### NSPS SUBPART DD COALITION

VIA ELECTRONIC MAIL

September 20, 2012

Mr. William Schrock U.S. Environmental Protection Agency Office of Air Quality Planning and Standards

109 T.W. Alexander Drive
Mail Code: E143-03 Research Triangle Park, NC 27709

Re: Follow-up to the July 25 Meeting of the NSPS Subpart DD Coalition with EPAOAQPS

Dear Bill:

On July 25, 2012, representatives of the NSPS Subpart DD Coalition 1 met in your offices to discuss the status of EPA’s efforts in revising the grain elevator new source performance standard (NSPS) found at 40 CFR Part 60, Subpart DD. We are submitting this letter on behalf

of the Coalition in order to comment on three issues that arose during the July 25 meeting:

1. Whether it would be appropriate to distinguish between permanent grain storage and temporary grain storage on the basis of the number of turnovers in a year;

2. Whether some fraction of the grain storage capacity of a temporary grain storage facility (TSF) should count toward quantifying the total “permanent” storage capacity at a given grain elevator; and,

3. What distinguishes emergency storage from a TSF.

We are submitting this letter also to provide you with an inventory and summary of the 11 “white papers” that the Coalition has submi tted previously on technical matters.

This letter does not signal any change in the Coa lition’s overarching views. The Coalition as a first priority continues to urge EPA to repeal Subpart DD for the reasons detailed in its February 6, 2012, petition. Also, in the event EPA were to deny that petition and move towards revising Subpart DD, the Coalition would continue to urge EPA to exclude TSFs from Subpart DD altogether. In the Coalition’s view, it would not be “appropriate” within the meaning of section 111 of the Clean Air Act to regulate by means of an NSPS the future addition of TSFs to grain elevators. TSFs do not present a nationally significant risk to air quality and, therefore, do not warrant a federal response in the form of an NSPS. Just as state/local air pollution control agencies can adequately address grain elevators (as the Coalition’s February 6, 2012 petition shows), they can also adequately address new TSFs.

1 The members of the NSPS Subpart DD Coalition include the Corn Refiners Association, the North American Millers’ Association,

the National Council of Farmer Cooperat ives, the National Grain and Feed Associ ation, the National Oilseed Processors

Association and the USA Rice Federation.Mr. William Schrock Follow-up to the July 25 Meeting of t he NSPS Subpart DD Coalition with EPA-OAQPS September 20, 2012 Page 2 of 6

1. Distinguishing Between Permanent Grain Storage and Temporary Grain Storage on the Basis of the Number of Turnovers per Year

The fundamental purpose of a TSF is for bulk storage of grain on a temporary basis. TSFs generally experience a single turnover annually. In 2010, the Coalition’s technical consultant, RTP Environmental Associates, Inc. (RTP), analyzed Coalition member companies’ responses to a 2009 EPA §114 survey . The responses collectively contained data for 121grain elevators, including data representing 119 storage-unit-years 2 of TSF operation. Of these, three TSFs reported a total of five storage-unit-years with more than one turnover per year; the maximum number of annual turnovers reported was two. At two of the three TSFs reporting more than one annual turnover, it appears that these TSFs were used to store two different grains in a single year, rather than being used as an “active” storage unit. In sum, according to the §114 data, annual turnovers for TSFs average about 0.9, with a few units experienci ng as many as two turnovers annually. Thatlow rate of turnovers makes sense, given that filling and emptying a TSF are laborintensive, time-consuming processes and not something routinely done on a daily, weekly, or even monthly basis.

In stark contrast, the rate of turnovers at permanent grain storage is much higher – averaging about 9.3 per year, based on the §114 data. That relatively high rate of turnover makes sense as well, because permanent storage and grain handling obviously are structured to operate much more efficiently and rapidly than TSFs.

These major differences in turnover rates and structure are so great, and so well substantiated by the §114 data, that there is no need for Subpart DD applicability purposes to build a turnover rate into a definition of TSFs in order to distinguish them from permanent capacity. There is, moreover, a risk in attempting to restrict the universe of TSFs by means of a turnover rate. While the §114 data clearly show that the vast majority of TSFs typically experience a single annual turnover, it is conceivable that due to weather extremes or other unforeseen factors, there may be periods when a larger fraction of the TSF population could experience multiple annual turnovers. But, even if they did, that would not materially diminish the reality that TSFs are structurally, functionally and operationally completely different from permanent storage. Accordingly, the Coalition maintains that the most appropriate definition of a TSF remains the generally accepted one which posits four key elements: (a) a base consisting of asphalt, concrete or similar material; (b) rigid, self-supporting sidewalls; (c) an aeration system; and, (d) a tarp or

similar cover.

2. Counting Some Fraction of a TSF’s Capacity as Permanent Storage Capacity

As noted above, RTP’s previous analysis of the §114 data determined that from 2005- 2007, the number of annual turnovers in permanent storage units averaged about 9.3,

while the annual turnovers for TSFs aver aged only about 0.9. RTP previously developed an emissions model to estimate the relative significance of temporary and permanent storage. This model suggests that the uncont rolled emissions from both types of storage

2 The term “storage unit year” is used here to refer to each year of storage/throughput data for an individual TSF. For example, if a single TSF reported data for three years, these da ta represent three storage-unit-years of operation.Mr. William Schrock Follow-up to the July 25 Meeting of t he NSPS Subpart DD Coalition with EPA-OAQPS September 20, 2012 Page 3 of 6

facilities are similar when compared on the basis of a unit of throughput. 3 Given the temporary-to-permanent storage throughput rati o from the survey data, however, this emissions model indicates that an uncontrolled bushel of temporary storage has approximately 10 times less environmental significance than a bushel of permanent storage.

Contrary to the facts discussed above, EPA’s Office of Enforcement and Compliance Assurance (OECA) has issued an opinion that for purposes of determining NSPS applicability, the storage capacity of a TSF is considered to be “permanent storage capacity” as this term is defined in Subpart DD. 4 While the OECA opinion disavows any binding effect on other EPA offices, state/local agencies or the regulated industry, in some cases this opinion is being treated as binding by both EPA regional offices and state/local permitting authorities in determining Subpart DD applicability for grain elevators. The Coalition believes that on the basis of the Subpart DD rulemaking record and the §114 data, TSF capacity is clearly not the same as permanent storage capacity and, therefore, it should not be considered at all in making Subpart DD applicability determinations. Indeed, as noted above, the Coalition believes that TSFs should be excluded from Subpart DD altogether.

The Coalition understands that, based on the §114 data, EPA’s Office of Air Quality Planning and Standards (OAQPS) is considering treating TSFs in the upcoming Subpart DD rulemaking in a manner that differs from the OECA opinion. One option that we understand OAQPS is considering is to have TSF capacity count towards permanent storage capacity at a fractional level (i.e., one bushel of temporary storage capacity is equivalent to a fraction of a bushel of permanent storage capacity). This concept was discussed during the July 25 meeting between Coalition representatives and OAQPS.

Since that meeting, the Coalition has considered this concept specifically. We believe that TSF capacity should not be considered in applicability determinations either now or in the future, for the following reasons:

• As discussed above, TSFs are starkly different from permanent storage capacity in all key respects, namely: structure, function, operation, and annual emissions of particulate matter (PM). There is no commonality that justifies grouping TSF capacity with permanent capacity from the standpoint of the logic of section 111 of the Clean Air Act. TSFs are not a “subcategory” of permanent storage capacity within the meaning of section 111.

• TSF are truly temporary. They are intended to handle intermittent surges and surpluses and, hence, are not used necessari ly every year. The current year is a good example. Low yields in 2012 will likely result in less use of TSFs.

3 The estimated uncontrolled PM 10 emissions factors for permanent storage and te mporary storage facilities are 0.077 pound per

ton of throughput and 0.084 pound/ton, respectively (see “Analysis of 114 Survey Data by the Subpart DD Coalition” presented to EPA on February 24, 2010).

4 See letter from Michael S. Alushin, Dire ctor, Compliance Assessment and Media Progra ms Division, Office of Compliance, EPA

to Mr. Kendall Keith, President, National Gr ain and Feed Association, November 21, 2007.Mr. William Schrock Follow-up to the July 25 Meeting of t he NSPS Subpart DD Coalition with EPA-OAQPS September 20, 2012 Page 4 of 6

• As can be seen in the §114 data, the amount of permanent storage capacity nationwide exceeds the amount of temporary storage capacity by an order of magnitude, thereby underscoring the concept that future TSFs, if any, do not pose a significant risk to air quality justifying regulation at the national level in the form of an NSPS. In other words, TSF capacity is too environmentally insignificant to be a rational basis for triggering Subpart DD applicability. State/local air pollution control agencies are able to address TSFs satisfactorily.

• Finally, the underlying data indicate that TSF emissions are too environmentally insignificant to justify regulation at the national level in the form of an NSPS, including having TSF capacity count towards permanent storage capacity at a fractional level. As noted above, the ratio of turnovers and, hence, emissions of TSFs versus permanent storage is roughly 1-to-10. But that is only a comparison of one bushel of TSF as against one bushel of permanent storage. Since Subpart DD is a national-scale rule, logic calls for taking also into account the ratio of TSF capacity nationally to permanent storage nati onally, as reflected in the §114 data. That ratio is also less than 10 percent, meaning that on a national basis, uncontrolled
TSF emissions amount to less than 1% of the uncontrolled emissions associated with permanent storage. Emissions of such a small magnitude would not be worth regulating by means of an NSPS or of counting any fraction of TSF as “permanent” capacity.

In sum, on the basis of the Subpart DD rulemaking record and the §114 data, TSF capacity is clearly not the same as permanent storage capacity and, therefore, it should not be considered at all in making Subpart DD applicability determinations. The Coalition urges EPA to exclude TSFs from Subpart DD altogether, and certainly from any quantification of permanent capacity.

The Coalition very much agrees with the view you expressed during the July 25 meeting that, assuming EPA does not repeal Subpart DD and instead revises it, the revised version and the old version should treat TSFs in the same way. From the Coalition’s standpoint,

that means that TSFs should be excluded from Subpart DD altogether. As the Coalition explained in its May 14, 2010, petition to rescind the OECA opinion, that opinion is incorrect in concluding that TSFs are a form of permanent storage. Based on the record for the original rulemaking, EPA could not have intended Subpart DD to apply in any way to TSFs when Subpart DD was promulgated. While TSFs have now come into widespread use, it is clear from the §114 data that they are too inconsequential to warrant national regulation in the form of an NSPS. State and local agencies can address them adequately.

The Coalition repeats the request in its May 14, 2010, petition that EPA squarely address the Coalition’s arguments in that petition against the OECA opinion and propose to rescind it as part of the Agency’s “review” of Subpart DD. The OECA opinion is an unavoidable part of that “review.” EPA at some point will have to respond to those arguments.Mr. William Schrock Follow-up to the July 25 Meeting of t he NSPS Subpart DD Coalition with EPA-OAQPS September 20, 2012 Page 5 of 6

3. Emergency Grain Storage Operations and How an Emergency Grain Storage Pile
Differs from a TSF

“Emergency grain storage” is a grain storage practice used by grain elevator operators during bumper-crop years and for other unique circumstances in “emergency” situations where there is no better alternative for grain storage. This practice, which involves outdoor piling of grain, is not regulated under Subpart DD. Emergency storage differs from temporary storage in an important way - it lacks one or more of the four key characteristics of TSFs. For instance, em ergency storage often lacks sidewalls, a cover and, sometimes, aeration.

The amount of particulate matter emissions from emergency storage piles may be similar to that of TSFs (on a “pounds per bushel of throughput” basis) during times when emergency storage piles are actually used. However, emergency piles are used infrequently and only in “emergency” situations where there is no better alternative for grain storage. Storage of grain in emergency piles is significantly less desirable when compared to storage in a TSF or permanent st orage facility because of the potential for loss of inventory and degradation of the grain quality. Simply put, emergency storage piles represent storage of last resort for grain elevator operators. Thus, emergency storage piles should not be considered equivalent to TSFs in terms of environmental impacts and it is appropriate to continue the historical practice of not regulating such infrequently used sources under Subpart DD, nor should such sources be considered in determining applicability of Subpart DD at a given facility.

4. Issues and Concerns That the Coalition Has Previously Discussed with the Agency

Coalition representatives met with EPA repr esentatives and representatives from EPA’s contractor ERG several times during 2010 to discuss a number of issues and concerns with NSPS Subpart DD. As a result of thes e discussions, the Coalition had RTP prepare 11 “white papers,” which provided analysis of certain of the issues discussed at these meetings as well as suggested revisions to Subpart DD language to address these issues. Electronic copies (PDF files) of these 11 wh ite papers were provided (via email) to EPA in June and August of 2010.

EPA is now renewing its efforts to revise and update Subpart DD. One purpose of this letter is to summarize the issues described in the previously submitted white papers. A brief summary of the issues addressed in the previously submitted white papers is included in Table 1, along with the title and date of each paper submitted to EPA. Note that the intent of the summary is not to replace the information in the white papers themselves, but to provide a quick refer ence guide to facilitate EPA’s review and consideration of these documents. Copies of the individual white papers are included with this letter, following Table 1.

* * * * * * *1Table 1. Summary of 11 Previously Submitted “White Papers” Developed by RTP on behalf of the CoalitionFile NameDateSubmitted toEPAStatusSummaryBarge Unloading Paper2010-06-28.pdf06/29/2010Only versionsubmittedThis paper identifies the fact that alternative barge unloadingsystems are not regulated under Subpart DD, identifies the factthat very little opacity data exist for such systems, and raisesthe question as to whether alternative barge unloadingoperations are significant enough to be regulated at all.Dry Mill Clarification2010-06-25.pdf06/25/2010Only versionsubmittedThis paper identifies an issue that has occurred where somestate/local permitting authorities have incorrectly appliedSubpart DD to dry corn mills that produce fuel ethanol andsuggests rule language that would clarify Subpart DDapplicability at these sources.Grain Dryer Paper2010-06-15.pdf06/15/2010InitialsubmittalThis paper demonstrates that Subpart DD does not currentlyapply to wire-screen (rice) dryers. It provides an estimate of theU.S. population of wire-screen dryers and their emissions. Itdemonstrates that wire-screen dryers are an insignificantemissions source and that theyshould not be regulated underSubpart DD. It determines, based on available data, that if anopacity limit is imposed, itshould be at least 10%.2Table 1. Summary of 11 Previously Submitted “White Papers” Developed by RTP on behalf of the CoalitionFile NameDateSubmitted toEPAStatusSummaryGrain Dryer Paper V22010-07-31.pdf08/02/2010SupplementalThis paper outlines a proposeddesign standard for wire-screendryers that is arguably more stringent than the present standardfor perforated-plate columndryers. Assuming that EPAdetermines that wire screen dryers are "significant" and,therefore, should be regulated under Subpart DD, the use of thedesign standard and definition outlined in this paper should beconsidered as the basis for such regulation.Grain ElevatorDefinition 2010-06-25.pdf06/25/2010InitialsubmittalThis paper is completely superseded by the July 31, 2010,version below.Grain ElevatorDefinition V2 2010-07-31.pdf08/02/2010Replacement submittalThis paper provides suggestedlanguage revisions to SubpartDD to address problems that some Coalition members haveexperienced with permitting authorities misinterpreting whatconstitutes the “grain handling operations” affected facility. Italso provides suggestions to address situations where morethan one grain elevator may exist at a single location.Grain Handling OpacityTesting2010-06-15.pdf06/15/2010Only versionsubmittedThis paper provides suggestedlanguage revisions to SubpartDD to address situations where opacity measurements arerequired for equipment that is fullyenclosed. The intent of thissuggested language is to avoid expending resources on opacitymeasurements for equipment that, by design, cannot havevisible emissions.3Table 1. Summary of 11 Previously Submitted “White Papers” Developed by RTP on behalf of the CoalitionFile NameDateSubmitted toEPAStatusSummaryGrain Unloading2010-06-25.pdf06/25/2010Only versionsubmittedThis paper provides suggestedlanguage revisions to SubpartDD to clarify the boundaries ofgrain loading and grainunloading stations. Such clarification is needed to ensureconsistent evaluations when determining whether a capitalexpenditure occurs or whetheran affected facility isreconstructed.Mineral Oil Paper2010-06-15.pdf06/15/2010Only versionsubmittedThis paper addresses the potential applicability of mineral oil asa control technique for reducing emissions from TSFoperations. It concludes thatthe control cost-effectiveness ofusing mineral oil is excessive. Note that in June 2012, asCoalition representatives alerted EPA on July 25, 2012, theEuropean Food Safety Authority (EFSA) published a scientificopinion on dietary exposure inhumans to mineral oilhydrocarbons. EPA needs to be mindful of this opinion in anyrequirements it might impose thatimplicate the use of mineraloil as a control technique for reducing emissions from TSFoperations.Representative Testing2010-06-25.pdf06/25/2010InitialsubmittalThis paper is completely superseded by the July 31, 2010,version below.Representative TestingV2 2010-07-31.pdf08/02/2010Replacement submittalThis paper provides suggested changes to Subpart DD to allowaffected facilities to conduct representative testing on "identicalaffected facilities." It also suggests a minor clarification to thelanguage in §60.303(b)(1).304-A West Millbrook Road Raleigh North Carolina 27609 (919) 845-1422 

# Memorandum

To: Jess McCluer and Dave Ailor

CC: Peter Wyckoff, NSPS Subpart DD Coalition

From: Jack Burke – RTP Environmental Associates, Inc.

Date: June 28, 2010

Re: Applicability of and Alternatives to the Current NSPS Subpart DD Barge Unloading

Standard

Background

Subpart DD defines each barge unloading station as an affected facility. The term “barge unloading station” is not specifically defined, but the term “grain unl oading station” is defined as “that portion of a grain elevator where the grain is transferred from a truck, ra ilcar, barge, or ship to a receiving hopper.”

Subpart DD regulates fugitive particulate ma tter emissions from certain barge unloading operations through a design/work practice standard at §60.302(d):

“The owner or operator of any barge or ship unloading station shall operate as follows:

(1) The unloading leg shall be enclosed from the top (including the receiving hopper) to the center line of the bottom pulley and ventilation to a control device shall be maintained on both sides of the leg and the grain receiving hopper.

(2) The total rate of air ventilated shall be at least 32.1 actual cubic mete rs per cubic meter of grain handling capacity (ca. 40 ft 3 /bu).

(3) Rather than meet the requirements of paragr aphs (d)(1) and (2) of this section the owner or operator may use other methods of emissi on control if it is demonstrated to the Administrator's satisfaction that they would reduce emissions of particulate matter to the

same level or less.”

To aid in understanding the scope of this requirement, RTP review ed the record for the original Subpart DD rulemaking. In regards to barge unloading, the “Standards Support” document for the 1977 proposed rule states:

“Grain is received by barge at inland terminal and port terminal elevators. The unloading areas are generally open to the weather. In most cases grain is unloaded with a bucketApplicability of and Alternatives to the Subpart DD Barge Unloading Standard

28 June 2010 Page 2 of 3

elevator (leg) that is lowered into the barg e. Their capacities range from 15,000 up to 75,000 bushels per hour; the average is about 30,000.” 1

And in the proposed rule, EPA states:

“All of the bucket elevators (legs) observed by EPA at barge and ship unloading stations during the development of the proposed standard s had various types of enclosures and were ventilated. A facility with the leg enclosed from the top (including the receiving hopper) to

the center line of the bottom pulley appeared to perform with the least emissions. This facility was observed in operation with and without the ventilation system in operation.

Visible emissions were observed to be significantly lower when the ventilation system was operating than when it was not. EPA conclude d that this system represents the best demonstrated system of emission reduction (c onsidering costs) and proposes an equipment standard based on the design of' this system.” [42 FR 2845]

There were no changes in the barge unloading provisions between the proposed and the final

rules. 2 In RTP’s view, the above statements de monstrate that Subpart DD is focused on regulating fugitive emissions from bucket elevator unloading legs used for barge unloading.

§60.302(d)(3) provides for equivalency determinations in situations where it is not possible to meet the design standards in §60.302 (d)(1) and (2). There are se veral types of barge unloading equipment that have been developed since S ubpart DD was promulgated, which appear to fall into this category. Specifically, continuous barg e unloaders (CBUs) and en-masse style drag conveyors could conceivably be cons idered to have “unloading legs” and, therefore, be subject to the provisions of Subpart DD. However, ne ither of these unloading systems is a “bucket elevator” as the term is used in the origin al Subpart DD rulemaking record. These unloading systems differ significantly in design fr om the unloading legs referenced in §60.302(d).

Based on discussions with Coalition members, RTP has determined that there is some confusion among both elevator owners and permitting authorit ies as to how alternative unloading systems (i.e., systems that do not employ a bucket el evator unloading leg) are regulated under Subpart DD. In some cases, members of the Coalition have applied for equivalency determinations under the provisions of §60.302(d )(3), even though their unloading system does

not include a bucket elevator un loading leg. And in some cases , Coalition members have had difficulty in obtaining equivalency determinations. The Coalition has expressed a desire to have Subpart DD modified to a ddress these issues.

1 “Standards Support and Environmental Impact Statemen t Volume 1: Proposed Standards of Performance for

Grain Elevator Industry,” EPA·450/2·77·001a, January 1977.

2 “Standards Support and Environmental Impact Statement Volume 2: Promulgated Standards of Performance for

Grain Elevator Industry,” EPA-450/2-77-001, April 1978.Applicability of and Alternatives to the Subpart DD Barge Unloading Standard

28 June 2010 Page 3 of 3

Analysis

A careful review of the provisions in §60.302(d) a nd the relevant rulemaki ng record leads one to conclude that the Subpart DD requirements apply only in those situations where an affected barge unloading operation employs a bucket elevator unloading leg to remove grain from a barge or ship. Other types of barge and ship unloa ding operations (e.g., barge unloading using a clam shell) are not subject to any specific requirements under Subpart DD. This interpretation is consistent with the data and information EPA used as the basis for the requirements in Subpart DD.

It would be helpful for EPA to eliminate the c onfusion surrounding the scope and applicability of the barge unloading provisions in Subpart DD. Additionally, it would be desirable for the Agency to streamline the equivalency determin ation process in situations where such a determination is required.

Based on a May 6 th meeting between RTP, EPA and ERG, it appears the Agency is considering an opacity limit as an alternative to the design st andard in the current rule. Based on discussions with and information received from Coalition members, RTP believes that available data are inadequate for developing an opacity limit for alternative unloading designs. Through a survey of Coalition members, RTP obtained opacity test data for only one alternative unloading leg. This is an en-masse drag conveyor at Bunge’s Cairo, Illinois facilit y. No opacity test data have been identified for a CBU and only two opacity tests were obtained for barge unloading operations that do not invol ve unloading legs (e.g., a clam-shell unloader).

Because alternative unloading systems (i.e., unloa ding systems that do not use a bucket elevator unloading leg) were not considered in the or iginal Subpart DD rulemaking, the threshold question that must be addressed going forwar d is whether such alternative systems are a significant source of emissions (i.e., Is it appr opriate to regulate these sources under Subpart DD?). RTP understands that the Coalition is prepar ed to work with U.S. EPA in addressing this question.304-A West Millbrook Road Raleigh North Carolina 27609 (919) 845-1422 

# Memorandum

To: Jess McCluer and Dave Ailor

CC: Peter Wyckoff; NSPS Subpart DD Coalition Members

From: Jack Burke – RTP Environmental Associates, Inc.

Date: June 25, 2010

Re: Dry Mill Clarification to Grain Storage Elevator Definition in NSPS Subpart DD

Issue:

§60.301(f)(2) of Subpart DD defines a “grain storage elevator” as:

“any grain elevator located at any wheat flour mill, wet corn mill, dry corn mill (human consumption) , rice mill, or soybean oil extraction plant whic h has a permanent grain storage capacity of 35,200 m 3 (ca. 1 million bushels).” [emphasis added]

Some permitting agencies have in terpreted this threshold incorrectly to apply to dry corn mills that do not produce products destined for human consumption (i.e., fuel ethanol plants). To eliminate confusion, the NSPS Subpart DD Coaliti on would like EPA clarify the definition of “grain storage elevator” to spec ifically exclude dry corn mill pl ants that produce fuel ethanol.

Suggested Clarifications to Subpart DD:

To eliminate confusion regarding dry corn mills, th e following change to the definition of grain storage elevator at §60.301 is suggested:

(f) Grain storage elevator means any grain elevator located at any wheat flour mill, wet corn mill, dry corn mill (human consumption), rice mill, or soybean oil extraction plant which has a permanent grain storage capacity of 35,200 m 3 (ca. 1 million bushels). Grain elevators at dry corn mills that produce ethanol for fu el use are not grain storage elevators.304-A West Millbrook Road Raleigh North Carolina 27609 (919) 845-1422 

# Memorandum

To: Jess McCluer & Dave Ailor

CC: Peter Wyckoff, NSPS Subpart DD Coalition

From: Jack Burke – RTP Environmental Associates, Inc.

Date: June 15, 2010

Re: Column Grain Dryers Using Woven Wire Screens as the Column Walls

Introduction and Summary

This memorandum summarizes RTP’s analysis of issues associated with the possible regulation of column grain dryers that use woven wire sc reens instead of perforated plates. RTP has reviewed available data on this ty pe of dryer. Based on this revi ew, the rate of emissions from these dryers is low and the rate of construction, modification, and reconstruction of such dryers

is also low. The combination of these factor s means that such dryers are an insignificant subcategory of equipment at grai n elevators from an emissions pe rspective and, therefore, are not appropriate for regulation under Subpart DD. RTP also found no data to support the position that these dryers can meet a 0 percent opacity limit. The lim ited data available suggest any opacity limit should be at least 10 percent.

Background

Subpart DD regulates emissions from certain co lumn dryers. Figure 1 is a simplified crosssection sketch of a column dryer. In this type of dryer, wet grain is fed to the dryer at the top and flows by gravity through a packed column to the bottom of the drye r. Heated air is introduced

on the inside of the columns and flows out thro ugh the grain to the atmosphere. The grain columns are contained by parallel walls constructe d of perforated plates or wire mesh screens, depending on the application. Air moving through the grain columns dries the grain but also can entrain particulate matter, which may be emitted to the atmosphere.

Subpart DD only regulates emissions from certain types of column dryers. The rule defines a column dryer to be “any equipment used to reduce the mois ture content of grain in which the grain flows from the top to the bottom in one or more continuous packed columns between two perforated metal sheets .”[emphasis added] Thus, column dr yers that contain the grain column between walls made of something other than perf orated metal sheets (e.g., woven wire screens) are not considered column drye rs for purposes of Subpart DD.Wire Screen Dryer Review

15 June 2010 Page 2 of 6

Figure 1. Simplified Sche matic of Grain Column DryerWire Screen Dryer Review

15 June 2010 Page 3 of 6

Under Subpart DD, any “column dryer” with a column plate perforation exceeding 2.4 mm diameter (ca. 0.094 inch) must meet a 0 per cent opacity standard. Otherwise, Subpart DD contains no specific emission limits or other requirements for column dryers. The standard was established in this way because, during the 1977-1978 rulemaking process, EPA concluded that add-on controls for column drye rs were not cost effective. 1 The structure of the rule language is such that meeting a design standard (e.g., a drye r having column plate perforations less than or equal to 2.4 mm in diameter) effectively exempt s regulated column dryers from the 0 percent opacity standard.

At the time the column dryer standard was devel oped, there may have been relatively few dryers that employed wire screens as walls to contain the grain columns in the dryer. 2 Wire screen walls are preferred for rice drying because they offer greater durability, result in less kernel damage, and provide for more efficient dryer oper ation. Figure 2 contains photographs of the two types of column dryer walls.

Figure 2. Woven Wire a nd Perforated Plate Materials

RTP has examined the database compiled from the responses by Subpart DD Coalition members to U.S. EPA’s September 2009 Section 114 information request. Of the 28 column dryers that

1 See “Standards Support and Environmental Impact Statement Volume 1: Proposed Standards of Performance for

Grain Elevator Industry;” U.S. EPA, OAQPS, January 1977. One r eason that controlling grain dryers is expensive is because typically they are only used for rela tively short periods each year as grain is harvested. In some years the dryers are not used at all.

2 Of the 28 wire screen dryers identified in the Subp art DD Section 114 survey responses, only two were

constructed prior to 1989 and only one prior to 1980. Ho wever, RTP is aware that this type of dryer was in relatively common use for drying rice in Calif ornia during the 1970s (see, for example, “Staff Report on Emissions from Rice Dryers in th e Sacramento Valley Air Basin” , California Air Resources Board, April 11, 1974).Wire Screen Dryer Review

15 June 2010 Page 4 of 6

indicate the use of wire screen column walls, all but two are used for rice or rice and some other grain. 3

RTP also contacted several dryer manufacturers to better understand the grain dryer marketplace in general and the market for wire screen dryers in particular. We identified two manufacturers who sell “rice dryers” that use wire screens as column walls. 4 Recent sales of these rice dryers have been limited to a one or two each year fr om each of these manufacturers. One of these

manufacturers described wire screen dryers as a “niche market.”

RTP also reviewed recent data on U.S. rice pr oduction. These data, which are plotted in Figure 3, show that rice production was relatively static between 2002 and 2009. 5 This steady production rate suggests that rice dryer sales are likely driven by the need for replacement units rather than a large expansion in capacity due to a long-term trend of increasing rice crop production.

Wire Screen Column Dryer Emissions

As part of its ongoing review of Subpart DD, U.S. EPA may be considering adding compliance requirements for column dryers that use wire screens (i.e., rice drye rs). One issue is whether the expected growth of this source subcategory wa rrants regulation under th e NSPS. To evaluate this issue, there are at least two questions th at should be addressed. Both relate to the significance of column dryers as s ources of emissions at grain elevat ors. The first question is the level of emissions from rice dryers. The second is the expected growth in the population of new and reconstructed rice dryers going forward. The di scussion that follows addresses each of these questions.

In an effort to assess emissions from new a nd reconstructed rice drye rs, RTP reviewed the background documentation for the development of AP-42 Section 9.9.1. 6 This review, which provided information on grain drye r emission factors specific to screen rice dryers, shows that these emissions are in general lower than the final AP-42 emission factor for column grain dryers. According to the data in the AP-42 background report, th e average particulate emissions from screen rice dryers is 0.051 lb/ton, as comp ared to the AP-42 general grain column dryer

emission factor of 0.22 lb/ton. 7

3 RTP also determined that one of the two non-rice dryers is actually not a woven wire screen-type dryer (i.e., the

Zimmerman dryer uses a thin sheet of stainless steel that appears to be a “screen,” but is actually a perforated plate).

4 The dryer vendors contacted by RTP in clude Shanzer (a Division of D & W I ndustries, Inc.) and GSI (a Division

of GSI Group).

5 These years represent the rice crop data th at are readily available on USDA’s website.

6 “ Emission Factor Documentation for AP-42 Section 9.9.1 - Grain Elevators and Grain Processing Plants - Final

Report ”, RTI International, April 2003.

7 Ibid , Tables 4-13 and 4-16.Wire Screen Dryer Review

15 June 2010 Page 5 of 6

Figure 3. Recent U.S. Rice Production

A typical rice dryer has a cap acity of about 5,000 bushels per hour and operates for about 2,000 hours per year. 8 Rough rice has a bulk density of about 45 pounds per bushel. Thus, using the

emission factor data cited above , a typical rice dryer would be expected to emit about 5.7 pounds per hour of particulate emission. The PM 10 and PM 2.5 fractions of these emissions are estimated to be about 2.2 and 0.4 lb/hr, respectively. 9 For 2,000 hours per year of operation, annual emissions from a typical rice dryer would be about 5.7 tons of PM, 2.2 tons of PM 10 , and 0.4 tons

of PM 2.5

.

8 Approximate average capacity and oper ating hours of rice dryers reported in surveys, per discussion with Neil

Washburn, Riceland Foods, Inc.

9 The average PM 10 fraction of screen rice dryer PM emissions is ~38 percent, and the average PM 2.5 fraction is

~6.5 percent; see “Staff Report on Emissions from Rice Dryers in the Sacramento Valley Air Basin” , California Air Resources Board, April 11, 1974, Figure 6. 400 420 440 460 480 500 520 540 560 580 600AnnualRiceProduction(millionbushels)Wire Screen Dryer Review

15 June 2010 Page 6 of 6

RTP estimates the current U.S. population of sc reen rice dryers to be somewhere in the neighborhood of 120 units. 10 Assuming these dryers have a 30 -year service life, about 3 percent

of them will be reconstructed or replaced each year. With no grow th in rice crop, this translates to about four new or reconstructed rice dryers annually. This value is consistent with the

anecdotal information obtained from the two ri ce dryer vendors contacted by RTP. Given the relatively low emissions from each dryer and th e small number of drye rs likely to become subject to any prospectiv e NSPS, it is reasonable to conclude th at wire screen rice dryers belong to a subcategory of sources that is not “signifi cant” from the perspectiv e of the NSPS process.

Opacity Standards

Through discussions with U.S. EPA, RTP is awar e that the Agency is considering a 0 percent opacity standard for screen rice dryers. This standard is based on current permit limits for several dryers in Arkansas. It is RTP’s unde rstanding that these limits were imposed by the Arkansas Department of Environmental Qu ality (ADEQ) based on the Department’s interpretation that the dryers ar e subject to Subpart DD. It is also RTP’s understanding that these dryers may not meet a 0 percent opacity standard under all operating conditions. In particular, during initial startup and when the rice supply is changed, the dryers exhibit short-term visible emissions in excess of 0 percent opacity. Finally, it is RTP’s unde rstanding that the dryers in question have never been compliance tested us ing Method 9, so no data actually exist to demonstrate the ability to comply with a 0 pe rcent opacity standard. Limited opacity data provided to U.S. EPA by the Coalition show that screen rice dryers typi cally cannot meet such a

limit on a short-term basis. 11 If such a limit cannot be achieve d in practice, then it should not

form the basis for an NSPS.

Conclusions

In the U.S., wire screen column dryers are used primarily for drying rice. If Subpart DD were to regulate wire screen column drye rs, about four dryers per year would become subject to the NSPS, for a total of 20 dryers ove r the next five years. Given the relatively small rate of emissions from these dryers, this subcategory of sources should be considered insignificant and therefore, should not be regul ated under the revised NSPS.

It does not appear that a 0 percent opacity standard for wire sc reen rice dryers has been achieved in practice. Therefore, this limit should not fo rm the basis for an NSPS for these dryers. Based on the data supplied to U.S. EPA in Septem ber 2009, a more appropriate limit would be 10 percent opacity.

10 This estimate is based on total U.S. rice production of about 450 million bushels in 2009, an average dryer size of

5,000 bushels per hour, average operating hours of 2,000 hours per year, the assumption that 90 percent of rice production is dried, and the assumpti on that each bushel of rice passes th rough a dryer three times. Thus, the number of 5,000 bushel/hour rice dryers can be estimated as follows: (450 MM bushels/yr) x (0.9 bushels dried /bushel) x (3 passes) / (5,000 bushels/hr/dryer x 2,000 hr/yr) = 121.5 dryers

11 Data provided to U.S. EPA by Riceland Foods, Inc. in a presentation made in September 2009.304-A West Millbrook Road Raleigh North Carolina 27609 (919) 845-1422 

# Memorandum

To: Jess McCluer & Dave Ailor

CC: Peter Wyckoff, NSPS Subpart DD Coalition

From: Jack Burke – RTP Environmental Associates, Inc.

Date: July 31, 2010

Re: Design Standard for Column Grain Dryers Using Woven Wire Screens as the Column

Walls

Issue:

In a previous memorandum dated June 15, 2010, RTP provided the Coalition w ith an analysis of rice dryers using woven wire screens as the column walls. In a discussion of this analysis during the Coalition’s July 8 th , 2010, meeting with U.S. EPA, an alte rnative approach to regulating these dryers was identified. This approach involved se tting a design standard for woven-wire screen rice dryers that would be analogous to the current design standard for column dryers.

As background, Subpart DD defines a column dr yer as “any equipment used to reduce the moisture content of grain in which the grain fl ows from the top to the bottom in one or more continuous packed columns between two perforat ed metal sheets.” As described in RTP’s June 15 memorandum, the definition of “column dryer” does not include wire screen rice dryers. It is my impression of the discussion of this i ssue with EPA, that the Agency agrees with the Coalition’s view regardi ng wire screen dryers.

The current standard for column dr yers requires that the perforati ons in the column walls be less than or equal to 2.4 mm (2,400 μ m) in diameter. Otherwise, the dr yer is subject to a zero percent opacity standard. A 2.4-mm diameter repr esents a cross-sectional area of 4.5 mm 2 , which is about equivalent to a 10 mesh scre en which has an opening size of 4.0 mm 2

.

The suggestion was made that the definition of “column dryer” be amended to include wire screen dryers, and that the design standard be modified accordingly. EPA agreed to consider such approach and the Coalition ag reed to provide EPA with additi onal information to aid in that consideration. This memorandum provides sugg ested revisions to the current Subpart DD language to address the issue of wire screen dryers using a design standard.Wire Screen Dryer Standard 31 July 2010 Page 2 of 2

Suggested Clarifications to Subpart DD:

First, revise the definition of column dryer in §60.301 as follows:

(m) Column dryer means any equipment used to reduce the moisture content of grain in which the grain flows from the top to the bottom in one or more continuous packed columns between two perforated metal sheets

, two woven wire screens, or a combination of perforated metal sheets and wire screens

.

Next, add a design standard to §60.302(a) for woven wire screen column dryers. The intent of this provision is to establish a design standard for rice dryers that requires that the dryers be enclosed, and that the enclosur e have 24 mesh control screens up to the level of the dryer column. Suggested language to implement this concept is added to the current NSPS language

below:

(a) On and after the 60th day of achieving the maximum production rate at which the affected facility will be operated, but no late r than 180 days after initial startup, no owner or operator subject to the provisi ons of this subpart shall caus e to be discharged into the atmosphere any gases which exhibit great er than 0 percent opacity from any:

(1) Column dryer with an outside column plate perforation exceeding 2.4 mm diameter (ca. 0.094 inch).

(2) Column dryer with column wire screens provided the dryer is not in an enclosure having control screens with 24 mesh or smaller openings with such control screens at least as high as the exterior dryer column walls.

( 3 2 ) Rack dryer in which exhaust gases pa ss through a screen filter coarser than 50

mesh.304-A West Millbrook Road Raleigh North Carolina 27609 (919) 845-1422 

# Memorandum

To: Jess McCluer and Dave Ailor

CC: Peter Wyckoff; NSPS Subpart DD Coalition Members

From: Jack Burke – RTP Environmental Associates, Inc.

Date: June 24, 2010

Re: Definition of Grain Elevator and Scope of Grain Handling Operations Under NSPS Subpart DD

Issue #1

§60.300(a) applies to each affected f acility at any grain terminal elevator or any grain storage elevator. This subsection identifies “all grain ha ndling operations” as a singl e affected facility. §60.301(b) defines the term “grain elevator” as any plant or installa tion at which grain is unloaded, handled, cleaned, dried, st ored, or loaded. At issue is whether two (or more) grain elevators at a single location (i .e., on the same or contiguous pr operty) are considered a single grain elevator, or whether they are different grain elevators for purposes of the definition of the affected facility consisting of “all grain handling operations.”

Consider the following example. An elevat or owner constructs a second, functionally independent elevator (sub ject to the NSPS) at a different location, but on the same property as an existing elevator that is not cu rrently subject to the NSPS. If the two elevators (new and existing) are considered a singl e grain elevator, then the cons truction of the grain handling operations associated with the new elevator woul d likely subject the grain handling operations at the existing elevator to NSPS requirements because of the way the affected facility is defined (i.e., “all grain handling ope rations”). None of the other activities at the existing elevator would be subject to the NSPS unle ss they are subsequently m odified or reconstructed.

Issue #2

Some permitting authorities ev aluate NSPS applicability for grain handling operations on an individual unit basis (e.g., a single bucket elevato r), as opposed to evaluating applicability for the collection of “all grain handling operations” at a s ite, despite the plain language of the rule and the discussion in the preamble to the rule. 1

1 See 42 FR 2843.Grain Elevator Definition June 25, 2010 Page 2 of 2

For example, in one case, replacement of a singl e bucket elevator at an existing grain elevator has been determined to subject the new bucke t elevator to Subpart DD, even though this replacement does not meet the definition of cons truction, reconstruction, or modification. This situation has occurred because some permitting au thorities view the bucket elevator replacement as construction of a new affected facility, ev en though it really represents a change to a potentially affected facility (i.e., “all grain handling operation s” at the elevator) and should, therefore, be evaluated to determine if it represents either reconstruction or modification of the existing affected facility.

Suggested Clarifications to Subpart DD

The Coalition has identified seve ral minor changes to the Subpart DD rule language to address the issues outlined in this memorandum. First, cl arify that the affected facility for grain handling operations is limited in scope:

§60.300 Applicability and designati on of affected facility. (a) The provisions of this subpart apply to ea ch affected facility at any grain terminal elevator or any grain stor age elevator, except as provided under §60.304(b). The affected

facilities are each truck unloadi ng station, truck loading stat ion, barge and ship unloading station, barge and ship loading station, railcar loading stati on, railcar unlo ading station, grain dryer, and the collection of all grain handling operations at each grain elevator

.

Next, adjust the definitions to provide for the pos sibility of multiple grain elevators at a single

location:

§ 60.301 Definitions.

(b) Grain elevator means any plant or installation at which grain is unloaded, handled, cleaned, dried, stored, or loaded. Grain elevators on the sa me or contiguous property and which are functionally independent, ar e considered separate grain elevators.

Functionally independent means a grain elevator is capable of unloading, handling, storing, and loading grain independen tly from any other grain elevator.304-A West Millbrook Road Raleigh North Carolina 27609 (919) 845-1422 

# Memorandum

To: Jess McCluer and Dave Ailor

CC: Peter Wyckoff; NSPS Subpart DD Coalition Members

From: Jack Burke – RTP Environmental Associates, Inc.

Date: July 31, 2010

Re: Definition of Grain Elevator and Scope of Grain Handling Operations Under NSPS Subpart DD – Revised

Introduction

In a previous memorandum dated June 25, 2010, RTP provided the Coalition with suggestions for addressing several issues related to the definition of a grain elevator and scope of the grain handling affected facility in Subpart DD. In a discussion of this memorandum during the Coalition’s July 8th, 2010, meeting with U.S. EPA, a concern was identified with one part of the suggested language. The memorandum revises the original suggestion to address the concern raised during the July 8 th meeting.

Issue #1

§60.300(a) applies to each affected facility at any grain terminal elevator or any grain storage elevator. This subsection identifies “all grain handling operations” as a single affected facility. §60.301(b) defines the term “grain elevator” as any plant or installation at which grain is unloaded, handled, cleaned, dried, stored, or loaded. At issue is whether two (or more) grain elevators at a single location (i.e., on the same or contiguous property) are considered a single grain elevator, or whether they are different grain elevators for purposes of the definition of the affected facility consisting of “all grain handling operations.”

Consider the following example. An elevat or owner constructs a second, functionally independent elevator (subj ect to the NSPS) at a di fferent location, but on the same property as an existing elevator that is not currently subject to the NSPS. If the two elevators (new and existing) are considered a single grain elevator, then the construction of the grain handling operations associated with the new elevator would likely subject the grain handling operations at the existing elevat or to NSPS requirements because of the way the affected fa cility is defined (i.e., “all grain handling operations”). None of the other activities at the existing elevator would be subject to the NSPS unles s they are subsequently mo dified or reconstructed.Grain Elevator Definition - Revised July 31, 2010 Page 2 of 2

Issue #2

Some permitting authorities evaluate NSPS appl icability for grain handling operations on an individual unit basis (e.g., a single bucket elevator), as opposed to evaluating applicability for the collection of “all grain handling operations” at a si te, despite the plain language of the rule and the discussion in the preamble to the rule. 1

For example, in one case, replacement of a single bucket elevator at an existing grain elevator has been determined to subject the new bucket elevator to Subpart DD, even though this replacement does not meet the definition of construction, reconstruction, or modification. This situation has occurred because some permitting authorities view the bucket elevator replacement as construction of a new affected facility, even though it really represents a change to a potentially affected facility (i.e., “all grain ha ndling operations” at the elevator) and should, therefore, be evaluated to determine if it repres ents either reconstruction or modification of the existing affected facility.

Suggested Clarificat ions to Subpart DD

The Coalition has identified several minor changes to the Subpart DD rule language to address the issues outlined in this memorandum. First, clarify that the affected facility for grain handling operations is limited in scope:

§60.300 Applicability and designa tion of affected facility. (a) The provisions of this subpart apply to ea ch affected facility at any grain terminal elevator or any grain storage elevator, except as provided under §60.304(b). The affected facilities are each truck unloading station, tr uck loading station, barge and ship unloading station, barge and ship loading station, railcar loading station, railcar unloading station, grain dryer, and the collection of all grain handling operations at each grain elevator

.

Next, adjust the definitions to provide for the possibility of multiple grain elevators at a single

location: § 60.301 Definitions.

(b) Grain elevator means any plant or installation at which grain is unloaded, handled, cleaned, dried, stored, or loaded. Grain elevators which are functionally independent, are considered separate grain elevators.

Functionally independent means a grain elevator is capable of unloading, handling, storing, and loading grain independently from any other grain elevator.

1 See 42 FR 2843. Deleted: ¶304-A West Millbrook Road Raleigh North Carolina 27609 (919) 845-1422 

# Memorandum

To: Jess McCluer and Dave Ailor

CC: Peter Wyckoff; NSPS Subpart DD Coalition Members

From: Jack Burke – RTP Environmental Associates, Inc.

Date: June 15, 2010

Re: Grain Handling Opacity Testing Under NSPS Subpart DD

Issue:

§60.302(c)(2) of New Source Performance Sta ndard (NSPS) Subpart DD limits visible fugitive emissions from any grain handling ope ration to 0% opacity. §60.30(b)(3) requires that Method 9 be used to demonstrate complian ce with this limit. A grain handling operation

is defined as “bucket elevators or legs (excluding legs used to unload barges or ships), scale hoppers and surge bins (garners), turn heads, scalpers, cleaners, trippers, and the headhouse

and other such structures.” In many grain elevators, much of th is equipment is fully enclosed and, therefore, has no fugitive emissions. Conducting Method 9 observations on fully enclosed equipment is not a productive use of resources.

Suggested Clarifications to Subpart DD:

Two changes to the rule are suggested to addr ess this issue. The first is to provide a definition of “fully enclosed” in §60.301, as follows:

(p) Fully enclosed means a grain handling operation that is inside an enclosure that is designed such that it contains no openings through which dust can escape directly to the atmosphere. Openings for aspiration are not considered to be openings through which dust can escape to the atmosphere.

The second suggested change provides an opt ional exemption for fully enclosed grain handling operations from the fugitive em issions opacity limit in §60.302, as follows:

(c) On and after the 60th day of achievi ng the maximum producti on rate at which the affected facility will be operated, but no late r than 180 days after initial startup, no owner or operator subject to the provisi ons of this subpart shall caus e to be discharged into the atmosphere any fugitive emission from:Grain Handling Operation Opacity Testing June 15, 2010 Page 2 of 2

(1) Any individual truck unloading station, rail car unloading station, or railcar loading station, which exhibits great er than 5 percent opacity.

(2) Any grain handling operation which is not fully enclosed and which exhibits greater than 0 percent opacity.

(3) Any truck loading station which exhib its greater than 10 percent opacity.

(4) Any barge or ship loading station which exhibits greater than 20 percent opacity.

An owner or operator of an affected grain handling operation may elect to make a onetime demonstration that any individual gr ain handling operation m eets the definition of fully enclosed in §60.301(p) or the owner or operator may elect to comply with the applicable opacity limit in (c)(2).304-A West Millbrook Road Raleigh North Carolina 27609 (919) 845-1422 

# Memorandum

To: Jess McCluer and Dave Ailor

CC: Peter Wyckoff; NSPS Subpart DD Coalition

From: Jack Burke – RTP Environmental Associates, Inc.

Date: June 25, 2010

Re: Suggested Revisions to NSPS Subpart DD Grain Unloading Station Definition

Issue

The current definitions of “grain unloading statio n” and “grain loading station” at §60.301(j) and §60.301(k), respectively, are in tended to be generally applicable to truck, railcar, barge and ship unloading and loading stations. The boundaries of the “unloading st ation” and “loading station”

affected facilities are a bit unclear in this defi nition. In addition, in some cases the termination point of a “grain unloading stat ion” may not include a receiving hopper. Better definition of the affected facility boundaries is important when de termining whether a capital expenditure occurs

or whether an affected f acility is reconstructed.

Suggested Clarifications to Subpart DD

The following changes to the definition of “grain unloading station” are su ggested to clarify the

intent of the definition:

(j) Grain unloading station means that portion of a grain elevator where the grain is transferred from a truck, railcar, ba rge, or ship to a receiving hopper or to the grain handling equipment that connects the unloading stat ion to the rest of the grain elevator

. A grain unloading station includes all of the equipment, support structures, and associated dust control equipment and aspiration systems connect ed to or required to operate the grain unloading station.

This suggested change clarifies that the unloadi ng station includes all of the equipment involved in unloading, up to the point that the grain is transferred to eith er storage or to grain handling operations associated with storage.Grain Unloading Station Definition June 25, 2010 Page 2 of 2

It is also suggested that the defini tion of “grain loading station” be revised in a parallel construct,

as follows:

(k) Grain loading station means that portion of a grain elevat or where the grain is transferred

from the elevator to a truc k, railcar, barge, or ship. A grain loading statio n includes all of the equipment, support structures, and associated dust control equipment and aspiration systems connected to or required to ope rate the grain loading station.304-A West Millbrook Road Raleigh North Carolina 27609 (919) 845-1422 

# Memorandum

To: Jess McCluer and Dave Ailor

CC: Peter Wyckoff; NSPS Subpart DD Coalition Members

From: Jack Burke – RTP Environmental Associates, Inc.

Date: June 15, 2010

Re: Potential Use of Mineral Oil for Control of Dust from TSF Operations under NSPS Subpart DD

Introduction

This memorandum summarizes RTP’s analysis of i ssues, effectiveness and costs associated with

the use of mineral oil as a dust suppressant for temporary storag e facility (TSF) applications. Attached to this memorandum are excerpts fr om various reference documents on which the analysis is based.

Summary

RTP evaluated the use of mineral oil for controll ing dust emissions from the operation of TSFs. Putting aside the question of feasibility, or whether this a pplication of mineral oil has been demonstrated in practice, the re sults of RTP’s evalua tion demonstrate that mineral oil is not a

cost-effective means of dust cont rol. Estimated control costs for particulate matter (PM) are approximately $7,500 per ton, with PM 10 and PM 2.5 control costs being much higher.

Background

Mineral oil is demonstrated to be an effective me ans of grain dust control for certain applications at grain elevators. Reported control efficiencies range from a high of n ear 90% to a low of 0%, depending on the specific circ umstances of the application. 1 RTP’s review of the available data suggests that initial control efficiencies of 50 to 60 percent appear more typical. Some of the

relevant factors known to influence the effectivene ss of mineral oil as a du st control agent are the degree of mixing that occurs betw een the mineral oil and the grain 2 and the length of time that

1 The background document for AP-42 cites a range of 60 to 80%. Lab studies show initial control efficiencies

resulting from mineral oil application can be close to 90%, but the effectiveness of mineral oil declines to zero (i.e., no control) after 9 to 12 months of storage of the grain to which it has been applied. Individual field tests also show a wide range of efficiencies. See Att achment A to this memorandum for additional details.

2 See, for example, “Emission Factors for Grain Elevators, Final Report;” Midwest Research Institute, Kansas City,

MO; January 3, 1997, page A-1.Mineral Oil Control for TSF Operations

15 June 2010 Page 2 of 10

has passed between the mineral oil applica tion and subsequent handling of the grain. 3 Both of these factors are important when considering wh ether mineral oil is an applicable control technology for reducing dust emissions from TSFs. 4

RTP has examined the Subpart DD database complied from Coalition member’s responses to U.S. EPA’s September 2009 Section 114 informati on request to owners/operators of grain elevators. Based on this review, we could not id entify any instances where mineral oil is applied to TSF filling operations that are managed exclus ively with portable or mobile conveying and unloading equipment. 5 This finding is significant because such TSF operations represent a large fraction of the total population of TSFs.

After examining the nature of TSF filling operati ons, RTP concluded that it should be possible to install mineral oil spray equipment on portable un loading/conveying equipment. The feasibility of this type of application is by no means certain, however, and the technology would at a minimum, require some engineering and develo pment effort. For example, for most such applications, a separate mobile spray system wo uld need to be designed and constructed because portable unloading/conveying equipment is typically not suited for mounti ng a heavy oil supply tank. Figures 1 and 2 are photos of this type of equipment.

Figure 1. Portable Conveyor Serving Temporary Storage Pile

3 See “Reducing Grain Dust with Oil Additives;” F. S. La i, et al., Transactions of the ASAE; 1981; Page 1628.

4 In this context, the emissions from temporary storag e facilities include the activities associated with filling and

reclaiming the storage pile, including truck unloading, pile building, pile reclaim, and truck loading.

5 In some cases, grain loaded onto temporary storage piles has had mineral oil applied to it during handling

activities within the permanent elevator operations. This grain is later loaded onto temporary storage piles using portable equipment.Mineral Oil Control for TSF Operations

15 June 2010 Page 3 of 10

Figure 2. Portable Auger System

If one ignores questions regarding the feasib ility of mounting mineral oil spray systems on portable unloading equipment, the question sti ll remains as to how effective mineral oil application would be in contro lling dust emissions from TSFs. There are two key reasons for questioning the effectiveness of mineral oil in this type of application:

• The first reason is the limited opportunity for mi neral oil to be mixed with grain as it is transferred from trucks onto a temporary stor age pile using portab le equipment. The best-case scenario is to apply the mineral o il immediately after the first transfer point (i.e., after the point where the grain drops from the truck into the ground-level hopper of the portable conveyor). In this situation, th ere would be no suppression of dust from the unloading operation, but dust emissions from any downstream transfer points and from the dropping of grain onto the storage pile would be suppressed. The effectiveness of mineral oil in controlling dusting would be limited due to the limited opportunity for mixing of the oil and grai n in this operation.

• The second reason has to do with the once-throu gh nature of temporary storage. In most cases, once a temporary storage pile is filled, it is covered and it sits virtually undisturbed until it is time for the pile to be reclaimed. During the storage period, dust emissions are minimal (with or without mineral oil dust s uppression). The next opportunity for mineral oil to be effective in suppre ssing dust is when the pile is reclaimed. This reclaimMineral Oil Control for TSF Operations

15 June 2010 Page 4 of 10

operation occurs on average about six months 6 following the pile fil ling operations. Tests

show that mineral oil loses about two-thirds of its effectivenes s in controlling dust emissions six months after the initial application. 7 Because of this loss of efficiency, the application of mineral oil to grain entering a temporary storag e pile has significantly less impact on emissions from subsequent handling than it would for grain that is stored for shorter periods of time (e.g., as it does w ith permanent storage, which typically experiences multiple turnovers annually).

Two final concerns exist. One is that soyb eans that are treated w ith mineral oil and are subsequently exported to the European Union may yield soybean oil having hydrocarbon levels in excess of a FEDIOL code of practice of 300 ppmw. 8 A second concern, which has been expressed by several Coalition members, is that applying mineral oil to wheat may have detrimental impacts on milling operations. Both issu es would have to be carefully investigated before a requirement that mandates mineral oil application to all grains in temporary storage

could be considered feasible.

Analysis

In an effort to assess the cost-effectiveness of using mineral oil for c ontrolling dust emissions from temporary storage, RTP defined a TSF emissions model and then applied reasonable estimates of mineral oil control efficiency to this model. The TSF emissions model, including expected mineral oil control efficiencies, and the basis for this model, are summarized in

Table 1. Note that PM emissions are used in this computation to provi de comparison to costeffectiveness values addressed in the Coal Preparation NSPS which EPA recently revised (74 FR 51950).

The TSF emissions model shown in Table 1 re sults in an overall uncontrolled PM emission factor of 0.174 lb/ton of grain thr oughput. The overall mineral oil c ontrolled emission factor is 0.118 lb/ton which yields a decrease of 0.056 lb/ton attributable to the effect of the mineral oil. This is the TSF PM emissions reduction that is estimated to result from mineral oil application immediately after the grai n receiving operation.

6 For 2007, the average TSF in the NSPS Subpart DD 114 survey was used for 22 weeks and the average turnover

factor was approximately one. RTP interprets these data to mean that the pile was filled and then emptied about 6 months later. This interpretation is consistent with how TSFs are used by elevator operators.

7 See “Reducing Grain Dust with Oil Additives;” F. S. La i, et al., Transactions of the ASAE; 1981; Page 1628.

8 The EU Oil and Proteinmeal Industry is known as FEDIOL. Part of its code of practice states “that any detection

of a level [of mineral oil] above 300 mg/kg shall mean that the [vegetable] oil shipment concerned is considered to be contaminated by mineral oil.” The code also st ates: “If the further analysis reveals a contamination by external mineral oil, the vegetable oil of the shipment concerned shall not enter the EU feed or food chain.”Mineral Oil Control for TSF Operations

15 June 2010 Page 5 of 10

At a mineral oil cost of $3.5/gallon and an applic ation rate of 0.02 weight percent, the cost of applying mineral oil to one ton of grain is 9 :

(2000 lb/ton) x (0.0002 lb oil/lb grain) / (6.7 lb /gallon) x ($3.5/gall on) = $0.21/ton of grain

And the control cost-effectiveness (not including other O&M costs or capital recovery costs for the mineral oil system) is:

($0.21/ton of grain) / [(0.056 lb PM/ton of grain) / (2000 lb/ton)] ≈ $7,500/ton of PM

The control cost effectiveness for PM 10 and PM 2.5 is much higher since these pollutants represent a relatively small fraction of total particulate emissions (less than 50 percent and 10 percent, respectively) from TSF operations. The above control costs are in excess of values that EPA has recently determined are not cost-effective. 10

Based on the above assessment, RTP concludes that the use of mineral oil is not a cost-effective means of controlling dust from TSF operations, even if one assumes its use is feasible. Also, note that to our knowledge, the application of mi neral oil to grain in c onjunction with portable conveyors and unloading equipment has not been demonstrated.

Table 1. TSF Emissions Model Basis

Activity Uncontrolled

PM Emissions (lb/ton)* Mineral Oil

Control Efficiency Controlled

PM Emissions (lb/ton) Basis / Discussion

Receiving: Hopper Truck 0.035 0% 0.035 Mineral oil cannot be applied until after grain enters conveying equipment.

Grain Handling 0.061 60% 0.0244 Reasonable best-case based on literature (see attachment).

Pile filling 0.002 60% 0.0008 Reasonable best-case based on literature (see attachment). Storage /

Aeration 0.013 40% 0.0078 Average between initial efficiency of 60 percent and final efficiency of 20 percent.

Pile Reclaim 0.063 20% 0.0504 Assumes that efficiency declines by 2/3 over a six-month storage period.

Overall 0.174 0.118

* Uncontrolled emission factors from AP-42, as described in RTP’s presentation to U.S. EPA on February 24, 2010.

9 The cost for mineral oil is based on large bulk purchases and is typical of costs reported by Coalition members.

Various mineral oil application rates have been studied. A value of 200 ppmw is used in this calculation because this rate represents the most common value cited in the literature. Also, the initial control efficiency of 60% is consistent with this rate of oil application (i.e., lower initial application rates are expected to lead to lower dust suppression efficiencies).

10 See, for example, 72 FR 22904: “In addition, the incremen tal benefit and cost of fabric filters at a bituminous

mine compared to application of chemical suppressants is a reduction of an additional 33 tons of PM, but the annual cost is an additional $200,000. Due to these high costs [$6,060/ton], we concluded that fabric filters are not BDT for any coal preparation plant processing bituminous coal.”Mineral Oil Control for TSF Operations

15 June 2010 Page 6 of 10



## ATTACHMENT A
BACKGROUND INFORMATIONMineral Oil Control for TSF Operations

15 June 2010 Page 7 of 10

“Emission Factor Documentation for AP-42 Section 9.9.1; Grain Elevators and Grain Processing Plants; Final Re port”; April 2003, page 2-44.

The emission control methods described above re ly on either process modifications to reduce dust generation or capture collection systems to control dust emissions after they are generated.

An alternative control measure that has develo ped over the last 10 years is dust suppression by oil application. The driving forces for developing most such dust suppression systems have been grain elevator explosion control as well as emission control. Cons equently, few data have been published on the amount of emission reduction achieved by such systems. Recent studies, however, have indicated that a PM reduction of approximately 60 to 80 percent may be achievable (see References 57 and 61 in Section 4).

Generally, these oil application dust suppression systems use either white mineral oil, soybean oil, or some other vegetable oil. Curren tly, the Food and Drug Ad ministration restricts application rates of mineral o il to 0.02 percent by weight. La boratory testing and industry experience have shown that oil additives applie d at a rate of 60 to 200 parts per million by weight of grain, or 0.5 to 1.7 gall ons of oil per thousand bushels of grain can provide effective

dust control. 36 The effectiveness of the oil suppressi on system depends to some extent on how well the oil is dispersed within the grain stream after it is applied. Several options are available for applying oil additives.

1. As a top dressing before grain en ters the bucket elevator or at other grain transfer points.

2. From below the grain stream at a grain tran sfer point using one or more spray nozzles.

3. In the boot of the bucket elevator leg.

4. At the discharge point from a receiving p it onto a belt or other type conveyor.

5. In a screw conveyor.

___________________________ Reference 57: Tests of Oil Suppression Of PM- 10 At Grain Elevators, Test Report, Midwest Research Institute, Kansas City, MO, November 1994.

Reference 61: Emission Factors for Grain Elev ators, Final Report to National Grain and Feed Foundation, Midwest Research In stitute, Kansas City, Missouri, January 3, 1997.

36 Letter from Thomas C. O’Connor, National Grain and Feed Association, to Dallas Safriet, U.S. Environmental Protection Agency, Research Tria ngle Park, NC, June 30, 1997.Mineral Oil Control for TSF Operations

15 June 2010 Page 8 of 10

“Test Of Oil Suppression Of PM-10 at Grain El evators, Test Report”; Midwest Research Institute, Kansas City, MO, 1994 [AP-42 S ection Number: 9.9.1; Reference Number: 16].

The Greenwood elevator applies food grade mine ral oil (Amoco Superl a DCO) through a spray system supplied by InterSystems of Omaha, Ne braska. A cost of $288.50 was quoted for a 55-gal drum of the oil during an Oc tober 1994 telephone conversation.

The system sprays oil through inspection ports on the elevator legs. The spray system contains a check valve and cannot operate with the oil pressure less than 20 psi. Facility personnel stated that they typically operate the system at 25 psi. A representative of Intersystems stated that the spray tip used (No. 8001) delivers 0.076 gal/min at 80°F and 20 psi and 0.1 gal/min at 80°F and 40 psi. [page 3 - 4]

Mineral Oil Control Efficiency(%)

Oil at 25 psi Oil at 20 psi

Grain PM-10 PM PM-10 PM

Milo 57 56 33 21

Corn 69 48 79 57

[page 13]

It should be noted that the mineral oil contro l efficiency values obtained during this scoping study may be lower than that wh ich can be achieved at other in stallations. This statement is based upon the fact that the Greenwood elevator app lies the oil to grain in the leg. As a result, not all of the oil adheres to the grain and only a limited amount of mixing can occur before the grain hits the gallery be lt. Other installations designed to sp ray oil during active grain tumbling are expected to exhibit higher control efficiency. [page 19]Mineral Oil Control for TSF Operations

15 June 2010 Page 9 of 10

“Reducing Grain Dust with Oil Additives”; F. S. Lai, et al., TRANSACTIONS of the ASAE; 1981; Page 1628.

Chart generated from data in paper. 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0 2 4 6 8 10

Months from Initial Application 

## Dust Control Efficiency vs. Time

mineral oil @ 0.02 wt. %

Corn

WheatMineral Oil Control for TSF Operations

15 June 2010 Page 10 of 10

“Emission Factors for Grain Elev ators, Final Report”; Midwest Research Institute, Kansas City, MO; January 3, 1997

Although the country elevator has an oil suppression system, it does not regularly apply oil to the grain received. The facility agreed to operate the system on a limited basis for testing purposes. Thus, the results obtained dur ing the BD tests reference fr eshly oiled grains. To obtain

information on how oil can become more effectiv e with the greater mixi ng that occurs with repeated handling, controlled tests were conducted in pairs. The fi rst test involved freshly oiled grain. Thereafter, the second test in the sequence used the same grain in a second "turn"; no additional oil was applied.

The first controlled test sequence involved in ternal handling of wheat (tests BD-107 and 108). When referenced against a mean uncontrolled PM 10 emission factor of 0.021 lb/ton, the first and

second turns resulted in effici encies of 16% and 48%, respectively. Note, however, that the facility reported low pressure when applying the oil. For th is reason, a second wheat test sequence was conducted (BD-l13 and 114). Here, the oi l pressure was reported as normal and the

first and second turns resulted in 68 % and 64% efficiency, respectively.

A similar test sequence of the internal hand ling of oiled com was conducted at the country

elevator. Referenced to an uncontrolled PM 10 emission factor of 0.023 lb/ton, the first and second turns exhibited 29% and 78%, respectively.

A second corn test sequence (BD-10 and 11) of shipping emissions was conducted. Again, the

com was first oiled and then handled. The first tu rn resulted in no observable control. The corn

was re-elevated and loaded a s econd time. For that test, an emission factor of 0.0203 lb/ton was found. This represented a 30% reduction from the uncontrolled average of 0.0295 lb/ton. Even more importantly, the second test represen ts a 60% reduction from the first turn.

Additional controlled tests were conducted at Terminal 1. Unlike the country elevator, Terminal 1 routinely oils all grains at the time of receipt. Both c ontrolled test sequences involved railcar shipping. Tests BE-111 and 113 were conducted on oiled wheat, and averaged

78% control of PM10 emissions. Tests BE-109 and 110 (conducted on oiled soybeans) did not exhibit any observable control when referenced against the average uncontrolled emission factor from Tests BE-106 to 108. [page A-1]304-A West Millbrook Road Raleigh North Carolina 27609 (919) 845-1422 

# Memorandum

To: Jess McCluer and Dave Ailor

CC: Peter Wyckoff; NSPS Subpart DD Coalition Members

From: Jack Burke – RTP Environmental Associates, Inc.

Date: June 25, 2010

Re: Representative Testing Under NSPS Subpart DD

Issue

§60.303 of New Source Performance Standard (N SPS) Subpart DD requires testing of each affected facility subject to a particulate matter emissions limit in §60.302. In some situations this requirement means that a number of substantiall y identical units must be tested. A single representative compliance test should be sufficient in these situations.

Suggested Clarifications to Subpart DD

To address the issue of representative compliance testing and to clarify a minor point of potential confusion in §60.303(b)(1), the followi ng revisions to §60.303 are suggested:

§60.303 Test methods and procedures.

(a) In conducting the performance tests required in §60.8, the owne r or operator shall use as reference methods and procedures the test met hods in appendix A of this part or other methods and procedures as specified in this section, except as provided in §60.8(b). Acceptable alternative methods a nd procedures are given in pa ragraph (c) of this section.

(b) The owner or operator shall determine complia nce with the particulate matter standards in §60.302 as follows:

(1) Method 5 shall be used to determine th e particulate matter concentration and the sampled volumetric flow rate of the effluent gas. The sampling time and sample volume for each

run shall be at least 60 minutes and 1.70 dscm (60 dscf). Th e probe and filter holder shall be operated without heaters.

(2) Method 2 shall be used to determin e the ventilation volumetric flow rate.

(3) Method 9 and the procedures in §60.11 shall be used to determine opacity.

(c) The owner or operator may use the following as alternatives to the reference methods and procedures specified in this section:Representative Testing June 25, 2010 Page 2 of 2

(1) For Method 5, Method 17 may be used.

(d) An owner or operator required to determ ine compliance with the particulate matter standards in §60.302 may elect to conduct representative testi ng if performance tests are required on more than one identical affected facility.

To clarify the intent of this provision, two key terms should be defined in §60.301, as follows:

Representative testing means testing of one affected facili ty in cases where two or more such facilities are otherwise required to be tested at a single location.

Identical affected facility means any affected facility that is substantially the same as any other affected facility in f unction, capacity, size, and design.304-A West Millbrook Road Raleigh North Carolina 27609 (919) 845-1422 

# Memorandum

To: Jess McCluer and Dave Ailor

CC: Peter Wyckoff; NSPS Subpart DD Coalition Members

From: Jack Burke – RTP Environmental Associates, Inc.

Date: July 31, 2010

Re: Representative Testing Under NSPS Subpart DD - Revised

Introduction

In a previous memorandum dated June 25, 2010, RT P provided the Coalition with suggestions for addressing an issue related to testing of mu ltiple identical affected facilities at a grain

elevator. In a discussion of this memorandum during the Coalition’ s July 8th, 2010, meeting with U.S. EPA, EPA indicated that any such revi sions would need to be consistent with existing policy. The memorandum revises RTP’s original suggestions to be consistent with EPA’s existing policy on this issue.

Issue

§60.303 of New Source Performance Standard (N SPS) Subpart DD requires testing of each affected facility subject to a particulate matter emissions limit in §60.302. In some situations this requirement means that a number of substantiall y identical units must be tested. A single representative compliance test should be sufficient in these situations.

Suggested Clarifications to Subpart DD

To address the issue of representative compliance testing and to clarify a minor point of potential confusion in §60.303(b)(1), the followi ng revisions to §60.303 are suggested:

§60.303 Test methods and procedures.

(a) In conducting the performance tests required in §60.8, the owne r or operator shall use as reference methods and procedures the test met hods in appendix A of this part or other methods and procedures as specified in this section, except as provided in §60.8(b). Acceptable alternative methods a nd procedures are given in pa ragraph (c) of this section.

(b) The owner or operator shall determine complia nce with the particulate matter standards in §60.302 as follows:Representative Testing - Revised July 31, 2010 Page 2 of 2

(1) Method 5 shall be used to determine th e particulate matter concentration and the sampled volumetric flow rate of the effluent gas. The sampling time and sample volume for each

run shall be at least 60 minutes and 1.70 dscm (60 dscf). Th e probe and filter holder shall be operated without heaters.

(2) Method 2 shall be used to determin e the ventilation volumetric flow rate.

(3) Method 9 and the procedures in §60.11 shall be used to determine opacity.

(c) The owner or operator may use the following as alternatives to the reference methods and procedures specified in this section:

(1) For Method 5, Method 17 may be used.

(d) An owner or operator required to determ ine compliance with the particulate matter standards in §60.302 may elect to conduct representative testi ng if performance tests are required on more than one identical affected f acility provided that the units are operated and

maintained in a similar manner and the owner or operator demonstrates that the emission rate of the tested unit is no more than 80% of the applicable emission limit.

To clarify the intent of this provision, two key terms should be defined in §60.301, as follows:

Representative testing means testing of only one identical a ffected facility in cases where two

or more such identical affected facilities are otherwise required to be tested at the same grain

elevator.

Identical affected facility means an affected facility that has the same or better emissionrelated design specifications as another aff ected facility at the same grain elevator.