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TECHNICAL MEMORANDUM

DATE: March 2013

TO: Docket EPA-HQ-OAR-2010-0707

FROM: Eastern Research Group

SUBJECT: Evaluation of Revisions to Grain Elevator Emission Standards

1.0 Introduction

EPA is required to periodically review new source performance standards (NSPS) to 

assess the need to revise them based on developments that have occurred since their

promulgation or last review. This memorandum documents the analyses conducted to review the 

NSPS for grain elevators in 40 CFR part 60 subpart DD. The NSPS for grain elevators was 

originally promulgated in 1978, and subsequently reviewed in 1984.

Section 2.0 discusses background information used to inform the evaluation of revisions 

to the NSPS. Section 3.0 presents the results of the analyses.

2.0 Background Information

This section discusses the current requirements in subpart DD and the data gathering 

activities conducted to identify changes in the grain elevator industry since 1984.

2.1 Summary of Subpart DD Requirements

The primary pollutant emitted and only pollutant regulated from emission sources at 

grain elevators is particulate matter (PM). Sources of PM include loading and unloading 

operations (at railcars, trucks, barges/ships), grain handling operations, and grain dryers. A 

detailed discussion of the processes, operation, and emission sources at grain elevators is 

provided in several EPA documents.1,2

Subpart DD applies to each affected facility at any grain terminal elevator or any grain 

storage elevator. Grain terminal elevators and grain storage elevators are defined by their 

permanent grain storage capacity. Subpart DD defines a grain terminal elevator as any grain 

elevator that has a permanent storage capacity of more than 2.5 million bushels (excluding

elevators located at animal food manufacturers, pet food manufacturers, cereal manufacturers, 

breweries, and livestock feedlots). Subpart DD defines grain storage elevator as any grain 

elevator located at any wheat flour mill, wet corn mill, dry corn mill used for human 

consumption, rice mill, or soybean extraction plant that has a permanent grain storage capacity of 

1 million bushels. The affected facilities listed in the standard are: each truck unloading station, 

truck loading station, barge and ship unloading station, barge and ship loading station, railcar 

loading station, railcar unloading station, grain dryer, and all grain handling operations. Subpart 
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DD standards apply to both process emissions and fugitive emissions. Process emissions from 

loading, unloading, and grain handling are required to be ventilated and conveyed to a control 

device and meet a PM limit. Fugitive emissions from grain elevators take the form of grain dust 

and can be emitted from almost any point in the grain elevator process. Depending on the 

fugitive emission source, the standard requires compliance with an equipment standard and/or 

meeting an opacity limit. Table 2-1 summarizes the subpart DD standards.

Table 2-1. Summary of Subpart DD Requirements

Type of 

Source

Affected Facility Type of 

Standard

Requirement

Process 

emissions

All loading and unloading operations at 

railcars, trucks, barges/ships; and grain 

handling operations

Opacity and 

emission 

limit

PM emission limit of 

0.01 gr/dscf ; 0% 

opacity.

Grain dryer Opacity and 

equipment 

specification

0% opacity for column 

dryers equipped with 

column plate 

perforations exceeding 

0.094 inches, and rack 

dryers equipped with 

screen filter coarser than 

50 mesh. 

Fugitive Truck loading Opacity 10%

Truck unloading, railcar loading, railcar 

unloading

Opacity 5%

Barge/ship loading Opacity 20%

Barge/ship unloading Equipment 

specification

Marine leg enclosed 

from top to bottom of 

leg, w/ ventilation flow 

rate of both leg and 

receiving hopper of 40 

ft3 per bushel of grain 

unloaded.

2.2 Data Gathering Activities

To characterize the current state of emissions, practices, operations, and controls in the 

industry, EPA conducted a survey of grain elevator operations in 2009. The survey targeted 

facilities with any grain elevator that would constitute a “grain terminal elevator” or a “grain 

storage elevator” (as defined in subpart DD (40 CFR 6-.301)) if only permanent storage or both 

permanent and temporary storage at the grain elevator were considered. To provide a general 

representation of the industry, respondents were required to submit information for facilities 

based on storage type, grain(s) handled, and EPA region. Survey responses were collected from 

121 grain elevators.3 The survey responses provided information on grain elevator capacity, 

grain elevator throughputs for three successive years, the use of temporary storage facilities, 
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barge unloading operations, dryer design, general information on facility characteristics, and 

control devices and work practices used to reduce PM emissions from various sources.

EPA also had several interactions with members of the grain elevator industry that 

resulted in collection of information. Several meetings were conducted where industry members 

provided information on current practices and provided technical presentations to EPA.4,5

EPA established the RACT/BACT/LAER Clearinghouse (RBLC) as a repository of 

information on air pollution technologies required by state air pollution control programs 

(including past RACT, BACT, and LAER decisions). RACT, or Reasonably Available Control 

Technology, is required on existing sources in areas that are not meeting national ambient air 

quality standards (i.e., non-attainment areas). Under the New Source Review program, BACT, or 

Best Available Control Technology, is required on new or modified major sources in attainment 

areas and LAER, or Lowest Achievable Emission Rate, is required on new or modified major 

sources in non-attainment areas. The RBLC was reviewed to identify any new control 

technologies that have been used at grain elevators since the last review of the rule.

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In order to assess whether requirements in state regulations provide more stringent or 

additional control than subpart DD, the regulations from the 12 states with the highest grain 

storage, and the highest number of grain elevators in operation, was conducted. The 12 states are: 

Iowa, Illinois, Minnesota, Nebraska, Kansas, Indiana, North Dakota, South Dakota, Ohio, Texas, 

Missouri, and Wisconsin. The review looked at how each state implemented subpart DD and also 

evaluated non-subpart DD regulations controlling PM, opacity, and fugitive dust emissions that 

may be applicable to grain elevators.7

3.0 Results of Review

The review of the state rules did not indicate any new requirements or more stringent 

standards than in subpart DD. Similarly, the review of the RBLC did not provide information on 

control techniques that are different that what grain elevators have typically used to comply with 

the subpart DD standards. 

The review of the survey responses and information gathered at meetings resulted in 

identifying: (1) emission test reports and one control technique that may be used to revise 

requirements for subpart DD affected facilities, and (2) several new emission sources since 

subpart DD was last reviewed in 1984.

3.1 Evaluation of Subpart DD Affected Facilities

Subpart DD requires affected facilities, except grain dryers, to meet a PM emission limit 

of 0.01 gr/dscf for process emissions (i.e., non-fugitive emissions). All affected facilities are 

required to meet opacity limits, specific to each affected facility, to control fugitive dust 

emissions. Some of the grain elevators responding to the 2009 CAA section 114 survey also 

provided emission test reports and permit information. Potential revisions to the grain elevator 

emission standards were evaluated by first assessing changes that have occurred to the grain 

elevator source category since the last review of the NSPS in 1984. Then, currently used, new 

and emerging control systems were identified and assessed whether they represent advances in 

emission reduction techniques compared to the control techniques used to comply with the 

existing NSPS. Each new or emerging control option identified was evaluated for emission 
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reductions, costs, energy requirements and non-air quality impacts. The PM emission test reports 

were evaluated to determine whether the PM emission limit in subpart DD could be revised. The 

survey responses, permit information, and information collected from a literature search 

provided information on application of mineral oil as a dust suppression technique to reduce 

fugitive PM emissions. 

Revisions to PM emission limits

The performance of emission control techniques at grain elevators determines if changing 

the NSPS emission limit is appropriate. Subpart DD requires process emissions from affected 

facilities (e.g., truck unloading stations, grain handling operations, etc., but excluding grain 

dryers) to meet a PM emission limit of 0.01 gr/dscf. Grain elevators typically meet the standard 

using fabric filters. 

The EPA estimates that between 340 and 920 grain elevators that could be subject to 

Subpart DD. In 2009, EPA sent CAA section 114 surveys to 120 grain elevators to characterize 

the industry and obtain data on PM control techniques and associated emissions. Respondents to 

the survey provided PM emission test reports from 15 grain elevators (i.e., between 1.6 percent 

to 4 percent of the grain elevator population potentially subject to subpart DD). The test reports 

are in docket EP-HQ-OAR-2010-0706. The test reports were evaluated to determine whether 

sufficient information existed to revise the PM emission limit. The 15 grain elevators tested PM 

emissions controlled with fabric filters from 7 railcar unloading stations, 4 truck unloading 

stations, 3 grain handling operations, and 2 barge unloading stations. The survey results indicated 

that a typical grain elevator has on average 2 truck unloading stations, 4 grain handling 

operations, and 1 barge unloading, and 1 railcar unloading station.3 Information provided in the 

survey responses indicated that approximately 75 percent of railcar unloading stations, truck 

unloading stations, barge unloading stations, and grain handling operations are subject to subpart 

DD.3 Applying the typical counts to the estimated range of grain elevators that could be subject 

to subpart DD, and accounting for the fraction that could be subject to subpart DD, the number 

of affected facilities potentially subject to subpart DD is between 2,200 and 6,200. Comparing 

these numbers to the number of tests results collected we estimated that these tested affected 

facilities account for approximately 0.3 percent to 0.7 percent of the population of railcar 

unloading stations, truck unloading stations, grain handling operations, and barge unloading 

stations at grain elevators that could be subject to subpart DD. Additionally, the test reports did 

not include any tests conducted at barge/ship loading stations, railcar loading stations, or truck 

loading stations. 

The PM levels from the available tests, measured as an average of 3 test runs, ranged 

from 0.01 to 0.00002 gr/dscf. The wide variation in emissions is due to the different affected 

facilities that were tested, other operational considerations (i.e., speed of the process) and grain 

characteristics. EPA had previously concluded that the amount of dust emitted during processing 

of grain in the various affected facilities depends on the type of grain being handled, the quality 

of the grain, the moisture content of the grain.1 The emission test information gathered for the 

1978 subpart DD proposal indicates that the type of grain processed affects the PM emissions8, 

with one to two orders of magnitude difference in PM emissions between affected facilities 

processing soybeans and corn (higher emissions) than those processing wheat and milo. The 

grain elevator standards cover eight different grains. However, the emission tests for the 15 grain 
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elevators do not cover all the eight grains. Many of the test reports do not indicate the grain type 

being processed during the test. 

In considering the limited data and the limitations of the data, EPA concluded that the 

emission test reports do not sufficiently characterize the performance of fabric filters controlling 

PM from the full range of affected facilities subject to subpart DD. Therefore, revised PM limits 

were not evaluated for this review. 

Application of Mineral Oil

Responses to the CAA 114 survey and permits submitted with the responses, indicate that 

some grain elevators use mineral oil as a fugitive dust suppression technique. Mineral oil 

application is primarily used to reduce the possibility of a grain elevator explosion caused by 

dust. 

EPA has previously studied the application of mineral oil at grain elevators noting that 

there were several potential benefits, such as reduced dust disposal cost, less grain weight loss, as 

well as improved safety in the working environment.9 However, compared to currently used 

technology for controlling process emissions, i.e., fabric filters, the study indicated that oil 

application systems achieved lower PM reduction efficiencies. EPA also concluded that the 

emission tests conducted were inadequate for the purpose of determining emissions and 

developing emission factors because they were pilot studies or controlled tests. Therefore, 

mineral oil application as a replacement for existing controls has not been demonstrated to be a 

feasible control option. No information was identified or collected on the appropriateness or 

effectiveness of using mineral oil in combination with existing technologies, such as fabric 

filters. 

The subpart DD fugitive standards require meeting a 0 percent opacity limit for grain 

handling operations, and require opacities ranging from 5 to 20 percent for loading and 

unloading stations. Information was not identified or collected on how the mineral oil application 

would affect the fugitive opacity limits, e.g., whether the opacity levels would decrease to 0 

percent, stay the same, or result in another limit. Additionally, portable grain handling 

equipment, such as portable augers, portable conveyors, and front-end loaders are often used at 

grain elevators. Information was also not available on whether mineral oil application is feasible 

or would reduce emissions at facilities that use portable grain loading equipment to reduce 

fugitive emissions. The size and design of these systems may affect both their ability and the 

time necessary to mix mineral oil thoroughly with grain to be an effective dust suppression 

technique.

The EPA mineral oil study also noted that there are concerns regarding the effect the oil 

has on grain quality, and consequently, its price. The EPA study indicates that mills and 

distilleries are concerned about the long-term effects of oil on grain. For some grains, the use of 

mineral oil may be more problematic, such as for wheat in the milling process. Therefore, 

mineral oil application might not be economically feasible for all grains.
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3.2 Evaluation of New or Significantly Changed Emission Sources

The survey responses and presentations by representatives of the grain elevator industry, 

identified the following three significant changes that have occurred to grain elevators since the 

last review of subpart DD:

• Use of new barge unloading technologies (e.g., en-masse drag conveyors). 

• Use of wire screen column dryers.

• Use of temporary storage facilities (TSFs).

Each of the changes was evaluated to determine if it results in new emission sources. If so, the 

available control measures applicable to each emission source were identified and these 

measures were evaluated to determine the emission reductions achieved, associated costs, nonair environmental impacts, energy impacts, and any limitations to their application. 

New Unloading Operation Emission Sources at Barge and Ship Unloading Stations

Barge unloading stations are an affected facility regulated by Subpart DD. Subpart DD 

standards for barge and ship unloading were established for a specific type of unloading 

mechanism, referred to as either a marine leg or bucket elevator. Under subpart DD, process 

emissions caused by unloading using a marine leg/bucket elevator must be controlled by 

enclosing the marine leg/bucket elevator from top to bottom of leg. Emissions must be vented to 

a control device using a ventilation flow rate of 40 ft3 per bushel of grain unloaded for both the 

marine leg/bucket elevator and receiving hopper. Subpart DD also provides for an equivalency 

determination in situations where it is not possible to meet the design standards. Since EPA’s last 

review of subpart DD, several new barge unloading mechanisms have been developed and used, 

at least one of which does not utilize a bucket elevator or marine leg, and, as such, cannot use the 

design standards. 

Some barge unloading stations currently use en-masse drag conveyors, and this type of 

conveyor was not in use the last time EPA reviewed subpart DD. En-masse drag conveyors 

operate under a different principle than bucket elevators or marine legs. En-masse drag 

conveyors are plug-flow drag conveyors that are designed to operate vertically. The conveyor 

uses paddles or flights mounted on a chain to move grain. The side of the conveyor where the 

grain is being transferred is filled with grain. Therefore, dust aspiration is not feasible, because 

there is no air passage to the grain inlet at the base of the conveyor. Additionally, the normal 

mode of operation is to bury the conveyor inlet into the grain being unloaded, which eliminates 

the need for dust aspiration at this point. Particulate emissions are controlled by the design of the 

unloader without an add-on emission control system. This newer unloading system was 

developed for a variety of reasons, including faster unloading rates, higher capacity unloading, 

cost savings, and other site-specific reasons.4,5

All emissions from barge unloading using an en-masse drag conveyor are fugitive in 

nature because they cannot be captured and ventilated to a control device. Some barges have a 

small opening where the en-masse drag conveyor enters and those openings can be covered 

around the en-masse loader, thereby limiting fugitive emissions. Other barges have a large 

opening where a bulldozer is lowered into the barge to move grain toward the unloader. This 

type of application of the en-masse drag conveyor does not allow openings to be covered, due to 
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safety requirements. No other technologies or techniques have been identified to control fugitive 

emissions from barge unloading.

Two 1-hour Method 9 tests for opacity were conducted at one en-masse system (loading 

into the barges with larger openings) to demonstrate equivalency with the current standards, per 

the requirements in 60.302(d)(3) of subpart DD. The opacity information is provided in 

Appendix A of the memorandum. Method 9 requires that opacity readings be recorded to the 

nearest 5 percent at 15-second intervals. Opacity is determined as an average of 24 consecutive 

observations, i.e., a set of observations. The average opacity levels during the highest set of 

observations of each test were 8.75 and 9.79 percent. Because Method 9 opacity measurements 

are taken in increments of five percent, a limit based on the opacity tests must be rounded to the 

nearest multiple of five. For the tests reviewed, the resulting emission limit is 10 percent opacity. 

No information was received on whether there would be any cost associated with meeting the 

limit (other than testing and recordkeeping and reporting), or if there would be any emission 

reductions. The data collected show that the 10 percent opacity limit can be met by affected 

facilities using the en-masse conveyor system to unload barges without using additional control, 

resulting in no cost or emission impacts for meeting the opacity limit. Additionally, no non-air 

quality health and environmental impacts or any changes in energy usage or emissions of any 

other pollutant are estimated for affected facilities because no add-on technologies would be 

needed to meet the limit.

En-mass drag conveyor systems that have a small opening could achieve a lower level of 

opacity if the opening was covered; however, no information was received to establish a 

different opacity limit for these systems or on the effectiveness of the cover, costs of the cover, 

procedures for using the cover, or if there are operational or health issues that may occur if the 

opening is covered. 

New Wire Screen Column Dryers

Grain dryers are an affected facility under subpart DD. The subpart DD emission limits 

for dryers were established for two types of grain dryers used at grain elevators: rack and column 

dryers. Subpart DD requires that PM emissions from dryers be reduced by meeting an opacity 

limit of 0 percent if a column dryer uses column plate perforations exceeding 0.094 inches, or if 

a rack dryer passes exhaust gases through a screen filter coarser than 50 mesh. 

An additional type of dryer not addressed in subpart DD is now being used at rice 

facilities. Most rice dryers currently use column dryers with woven wire mesh screens in place 

of, or in addition to, perforated plates because perforated plates damage the rice kernel, are less 

efficient for rice drying, and are not durable. The wire mesh also allows for air transport from the 

dryer while entrapping PM from the rice. Information provided by one company drying rice 

shows that of the 126 dryers they operate, 115 are column dryers; 115 of all the dryers (column 

and rack) use a wire screen of 24 mesh size, and 9 use a 50 mesh size for controlling PM 

emissions (50 mesh is a smaller screen size than 24 mesh). The 50 mesh screens are being 

replaced over time because of maintenance and plugging problems. The rice dryer information is 

presented in Appendix B.

Emissions from dryers are fugitive in nature. It is not possible to fully enclose dryers and 

vent PM emissions to a control device because of the large size of the dryer, the way that PM is 

emitted (through the side walls of the dryer rather than from a stack or vent), and because the 
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dryer needs sufficient air flow to work properly and an enclosure would restrict the airflow. 

Therefore, there are no add-on controls that can be applied to control PM emissions from these 

dryers. The PM emitted is a function of the size of the openings on the dryer sidewalls. Larger 

openings emit more PM. The current industry practice is to use wire screens (of 24 mesh size) to 

reduce the size of the openings, resulting in reduced PM emissions. Higher mesh sizes (e.g, 50, 

100) are available that would have smaller openings, resulting in even greater emission 

reductions. However, information from one rice facility, in Appendix B, indicates that the 50 

mesh screens cause plugging problems and choke the airflow of the dryers, and require 

substantial maintenance to clean. EPA also determined, during the development of subpart DD in 

1978, that the higher sizes, such as 100 mesh screens, would restrict air flow and result in more 

plugging of the openings such that there would be an unreasonable cost impact due to the need to 

clean the screens frequently, reduced drying performance, and additional energy requirements.8

Opacity information was collected for four column dryers with 24 mesh wire screens for 

drying rice. The opacity data for these dryers consist of one run of 30 minutes of observation for 

each dryer. The average opacities for the four dryers ranged from 1.13 to 8.38 percent, with the 

average opacities for the highest period of observation ranging from 5 to 10 percent. After 

rounding to the nearest increment of 5 percent, the corresponding opacity limit based on the data 

from the four rice dryers is 10 percent. The opacity information is presented in Appendix C.

Because this limit is achievable by the dryers that provided information, and these dryers would 

be similar to or the same as future dryers constructed (i.e., column dryers using 24 mesh 

screens), no costs or emission impacts are expected from meeting a 10 percent opacity limit

(other than testing, recordkeeping, and reporting costs). Similarly, no non-air quality health and 

environmental impacts are estimated to be associated with the limit, nor any changes in energy 

usage or emissions of any other pollutant, because no add-on technologies would be required.

Information was also collected from one Method 9 test conducted during filling and 

emptying operations for one wire mesh column dryer drying rice. The average opacity for one 

run of 30 minutes was 15.6 percent, with the average opacity for the highest period of 

observation during the run at 28.75 percent. No further evaluation of developing opacity limits 

for filling and emptying operations were conducted because EPA determined additional 

information was needed on the filling and emptying process, and emissions, control, and cost 

information associated with them.

Temporary Storage Facilities

Subpart DD does not regulate grain storage units (buildings, bins, silos). Instead, subpart 

DD regulates each affected facility (e.g., loading and unloading stations, grain dryers, grain 

handling operations) at any grain terminal elevator or any grain storage elevator. Under subpart 

DD, grain terminal elevators and grain storage elevators are defined in part by their permanent 

grain storage capacity. Grain terminal elevator means any grain elevator that has a permanent 

storage capacity of more than 2.5 million bushels (excluding elevators located at animal food 

manufacturers, pet food manufacturers, cereal manufacturers, breweries, and livestock feedlots). 

Grain storage elevator means any grain elevator located at any wheat flour mill, wet corn mill, 

dry corn mill used for human consumption, rice mill, or soybean extraction plant that has a 

permanent grain storage capacity of 1 million bushels. 
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TSFs started to be used in the early 1990’s. They are intended for bulk storage of grain on 

a temporary basis, i.e., they are intended to handle intermittent surges and surpluses, and are not 

used necessarily every year. Under the U.S. Warehouse Act, TSFs are licensed and are defined 

by the following criteria:10

• Use of asphalt, concrete, or other approved base material;

• Use of rigid, self-supporting sidewalls;

• Use of aeration;

• Use of an acceptable covering (e.g, tarp).

Information from survey responses indicate that only truck unloading and loading 

stations and grain handling operations are used at TSFs. Based on the survey responses and 

information provided by the industry, there are two types of grain handling and 

loading/unloading operations associated with TSFs: (1) those associated with portable grain 

handling and loading/unloading equipment; and (2) those associated with fixed grain handling 

and loading/unloading equipment. 

Portable grain handling/loading/unloading equipment include (but are not limited to) 

portable augers, portable conveyors and front-end loaders that are not fixed at any one spot and 

can be moved around the site. These pieces of equipment are typically not enclosed and vented 

to a control device. As such, their emissions are fugitive in nature. No emission test information 

on portable grain handling, unloading stations and loading stations was received or identified in 

literature searches and searches of EPA databases. Additionally, no technically viable emission 

control options for portable equipment were identified. Application of mineral oil for dust 

suppression is used as dust suppression for other emission sources, but was determined to not be 

an appropriate emission control technique, as discussed in section 3.1. Consequently, no control 

options could be identified for portable equipment.

Fixed grain handling and loading/unloading equipment are constructed to be stationary 

and directly connected to the storage facilities for ease of transferring grain. Fixed equipment can 

also be enclosed and emissions can be vented to a control device. Fixed equipment at TSFs are 

similar to those associated with permanent storage units. One regulatory option identified to 

control emissions from fixed grain handling and loading/unloading equipment at TSFs is to set 

emission limits equal to the subpart DD requirements for affected facilities for permanent storage 

units. These requirements include: (1) meeting a PM emission limit of 0.023 g/dscm and an 

opacity limit of 0 percent for process emissions; and (2) meeting fugitive emission standards of a 

5 percent opacity limit for truck unloading stations, and 0 percent opacity for grain handling 

operations. No other regulatory options were identified that are more stringent than the subpart 

DD requirements. As discussed in section 3.1, test information submitted with the grain elevator 

survey responses and determined that the emission limit that has been demonstrated to be 

achievable is the same as the current subpart DD standards. Controls used at grain elevators are 

well-operated fabric filters; no controls more effective than fabric filters were identified. Based 

on information provided in survey responses and from industry representatives, the majority of 

grain handling/loading/unloading at TSFs are done using portable equipment. Fixed equipment is 

often shared between permanent storage units and TSFs. 

An analysis was conducted to evaluate the cost and emission reduction resulting from a 

potential change to the definition of “permanent storage capacity” that would include the 
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capacity of TSFs.11 The impacts are expressed as incremental differences between the impacts of 

grain elevators complying with the proposed subpart DDa and the current NSPS requirements of 

subpart DD. The cost and emission reductions estimates also incorporate control requirements 

for fixed grain handling/loading/unloading operations.

Three scenarios at grain elevators were identified that would be affected by adding TSFs: 

(1) a greenfield facility that exceeds the subpart DDa applicability criteria due to the capacity of 

TSFs; (2) an existing facility that is below the subpart DDa applicability criteria, but then adds a 

TSF and exceeds the criteria; and (3) an existing facility already subject to subpart DD (because 

it exceeds the subpart DD applicability criteria) that then adds a TSF. The additional capital costs 

associated with these scenarios are addition of a three-sided shed for truck unloading operations, 

fabric filters for dust control and to meet the PM limits, and screens for dryers to meet limits, as 

applicable. Annual costs include capital recovery, operating and maintenance costs, and indirect 

costs (such as overhead, property taxes, etc). Emission reductions were estimated based on 

routing PM emissions from grain sent to the TSF (and using truck unloading and grain handling 

affected facilities) to a fabric filter, or grain associated with TSFs being sent to a dryer with 

screens.

Table 3-1 summarizes the capital and annual costs, and the PM10 emission reductions 

associated with each scenario. The impacts estimation methodology is presented in another 

memorandum.11

Table 3-1. Summary of Costs Estimated for Scenarios Where the Capacity of TSFs are

Included in Permanent Storage Capacity

Scenario Description Capital Cost ($) Annual Costs ($/yr) PM10 Emission 

Reduction (tons/yr)

Greenfield GE 

w/capacity > DDa 

cutoffs due to adding 

TSF capacity

589,400 233,946 17

Existing GE w/ 

capacity <DDa 

cutoffs, but then adds 

TSF capacity and 

exceeds cutoffs

166,000 168,063 6.9

Existing GE w/ 

capacity >DDa 

cutoffs, but then adds 

TSF capacity

332,000 214,207 6.9

Total 1,087,000 616,207 31 a

Costs were estimated on a 2012 basis.11
11

4.0 References

1. Compilation of Air Pollutant Emission Factors, Volume I: Stationary Point and Area 

Sources. U.S. Environmental Protection Agency. Fifth Edition. January 1995. 

http://www.epa.gov/ttnchie1/ap42/

2. Review of New Source Performance Standards for Grain Elevators. U.S. Environmental 

Protection Agency. EPA-450/3-84-001. January 1984.

3. Database of Grain Elevator Survey Responses. Docket ID Number EPA-HQ-OAR-2010-

0706.

4. Letter from the NSPS Subpart DD Coalition to Mr. William Schrock, U.S. Environmental 

Protection Agency regarding Follow-up to the July 25 Meeting of the NSPS Subpart DD 

Coalition with EPA-OAQPS, September 20, 2012. Docket ID Number EPA-HQ-OAR-2010-

0706.

5. Letter from the NSPS Subpart DD Coalition to Mr. William Schrock, U.S. Environmental 

Protection Agency regarding Two New Issue Papers Developed By RTP Environmental 

Associates on Certain NSPS Subpart DD Issues, September 21, 2012. Docket ID Number 

EPA-HQ-OAR-2010-0706.

6. RACT/BACT/LAER Clearinghouse. http://cfpub.epa.gov/RBLC/

7. Evaluation of the Grain Elevator Emission Standards In Response to Executive Order 13563. 

Memorandum from ERG to Bill Schrock, U.S. Environmental Protection Agency. December

2013. Docket ID Number EPA-HQ-OAR-2010-0706.

8. Standards Support and Environmental Impact Statement Volume 1: Proposed Standards of 

Performance for Grain Elevator Industry. EPA-450/2-77-001a. January 1977

9. Oil Suppression of Particulate Matter at Grain Elevators. U.S. Environmental Protection 

Agency. EPA-453/R-94-049. July 1994.

10. United States Warehouse Act. 

http://www.fsa.usda.gov/FSA/webapp?area=home&subject=coop&topic=was-ua

11. Impacts of Grain Elevator NSPS Subpart DDa Requirements. Memorandum from ERG to 

Bill Schrock, U.S. Environmental Protection Agency. December 2013. Docket ID Number 

EPA-HQ-OAR-2010-0706.
Appendix A

Opacity Tests From Barge Unloading Using En-Masse Conveyor Systems






Appendix B

Information on Wire Screen Column Dryers at Rice Facilities
Riceland – Request for Additional Information and Clarification

08/28/2012

Riceland Response

Population Information

Q1. How many Rice dryers are at the Riceland facilities?

A1. There are 126 grain dryers at Riceland facilities.  Riceland primarily dries rice in these dryers but

some of them are occassionally used to dry other commodities delivered to Riceland such as

soybeans, wheat, and corn.

It should be noted that in the last 5 years Riceland has installed four (4) grain dryers.  All 4 of

those dryers were replacements for existing dryers.   Also, over the next 5 years Riceland

expects to install six (6) new grain dryers.  Four (4) of those will be replacements and two (2) will

be additional.

Riceland mentions this because we think it’s important for EPA to understand that the rice dryer

population is not experiencing any significant growth.    

Q2. What percentage of the rice dryers are column dryers vs. rack dryers?

A2. Of the 126 dryers, 115 are column dryers and 11 are rack dryers.

Q3. What percentage of the rice dryers use wire screens to control opacity/PM?

A3.   Of the 126 grain dryers, 124 use some type of screen, either 24 or 50 mesh, for controlling

emissions.  The other two dryers are outside dryers having perforated plate columns and are not

located in an enclosure.

Of the 124 dryers using screens, approximately 115 use 24 mesh and 9 use 50 mesh.

Of the 9 dryers using 50 mesh, only 1 was installed after 1970.

Q4. Do you have similar information for rice dryers at other companies?

A4. No.

Control Information

Q. From previous meetings, site visits, and 114 responses, it appears that Riceland uses a variety of

control scenarios and screening configurations.  We would like to get a better understanding of:  (1) The

population of sources with the controls, (2) which control scenarios and screening configurations are

associated with test data you have, (3) how the controls work, (4) the reduction in emissions that each

achieves.  

A1.  Riceland basically uses three (3) control configurations.   

a.  New outside dryers are housed in an enclosure.  The enclosures are constructed of louvered panels
that have a 24 mesh screen on the inside of the louvers up to the elevation of the exterior dryer column

walls.   Attachment 1 shows an outside dryer with an enclosure constructed of louvered panels.

b.  For dryers located inside the headhouse, Riceland constructs what we refer to as a “hull settling

chamber.”  This is a louvered panel enclosure attached to the front of the headhouse that catches rice

hulls from inside dryers.  The louvered panels also have 24 mesh screen on the inside of the louvers.  

Attachment 2 shows such an enclosure.  In all instances, these hull chambers have been retrofits.  They

are installed on headhouses where dryers vent directly through the wall with no screening or to replace

the Tech Air screens described below.

c.  Also Riceland operates several facilities that were built in the 60’s that have Tech Air Screen Air units   

attached to the headhouse wall to vent dryer emissions and act as emissions control devices.  These

Tech Air units use a 50 mesh screen and a rotating vacuum system for continuous cleaning.   

Attachment 3 is a Screen Air brochure.  Because the Screen Airs are not ideally suited for rice

applications, Riceland has been replacing these units when possible with the hull chambers shown in

Attachment 2.  The 50 mesh screens blind over easily, thus choking down the dryers, and the vacuum

systems are a maintenance problem.   

A2.  Control scenarios for each dryer tested in 2009 are shown in the table below.

A3.  Rice drying requires large volumes of air.  Most of Riceland’s dryers have fans rated in the range of

150,000 to 250,000 cfm.   Rice hulls and chaff, as they exit the dryer column screen, can have a velocity

of approximately 200 ft/min.  However, once the material is outside the column screen the velocity

quickly drops and the hulls and chaff fall to ground.  The enclosures and 24 mesh panels are intended to

capture those hulls and chaff that are discharged by the dryer.  The enclosure devices used by Riceland

rely on velocity reduction and gravity settling to control emissions.

A4.  The 24 and 50 mesh openings are approximately ASTM sieve sizes of 710 microns and 300 microns

respectively.  The enclosures effectively reduce opacity but there are no data on how effective they are

in capturing regulated pollutants such as PM10.   

Test Data

Q1. In previous meetings, there was some indication that Method 9 test data results were available

for 5 rice dryers. If so, please provide:

a. Test results and any description of test procedures followed

b. Rice processing rate during test

c. Description of each rice dryer tested:  

i. Location (facility name and location)

ii. Type of rice dryer (make, model, wire mesh size, size, max processing rate,

description, schematic)

iii. Type of controls (mesh screen/perforation size, schematic of screens,

description and schematic of any enclosure, other)
A1.  At Attachment 4 is the test report for the visible emissions (VE) testing conducted in September

2009 on five ( 5 ) grain dryers all located in Arkansas.  At the time of testing all were drying rice.  Four (4)

of the dryers are located at Riceland facilities and one (1) is located at one of Riceland’s competitor’s

facilities.

At the Hazen location, Dryer #2 was tested twice.  Once during the emptying/filling of the dryer and

once while running normally.  The tests were reported incorrectly.  The filling of Dryer #2 occurred

during the first test, Run #1, and the normal operation occurred in the second test, Run #2.  

   

a.   All tests were conducted in using EPA Method 9 procedures.

   

b.  The table below summarizes the dryer information presented in the VE test report.

       The test report includes the results of the VE test, the VE observation form and photographs  

                    of each dryer.

Dryer Location

(AR)

Processing

Rate (bu/hr) Manufact. Column(wire/perf)

Control

Screen Opacity

1 Lonoke 5,000 Shanzer Wire 24 mesh R1 – 1.13%

2 Hazen 6,500 Shanzer Wire 24 mesh R1 – 15.63%

R2 – 8.38%

3 Hazen 2,800 Zimmerman Perforated Plate

(NSPS compliant) None R1 – 3.79%

4 Wheatley 8,500 Shanzer Wire 24 mesh R1 – 3.00%

5 DeWitt 5,000 Shanzer Perf (outside)/

Wire (inside) 24 mesh R1 – 0.00%

  

Q2. In conducting this survey of 5 rice dryers, how did Riceland select these dryers (e.g., randomly,

convenience)?

A2. We attempted to select dryers with both wire columns and perforated columns.  We also

wanted to vary the size of the dryers.

Q3. Has Riceland conducted any previous opacity or PM tests on its rice dryers? If so, can they

provide the data?

A3. We have no other opacity data available for rice dryers.

Cost Data

For each type of control (enclosure, mesh control screen, Screen Airs, other?) can you provide:

1. Capital cost of control equipment:  All cost items necessary to design, purchase, and install the

control system:

a. Purchased cost of enclosure, screen and auxiliaries (e.g., hoods, fans, and any

instrumentation);

b. Equipment installation cost (e.g., foundations, piping, electrical, wiring, retrofitting,

installation)

c. Engineering, construction overhead, and contingencies.
d. Year of cost data.

2. Annualized cost to operate and maintain control equipment

a. Life of equipment:  15 years?

Cost Data ‐ answers  

1. Capital cost of control equipment

Enclosure costs:   From 2012 Cost estimates

It has been estimated that the cost of the enclosure adds about 33% to the cost of the dryer.  Riceland

plans to begin construction of a 10,000 bu/hr dryer this winter.  The cost of the dryer is $1,130,000.  The

cost of the enclosure, screens, dust system and associated equipment is estimated at about $370,000.

Bringing the total project costs to $1,500,000.

Hull Chamber costs:  From 2012 cost estimates

Each hull chamber is made to fit the particular headhouse and dryer it serves.    

Riceland estimates that a typical hull chamber retrofit consisting of a headhouse having two grain dryers

rated at 5,000 bu/hr each would cost around $440,000.

   

Tech Air Screen Air costs: From 2007

Riceland completed a Screen Air retrofit on one (1) dryer. The approximate cost for this retrofit in 2007

dollars was $515,000.

2.  Annualized cost to operate and maintain control equipment

Riceland has no detailed information regarding operating and maintenance costs for the grain dryer dust

control systems it employs.  However, each enclosure is made of 3’ x 10’ louvered panels with 24 mesh

stainless steel screen on the inside of the panel.  The approximate life of the 24 mesh screen is 15 years.   

Riceland rescreened a hull chamber enclosure comprised of 203 panels prior to the 2012 harvest.  The

installed cost of the rescreen was $200 per panel.

Additional Information

As per your telephone inquiry, Riceland handled approximately 20% of the 2011 US rice crop.
Appendix C

Opacity Test Results For Wire Screen Column Dryers
Survey of Source Emissions

Opacity Testing

Various Subpart DD Grain Dryers

Test Date: September 3, 2009

Environmental Services Company, Inc.

Corporate Office: Northwest Branch:

13715 West Markham 1107 Century Avenue

Little Rock, Arkansas 72211 Springdale, Arkansas 72762 

Phone: 501-221-2565 Phone: 479-750-1170

Fax: 501-221-1341 Fax: 479-750-1172

 Email: corporate@esclabs.com Email: nwbranch@esclabs.com

Web Site: www.esclabs.com

1 Project No. 0908520017
Table of Contents

 Section

Introduction and Summary of Results 1 

1.1 Scope of Work

1.2 Facility and Test Contacts

1.3 Acknowledgments and Certification 

1.4 Discussion of Results

1.4.1 Summary of Results – Dewitt, Arkansas (Dryer #5)

1.4.2 Summary of Results – Hazen, Arkansas (Dryer #2) 

1.4.3 Summary of Results – Hazen, Arkansas (Dryer #3) 

1.4.4 Summary of Results – Lonoke, Arkansas (Dryer #1) 

1.4.5 Summary of Results – Wheatley, Arkansas (Dryer #4) 

Quality Assurance 2 

2.1 Visual Emissions Certification

2 Project No. 0908520017
Introduction and Summary of Results 

1.1 Scope of Work

At the request of Mr. Neil Washburn of Riceland Foods, Inc., Environmental Services Company, Inc. 

(ESC) performed opacity testing on several grain dryers across the state of Arkansas. These dryers are 

subject to 40 CFR Part 60 – Standards of Performance for Grain Elevators. The individual who 

performed the evaluation of opacity was certified per USEPA Method 9 – Visual Determination of 

Opacity from Stationary Sources. 

3 Project No. 0908520017
1.2 Facility and Test Contacts

Facility Contact 

Mr. Neil Washburn

Riceland Foods, Inc. 

709 East 22nd Street

Stuttgart, AR 72160 

Phone: (870)673-5337 

Fax: (870)673-5720 

email: nwashburn@riceland.com

Test Contact

Mr. Jeff Woosley

Environmental Services Co., Inc. 

13715 West Markham 

Little Rock, AR 72211 

Phone: (501)221-2565 x 116 

Fax: (501)221-1341 

email: jeffw@esclabs.com

4 Project No. 0908520017
1.3 Acknowledgements and Certification 

The staff of Environmental Services Company, Inc. (ESC) sincerely wishes to thank all personnel 

involved in the success of the testing program, especially Mr. Neil Washburn of Riceland Foods, Inc.

Having worked on this project, reviewed all data, and prepared this report, I hereby certify that the 

information contained herein is accurate and true according to the methods and procedures used and take 

responsibility for the contents thereof. Additionally, this report shall not be reproduced, except in full, 

without the written approval of the testing organization. 

 

Jeffrey Woosley 

Special Projects Manager

5 Project No. 0908520017
1.4 Discussion of Results

The results from this testing program are summarized in the attached tables. The opacity results are 

reported as percent (%) for each test run. Also included are opacity readings and pictures for each dryer. 

6 Project No. 0908520017
1.4.1 Summary of Results - Dewitt, Arkansas (Dryer #5)

Run #1

Sample date 09/03/09

Sample time 1410-1440

Throughput

Throughput, bushels/hr 5,000

Opacity

Opacity, % 0.00

SUMMARY OF RESULTS

DEWITT, ARKANSAS

DRYER #5

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1.4.2 Summary of Results - Hazen, Arkansas (Dryer #2)

Run #1 (Running) Run #2 (Empty and Filling)

Sample date 09/03/09 09/03/09

Sample time 0905-0935 1025-1055

Throughput

Throughput, bushels/hr 6,500 6,500

Opacity

Opacity, % 15.63 8.38

SUMMARY OF RESULTS

HAZEN, ARKANSAS

DRYER #2

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1.4.3 Summary of Results - Hazen, Arkansas (Dryer #3)

Run #1

Sample date 09/03/09

Sample time 0940-1010

Throughput

Throughput, bushels/hr 2,800

Opacity

Opacity, % 3.79

SUMMARY OF RESULTS

HAZEN, ARKANSAS

DRYER #3

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1.4.4 Summary of Results - Lonoke, Arkansas (Dryer #1)

Run #1

Sample date 09/03/09

Sample time 0755-0825

Throughput

Throughput, bushels/hr 5,000

Opacity

Opacity, % 1.13

SUMMARY OF RESULTS

LONOKE, ARKANSAS

DRYER #1

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1.4.5 Summary of Results - Wheatley, Arkansas (Dryer #4)

Run #1

Sample date 09/03/09

Sample time 1150-1220

Throughput

Throughput, bushels/hr 8,500

Opacity

Opacity, % 3.00

SUMMARY OF RESULTS

WHEATLEY, ARKANSAS

DRYER #4

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Quality Assurance

2.1 Visual Emissions Certification

The individual who performed the evaluation of opacity was certified per USEPA Method 9, Sections 2 

and 3. A copy of the certificate of qualification is included in this section of the report. 

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