### NSPS SUBPART DD COALITION

VIA ELECTRONIC MAIL

September 21, 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.: TWO NEW ISSUE PAPERS DEVELOPED BY RTP ENVIRONMENTAL ASSOCIATES ON CERTAIN NSPS SUBPART DD ISSUES

Bill:

During June and August 2010, the NSPS Subpart DD Coalition provided you via e-mail with 11 papers developed by RTP Environmental Associates (RTP) (Raleigh, NC) on certain issues related to EPA's ongoing review of New Source Performance Standard (NSPS) Subpart DD for Grain Elevators. By this letter, we providing you with two new “issue papers,” which RTP has developed. These issue papers, like those I prov ided you in 2010, reflect the conclusions of RTP, as reviewed and endorsed by the Coalition.

The two papers address:

• Barge/Ship Unloading Systems, where RTP concludes that, “... based on the results of ... survey data, there is no indication that alternative forms of barge/ship unloading are of environmental significance and, therefore, it is not appropriate to regulate these forms of barge/ship unloading under a new NSPS, particularly when, as the Coalition has emphasized separately, state/local air pollution control agencies can be expected to adequately address significant emissions, if any, from new barge/ship unloading equipment, even in the absence of Subpart DD;” and,

• Wire Screen Column Dryers, where RTP concludes that “Given the relatively small rate of emissions from these dryers (i.e., only about 25% of the emissions from a comparably-sized column grain dryers) and the fact that most of these dryers do not create any new emissions (i.e., most are replacement units), this subcategory of sources should be considered insignificant and, therefore, should not be regulated under any revised NSPS. In any event, state/local air pollution control agencies can be expected, as the Coalition has emphasized in its petition for repeal of Subpart DD, to address PM emissions from new “rice” dryers appropriately, even in the absence of Subpart DD.”

These issue papers supplement company-specific information on these issues provided you earlier this week by two companies the C oalition represents, Bunge North America and Riceland Foods, respectively.304-A West Millbrook Road Raleigh North Carolina 27609 (919) 845-1422 

# Memorandum

To: Jess McCluer (NGFA) and Dave Ailor (NOPA)

CC: Peter Wyckoff, NSPS Subpart DD Coalition

From: Jack Burke – RTP Environmental Associates, Inc.

Date: September 21, 2012

Re: Review of Data on Barge/Ship Unloading Systems

This memorandum builds on an assessment of barg e/ship unloading issues related to Subpart DD addressed in my memorandum of June 28, 2010. 1 I have prepared this document at the request of the NSPS Subpart DD Coalition (the “Coalition”). Two general topics are addressed herein. The first topic is a brief summary of the conc lusions provided in RTP’s June 2010 memorandum. The second topic is an assessment of data r ecently provided by Coalition member companies regarding present and planned barge/ship unloa ding operations at Subpa rt DD grain elevators. 2

Summary of Previous Analysis RTP’s previous review of the provisions in §60.302(d) and the relevant rulemaking record reached the conclusion that Subpa rt DD requirements apply only in those situations where an affected barge/ship unloading operation employs a bucket elevator unload ing leg (i.e., a Marine Leg) to remove grain from a barg e or ship at a Subpart DD grain elevator. Other types of barge and ship unloading operations are not subject to any specific requireme nts under Subpart DD.

1 See “Applicability of and Alternatives to the Curr ent NSPS Subpart DD Barge Unloading Standard” to Jess

McCluer (NGFA) and David Ailor (NOPA) from Jack Burke, RTP Environmental Associates, June 28, 2010.

2 I use the term “Subpart DD grain el evators” here as shorthand to describe grain storage elevators with a

permanent storage capacity of 1 milli on bushels or more and grain terminal elevators with a permanent capacity of 2.5 million bushels or more.Review of Barge/Ship Unloading Data 21 September 2012 Page 2 of 5

This interpretation is consistent with the data and information U.S. EPA used as the basis for the unloading station requirements in Subpart DD. 3

Previous discussions between the Coalition and U.S. EPA indicated that the Agency may be considering an opacity limit as an alternative to the design standard 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 an April 2010 survey of Coalition members, RTP obtained opacity te st data for only one alternative unloading leg. This is an en-masse drag conveyor at Bunge’s Cairo, Illinois facility. No opacity test data were obtained for a CBU a nd only two opacity tests were obtained for barge unloading operations that do not involve unl oading legs (e.g., a clam-shell unloader).

Summary of September 2012 Survey Data At your request, RTP conducted a voluntary surv ey of the nine Coalition member companies who responded to U.S. EPA’s original §114 Subpart DD information request. This confidential survey requested information on barge/ship unloading activities at the companies’ Subpart DD grain elevators. Of the nine companies surveye d, I received responses from eight of them. Some results of this survey are summarized in Ta ble 1. The data in this table show that:

 Only about 6% of the surveyed Subpart DD grain elevators have barge/ship unloading stations; and

 Few new barge/ship unloading stations ar e planned for the next five years.

3 §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 several types of barge unloading equipment that have been developed since Subpart DD was promulgated, which appear to fall into this category. Specifically, continuous barge unloaders (CBUs) and en-masse style drag conveyors could conceivably be considered to have “unloading legs” and, therefore, be subj ect to the provisions of Subpart DD. Howeve r, neither of these unloading systems is a “bucket elevator” as the term is used in the original Subpart DD rulemaking record. These unloading systems differ significantly in design from the unloading legs referenced in §60.302(d). The inherent design differences are the basis for RTP’s conclusion that such unloading systems are not currently regulated under Subpart DD.Review of Barge/Ship Unloading Data 21 September 2012 Page 3 of 5

Table 1. Summary of New Su rvey Data on Barge/Ship Unloading
Survey Question Response Number of Subpart DD Elevators 296 Number of Subpart DD Elevators with Barge/Ship Unloading 17 Number of Existing Barge/Ship Unloading Stations 20 Number of Planned Barge/Ship Unloading Stations (next 5 years) 2

The survey also requested data on the types of barge/ship unloading systems currently employed at the companies’ Subpart DD grai n elevators. The results of the survey in this regard are
summarized in Table 2. As the data in Table 2 show, CBUs a nd marine legs are the most commonly employed types of unloading systems a nd they have the highest average installed capacities. Combined, these two types of unloading systems account for over 90% of the installed barge/ship unloading system capacity at the Subpart DD grain elevators surveyed. Except for a few of the clam shell unloading systems, all of the unloading systems shown in Table 2 have the conveying equipment ventila ted to a baghouse for emissions control.

Table 2. Summary of New Su rvey Data on Barge/Ship Unloading

Type of Unloading System Number of Systems Nominal Average Capacity of Systems (tons/hr) CBU 6 2,400 Clam Shell 4 300 En-masse Conveyor 2 200 Marine Leg (Bucket Elevator) 6 1,100 Other 2 400

Analysis of September 2012 Ba rge/Ship Unloading Survey Data RTP’s previous assessment of barge/ship unloa ding issues raised the threshold question of whether alternative means of barge/ship unloading warranted regulation at a ll. The results of the survey data described herein provide information th at can be used to help answer this question. Specifically, the future plans of the survey resp ondents provide one persp ective on the answer to the question of whether alternative forms of barge/ship unl oading should be regulated under any future revision of Subpart DD. As indicated in Table 1, only two new barge/ship unloading stations are planned at the 296 Subpart DD grain elevators in cluded in the survey. These planned new stations are to be Ma rine Legs. Consequently, the su rvey data suggest that 100% ofReview of Barge/Ship Unloading Data 21 September 2012 Page 4 of 5

the new barge/ship unloading stations to be co nstructed in the next fi ve years at Subpart DD elevators are already regulated under the current rule. This result argues for no new regulation of barge/ship unloading stations.

The new survey data provide another perspec tive on the answer to the threshold question regarding regulation of ba rge/ship unloading stations. From the survey data, it is clear that CBUs are on a par with Marine Leg unloading system s in terms of installed capacity at existing Subpart DD elevators. So answering the questi on of whether CBUs are worthy of regulation will help answer the question of whether Subpart DD should address alternativ e forms of barge/ship unloading at all.

Figure 1 is a photo of the unloading end of a CB U in operation. Aspiration of the casing surrounding the buckets in a CBU to a baghouse provi des control of some emissions. However, as evident from Figure 1, it is not feasible to encl ose these units to the center line of the bottom pulley as required for Marine Legs unde r the current Subpart DD regulations.

Figure 1. Continuous Barge UnloaderReview of Barge/Ship Unloading Data 21 September 2012 Page 5 of 5

Conclusions Table 3 shows the potential uncont rolled particulate emissions fr om a CBU and a Marine Leg. As this table shows, CBU emissions on a “pound pe r ton” basis are significantly less than those from a Marine Leg. Given the ratio of aver age capacities shown in Table 2, these data
demonstrate that emissions of PM and PM 10 from an average sized CBU are of lesser significance than from an average sized Marine Leg (i.e., about ha lf) and on par with an average sized Marine Leg with respect to PM 2.5 emissions. However, the limited number of CBUs in existence at Subpart DD grain elev ators, the fact that none of th e survey respondents has plans to install a new CBU in the next five years, and th e fact that all of the CBUs in the survey are ventilated to a baghouse lead to the conclu sion that CBUs do not wa rrant regulation under Subpart DD.

This conclusion can be extrapolat ed to other forms of barge/ship unloading by considering their relative insignificance when compar ed to Marine Legs and CBUs. Based on the results of the September 2012 survey data, there is no indication that alternative forms of barge/ship unloading are of environmental significance and, therefore, it is not appropriate to regulate these forms of barge/ship unloading under a new NSPS, partic ularly when, as the Coalition has emphasized separately, state/local air pollution control agen cies can be expected to adequately address significant emissions, if any, from new barge/ship unloading equipment, even in the absence of Subpart DD.

Table 3. CBU a nd Marine Leg Emissions 4

Pollutant CBU (lb/ton) Marine Leg (lb/ton) CBU-to-Marine Let Ratio PM 0.029 0.15 19% PM 10 0.0073 0.038 19% PM 2.5 0.0019 0.0050 38%

It is also important to re-empha size the conclusion of RTP’s prio r analysis in regards to CBUs, en-masse conveyors, pneumatic unloaders and ce rtain other forms of barge/ship unloading. These types of unloading systems were not cons idered in the original Subpart DD rulemaking process and, therefore, they are not “unloading legs” as this term is defined in Subpart DD (i.e., these units are not subject to regulation unde r the current version of Subpart DD).

4 Source: AP-42, Table 9.9.1-1, 3/2003.304-A West Millbrook Road Raleigh North Carolina 27609 (919) 845-1422 

# Memorandum

To: Jess McCluer (NGFA) and Dave Ailor (NOPA)

CC: Peter Wyckoff, NSPS Subpart DD Coalition

From: Jack Burke – RTP Environmental Associates, Inc.

Date: September 21, 2012

Re: Review of New Data on Wire-Screen Column Dryers

Background In a previous assessment of column-type grain dryers that employ woven wire screens (“rice dryers”) as the column walls, RTP Environmen tal Associates, Inc. (RTP) concluded that:

 This type of dryer is not currently regulated by 40 CFR Part 60, Subpart DD because it does not meet the regulatory definition of either a column or rack dryer and these are the only types of grain dryers re gulated by Subpart DD; and

 Based on a projected rate of wire-screen dr yer construction and th e emissions of fine particulate (i.e., PM 10 and PM 2.5 ) from such dryers, this t ype of dryer should not be regulated under any revised form of Subpart DD.

On August 28, 2012, Riceland Foods (Riceland) r eceived an email from Roy Oommen of ERG (U.S. EPA’s technical support contractor for the Subpart DD regulator y review) soliciting additional information on the rice dryers at Ri celand’s facilities. Riceland has provided ERG with a response to its questions. The data in Ri celand’s response raise some questions in regard to RTP’s previous analysis of the environmental significance of wire scre en rice dryers. The purpose of this memorandum is to revisit RTP’s or iginal assessment in light of the data Riceland has recently provided to ERG.

Rice Production One conclusion of RTP’s original assessment of wire screen dryers was that “rice production was relatively static between 2002 and 2009.” Figure 1 is an updated graph of rice production dataReview of New Data on Wire-Screen Column Dryers 21 September 2012 Page 2 of 5

through July 2012. As this figure shows, U.S. ri ce production continues to remain at a relatively constant level, fluctuating between 400 milli on and 550 million bushels per year with no upward trend in production rates. Thes e data suggest that there is no underlying trend in place that would drive an expansion in ri ce drying capacity in the U.S.

Figure 1. Recent US Rough Rice Production (source: http://www.ers.usda.gov/data -products/rice-yearbook-2012.aspx)

Size of U.S. Rice Dryer Population RTP made an estimate of the U.S. rice drye r population in 2010 based on the following assumptions:

 Average Rice Dryer Size = 5,000 bushels

 U.S. Rice Crop = 450 million bushels 300 350 400 450 500 550 600AnnualUSRoughRiceProduction(millionbushels)Review of New Data on Wire-Screen Column Dryers 21 September 2012 Page 3 of 5

 Average Annual Rice Dryer Op erating Hours = 2,000 hours

 Percent of Rice Crop Dried = 90%

 Number of Drying Pass es per Bushel = 3

 Rough Rice Bulk Density = 46 lb/bushel

Using these assumptions, the U.S. dryer popul ation was estimated at around 120 units. Riceland’s response to ERG’s recent questions demons trates that this estimate is likely low by a significant amount. After discus sion with Neil Washburn of Ri celand, it appears that RTP’s prior estimate of the dryer population, which wa s derived using average values, did not properly account for the peak demand for rice drying that occurs during the harvest season. Thus, any estimate of rice dryer population must take the peak drying demand into account.

Riceland processes about 20% of the U.S. rice cr op. A simplistic way to estimate the U.S. rice dryer population based on the rice dryer population in Riceland’s facilities would be to scale the Riceland rice dryer population upward, assuming that the remaining 80% of U.S. rice processed by other companies requires a proportional number of rice dryers. A review of data from one rice dryer vendor suggests that this simplisti c approach appears reasonable. To RTP’s knowledge, there are two primary dryer vendors that supply rice dryers: Shanzer and GSI (Grain Systems Inc). Assuming that these vendors have about equal market share yields an estimate of approximately 56 new rice dryers installed between 2001 and 2011. 1 Riceland installed 11 new rice dryers during this period, or approximately 20% of the estimated total. Since Riceland processes about 20% of the U.S. rice crop, Riceland’s share of ri ce dryer purchases appears to mirror its share of the U.S. rice crop. Using a 20% factor to approximate Ri celand’s share of the U.S. rice dryer population results in an estimate of approximately 600 rice dryers in the U.S.

Rice Dryer Construction Rates

Given the fact that Riceland’s ri ce dryer population appears to be re presentative of the U.S. rice dryer population, then Riceland’s past rice drye r purchases can be used as the basis for estimating total U.S. rice dryer purchases. As stated above, from 2001 through 2011, Riceland purchased 11 new rice dryers. 2 Assuming this value represents 20% of the U.S. market results in an estimate of 55 rice dryers constructed be tween 2001 and 2011, or 5.5 dryers per year. This

1 Shanzer’s experience list indicates that it su pplied 28 rice dryers during this period.

2 The term “new” is used here to represent both replacem ent dryers and additional dryers installed by Riceland.Review of New Data on Wire-Screen Column Dryers 21 September 2012 Page 4 of 5

value is slightly higher than RTP’s previ ous estimate of 4 new rice dryers per year. 3 Note however, that most of these dryers are likely replacement units. 4 Thus, for the most part, they do
not result in new emissions from existing facilities. Also, it is RTP’s unders tanding that not all of these dryers are wire screen dryers (i .e., some are NSPS Subpart DD column dryers).

Rice Dryer Emissions RTP reviewed the background documentation fo r the development of AP-42 Section 9.9.1. 5 This review, which provided informa tion on grain dryer emission fact ors specific to wire-screen column rice dryers, shows that these emissions ar e lower than the final AP-42 emission factor for column grain dryers. According to the data in the AP-42 background report, the average particulate emissions from screen rice dryers is 0.051 lb/ton, or about 25% of the AP-42 general grain column dryer emission factor of 0.22 lb/ton. 6

A typical rice dryer has a cap acity of about 5,000 bushels per hour and operates for about 2,000 hours per year. 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. 7 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
.

Conclusion The current version of Subpart DD does not apply to wire-screen column dryers. If a revised Subpart DD were to regulate such dryers, as many as 5 or 6 dryers per year could become subject to the NSPS (if all of the new dryers are constr ucted at Subpart DD aff ected grain elevators).

3 See Column Grain Dryers Using Woven Wire Screens as the Column Walls , memorandum from Jack Burke, RTP

Environmental Associates, Inc. to Jess McCluer and David Ailor, June 15, 2010.

4 As discussed in Neil Washburn’s response to ERG’s August 28, 2012, questions, 100% of Riceland’s new dryers

installed in the last five years were replacement units and two-thirds of the dryers plan ned for the next five years will be replacement units.

5 Emission Factor Documentation for AP-42 Section 9.9.1 - Grain Elevators and Grain Processing Plants – Final

Report , RTI International, April 2003.

6 Ibid , Tables 4-13 and 4-16.

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

about 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.Review of New Data on Wire-Screen Column Dryers 21 September 2012 Page 5 of 5

Given the relatively small rate of emissions fr om these dryers (i.e., only about 25% of the emissions from a comparably-sized column grain dr yers) and the fact that most of these dryers do not create any new emissions (i.e., most are replacement units), this subcategory of sources should be considered insignifi cant and, therefore, should not be regulated under any revised NSPS. In any event, state/local air pollution cont rol agencies can be expe cted, as the Coalition has emphasized in its petition fo r repeal of Subpart DD, to ad dress PM emissions from new “rice” dryers appropriately, even in the absence of Subpart DD