## Response to Public Comments

The Amalgamated Sugar Company LLC (TASCO)

Nampa Factory

Nampa, Idaho

Facility ID No. 027-00010

Tier II Operating Permit No. T2-2009.0105 Project 60867

December 23, 2011

Morrie Lewis

Permit WriterT2-2009.0105 Project 60867 Page 2 

### BACKGROUND

As deemed appropriate by the Director, the Id aho Department of Environmental Quality (DEQ) provided for public comment on the proposed permit from October 31, 2011 through November 30, 2011 in accordance with IDAPA 58. 01.01.404.01.c. During this period, comments were submitted in response to DEQ’s proposed action. Each comment and DEQ’s response is provided in the following section. Comments with a common theme have been grouped together and responded to as one comment. All comment s submitted in response to DEQ’s proposed action are included in the appendix to this document.

Additional information concerni ng this permitting action, the BART and BART Alternative determinations, and the Regional Haze program and its requirements can be found in the following documents:

• Tier II Operating Permit No. T2-2009.0105 Project 60867 and Statement of Basis (proposed for issuance)

• Tier II Operating Permit No. T2-2009.0105 and Statement of Basis, issued September 7, 2010

• State of Idaho Regional Haze State Implementation Plan (Regional Haze SIP) and Interstate Transport Plan, Final and Proposed Rules

• www.deq.idaho.gov/air/prog_issues/pollutants/haze_overview.can

• www.epa.gov/visibility/program.html



### PUBLIC COMMENTS AND RESPONSES

Public comments regarding the technical and regul atory analyses and the air quality aspects of the proposed permit are summarized below. Questi ons, comments, and/or suggestions received during the comment period that did not relate to the air quality aspects of the permit application, the Department’s technical analyses, or the proposed permit have not been addressed. For reference purposes, a copy of the Rules for the Contro l of Air Pollution in Idaho can be found at: http://adm.idaho.gov/adminrules/rules/idapa58/0101.pdf. Comment 1: Will the project or the proposed controls address odors? ( Freeman ) Is this project mainly about plant efficiency, to reduce NO x emissions, or to reduce ozone formation? ( Johnson )
Response: The primary focus of this project is to redu ce visibility impacts and to reduce regional haze to meet Regional Haze program requirements. Odors were not the primary focus of this pr oject, and impacts were not assessed. Although the project reduces combustion emissions from the boilers at the Nampa Factory, the process equipment and the emissions from these processes are not expected to change. So with regard to odors, a change may or may not be noticeable. Although the implementation of BART cont rols will result in the reduction of NO x emissions and thereby reduce ozone formation, this additional e nvironmental benefit was incidental to meeting the requirements of the Regional Haze program, and was not a BART requirement. Nevertheless, as part of an ongoing effort to be proactiv e in addressing Treasure Valley summer ozone conditions, DEQ assessed the ozone impacts of this project. The NO x emission reductions achieved by the BART Alternative represent the greatest NO x reduction of any control measures that DEQ has evaluated to date, and may help to avoid non-attainment designation over the next few years (see the “Additional Environmenta l Benefits in Reducing Ozone” section in Appendix B to the Statement of Basis for additional discussion).T2-2009.0105 Project 60867 Page 3 Similarly, any change in plant efficiency resulting from this project would also be incidental. It may be noted that an application for permit modifi cation will be required if this project results in a significant increase in emissions in accordance with IDAPA 58.01.01.200-228. Comment 2: Why will it take until 2016 to implement this project? ( Quignon )
Response: The Regional Haze program allows five years to install and operate Best Available Retrofit Technologies (BART). In accordance with 40 CFR 51.308(e)(1)(iv) and IDAPA 58.01.01.668.04: Each source subject to BART shall be required to install and operate BART as expeditiously as practicable, but in no event later than 5 years after approval of the implementation plan revision.

This schedule includes time for federal BART a pproval and incorporation into the Regional Haze State Implementation Plan (RH SIP), and time necessary to install BART controls. Comment 3: Can you absolutely prove that the pollutants from TASCO are impacting Hells Canyon? ( Johnson )
Response: DEQ has determined that the Amalgamated S ugar Company’s (TASCO) Riley Boiler has caused significant contribution to haze at Eagle Cap, Strawberry Mountain, and Hells Canyon areas. These determinations were based on modeling anal yses which predicted elevated haze impacts on days when elevated impacts were also measure d in these areas, and when upper level transport winds were flowing from the Nampa area toward these areas. Such conditions occurred during wintertime stagnant air periods. In addition, th e patterns of fine particle chemical composition measured at these wilderness areas closely para llel the patterns expected from the chemical composition of emissions from the Riley Boiler at the Nampa Factory when combined with the other emission sources in the Nampa-Boise area. In the modeling analyses, DEQ utilized modeling approaches which have been used nationwide and developed by several federal agencies, incl uding the EPA, National Park Service, and U.S. Forest Service. The analyses used appropriate i nputs developed jointly by modeling experts at the Idaho DEQ, EPA Region 10, Washington Depa rtment of Ecology, and Oregon DEQ. The modeling system used has undergone extensive t esting by its developer and the EPA, and is identified in Appendix W to 40 CFR Part 51, the Guideline on Air Quality Modeling, as the recommended model for long-range transport based on validation studies in which it was compared to measured values. In summary, the measurements and modeling me thods which demonstrate that emissions from the TASCO Nampa Factory are impacting Hells Canyon are accepted as the best science available by scientists, agencies, and the regulat ed community within our region and nationwide. As a result, these methods were selected by EPA and utilized by DEQ to implement Regional Haze program requirements. Comment 4: Does the BART Alternative result in a great er reduction in haze at the affected Class I areas as compared with the EPA-approved BART determination for the Riley Boiler? ( Forsgren, USFS )
Response: During and subsequent to issuance of the initia l BART Tier II operating permit and EPA partial approval of the Regional Haze SIP, substantiv e comments and information were provided by TASCO which supported the position that certain control technologies would not be feasible to implement at the Nampa Factory, and that reconsideration of the NO x BART determination was warranted. Specifically, selective catalytic reduc tion (SCR) and over-fired air (OFA) technologies were determined to be technically infeasible in the revised BART determinations (Step 2 in the top-down BART determination; see Tables 4 and 5 of the Statement of Basis). DEQ believes it is therefore inappropriate to compare the visibility impacts of the revised BART determination to the initial BART NO x determination (which included infeasible control technologies), and that such comparison is not required by the Regional Haze program.T2-2009.0105 Project 60867 Page 4 Comment 5: What are the regulatory hurdles and policy implications that need to be addressed when including the non-BART units (i.e., the B&W bo ilers and pulp driers) in an alternative to BART determination? ( Forsgren, USFS )
Response: DEQ believes that inclusion of non-BART em ission units in the evaluation of the BART Alternative does not require new regulatory interp retations nor introduce new policy implications. DEQ agrees with the commenter that once a source-by-source BART determination has been made for a BART-subject unit, emission reductions from other sources may then be considered as part of a BART Alternative. Non-BART units were included only with resp ect to the BART Alternative analysis and determination, and included only those units participating in the proposed alternative. Specifically, the “BART Alternative” scenario included the three pulp dryers (for which shutdown was proposed), the B&W Boilers (for which installation of Low NO x Burners was proposed), and the Riley Boiler (the BART-subject unit). In accordance with 40 CFR 51.308(e)(2) and IDAPA 58.01.01.668.06 , DEQ may approve: ...an alternative measure rather than to require sources subject to BART to install, operate, and maintain BART. Su ch...alternative measure must achieve greater reasonable progress than would be achieved through the installation and operation of BART. For the unique circumstances of this project, DEQ chose not to adopt the SO 2 emission control limits indicated by the BART analyses for SO 2 emissions, but instead a dopted BART Alternative NO x emission limits for the B&W Boilers and shutdo wn requirements for the pulp dryers. These combined measures were predicted to result in greater projected emission reductions and in greater visibility improvement. In accordance with 40 CFR 51.308(e)(3) and as provided in the BART Guidelines (Appendix Y to 40 CFR 51), the BART Alternative meets the “better-than-BART test”: If the distribution of emissions is significantly different, the State must conduct dispersion modeling to determine differences in visibility between BART and the trading program for each impacted Class I area, for the worst and best 20 percent of days. The modeling would demonstrate “greater reasonable progress” if both of the following two criteria are met: (i) Visibility does not decline in any Class I area, and (ii) There is an overall improvement in visibility, determined by comparing the average differences between BART and the alternative over all affected Class I areas.

Because the distribution of emissi ons could be cons trued to be “ significantly ” different in the “BART Alternative” scenario than in the “BART” scenario (in terms of trading SO 2 emission reductions for NO x emission reductions), dispersion mode ling was conducted to demonstrate that the BART Alternative will not result in a decline in visibility in any Class I area and will result in an overall improvement in visibility.

The “BART Alternative” scenario di d not result in a decline in visibility at any Class I area, and on the balance resulted in greater improvement than the “BART” scenario across the seven Class I areas evaluated (see Table 9 in the Statement of Basis). The site-specific technical demonstration relied on both speciation and disper sion modeling to demonstrate that the net air quality benefits of the BART alternative will result in greater reasonable progress.T2-2009.0105 Project 60867 Page 5 

### Table 1 GREATER REASONABLE PROGRESS DETERMINATION (a)

Reasonable Progress Criteria Benchmark BART BART Alternative “Better-than-Baseline” Improvement “Better-than-BART” Improvement

Visibility-Impairing Emissions (PM 10

+ NO x + SO 2 ) – Rate in lb/hr Reductions in lb/hr

BART Alternative Emission Units 1,929.2 1,277.6 1,276.6 + 1.0 (b)

Class I Area Visibility – Number of Days Above 0.5 Δ dv Number of Days Improved to Less Than 0.5 Δ dv
Eagle Cap 195 149 126 + 69 (c)

+ 41 (d) Craters of the Moon 10 4 3 + 7 (c)

Hells Canyon 129 87 80 + 49 (c)

Jarbidge 8 5 5 + 3 (c)

Sawtooth 18 6 6 + 12 (c)

Selway-Bitterroot 15 3 4 + 11 (c)

Strawberry Mountain 80 62 51 + 29 (c)

Result No degradation in any Class I area (c) Overall improvement in visibility and Greater Reasonable Progress (b,d)
(a) This table contains a summary of results from the Statement of Basis (see Tables 6, 7, and 9). (b) BART Alternative results in greater emission re ductions as described under 40 CFR 51.308(e)(3). (c) For the BART Alternative, visibility do es not decline in any Cla ss I area, meeting the criteria in 40 CFR 51.308(e)(3)(i). (d) For the BART Alternative, there is an overall improvement in visibility, determined by comparing the average differences between BART and the alternative over a ll affected Class I areas, meeting the criteria in 40 CFR 51.308(e)(3)(ii). As summarized in Table 1, the BART Alternative satisfies the “Better-than-BART” test criteria in 40 CFR 51.308(e)(3); the BART Alternative r esults in greater emission reductions, does not result in a decline in visibility in any Class I ar ea, and results in an overall improvement in visibility when the average differences between BART and the BART alternative over all affected Class I areas are compared. These demonstrations fulfill 40 CFR 51.308(e)(2 ) and (e)(3), and IDAPA 58.01.01.668.06, and the overarching statutory requirement in 42 U.S.C. § 7491(b)(2) that States make reasonable progress toward the national visibility goal. Comment 6: Citing an EPA letter to the Colorado Air Pollution Control Division, 1 the use of an Alternative-to-BART approach within a source's fence line may not be appropriate. Although 40 CFR 51.308(e)(2) is silent on the applicability of an Alternative-to-BART occurring within a fenceline, it could be rea sonably construed that Section V of the BART guidelines would govern such a situation. ( Silva, FWS )
Response: In the letter and guidelines cited, concern is raised that although “averaging across BART emission units within a source’s fenceline” was contemplated in making BART determinations, that this was not explicitly characterized as a BART alternative. Citing Section V: You should consider allowing sources to "average" emissions across any set of BART-eligible emission units within a fenceline, so long as the emission reductions from each pollutant being controlled for BART would be equal to those reductions that would be obtaine d by simply controlling each of the BART-eligible units that cons titute BART-eligible source.

1 Letter from EPA Region 8 to Paul Tourangeau, Colorado Department of Public Health and Environm ent, “EPA Region 8 Comments on D raft BART Analyses,” Cynthia Cody, EPA, February 16, 2007.T2-2009.0105 Project 60867 Page 6 DEQ believes it is important to distinguish that this guidance is directed toward the BART determination process, and is not controlling of BART alterna tive measures. While EPA does not characterize an inside-the-fenceline approach as a BART alternative, such an approach was also not expressly excluded from consideration. As described in the response to Comment 5 and in accordance with the requirements of 40 CFR 51.308(e)(2) and (e)(3) and IDAPA 58.01.01.668.06, DEQ has the discretion to adopt implementation plan provisions other than those pr ovided by BART analyses in situations where it has reasonably concluded that more “reasona ble progress” will thereby be attained. Beyond meeting these requirements, it may also be ar gued that the trading of emission reductions inside-the-fenceline in accordance with 40 CFR 51. 308(e)(3) is more narrow in focus than the implementation of a cap-and-trade program allowable under 40 CFR 51.308(e)(4), which implicitly allows trading of emissions beyond the fenceline and across different source categories.
Furthermore, there are other notable differen ces between the TASCO BART Alternative and Public Service Company’s (PSCo) BART alterna tives for the Hayden 1 and 2 and Comanche 1 and 2 facilities:

• The TASCO BART Alternative meets the r ecommended criteria under 40 CFR 51.308(e)(3) for demonstrating that the alternative achie ves greater reasonable progress (see response to Comment 5), as compared to the use of a “weight-of-evidence” approach under 40 CFR 51.308(e)(2)(i)(E) in PSCo BART alternative demonstrations.

• The TASCO BART uses a conventional top-down and case-by-case approach to determining BART, as compared to the use of presumptive emission limits for 750 MW coal-fired power plants in PSCo BART determinations.

• The TASCO BART Alternative emission limits were specified on a basis consistent with the maximum hourly emission rates used in the BA RT analyses, as compared to limits specified with a longer (less stringent) averaging period in PSCo BART Alternative demonstrations.

• The TASCO BART and BART Alternative were compared using both emission reductions and modeling analyses to demonstrate greater vi sibility improvement, as compared to the use of emission reductions alone in PSCo BART Alternative determinations. The purpose of the BART analyses was to identify existing, older stationary emission sources that contribute to haze at Class I areas and could be retrofit to reduce emissions. The B&W Boilers participating in the BART Alternative share sim ilar characteristics with the Riley Boiler – these units predate the 1977 Clean Air Act Amendments, derive from the same emission source category, and share in purpose and function at th e Nampa Factory. Boiler steam load is presently distributed across all three of the boilers at th e Nampa Factory according to process needs, and requiring BART controls on a single boiler could preferentially shift load distribution and shift emissions toward the uncontrolled (B&W) non-BA RT boilers under certain boiler operating scenarios. Beyond meeting Regional Haze program requirements, these characteristics further support inclusion of non-BART units and use of an inside-the-fenceline approach in the BART Alternative in order to achieve greater reasonable progress.

Comment 7: Can credit for emission reductions achiev ed by the shutdown of the pulp driers be applied under the Regional Haze Rule if these units were shutdown as a result of another regulatory action under the Clean Air Act (i.e., compliance with the NAAQS for PM 10 )? Discussion in Attachment #2 to the application states that shutdown was required to support the PM 10 NAAQS Maintenance Plan for Ada County. ( Forsgren, USFS )( Silva, FWS )
Response: In approving the proposed BART Alternative, DEQ credited TASCO with emissions reductions resulting from shutdown of all three pulp dryers - the North Pulp Dryer, the Center Pulp Dryer, and the South Pulp Dryer. DEQ believes it was reasonable to credit TASCO with these emission reductions.T2-2009.0105 Project 60867 Page 7 The Center Pulp Dryer (S-D2) and the North Pulp Dryer (S-D3) were required to be shut down by September 30, 2007 as part of a compliance schedule, 2 which included conditions established to ensure that emissions (and modeled impacts) will not cause or significantly contribute to a violation of PM 10 National Air Quality Standards (N AAQS) in areas surrounding the Nampa Factory and as part of the Northern Ada County PM 10 SIP Maintenance Plan and Redesignation Request. An enforceable requirement to shut dow n the remaining coal-fired pulp dryer, the South Pulp Dryer (S-D1), was included as BART Alte rnative requirement in the proposed permit (Permit Condition 4.1). In accordance with 40 CFR 51.308(e)(2)(iv), a BA RT alternative measure must achieve greater reasonable progress than would be achieved through the installation and operation of BART, and DEQ must submit an implementation plan including:

A demonstration that the emission re ductions resulting from the emissions trading program or other alternative meas ure will be surplus to those reductions resulting from measures adopted to meet requirements of the CAA as of the baseline date of the SIP. The five-year average of emissions (statewide baseline emission inventory) over years 2000 through 2004 established the baseline against wh ich reasonable progress will be measured (see the Regional Haze SIP, cited in the “Backgroun d” section above, for additional information). Similarly, emissions over years 2003 through 20 05 (Nampa Factory BART inventories) were used to determine the baseline visibility modeling scenario against which TASCO BART visibility improvement was meas ured (“Alternative Benchmark” scenario; see Table 8 of the Statement of Basis). Thus the emission reductions associated with shutdown of the pulp dryers were not included nor accounted for within th ese baseline scenarios (i.e., the baseline modeling analyses included full operation of the pulp dryers). Because the pulp dryer emission reductions were implemented following the baseline period, DEQ believes that including the emission reductions from shutdown of the pulp dryers as part of the BART Alternative is acceptable under the rule. Comment 8: The proposed BART Alternative does no t address each pollutant because there will be no control of SO 2 at the BART-eligible Riley Boiler. Although under the proposed Alternative scenario SO 2 will not be controlled, limits should still be established to ensure compliance with the 0.75% sulfur content used in the emissions used in the modeling, rather than relying upon the 1.0% limit under IDAPA. ( Silva, FWS )
Response: As described in the response to Comment 5 and in accordance with the requirements of 40 CFR 51.308(e)(2) and (e)(3) and IDAPA 58.01.01.668.06, DEQ has the discretion to adopt implementation plan provisions other than those pr ovided by BART analyses in situations where it has reasonably concluded that more “r easonable progress” will thereby be attained. EPA guidance further supports that “inter-polluta nt trading” was contemplated and is supported when greater reasonable progress will be attained: 3

...a State could demonstrate that a trad ing program that addresses one or two visibility-impairing pollutants under an alternative program would provide greater reasonable progress than would case-by-case BART applied to all visibility-impairing pollutants. The actual average coal sulfur content level ove r the baseline years (2003-2005) was used in the BART analyses and modeling in accordance with BART protocol, which was achieved by TASCO compliance with the 1.0% coal sulfur content limit required by IDAPA 58.01.01.725.

2 Required in Permit Condition 13.8 of Tier II Operati ng Permit No. T2-050021, final, revised March 8, 2006. 3 Regional Haze Regulations; Revisions to Pr ovisions Governing Alternative to Source-Sp ecific Best Available Retrofit Technology (BART)

Determinations, 71 FR 60612-60634, Final, Oc tober 13, 2006. See also response to Regi onal Progress Question #5, “Additional Reg ional Haze Questions,” EPA Q&A document, revised September 27, 2006.T2-2009.0105 Project 60867 Page 8 Because actual emissions have been effectively re gulated by compliance with this sulfur content limit, and after a review of TASCO’s compliance history, DEQ does not believe a more stringent limit is supported at this time. Existing sulfur content limits co rresponding to the baseline case (1% sulfur content by weight) and supporting monitoring requirements were re lied upon from TASCO’s Tier I operating permit 4 to address concerns regarding the inclus ion of an enforceable emission limit. Comment 9: Should 90% control efficiency be a pplied to Spray Dry FGD in lieu of 80%? Would the conclusion of greater reasonable progress be rea ched in this instance? Development of the Spray Dry FGD costs using the EPA Control Co st Manual should be available for public review. ( Silva, FWS )
Response: The initial BART determination for SO 2 approved by EPA has not been revised as a result of this permitting action, and therefore DEQ believes revisiting the elements and results of the initial BART SO 2 determination is not supported. As provided in the Statement of Basis for Tier II Operating Permit No. T2-2009.0105, issued September 7, 2010, due to concer ns related to protecting the integrity and performance of the baghouse (BART) control device, a conservativ e adiabatic approach temperature of 40 ◦ F above the adiabatic saturation temperature was assumed for the Spray Dry Flue Gas Desulfurization (Spray Dry FGD) control device. This corres ponded to estimated performance of 80% removal efficiency, which fell within the range of 80-90% control efficiencies typically cited for Spray Dry FGD. 5 Cost estimates were also reviewed in the initial BART determination. Comment 10: Cost justification in terms of cost per deciview of visibility improvement/cumulative visibility impact should be considered. ( Silva, FWS )
Response: Consistent with the response to Comment 9, DEQ’s regulatory approach to making the BART determinations is not being r econsidered at this time, and the ranking methodology used in comparing control technologies has not been alte red since approval of the Regional Haze SIP. Introducing a cost-per-deciview metric (in lieu of or in addition to ranking by dollars-per-ton) at this time would be inconsistent with the met hodology used in the initia l BART determinations. Use of dollars-per-ton of emission reduction in ranking control technologies is an accepted convention and recommended by EPA in Appendix Y to 40 CFR 51, and it has been used extensively in the Regional Haze and Prevention of Significant Deterioration programs under the Clean Air Act (CAA). Use of dollars-per-decivi ew is a relatively new approach without established guidance, and it has been used only in a limited number of determinations.

Comment 11: Additional clarification is recommended to assist the public in further understanding the complexities of regional haze predictions. ( DeLorey, TASCO )
Response: DEQ does not interpret the comments provided by TASCO as requesting or supporting any change to the BART analyses or to the BA RT determinations as proposed. Information concerning visibility monitoring and measurement , the modeling protocol, and the approach toward evaluating BART emissions and impacts is addressed within the Statement of Basis and within the references cited in the “Background” section (see above). Without endorsement, the comments and information provided by TASCO (and all other commenters) have been included in Appendix A for the record and for public review.

4 Permit Conditions 2.14 and 2.15 of Tier I Operating Permit No . T1-050020, final, revised May 23, 2006. See additional discussi on provided concerning

Permit Conditions 3.11 and 3.13 in the “Permit Conditio ns Review” section of the Statement of Basis. 5 Air Pollution Control Technology Fact Sheet, EPA-452/F-03-034.T2-2009.0105 Project 60867 Page 9 

### APPENDIX A

PUBLIC COMMENTS RECEIVEDT2-2009.0105 Project 60867 Page 10 Name: Dennis Freeman Email Address: dlfreeman50@gmail.com Sent: Tuesday, November 01, 2011 5:48 AM To: Martin Bauer Subject: Amalgamated Sugar Plant – Nampa

In today’s issue of Idaho Press Tribune, $8 million in upgrades were announced for air quality improvements. Will any of the improvements address the obnoxious odor that residents for miles around have to endure from October thru March during the processing period? Please let me know what is being done to address this issue.

Name: Bonnie Quignon Email Address: bfquignon@hotmail.com Affiliation: None Sent: Tuesday, November 01, 2011 2:05 PM To: Tessa Stevens Subject: Public Comment

I think this is a very positive step, but why will it take t ill 2016 to accomplish it? It could be done in their off season and be finished in one year. Those around them who suffer with their pollution would thank you.

## Comments of the US Fish & Wildlife Service (FWS) Re garding an

“Alternative-to-BART” Proposal to Meet Best Availab le Retrofit Technology (BART) for The Amalgamated Sugar Company LLC (TASCO) Nampa Factory as Proposed by the Idaho Depa rtment of Environmental Quality (IDEQ)

The IDEQ determined that the Riley Boiler at the TA SCO Nampa Factory is subject to BART under the EPA Guidelines for Best Available Re trofit Technology Determinations 1 

### and IDEQ provided an original BART determination o n July 17, 2009. TASCO objected to the original BART determination a nd pursued an “Alternative-toBART” in negotiations with the IDEQ. Subsequently, IDEQ provided to the FWS, “Proposed Revision to ‘Section 10.5 TASCO BART Dete rmination’ of the RH SIP” (Proposed Revision), along with an Air Quality Perm it Statement of Basis for the Tier II Operating Permit No. T2-2009.0105 Project 60867 and “BART Alternative Visibility Modeling for the Riley Boiler at TASCO – Nampa Fact ory” which propose an Alternative-to-BART under 40 CFR Part 51.308(e)(2). The FWS has several questions and comments relating to IDEQ’s proposed Alternativ e to BART determination for the TASCO Nampa Factory.

The FWS does not believe that IDEQ’s approach shoul d or can be evaluated as an Alternative-to-BART; however, such a determination will ultimately be made by EPA, Region X. In a letter dated February 16, 2007, EPA , Region VIII communicated to the Colorado Air Pollution Control Division that regard ing Public Service Company’s Hayden 1 and 2 and Comanche 1 and 2 facilities, use of an Alternative-to-BART approach within a source’s fence line may not be ap propriate. The letter discusses that while EPA’s BART guidelines 2 

### contemplate that BART determinations may include averaging across BART emissions units within a sour ce’s fence line, EPA does not characterize this as a BART alternative. Also, Sec tion V of the BART guidelines discusses averaging emissions across any set of BART-eligible emission units within a fence line for each pollutant. The proposed Alternative-to-BART does not address each pollutant because there will be no control of SO 2 

### at the BART-eligible Riley boiler. Further, Section V seems to contemplate averaging a cross only BART-eligible emission units without including non-BART-eligible emission units. Since, 40 CFR Part 51.308(e)(2) is silent on the applicability of an A lternative-to-BART occurring within a fence line, it could be reasonably construed that S ection V of the BART guidelines would govern such a situation.

This paragraph relates to the inclusion of emission s reduction credits from the permanent shutdown of three coal-fired pulp dryers as part of the Alternative-to-BART demonstration. For purposes of Best Available Cont rol Technology (BACT) under the Prevention of Significant Deterioration (PSD) Progr am emission credits from the shutdown of emission units cannot be used as credit to meet BACT. We are not aware of any definitive language under the BART program that allows or disallows such shutdown

1 See “Guidelines for BART Determinations Under the Regional Haze Rule.” 40 CFR Part 51, Appendix Y.
2 Ibid., Section V – first paragraph.

### 2

credits for purposes of meeting BART, so it remains an open question for EPA, Region X to address in the case of the TASCO Alternative-to- BART proposal. In 40 CFR Part 51.308(e)(2)(iv) it is stated that, “. . . emission reductions resulting from the emissions trading program or other alternative measure will b e surplus to those reductions resulting from measures adopted to meet requirements of the C AA as of the baseline date of the SIP.” Page 33 in Attachment #2 of the Proposed Rev ision states that, “. . . shut down of the coal-fired pulp dryers was required to support the PM10 NAAQS Maintenance Plan for Ada County . . .” This issue bears further scr utiny before the Alternative-to-BART proposal is approved.

The underlying requirement for use of an Alternativ e-to-BART rather than BART for the Riley boiler is that the Alternative achieves great er reasonable progress toward meeting the long term strategy for visibility protection. Table 10-13 in Attachment #1 of the Proposed Revision develops the greater reasonable p rogress justification for the Eagle Cap Wilderness area using Spray Dryer Flue Gas Desu lfurization (FGD) for SO 2 

### control as the SO 2 

### BART control (line 2 on the table). In Table 6 of the Statement of Basis for the Tier II Operating Permit, IDEQ presents an 80% emission reduction capability of Spray Dryer FGD for SO 2 

### control (522.3 lb/hr benchmark emissions vs. 104.0 lb/hr controlled emissions). Spray Dryer FGD can routine ly be assumed to attain 90% control efficiency. Some examples for plants using Lime S pray Dryer FGD technology on low sulfur coal are as follows: Newmont Nevada - 93.1% , LS Power – White Pine - 89.8%, LS Power – High Plains - 93.4%, Two Elk Expansion - 89.9%, Basin Electric – Dry Fork - 92.9%, and AES-Colorado - 90.7%. If a modeling i nput of 90% SO 2 

### control was used for the BART case instead of 80%, the outcome for g reater reasonable progress for the Alternative method would be more muted and possibly not show greater reasonable progress. Since it seems that the 80% control assu mption was used for the greater reasonable progress demonstration, then the BART co ntrol level was understated, leaving a lower hurdle to demonstrate greater reasonable pr ogress. The modeling should be performed using a 90% control efficiency assumption for the BART case.

It should be noted that the FWS still considers the Spray Dryer FGD SO 2 

### control alternative to be viable for BART. The IDEQ agreed with a $2,663 per ton of SO 2 

### control cost for this alternative, including the co sts of non-air quality environmental impacts. This value could be decreased to $2,367 i f the control efficiency were presented as 90%, rather than 80% in the cost development. A control efficiency of 90% for Spray Dryer FGD is certainly attainable as shown above. Either of the above costs should be considered as being reasonable for BART. It was in dicated that the EPA Control Cost Manual was used to develop the Spray Dryer FGD cost s. This analysis should be available in the record for third-party reviewers.

The following paragraph is moot if IDEQ proceeds wi th the Alternative-toBART. However, should the discussion ever revert b ack to using Spray Dryer FGD as BART for SO 2 

### control, cost justification in terms of cost per d eciview of visibility improvement should use the concept prese nted below. The concept of cumulative visibility impact reductions at all seve n affected Class I areas should be considered. Such considerations have been emplo yed in BART determinations

### 3

by Alaska, Oregon and Wyoming. Earlier the IDEQ ma de judgments on cost per deciview based on only the most impacted Class I ar ea, Eagle Cap Wilderness Area. We continue to believe that it is appropriat e to consider both the degree of visibility improvement in a given Class I area as w ell as the cumulative effects of improving visibility across all of the Class I area s affected. It simply does not make sense to use the same metric to evaluate the e ffects of reducing emissions from a BART source that impacts only one Class I ar ea as for a BART source that impacts multiple Class I areas. And, it does not ma ke sense to evaluate impacts at one Class I area, while ignoring others that are si milarly significantly impaired. If emissions from TASCO are reduced, the benefits will be spread well beyond only the Eagle Cap Wilderness Area to the other six affe cted Class I areas.

In Section 5 of Proposed Revision - Attachment #3, “Redlined Version of the Revised BART Tier II Operating Permit”, no SO 2 

### emission limits are provided for the Riley Boiler or the two Babcock and Wilcox Boil ers. Even though under the proposed Alternative scenario they will not be cont rolled, there should be SO 2 

### emission limits for these units (e.g., 522 lb/hour for the Riley Boiler and 435 lb/hr for the two B&W boilers). Such emission limits cou ld prevent a future TASCO transition to a coal that has higher sulfur content than the current average being used (0.75% sulfur) up to the current state limit o f 1.0% sulfur. In such a case actual visibility improvement would not likely meet the performance provided in the Alternative-to-BART. A similar situation could exist if the two B&W boilers undergo a BACT analysis for expansion in the future without considering the BART premises being instituted at this time.