods should be lengthened to allow
for diffusion of gas to all parts of the bin if PHOSTOXIN® has not been applied
uniformly throughout the commodity mass.
8. Place warning placards on the discharge gate and on all entrances.
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