# SOUTH DAKOTA’S

REGIONAL HAZE

STATE IMPLEMENTATION PLAN

RESPONSE TO COMMENTS

DURING PUBLIC NOTICE

South Dakota Department of Environment and Natural Resources

### Table of Contents

Page

ii 

### 1.0 Introduction .....................................................................................................1
2.0 EPA’s Comments ............................................................................................1
3.0 Sierra Club’s Comments ................................................................................7
4.0 Otter Tail Power Company’s Comments ...................................................171 

### 1.0 Introduction

DENR public noticed South Dakota’s Regional H aze Program for public comments on or before August, 26, 2010. South Dakota’s Regional Haze Progr am consists of “South Dakota’s Regional Haze State Implementation Plan” which addresse s the federal requirements in 40 Code of Federal Regulations (CFR), Part 51, Section 308 and the proposed rule ch anges that incorporate the Best Available Control Technology require ments. On September 15, 2010, a public hearing in front of the Board of Minerals and Environment was held to take testimony on South Dakota’s Regional Haze Program.

DENR received comments from the United States Environmental Protection Agency (EPA) – Region 8; the Sierra Club, National Parks C onservation Association and Plains Justice, hereinafter referred to as th e Sierra Club; and Otter Tail Power Company. The comments without attachments may be viewed in Appendix A.

This document contains a summary of the co mment and DENR’s responses to the comments received during the pub lic notice period.



### 2.0 EPA’s Comments

1. Additional details are necessary to ensure BA RT emission limits will be enforceable as a practical matter. The BART emission limits, compliance schedule, monitoring, recordkeeping, and compliance determining methods for Big Stone I must be specified in the text of the Regional Haze State Implementation Pl an or in a permit that is incorporated into the State Implementation Plan. For example, in your response to our comment on this issue (#1 and #39 from Appendix D), you relied heav ily on requirements of your Title V program (ARSD 74:36:05). As this program is not part of the State Implementation Plan, our concerns with reliance on the Title V program in this area remain. EPA provided examples from Colorado and Wyoming.

Response: DENR believes it already satisfied EPA’s concerns involving the enforceability of the BART emission limits, compliance schedules, monitoring, recordkeeping, and compliance determining methods as outlined in Appendix D of South Dakota’s Regional Haze State Implementation Plan. EPA’s initial comments noted BART needed to be specified as part of South Dakota’s State Implementation Pl an or the BART requirements need to be incorporated in a permit thatis incorporated in South Dakota’s State Implementation Plan. DENR decided to include the BART requirements as part of its State Implementation Plan.

DENR drafted rules in the Administrative Rules of South Dakota (ARSD), Chapter 74:36:21 and the Board of Minerals and Environmen t unanimously approved the rules during the public hearing on September 15, 2010. The final rules will be submitted to EPA for approval in South Dakota’s Regional Haze State Implementation Plan.2 

### DENR adopted the BART emission limits in ARSD § 74:36:21:06 – BART determination for a BART-eligible coal fire d power plant. This section also specifies the method of determining compliance for each air pollutant. The section requires an annual performance test be conducted to determine compliance wi th the particulate matter BART emission limit based on the average of three 1-hour test runs and a continuous emission monitoring system to determine compliance with the sulfur dioxi de and nitrogen oxide BART emission limits based on a 30-day rolling average. The performance test for particulate matter is based on South Dakota’s existing State Implementation Pl an which adopts federal performance testing requirements by reference in 40 CFR Part 60, Appendix A, 40 CFR Part 63 Appendix A, and 40 CFR Part 51, Appendix M. South Dakota’s existing State Implementation Plan also includes the specific requirements on monito ring and recordkeeping associated with continuous emission monitoring systems. Th ese requirements are identified in ARSD Chapter 74:36:11 and 74:36:13 and are identified by EPA as being part of South Dakota’s State Implementation Plan in 40 CFR § 52.2170.

In accordance with 40 CFR § 308(1)(e)(1)(iv), DENR identified Otter Tail Power Company must install BART on Big Stone I as expeditiously as practicab le, but no later than 5 years from EPA’s approval of South Dakota’s Regi onal Haze State Implementation Plan. EPA may observe the compliance schedule in ARSD § 74: 36:21:07 – Installation of controls based on visibility impact analysis or BART determin ation. This section specifies BART must be installed, operated, and complied with as expedi tiously as practicable; but no later than five years from EPA’s approval of South Dakota’s Regional Haze State Implementation Plan.

EPA may observe the operati on and maintenance requirements for air pollution control devices and the monitoring, recordkeeping, a nd reporting requirements for determining compliance with the BART emission limits in ARSD § 74:36:21:08 – Operation and maintenance of controls and ARSD § 74: 36:21:09 – Monitoring, recordkeeping, and reporting. The continuous emission monito ring requirements reference ARSD Chapter 74:36:13 which is part South Dakota’s State Implementation Plan and the monitoring, recordkeeping and reporting requirements reference the appropriate sections in South Dakota’s Title V air quality permit program which is approved by EPA.

Otter Tail Power Company is also required to meet other independent requirements under ARSD Chapter 74:36:16 – Ac id Rain Program. South Dakota’s continuous emission monitoring requirements for the Acid Rain progr am are the same as EPA’s (40 CFR Part 75). 40 CFR Part 75 specifies monitoring provision s, operation and mainte nance requirements, missing data substitution procedures, reco rdkeeping and reporting requirements for the monitored data.

EPA repeats its concern that DENR referen ces South Dakota’s EPA approved Title V air quality permit program for implementing the BA RT requirements. As discussed above, the BART limits, recordkeeping, monitoring, compliance schedules, etc. are either already part of South Dakota’s State Implementation Plan or will be once EPA approves ARSD Chapter 74:36:21. The rules are designed to fit within South Dakota’s current established rules and regulations. DENR is clarifying and acknowledgi ng the BART requirements are required to be incorporated in Otter Tail Power Company’s Title V air quality permit. Some of which are3 

### already established in Otter Tail Power Co mpany’s current Title V air quality permit #28.0801-29 such as recordkeeping, reporting, and m onitoring requirements associated with performance tests and continuous emission monitoring systems.

DENR believes EPA’s concerns are addresse d in South Dakota’s Regional Haze State Implementation Plan which includes ARSD Ch apter 74:36:21 and will be submitted to EPA for approval in South Dakota’ s State Implementation Plan.

2. EPA states footnote 5 references a 1999 EPA Te chnical Bulletin on nitrogen oxide controls as justification for the 35% to 90% control efficiency range for the top three options. The large range in EPA’s bulletin is due to incl usion of selective catal ytic reduction (SCR), selective non-catalytic reducti on (SNCR), and fuel re-burning for wet-bottom boilers. EPA states it is well documented that a SCR achieve s the high end of the range. Therefore, the proposed BART determination of SCR plus separated over-fire air (SOFA) should be better than the 90% control efficiency of SCR alone. In our response to this comment (#31 from Appendix D), EPA indicates there was no disc ussion regarding how the addition of SOFA would not contribute to a betterthan 90% control efficiency. EPA indicated our response to this comment (#31 from Appendix D) previous ly did not discuss how the addition of the separated over-fire air would not contribute to a better th an 90% efficiency and would like this addressed.

Response: DENR believes it has addressed this i ssue in its initial response outlined in Appendix D of South Dakota’s Regional Haze State Implementation Plan. As discussed previously, DENR considers the c ontrol efficiency of a control de vice to be variable and it is inappropriate to take an arbitrary emission rate Otter Tail Power Company actually emitted and multiply it by an arbitrary control efficiency to establish an air emission limit. This concept does not change if one is looking at ju st the addition of a sel ective catalytic reduction system or a combination of separated over-fire air and a selective catalytic reduction system. DENR provided examples by EPA that agree withthis concept from technical documents to EPA’s regulations.

Also discussed in Appendix D, none of the documents identified or provided by EPA identify under what operating conditions these control effi ciencies will occur (e.g., low, mid or high loads); the time period for demonstrating compliance (e.g., hourly or 30-day average emission rate); or the inlet pollutant loading rate. Therefore, one does not know if these cited control efficiencies are based on systems that have or do not have specific combustion controls (e.g. low nitrogen oxide burners, over- fire air systems, flue gas recirculation). Without knowing this information, the inform ation provided by EPA does not support their claim that a selective catalytic reduction syst em will obtain 90% control efficiency at any inlet concentration loading to the sel ective catalytic reduction system.

The selective catalytic reduction system is a n itrogen oxide control t echnology utilizing the injection of a nitrogen-based reagent, such as ammonia or urea, in combination with a precious metal catalyst to reduce nitrogen to molecular nitrogen. The catalyst provides a substrate for reaction and reduces the required reaction temperatures. The selective catalytic reduction system is typically operated from 650 to 750°F. Large deviations from this4 

### temperature range will signifi cantly impact the nitrogen oxide control efficiency. Ammonia injection rates also impacts the nitrogen oxidecontrol efficiency. Increased molar ratio of ammonia to nitrogen oxide results in enhanced nitrogen oxide reduction but increased ammonia slip from the selective catalytic reducti on system. Over-fired air is a nitrogen oxide control technology that contro ls the amount of oxygen and flame temperature in the combustion zone reducing the formation of th ermal nitrogen oxide. Separated over-fire air (SOFA) is an air-staging nitrogen oxide reduction technique that is usually based on withholding 15 to 20 percent of the total combus tion air conventionally supplied to the firing zone. The selective cataly tic reduction system must be installed with the constraints of an existing coal fired boiler. As such, Otter Tail Power Company may not be able to locate the selective catalytic reduction system in th e most ideal and optimal location. Combining combustion controls (SOFA) and post-combustion c ontrols (SCR) allows the facility to meet BART limits within the limit/confines of the identified control options.

It should be noted that in the October 19, 2010, federal register notice, EPA is proposing to require a selective catalytic reduction system be installed on the five units at the Four Corners Power Plant located on the Navajo Nation. EPA is proposing the Four Corners Power Plant must meet a BART plantwide emission limit of 0.011 pounds per million Btus, which EPA notes represents an 80% reducti on in nitrogen oxide emissions. Both the emission rate and specified efficiency are less st ringent than that being required for Otter Tail Power Company. EPA acknowledges in its own BART analysis for the Four Corners Power Plant that the review needs to be conducted on a case-by-case analysis and the emission rates have to be achievable for the facility being reviewed.

DENR conducted a case-by-case BART analysis of Otter Tail Power Company’s facility and determined the nitrogen oxide BART emi ssion limit is 0.10 pounds per million Btu using a selective catalytic re duction and separate over-fire air system.

3. In order for EPA to accept the establishmen t of separate BART limits for startup and shutdown condition versus normal operation, an ad equate record showing that the otherwise applicable limits are not achievable and separate startup and shut down limits constitute BART is required as justification. EPA indicated that DENR’s previous response to this comment did not provide sufficient justification for separate startup and shutdown limits.

Response: As defined in 40 CFR § 51.301, Best Available Retrofit Technology (BART) means an emission limitation based on the degree of reduction achievable through the application of the best system of continuous emission reduction for each pollutant which is emitted by an existing stationary facility. The emission limitation must be established on a case-by-case basis taking into consideration the technology available, the costs of compliance, the energy and non-air quality e nvironmental impacts of compliance, any pollution control equipment in use or in existen ce at the source, the remaining useful life of the source, and the degree of improvement in visibility which may reasonably be anticipated to result from the use of such technology. DENR disagrees with EPA that the BART emission limits must be in pounds per million Btus because the rule does not specify the units. The rule simply states the emission limits must be established on a case-by-case basis.5 

### When comparing control technology’s and emi ssion limits across or with in industrial sectors a generalized emission rate is used. The ge neralized emission rate such as a pound per million Btus allows emission rates across boile rs of varying sizes to be compared. A pound per hour emission rate is difficult to compare from one boiler to the next if the heat input of the boilers are not identical. Whereas, the pound per hour emission rateis a case-by-case emission limit and is specific to an emission unit. DENR established a pound per hour BART emission limit for particulate mater, sulfur di oxide, and nitrogen oxideto represent BART since DENR used the hourly limits in the modeling analysis to demonstrate Otter Tail Power Company was not causing visibility impairmentin a Class I area. The pounds per hour BART emission limits cover all normal operations including startup and shutdown.

At Otter Tail Power Company’s listed maximum capacity the pounds per hour and pounds per million Btus BART emission limits are equivalent as noted by Equations 1-1. Substituting the “Emission Limit (pounds per million Btus)” and “Maximum Capacity (million Btus per hour)” from Table 1-1 into Equation 1-1 provides the BART emission limits in ARSD § 74:36:21:06 and also liste d in the fourth column of Table 1-1.

Equation 1-1 – Converting from “pounds per MMBtus” to “pounds per hour” ⎟ ⎠ ⎞ ⎜ ⎝ ⎛

= ⎟ ⎠ ⎞ ⎜ ⎝ ⎛
× ⎟ ⎠ ⎞ ⎜ ⎝ ⎛
hour pounds Limit Emission hour MMBtus Capacity Maximum MMBtus pounds Limit Emission



### Table 1-1 – BART Emission Limit Comparison BART Emission Limit Maximum Capacity BART Emission Limit Pollutant (pounds/MMBtus) (MMBtus/hour) (pounds/hour) Particulate Matter 0.012 5,609 67.3 Sulfur Dioxide 0.09 5,609 505 Nitrogen Oxides 0.10 5,609 561

During the public hearing on South Dakota’s Regional Haze State Implementation Plan, the Board of Minerals and Environment revised th e particulate pounds per million Btus limit in ARSD 74:36:21:06(2) to cover all operati ons including startup and shutdown based on previous testimony from Otter Tail Power Company. Otter Tail Power Company had testified the baghouse would be in operation prior to st arting up the boiler and could meet the pounds per million Btus limit even during startup and shutdown.

4. In accordance with ARSD 74:36:21:11, a permit to construct is required to include the controls, emission limits, monitori ng, recordkeeping, and reporti ng requirements identified in the BART determination and approved by DENR . EPA states without seeing the details of such permit; it is difficult to determine whethe r this section of the SIP adequately addresses the requirements for enforceability, including appropriate averaging times, compliance verification procedures, and r ecordkeeping and reporting requir ements, and proper operation and maintenance procedures.

Response: DENR discusses this in the writte n portion of South Dakota’s Regional Haze State Implementation Plan and as we responde d in response to Comment #1, DENR adopted6 

### these requirements in ARSD Chapter 74:36:21. The requirements in ARSD Chapter 74:36:21 will be submitted as part of South Dakota’s State Implementation Plan and included in the permit to construct and eventually in the Title V air quality permit as applicable requirements.

DENR believes it has already satisfied EPA’s concerns involving the enforceability of the BART emission limits, compliance schedules, monitoring, recordkeep ing, and compliance determining methods.

5. EPA stated the public must be provided a cal culation of the number of years required to reach natural conditions if the Reasonable Progress Goalprovides a slower rate of improvement than that needed to attain natural conditions by 2064 per 40 CFR §51.308(d)(1)(ii). Although DENR indicates the goal of reaching natural visibility by 2064 is still achievable, EPA believes the modeli ng results does not support DENR’s conclusion and is requesting that we identify when the current evidence indicates natural conditions will be achieved.

Response: Although DENR believes it will achiev e natural conditions by 2064, DENR will project when WRAP’s modeling depicts natural conditions will be achieved in South Dakota’s Regional Haze State Implementation Plan.

6. Despite the fact that South Dakota’s sulfur dioxide and nitrog en oxide emissions from point sources represent 1.5% and 4% of the contri bution from point sour ces on our two Class I areas, respectively, EPA believes a four factor analysis is still re quired for GCC Dacotah, Black Hills Corporation (Ben French ), and Pete Lien and Sons.

Response: Although DENR demonstrated in the orig inal response to EPA’s comment that South Dakota’s sulfur dioxide and nitrogen oxide c ontributions to visibility impairment in the Class I areas is minimal based on WRAP’s modeling, DENR will conduct a four factor analysis on GCC Dacotah, Black Hills Corporati on (Ben French), and Pete Lien and Sons.

7. EPA states the BART requirements need to be incorporated in the state implementation plan and does not believe it appropriate for DENR to rely on the construction permit since EPA has not been approved in our St ate Implementation Plan yet.

Response: DENR addressed this in Comment #1.

8. EPA reiterated Comment #5 involving the recal culation of when South Dakota plans on achieving natural visibility and w ould like the year recalculated.

Response: DENR addressed this in Comment #5.

9. EPA stated federal land managers must be prov ided a 60-day consultation period prior to any public hearing on the regional ha ze state implementation plan. Since the BART permit is an integral part of the Regional Haze state impl ementation plan, the 60- day consultation period7 

### must extend to the federal land managers’ BARTpermit review as well. EPA did not believe our response to this comment ear lier addressed th eir concern.

Response: Again, South Dakota’s draft Regional Haze State Implementation Plan was submitted to the federal land managers on January 15, 2010, which included the BART determination and requirements. DENR adopted those requirements in ARSD 74:36:21 to be submitted as part of the state implementation plan.

DENR revised ARSD 74:36:21:12 to state federal land managers will have 60 days to submit an analysis on a BART determination or by the end of the public pa rticipation process, whichever is later. However, DENR believes this is a mute point since the federal land managers were provided 8 m onths to provide comments on the BART determination and requirements.

DENR believes the federal managers had over 60 days to review the BART requirements specified in South Dakota’s draft Regional Haze state implementation plan. DENR established EPA’s comment in ARSD 74:36:21 which will be submitted as part of South Dakota’s Regional Haze State Implementation Plan.



### 3.0 Sierra Club’s Comments

10. South Dakota’s draft regional haze plan states that, because Big Stone I has a generating capacity less than 750 megawatts, the state is not required to follow the BART Guidelines in 40 CFR Part 51, Subpart Y. South Dakota Draft Regional Haze Plan at 82. Specifically, the South Dakota Regional Haze Plan states “...in id entifying the available control technologies, DENR is not listing any of the pe rmutations of the control levels for each identified control technology as suggested by EPA’s guidance.” Whilethe Federal regional haze regulations mandate that BART for units of 750 megawatts or greater must follow the BART Guidelines, the fact that Big Stone I ha s a generating capacity less than750 megawatts does not mean South Dakota does not have to follow a reasone d analysis in evaluating BART and setting BART emission limitations. Thus, there is no justif ication for the state toignore the fact that pollution controls can be designed and operated at varying levels of control efficiency. If the state does not consider the capabilities of the various pollution controls evaluated in the case by case BART analysis, its cost impacts analysis will be skewed in favor of the lowest capital cost equipment rather than pr operly evaluating cost impacts interms of amount of pollution reduced. Thus, South Dakota must consider the varying levels of c ontrol efficiency of pollution controls in the BA RT analyses for Big Stone.

Response: The Sierra Club appears to be singling out a specific sentence and not reading the entire BART determination on how DENR decided on the case-by-case BART emission limits. As noted on page 82 of the South Dakota’s Regional Haze State Implementation Plan, DENR identified that “Otter Tail Power Company’s Big Stone I facility does not have a total generating capacity greater than 750 megawatts. Therefore, DENR is not required to follow these guidelines. As such, DENR will follow the steps identified in Appendix Y with some slight differences. For example, in identifying the availabl e control technologies,8 

### DENR is not listing any of the pe rmutations of the control levels for each identified control technology as suggested by EPA’s guidance. DENR will use the initial step to identify control technologies without including the control levels. Step 3 is used to evaluate the control effectiveness or permutations of the control levels for those control technologies that are considered feasible to install or maintain as identified in Step 2.” This approach allowed DENR to remove the infeasibletechnology in Step 2 before c onsidering the permutations of the varying control efficiencies that were us ed to rank the control options in Step 3.

Based on the cost analysis for both the dry and wet scrubber technology discussed to control sulfur dioxide emissions, the capital cost of th e scrubbers did not change with the varying level of control efficiencies. There would be operational and maintenan ce costs; but the cost differences would be insignifican t. As such, Sierra Clubs’ co mment that the cost impacts would be skewed in favor of the lowest cap ital cost equipment did not occur.

11. The Sierra Club believes the BART analysis for sulfur dioxide is flawed because DENR based the analysis on coal with higher uncontrolled sulfur di oxide emissions than historically burned at Big Stone I. The Sierra Club took the last 10 years of data from EPA’s Clean Air Markets Database and stated the highest annual average sulfur dioxide emission rate was no higher than 0.70 pounds per million Btus. The Si erra Club stated DENR should use this uncontrolled sulfur dioxide emission rate or at worst, determined the highest 30-day average uncontrolled sulfur dioxide emission rate in setting the BART emission limit for Big Stone based on the control efficiency of the sulfur dioxide controls evaluated.

Response: In considering what emission limit repres ents BART, one needs to consider the operation of the emission unit and the control device. DENR considers it inappropriate to take an arbitrary emission rate Otter Tail Power Company has actually emitted and multiply it by an arbitrary control efficiency to develop an emission limit.

The control efficiency is vari able as recognized by EPA’s fa ct sheet (EPA-452/F-03-024) for fabric filters controlling particulate matter emissi ons. The fact sheet notes a fabric filter is a constant outlet device and not a constant collec tion efficiency device. This fact sheet also notes the collection efficiency of the fabric filter is constantly changing and average collection efficiencies are based on tests with a constant inlet pollutant loading. EPA also recognized the variability inanother fact sheet (EPA -452/F-03-034) for flue gas desulfurization (wet and dry) controlling sulfur dioxide emissions. In this fact sheet, EPA states control efficiencies range from 50 percent to 98 percent.

In addition, EPA acknowledges this concept in rules. For example, in accordance with 40 CFR §60.482-10, a vapor recovery system shall be designed and operated to recover the volatile organic compound emissions vented to them with an efficiency of 95 percent or greater or to an exit concentration of 20 parts per million by volume, whichever is less stringent. Another example is in the new source performance st andard for electrical utility steam generators. In accordance with 40 CFR 60.43Da(i)(1), an elec trical utility steam generating unit that commenced construction after February 28, 2005, sh all not emit sulfur dioxide in excess of 1.4 pounds per megawatt hour or 5 percent of the potential combustion concentration (95 percent reduction).9 

### DENR does not recommend any changes.

12. The Sierra Club believes the BART analysis for sulfur dioxide is flawed because DENR failed to consider the level of control ach ievable with wet scrubbers. The Sierra Club identified wet scrubbers in Japan that guaranteed 99% sulfur dioxide control efficiency and claimed this technology was demonstrated at the University of Illinois’ Abbott power plant, Georgia Power’s Plant Yates, Dayton Power & Light’s Killen Unit 2, and Plant Bowen Unit #3. The Sierra Club went on to identify other facilities that identif y 97.5% efficiency or better. The Sierra Club’s conclusion was the BART analysis should have evaluated these levels of control based on the actual uncontrolled sulfur dioxide emissions emitted by the unit over a 30 day average basis in the ev aluation of a wet scrubber for BART.

Response: The Sierra Club provided vender data for several systems implementing the Chiyoda CT-121 wet flue gas desulfurization syst em. With the exception of the data for the Shinko-Kobe power plant in Japan, the 2008, 2009, and 2010 data notes that to obtain the 98% and greater control efficiency the inlet sulf ur dioxide concentratio ns to those scrubbers needed to be greater than 1,680 parts per million. At these inlet concentrations and control efficiency, this data indicates that controlled emission rate fo r these systems would be in the range of approximately 0.07 and 0.15 pounds per million Btus. DENR calculated these emission rates using EPA’s Method 19 at 5% oxygen. Since the oxygen content of the data was not given, the calculated concentrati ons will vary slightly.

The Chiyoda CT-121 wet flue gas desulfurization vender data indicates that for those systems with an inlet concen tration between 500 and 1,000 part s per million, an average of 95% control efficiency was obtai ned. At these inlet concentrations and control efficiency, this data indicates that controlled emission rate for these systems woul d be in the range of approximately 0.05 and 0.10 pounds per million Btus. Again, DENR calculated these emission rates using EPA’s Me thod 19 at 5% oxygen.

As discussed in Appendix D of South Dakota’ s Regional Haze State Implementation Plan, for calendar years 2006, 2007, and 2008, and not considering periods of startup and shutdown, Otter Tail Power Company’s hourly su lfur dioxide emission rates ranged from approximately 0.5 to 1.3 pounds per million Btus . These emission rates correspond to a sulfur dioxide inlet concentration of 262 to 683 parts per million. This range represents the data associated with the 500 to 1,000 parts per million (95% control efficiency) but is also below that range which means the control e fficiency would be less than 95%. DENR’s BART emission limit for sulfur dioxide of 0.09 pounds per million Btus is within the emission rate range for both the 95 % and 98% control efficiencies.

In regards to the Shinko-Kobe power plant in Japan, the CT-121 wet flue gas desulfurization Kobe was designed for operation at 99 percent sulfur dioxide removal for a one percent sulfur bituminous coal, analogous to an Easter n U.S. low-sulfur coal. Otter Tail Power Company burns Powder River Basin subbituminous coal, which is a Western U.S. low-sulfur coal. Due to the coal characteristic differences, this plant is not comparable.10 

### The Sierra Club also states Mitsubishi guarantees a control efficiency of 99.8%. The document submitted by the Sierra Club does not state Mitsubishi guarantees this control efficiency for every project. The data indicates this guarantee was asso ciated with a sulfur dioxide inlet concentration of 7,800 parts per million. As stated above, the sulfur dioxide inlet concentration for Otter Tail Power Company’s facilityranges from 262 to 683 parts per million, which is well below the range Mitsubis hi guaranteed a 99.8% control efficiency for and is not comparable to Otter Tail Power Company’s facility.

The Sierra Club references a permit issued by the Georgia Environmen tal Protection Division for Plant Washington. In reviewing this permit, on page #9, Georgia appears to have established Best Available Control Technol ogy Limits of 0.052 pounds per million Btus on a 12-month rolling basis, 0.069 pounds per million Btus on a 30-day rolling average, and 959 pounds per hour (equivalent to 0.116 pounds per million Btus at maximum capacity) on a 3- hour average. DENR’s BART emission limit fo r sulfur dioxide is 0.09 pounds per million Btus on a 30-day rolling average which is comp arable to Georgia’s BACT emission limit for that same time period.

The Sierra Club also references actual mon itoring data from EPA’s Clean Air Markets division for several coal fired pow er plants. The Sierra Club not es there is actual monitoring data that indicates lower emission rates are being achieved. DENR agrees actual monitoring data is useful information. However, DENR di sagrees with the concept or emphasis that an emission rate limit should be set at the same level of the actual monitoring data. In evaluating an emission rate that will be usedas an emission limit, DENR considers the variability within the actual monitoring data to determine if a facility is able to achieve an emission limit on a continuous basis underneath all proposed operations and into the future. DENR reviewed the monitoring data for Pleasant Prairie for calendar year 2008. The monitoring data notes that Plea sant Prairie had on an hourly basis actual emission rates as high as 0.22 pounds per million Btus per hour, whic h is approximately 10 times higher than the annual average. These higher hourly emissionrates need to be cons idered in establishing an emission rate to ensure the emission limit may be achieved continuously and at all proposed operations.

In summary, DENR conducted a case-by-case BART determination for Otter Tail Power Company’s facility and determined the BART emission limit should be 0.09 pounds per million Btu using a dry flue gas desulfurization unit to control sulfur dioxide emission and is within the range Sierra Club provided fo r a wet flue gas desulfurization unit.

13. The Sierra Club believes DENR and Otter Tail Power Company failed to evaluate the highest sulfur dioxide removal efficiencies achievable with a state-of-the-art dry scrubber. The Sierra Club mentioned four coal fired power plants that will orhave installed a dry scrubber and are subject to higher control efficiency re quirements and/or lower sulfur dioxide BACT emission limits than the 0.09 pounds per million Btu proposed by DENR. The four coal fired power plants are: 1) Newmont Nevada TS power plant; 2) White Pine power plant; 3) Toquop power plant; and 4) Dry Fork power plan t. Thus DENR should have evaluated these levels of control based on the uncontrolled su lfur dioxide emissions emitted by the unit over a 30-day average basis.11 

### Response: The Sierra Club references four coal-fired power plants that ha ve installed or are proposing to install a “state-of-the-art” dry sc rubber. DENR reviewed three of the four facilities but was unable to review Dry Fork si nce it was not available and the Sierra Club did not provide Exhibit 13 to DENR. DENR dete rmined that the Newmont and White Pine power plants installed or proposed to install a dry scrubber system to control sulfur dioxide emissions. However, the Toquop power plant actu ally proposed to install a wet scrubber system so is not comparable in this scenario. The Newmont and White Pine are located in Nevada and have the same sulfur dioxide BACT emission limits which consist of the following:

1. 0.09 pounds per million Btu based on a 24-hour av erage if the sulfur content of the subbituminous coal is equal to or greater than 0.45% based on a 30-day rolling average and a 95% sulfur dioxide remova l efficiency based on a 30-day rolling average; and 2. 0.065 pounds per million Btu based on a 24-hour av erage if the sulfur content is less than 0.45% based on a 30-day rolling aver age and a 91% sulfur dioxide removal efficiency based on a 30-day rolling average.

The Sierra Club identifies the sulfur dioxi de BACT emission limit of 0.07 pounds per million Btu.

As the Sierra Club indicates, these four powerplants either have just started operation (Newmont began operation in 2008) , are currently under constructi on (Dry Fork), or have not started construction (White Pine). These permits established emission limits that represent best available control technology for new coal fired power plants and not a retrofit of an existing power plant that repres ents Best Available Retrofit Technology. After taking that into consideration, DENR established a su lfur dioxide BART emission limit of 0.09 pounds per million Btu based on a 30-day rolling aver age which is comparable to Newmont and White Pine.

As outlined in Appendix D of the Regional Haze State Implementation Plan submittal, DENR reviewed EPA’s Reasonable AchievableControl Technology, BestAvailable Control Technology, and Lowest Achievable Emissi on Rate Clearinghouse (RBLC) for permits issued after calendar year 2000 on the emission limits established for coal fired boilers using a flue gas desulfurization system. The RBLC not es that the best ava ilable control technology emission limits for new coal fired boilers using a flue gas desulfurization system (either wet or dry) were in the range from 0.04 to 0.17 pounds per million Btu. DENR’s sulfur dioxide BART emission limit is within the range iden tified for BACT emission limits for new boilers.

14. The Sierra Club believes DENR’s cost effec tiveness calculatio n of the wet scrubber at a sulfur dioxide emission rate of 0.043 pounds pe r million Btu of $1,699 per ton is a reasonable cost when compared to other sulfur dioxi de BART determinations. The Sierra Club references a spreadsheet put t ogether by the National Park Service with cost information for BART determinations. According to the Sierra Club, the spreadsheet identifies the average12 

### cost effectiveness of sulfur dioxide BART controls as $1,571 pounds per ton, the mean cost effectiveness as $1,966 per ton, and the highe st cost is $7,309 pounds per million Btu. The Sierra Club states that similar facilities w ill have to incur similar costs to meet BART; therefore, DENR has no justification to discount installation of a wet scrubber based on costs.

Response: The Sierra Club did not provide a copy of the spreadsheet they used to provide the different effectiveness. It is impossible to compare the effectiveness since the Sierra Club uses three different units in comparing cost effectiveness, mean cost effectiveness, and highest costs. DENR was unsuccessful in obtai ning the National Park Services’ spreadsheet from the internet and was unabl e to compare the numbers.

DENR based its BART determination on a case- by-case basis taking into consideration the technology available, the costs of compliance, the energy and non-air quality environmental impacts of compliance, any pollu tion control equipment in use or in existence at the source, the remaining useful life of th e source, and the degree of improvement in visibility which may reasonably be anticipated to result from th e use of such technology. As noted one of the consideration is the improvement in visibility. Based on the visibility modeling, there was no discernable difference between installing a wet or dry flue gas desu lfurization system.

In making its BART determination, DENR review ed the modeling results and in some cases the wet flue gas desulfurization system would cause a higher visibility impact than the dry flue gas desulfurization system. Just as the modeling shows in some other cases the dry flue gas desulfurization system would cause a higher visibility impact than a wet flue gas desulfurization system. After taking everything into consider ation, DENR determined a dry flue gas desulfurization system represented BART.

15. The Sierra Club states DENR and Otter Tail Power Company did not fully evaluate the environmental impacts of a wet scrubber versus a dry scrubber. Specifically, they mention a wet scrubber will provide lower sulfur dioxide emission rates which will be needed for the effective removal of carbon dioxide from the ga s stream once it is requ ired; greatly improve the removal of hydrogen chloride and hydrogen fluoride; significantly remove arsenic, beryllium, cadmium, chromium, lead, mangane se, and mercury from flue gas; lower particulate matter 2.5 microns indiameter or less concen trations; and decrease the methylization of mercury.

Response: As defined in 40 CFR § 51.301, BART is established on a case-by-case basis taking into consideration the te chnology available, the costs of compliance, the energy and non-air quality environmental impacts of compliance, any pollution control equipment in use or in existence at the source, the remaining useful life of the sour ce, and the degree of improvement in visibility which may reasonably be anticipated to result from the use of such technology.

There are advantages and disadvantages to ope rating a wet and dry flue gas desulfurization system. The Sierra Club identifies what it be lieves to be advantages of a wet flue gas desulfurization system but do notidentify the disadvantages of a wet flue gas desulfurization system or the advantages of a dry flue gas desulfurization system.13 

### The Sierra Club cites a letter from Alstom to Duke Energy and testing data from the WYGEN II facility in Wyoming as documentation that a wet scrubber is better at reducing hydrogen chloride and hydrogen fluoride emi ssions. The hydrogen chloride and hydrogen fluoride emission rates for both a wet scrubber and a dry scrubber are dependent upon several factors, which include the type of coal, boiler design, inlet concentrations , etc. These factors are innately important when trying to compar e control efficiencies. Unfortunately, DENR did not receive the exhibits th e Sierra Club cites and is unable to locate these specific documents. Therefore, DENR was unable to de termine how the efficiencies cited by the Sierra Club were derived.

The Institute of Clean Air Companies webpage cited by the Sierra Club also specifies the following: “According to the EPA and others, both wet and dry scrubbers have been shown to reduce HCl emissions by 95% and more...Oth ers have reported ranges of 87-94% removal of chlorine and 43-97% removal of fluorine by bo th wet and dry scrubbers.” As indicated by the Sierra Club and the documents cited, botha wet scrubber and dry scrubber will reduce hydrogen chloride and hydrogen fluoride emissions , which notes the two control options are beneficial in reducing hydrogen ch loride and hydrogen fluoride.

The Sierra Club also cites the Institute of Clean Air Companies as specifying that a wet scrubber “significantly remove arsenic, bery llium, cadmium, chromium, lead, manganese, and mercury from flue gas.” In reviewing th e cited webpage, DENR c ould not locate what was classified as “significant,” or what type of coal was being burned in the system being referenced.

The emission rates of heavy metals are dependentupon several factors, such as the type of coal being burned. For example, mercury is pres ent in coal in trace amounts. When coal is burned, the mercury is found in the gas stream inseveral forms. Mercury is volatilized and converted to elemental mercury vapor in the hightemperature regions of a coal-fired boiler. As the gas stream cools, a series of comple x reactions begin to c onvert a portion of the elemental mercury into ionic mercury compounds and particulate mercury.

This partitioning of a portion of the elemental mercury into ionic mercury and particulate mercury is known as mercury speciation, whic h can have considerable influence on the selection of mercury control approaches. In ge neral, the majority of gaseous mercury in bituminous coal-fired boilers is ionic mercury. On the other hand, the majority of gaseous mercury in subbituminous and lignite fired boilers is elemental mercury.

To complicate the mercury speciation, the type of coal burned, the chlo rine content of the coal, fly ash content (unburned coal), sulfur trioxide, and wa ter concentrations of the gas stream appear to impact the mercury reactions and chemistry. The mercury chemistry is important because the particulate mercury may be captured and controlled by a particulate matter control device such as a baghouse but ionic mercury is captured and controlled more efficiently by a wet scrubber system. The hardest to capture and control with existing technology is elemental mercury. Therefore, bei ng able to convert elemental mercury to one of the other two forms is esse ntial in capturing a high percenta ge of the mercury emissions.14 

### Regardless of the technology both a wet scrubbe r and dry scrubber are expected to reduce mercury emissions.

Other advantages identified in Otter Tail Powe r Company’s BART analysis are 1) a dry flue gas desulfurization system generates a dry byproduct which can be handled with conventional ash handling systems which is not available to a wet flue gas desulfurization system, 2) the dry flue gas desulfurization syst em does not have true “w et zone” so there is less corrosion issues and reduces the “exotic” co nstruction materials and 3) the dry flue gas desulfurization system also produces less acid aerosols such as sulfuric acid.

The BART determination is a cas e-by-case review that takes in to account several factors. After taking everything into consideration, DENRdetermined a dry flue gas desulfurization system represented BART.

16. The Sierra Club believes the BART analysis for nitrogen oxide is flawed because DENR failed to consider the level of control achie vable with the proposed selective catalytic reduction at Big Stone I. The Si erra Club indicates a selective catalytic reduction system is capable of achieving an addi tional 90% nitrogen oxide reduc tion. The Sierra Club reviewed recent selective catalyst reduc tion retrofits and states establishing BACT nitrogen oxide emission limits of 0.05 to 0.06 pounds per million Btu with at least one nitrogen oxide BACT emission limit as low as 0.035 pounds per milli on Btu. Because of this, the Sierra Club believes DENR must establish a lower nitrogen oxide BART emission limit.

Response: The response to this comment is alrea dy addressed in the response to Comment #2.

17. The Sierra Club states that DENR must lower its particulate matter BART emission limit of 0.012 pounds per million Btu to 0.010 pounds per million Btu or lower because baghouses can achieve much lower emission rates and permitting authorities have required lower limits as BACT. The Sierra Club cites the BACT limits in a permit for Plant Washington in Atlanta, Georgia that was issued April 8, 2010.

Response: The Sierra Club identifies one Prevention of Significant Deterioration (PSD) permit with a BACT particulate matter emission limit of 0.010 pounds per million Btu. DENR reviewed three of the permits the SierraClub mentioned in this comment that have opacity limits to determine what was used for BACT particulate matter emission limits. In the three permits, MidAmerican in Council Blu ffs, Iowa has a particulate matter limit of 0.027 pounds per million Btu (e.g., includes front and back half); Plum Point in Osceola, Arkansas has a particulate matter limit of 0.018 pounds per million Btu; and Desert Rock has a particulate matter limit of 0.010 pounds per million Btu and a total particulate matter 10 microns in diameter or less (PM10) emi ssion limit of 0.020 pounds per million Btus. It appears there is a range of BACT emission limit s that states and EPA have determined on a case-by-case basis.

In the December 11, 2006, application, Otter Tail Power Company proposed to replace the advanced hybrid particulate collector control system with the current day baghouse. In that15 

### application, Otter Tail Power Company noted that the baghouse would have a maximum filterable particulate matter emission rate of 0.012 pounds per million Btu of fuel heat input. In May 2009, Otter Tail Power Company conducte d a performance test on the baghouse. The test results noted an averag e filterable particul ate matter emission rate of 0.011 pounds per million Btu. DENR decision to establish a BART PM10 emission limit of 0.012 pounds per million Btu is based on a case-by-case basis and m eets the requirements to improve visibility at Class I areas.

18. The Sierra Club recommends DENR require Otter Tail Power Company to install a particulate matter continuous emission monitoring system or establish an opacity limit as an indicator of compliance. Sin ce Otter Tail Power Company alr eady has a continuous opacity monitoring system, the system can be used as an indicator of continuous compliance with the particulate matter BART emission limit. The Sie rra Club identified the following coal plants with stringent BACT opacity limits: 1) MidAmerican facility in Council Bluffs, Iowa (5%); 2) Plum Point facility in Osceola, Arkansas (10%); 3) Fort Howard (Fort James) Paper Company’s 500 megawatt coal-fired boiler in Wisc onsin (10%); 4) Desert Rock (10%).

Response: The Sierra Club provided examples of st ates which established Best Available Control Technology (BACT) limits for partic ulate matter and opac ity. In the case of MidAmerican in Council Bluffs, Iowa, the permit identifies a BACT opacity and particulate matter limit. However, compliance with the two limits are not related to each other. Compliance with the particulate matter limit is based on an annual stack test while the opacity limit is based on a continuous opacity m onitoring system. In the case of Plum Point in Osceola, Arkansas, compliance with the BACTparticulate matter limit is based on an annual stack test and compliance with th e opacity limit using a continuous opacity monitoring system. In the case of Desert Rock, compliance with the particulate matter BACT emission limit is based on annual stack tests and a particulate matter continuous monitoring system. However, for particulate matter 10 micr ons in diameter or less (PM10), compliance is based just on annual stack performance tests.

The BART determination is based on a case-by- case basis taking into co nsideration a variety of situations similar to how a BACT analys is is conducted. As you can see, one state and EPA based compliance with the particulate matt er and opacity limits separately while one state based compliance together. In the EPA cas e, EPA based compliance with the particulate matter emission limit on annual stack tests plus a particulate matter continuous emission monitoring system. In the case of PM10, EPA based compliance on annual stack tests. The BART particulate matter emission limits for Bi g Stone I are based on PM10. DENR agrees it has the authority to re quire a particulate matter continuous emission monitoring system. But like some states and EPA, DENR considers an annual stack test sufficient at this time to demonstrate compliance with the BART particulate matter limit.

DENR agrees it has the authority to establis h an opacity limit. However, establishing an opacity limit is at the reasonable discretion of the permitting authority based on its case-bycase analysis of the facility. DENR believe s the PM10 BART emission limits and annual stack performance test are adequate to meet the requirements to improve visibility at Class I

areas.16 

### 19. The Sierra Club states there should be no exemptions from BART emission limits during startup and shutdown periods. The Sierra Club bases this on EPA’s BART Guidelines which state the BART emission limits must be met on a continuous basis pursuant to section 302(k) of the Clean Air Act. Startup and shutdown are part of the normal operations of a power plant like Big Stone, and the emissions during startup and shutdown impact visibility and regional haze. So DENR’s proposed BART limits must in clude periods of startup and shutdown. The Sierra Club also brought up that during the 2008 contested case hearing for the Big Stone II permit, Otter Tail Power Company’s Terry Grau mann made clear in his testimony that Otter Tail Power Company was not requesting exempti ons from emission limits during periods of startup and shutdown and Otter Tail Power Company’s Mark Ro lfes indicated the pollution controls would operate duri ng startup and shutdown.

Response: As outlined in Comment #3, DENR is not exempting Otter Tail Power Company’s Big Stone I facility from BART emission limits during periods of startup and shutdown. Just because there is no startup and shutdown emission limit in pounds per million Btu does not mean DENR exempted the Big Stone I facility from a BART emission limit during startup and shutdown. On the contrary, DENR established a pound per hour emission limit for particulate mater, sulfur dioxide, and nitrogen oxide to represent a BART emission limit during normal operations, including startup and shutdown. The pounds per hour limit is based on the maximum capacity of the unit and the pounds per million Btu BART emission limit. In addition, the pounds per hour BART emission limit was used in the modeling analysis to demonstrate Otter Tail Power Comp any was not causing visibility impairment in a Class I area.

During the public hearing on South Dakota’s Regional Haze State Implementation Plan and associated rules, the Board of Minerals and Environment revised the particulate pounds per million Btus limit to cover all operations including startup and shutdown based on previous testimony from Otter Tail Power Company that the baghouse would be in operation prior to starting up the boiler and could meet the pounds per million Btus hour limit even during startup and shutdown.

20. The Sierra Club indicates the state’s regul ation under ARSD 74:36: 21:06-09 must identify Big Stone I as the source subject to these emission limits to ensure enforceability of the BART limits.

Response: In developing our rules, DENR consults with our Legislativ e Research Council, which approves the proposed state rules for form, style, and lega lity. The Legislative Research Council informed DENR that South Dakota has as part of its Constitution a clause that states private and special laws are prohi bited. This may be found in Constitution 3-23 – Private and Special Laws Prohibited. The stat e constitution states that “In all other cases where a general law can be applicable no speci al law shall be enacted.” The Legislative Research Council required DENR to word the language in a form which applies only to Otter Tail Power Company’s Big Stone I facility and meets the requirements in South Dakota’s Constitution.17 

### 21. The Sierra Club recommends the state’s BART regulation should require compliance with the particulate matter BART emission limit nowgiven Big Stone has already installed a fabric filter baghouse and can co mply with the BART limit now.

Response: As Otter Tail Power Company’s BART submittal notes, a dry flue gas desulfurization system must belocated upstream of the partic ulate control devices. Two of the issues associated with adding this system are: 1) can the existing particulate control device handle the particulate loading; and 2) wi ll the existing particulate control device still be able to meet its BART emission limits. As the Sierra Club mentions in its comments, the federal regulations under 40 CFR §308(1)(e)(1)(i v), requires each source subject to BART to install BART as expeditiously as practicable, but no later than 5 years from EPA’s approval of the implementation plan revision. Since demo nstrating compliance withthe sulfur dioxide BART affects the compliance demonstration for particulate matter, maintaining the compliance periods as allowed under federal re gulations is considered appropriate and reasonable.



### 4.0 Otter Tail Power Co mpany’s Comments

22. Otter Tail Power Company suggested a clarif ication revision to ARSD 74:36:21:11. The revision moves “in accordance with§ 74:36:20” after “application” instead of at the end of the sentence to clarify the application is to be processed through the cons truction permit program.
Response: DENR agreed and revised AR SD 74:36:21:11 appropriately.

# Appendix A

Comment Letters Received

During Public Notice Period for

South Dakota’s Draft Regional Haze ProgramUNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGIONS

Ref: 8P

- AR

Brian Gustafson. Administrator Air Quality Program 1595 Wynkoop Street DENVER, CO 80202·1129 Phone 800-227-8917 hltp : /Iwww

. epa

. gov/region08



### SEP I 3 ZO In



### South Dakota Department of Environment and Natural Resources 523 E ast Capitol Avenue Pierre
, SD 57501-3182



### Dear Mr. Gustafson: R E : EPA Preliminary C omments on August 2010 Draft Regional Haze State Implementation Plan (Public C omment Version)



### EPA has completed a preliminary review of South Dakota's August 20 IO draft Regional Haze State Implementation Plan (SIP). Our comments and questions are detailed in Enclosures 1 

### through 3 to this letter.

We understand that you intend to 

### consider all comments received on this public comment version of the Regional Haze SIP prior to finalizing and adopting the documents for submission
to EPA. We emphasize that we will only reach a final conclusion, and perform our complete review, regarding the adequacy of South Dakota ' s Regional Haze SIP when we act on the South Dakota Regional Haze SIP revision through our own public notice and comment rulemaking.

We look forward to continued communications to resolve the remaining concerns with the Regional Haze SIP. If you have any questions on E PA 's comments, p l ease contact me a t 303

- 312

- 6434, or your stafT may contact Gail Fallon at 303

- 312

- 6281.

E nclosures

cc: John Bunyak, NPS Sandra Silva
, USFWS Thomas Dzomba, USFS Sincerely,



# ,**~47#id:4:,j-=-** L--t... 1iIlie A. Videtich
, Director Air Program

### ENCLOSURE I

EPA Region 8 Preliminary Comments on the August 2010 Draft Regional Haze SIP 

### (Public Comment Version)

Summary of Major Concerns

- (see detailed comments for more information):

• Many comments from our March 12,2010 letter were not sufficiently addressed

. All of the detailed preliminary comments below pertain to those previous comments and provide add it i ona l in fo rmation on areas which arc still problematic.



### • Insufficient details were provided on how the best available retrofit technology (BART)

em i ssion limits 

### will be made enforceable as a practical matter. Se e comments #1, #4 and # 7 below.

• No identification of the number of years to reach natural conditions was provided as required when the Reasonable Progress Goal is less tha n the Uniform Rate of Progress. Sce comments #5 and #8 below.

• No four

- factor Reasonable Progress analysis was completed. See comment #6 below.

• Recommcnd reviewing ARSO regulation references for typographical errors throughout both the response to comments (for future clar i ty in the SIP record) as well as the main SIP document. T here arc numerous errors likely due to the addition of 74:36:21 :06, which changed the numbering of the subsequent chapters.



### Detailed Comments:

I. Executive Summary. pp. vii-viii : Additional details are necessary to ensure that BART emission limits will 

### be enforceable as a practical matter. The BART emission limits, compliance schedules, monitoring, recordkeeping
, and compliance determ i ning methods for Big Stone I must be specified in the text of the Regional Haze SIP or in a permit that is incorporated into the SIP. For example, in your response to our comment on this issue (#1 and #39 from Appendix D), you relied heavily on requirements of your Title V program (ARSO 74:36:05). As this program is not part of the SIP, our concerns with reliance on the Ti tle V program in this area remain. T wo examplcs of all the various elements of adequate language that were coordinated with the States of Wyoming and Colorado are provided in E nclosures 2 and 3 for reference.

2. Table 6

- 9, p. 91: Footnote 5 references a 1999 E PA Technical Bulletin on NQ'( controls as justification for the 35%-90% control efficiency range for the top three options. The large
range in EPA's bulletin is due to in clus i on of selective catalytic reduction (SCR), selective

non

- catalytic reduction (SNCR), and fuel reburning for wet

- bottom boilers. It is well documented that SCR achieves the high end of the range. The E PA bulletin also lists a 30%

- 70% control efficiency for a group of tempera tu re-redu cing controls, incl uding over-fire air. Therefore, the proposed BART determination ofSCR plus separated over

- fire air (SOFA) should be better than the 90% control efficiency of SCR alone. In your response to thi s comment (#31 from Appendix D), there was no di sc ussi on regarding how the addition ofSOFA would not contribute to a better than 90% contro l efficiency. T his needs to be addressed.

3. Section 6.3.5. BART Emissions Limits for Big Stone I
, pp. 99

- 103: In order for EPA to entertain the establishment of separate BART limits for startup and shutdown conditions, an adequate record showing that the otherwise applicable limits are not achievable and that the separate startup/shutdown limits constitute BART is required as justification. Your response to thi s comment (#38 from Appendix D) does not provide sufficient justification for establishing the separate startup/shutdown limits. We continue to offer to work closely with
you to establish appropriate 30

- day rolling average emissions limit s for particulate matter, sulfur dioxide and nitrogen oxides tha t allow for startup/shutdown conditions to help ensure SIP approvability.

4. Section 6.4, BART Requirements, p. 103: According to your proposed revisions to the South Dakota Administrative Rules, C hapter 74:36:21: 1 0
, a pennit modification will be required for your BART detennination on Otter Tail's B ig Stone 

### I. Without seeing the details of such pennit, it i s difficult to determine whether this section of the SIP adequately addresses requirements for enforceability, including appropriate averaging times, compliance verification procedures
, and recordkeeping and reporting requirements
, and proper operation and maintenance procedures

. As noted in comment # 1 above, these requirements must be
spec ified either in the text of the Regional Haze SIP or in a permit tha t is incorporated into the SIP. Your response to this comment (# 39 from Append i x D) relied heavily on your T itle V program which is not part of the SIP and does not fully address this is sue.

5. Section 

### 7.2.1. Breakdown of CMAQ Modeling Results, pp. 106

- 107: Your response (#47 from Append ix D) addressed most of our questions with one exception. The SIP must provide the number of years necessary to reach natural conditions, as required by 40 CFR SI.308(d)( 1 )(ii) when the reasonable progress goal (RPG) is less than the uniform rate of
progress (URP). While you state in Section 10.3 on page 127 that you believe Sou th Dakota

can still meet the reasonable progress goals and achieve natural conditions by 2064, the data,

as currently presented, does not support this proposed conclusion.

6. Section 7

. 2.2, Four Factor Analysis, pp. 107-109: DENR's detcnnination that a four-factor analysis is not warranted a t this time is not acceptable. A four-factor analysis must be completed in establishing the RPGs for Class I areas impacted by South Dakota emissions, as well as in justifying a RPG that is less than URP

. Despite your response to this comment (#49 from Appendix D) regarding minimal contribution from point sources to visibility impainnent
, a four-factor analysis is required to justify this conclusion. Again
, we s u ggest looking for additional reductions from GCC Daeotah, Ben French
, and Pete Lien as well as the potential from the close proximity of Rapid C ity to Badlands.

7. Section 8.5.6, Enforcea ble Em i ssion Limits and Cont rol Measures, p. 116: Though this section was slightly reworded per your response ( # 56 from Appendix D), your intention to establish the Big Stone I BART limits an d control measure requirements in an air quality permit requires the pennits' inc orporation into the SIP. The South Dakota draft construction



### 2

### permit program regulations are currently under review by our office. U ntil this has been approved into the SIP
, it will not be appropriate to rely upon the program for your BART
perm its.

8. Section to.3
, Public Input, pp. 126

- 127: As noted in comment #5 above, the SIP must provide the public with a calculation of the number of years required to reach natural conditions i f the RPG provides a slower rate of improvement than that needed to attain natural conditions by 2064 per 40 eFR 

### SIJ08(d)( I )(ii). We understand your concerns regarding assumptions for other states included in the WRAP analysis; however
, this SIP
must include your best estimate of number of years to reach natural c o nditions with the proposed RPGs. Though this section was slightly reworded per your response (#48 from Appendix D)
, the number of years is still lacking.

9

. ARSD Chapter 74:36:21: 12, Federal Land Manager Notification and Review: Your response (#65 from Appendix D) did not adequately address our concern related to FLM consultation

on BAR T permit reviews. As required by the Regional Haze Rule, the Federal Land Managers must be provided a 60

- day consultation period prior to any p ublic hearing on the Regional Haze SIP

. Since a BAR T permit is an integral part of the Regional Haze SIP, this 60

- day consultation period must extend to FLM BART pennit review as well. In addition, since any BART permit must 

### be incorporated into the Regional Haze SIP, the**3~ day**  

### public notice for the SIP needs to identify the inclusion of any BART permits.



### 3

### ENCLOSURE 2

EPA RegionS

- Preliminary Comments on Wyoming's Regional Haze Monitoring. Recordkeeping, and Reporting**Requiremenl~** (MRR)

Please note: This document is d i vided in t o two sections

. The first section provides
comments on the current MRR language in the State's Regional Haze SIP. We have included
comments (in italics) and in som e instances suggested language. The second se c tion of this documenl contains i nfonnation on SIP MRR elements that need to be added to the SIP and suggested language

.
I. Current SIP Language for Pacificorp Unit

The State of Wyoming considers the control effectiveness of a control techno logy to be cquivalem to the BART -det e nnin c d penn it limit <1\ indir.:ated 111 Tallie XX hclov.

. The Slate ,hllUIJ challW; the pn:q;d!Dg**~cntcncc** to n.:ad "The State (If Wyoming**nlm,isJer~** the BARl determined rx.'nniL limit ttl he euuivalentt" the t.:ontnll ctTccti\ene"', of a (,:Iliuml tedmulu)!\ The limit is based on continuous compliance when the contwl equipment is well maintained and operated in a manner consistent with good air pollution control pmctices for minimizing emissions

. flit' SIP mil 1/ h"/iI CI/r /hlll/he SmUll' 11/1/**(fl/l~** 1111 JJANfJil all limn LliT lillie ill Snliol! 1\:, h!'lml'!

rubl,' XX

.. Unit-by-unit BART determinations for**NO~** and PMlPMlo :

Un i t Pollutant Comrol Type l bfMMBtu Ibfhr tpy J NO" LNB/OFA 0.28 nil· day 784 em·day 3.434 rolling) rolling) PMfPMI!),,, Fabric Hlter 0.015 42.1 IH4 4 NO, LNBfOFA 0.15 OO-day 615130-day 2.694 rolling) rolling) PMlPMI!)'al Fabric Filter 0.015 61.5 269

III. Expeditious Installation and Operation of BART**""i~ ~"lIk**  1/1'1'(/1 til /IIdiw/(' ill Iltil ItTljell! IlIlIl III(' HARr dl'/(,r/1111/11/1II1/ i

, 1 1l!'l11'IIt/OIl IlII IlfJllrO\ /1/ hi' 1:"1'. \. 

### nit' S'I/It' 1//11\1 (//\0 {lrm'lell' III/Ilk hi 11"111('1, rill' IIII/ra IIn'dl (111m/all (lIId t '/1//111/\ 1IIIIi till' Il. 'Sf limil.1 I/0' lUll lit,' l"t'IIIl/rt'I1N'nt til ill l'lltll (11f' "/IIlirml'llf_ Pa (Iw /I, lSf (.illiddi/lt" I \o/lrn'.1 .1//lmM ill\(/I/l cllllfro!1 CI\ t'.lflnJi/lOu,l/) til IIrIU-rinlblr hllllW lu(n
IIIWI/ii/' Win fllit"!" EP

.. \ t/lmrow{ of'lht' SIP_ The State of Wyoming cropms;" that PacifiCorp install new low NOx burners with advanced OFA on Units 3**and~ .**  in accordance with the Division ' s BART dctennination
, and conduct the required initial perfonnance tests

no later than December 31. 2010 and December 3 1,2009, respectively

. The State of Wyoming nropll"C' that PacifiCorp install new full-s c ale fabric filters on Units 3 and 4. in accordance with the Division's BART detcnnination. and conduct the initial perfonnancc
tests required no laterthan De c ember 31, 2010 and Decemb e r 3 L 2 012

. respectively. For 111'rlinm(/IIII' (I'Hill!!. flrl' mmfimb/r 

### [P. \ (('If mcrltmJ mil\! he If/fL'ilit,d 1I101/I! with 1111' In'tlllell('\' of '('Hill!! alit! olilef felt'I'(JII( mtflf/1/(ui(m.IV. Proper Maintl!nance and Operation of Control Equipment

\t illl**urllC~** ilftcr Ihe cmnpl1il1ll'l! dcadlLnc**~rc(llictlllllbuccih ~di()nll.**  Ihe O\\nCr/opcralnr Hf cal:h BART umt ..,hall maintalll, l:alibr.llt!. ilnd operall! il Cl:MS, in lull ctllllphancl!

..... lIh the**rcyuircmct1hJ~~ynl.titl·!Q..C~~~** part 7'), 10**al,'f~r.!t<;lLl1lca~~n;** SOl. NOx, diluent**jCO~** or o,!, ilnd**:-.I"C~ I!a~**  \olulllctric nnw mtl! from each BART unit. Thc**('I·,.~tS_-".b<lJI ~** **1~t:.,.I.!!.I_IIt.:".!lJuiIiC compliallc~**  wlth Ill£. SO:!**an~l N()~_B:\R**  T Cllll""'l\lIl Ijllllh_fuLl':!.\,;.!lBART ..!!!!!L

111 uelcflllll1l1lg compliancc \.\ ith the 

## sen and NOx HART IIml"'. all pcrilxh {If cmi

......**lOn~**

... hall he**In~Jllticlli..in!:=!!Jdi~hlnulh, ~huldnwn**  ... , l!l1lcrgenl.'il''',**;1I!lUJ~:~!f~~I!lJ.!£l.Il'>,**
S()TR: t'er !'e('li(}tI 3fJZOd II{tJre etA. B.tR" limits**"II/_~t** he met CO",i,llwlI'ilr. rhe HART limits sectioll o{the 5i/P Ileed tu ,"tate tlral tire RART**/illlir,~** apnlv at**allliml'~,** illL'iudim! "erioti,\ o(SS,'/.

The State of Wy o ming**rrO(ltl~l'~** I hat PacifiCorp conduct initial**NO~** perfonnance tesls on Units 3 and 4 after the inslallation of low NOx burners and advanced OFA. within 30 days of achiev i ng a maximum design rate, but not later than 90 days following init ial start-up, I'"or ualim11l1111 I II'I/ill!! (11(' IllJllIiC"llh/e f.P \ It's/lIIeth"d I1Im( he \/lnirh'd (11ol/l! \l'llh 11/1'

""/'(/111"111') III fflflll!! Ill/sf olha rril'\',l//f l/I(or/1ldfio/l.

(h\**ner/llrel~tJO[** -JHII**~uhmit n:ron~**  of all\' rcuuir!!ti pcrfnnnanr.:!!**:-.tit~,,"** le'>l**~** ,li!r!\ll h**\~Ithln** 6() r.:alcndar t.!a

..... aJh:r n'll1pll!lion of the Il!'>t, If a maximum design rate is not achieved within (,)0 days of slart-up. the AQD Administrato r may require tcsting be done al the rate achieved and again when a maximum rate is achieved_ {1,1' SlIIll' ,lIl1l/ltl !"I'fllt/n'

'/1111 I I" till' IIrn'WI/I \I 1111'1/1" II'ill!

. 1/1t/"", I 

### r iI max imul1l i.il!:-.i<lll mit' I..; nnl .,chi\.!, l'tI ",Ith,n 1)0**da\~** III**~tan-up,** the AQI)**:\dmini~trilwr** ,>hall require**tC~ling** he done ;tllhe r,IIC ih:hIC\cd ,Uld 'Igain \1.1\1,,'11 a lllirl>imUIIl ralC i'> adllc\ed. A tesl protocol shall be submiued for Division approval prior 10 testing and a written rcpon of the test results shall be submiucd
to the Division

. Testing required by the WAQSR Chapter 6, Section 3 operating pennit '> Ilr tllllwlll''>tIIlL**r~qLllrcd** h\ \\'

.. \QSR t 'halll!!! h SCI.·lio/l ! I\r Sl'CI1UIl'" may be submitted to satisfy the testing required

. fhl' "rior \1'1I1l'11n' i,1 II rdi'I"l'IIn' /0 till Ihl' (lOadlilll! "ama rn!/I/111ioll.\. fhi.1 1/1,(,111 fo ht' rl'{I/III"I'd \l'ith (/ ortH'i,\;Olllhlll \\,;1/ Itt' i" IIIl' SIP,

The State of Wynming nrorn)<;,c<;, that PacifiCorp conduct initial PM/PM I 0 perfonnance
tests on Units 3 itnd 4 after the installation of fabric filters within 30 days of ach i eving a maximum desig n rate, but not l ater than 90 days following initial start-up, For palilf}!lfill/"l' Inl/II!!. Ihl' Im"ji.!jlhll .rPr) 1/'11 /lIl'lhod 1/1/1.\/ ht, ,\I'I'I';li("l1 II/Oil!! wilh Ihl In'wlt'lI('\' 

## or 1('ltim! Will oIlier rl'i(,!,(1II1 ill{orllltlfio//, It " m<l.\Illlum**dc~'!.i.&!! Gtl~!.':!Jl!--'UIr.:hIC\**  cd '"' ithin YO**dil\:~** 01 ,>tart-up. the AOn :\dmini'>tralo[

... hall rcuuin:**Ic~llm;** hc done al tht' rate al'hie\ cd anti it"ain**\~** hell.i!**1ll,I~iIllUm** ritlc**.i~.acbj~_'-t'~,J2~\-ncr/opcralor ~I!illl,>uhmit**  repon

... Ill' .lIly rClluirl'd ocrfnrmalKt' stac,," tC<;,h for paniculutc mailer. within 00 calendar dav

... after I.·omn!ction

Ilf the tt;

... t, In**"d~jtion 1.!!.,tIll~!J<l1** **"'Ia~k t!!\I~,** **1)~}l~r/(~r;~I.!.lr** "hal!**!lH~[lHI!f...p;m_~!J!,ttt~ ClTli"~lIlrl'>**  for**r.:olllrlian~c** w ilh tht' BART clllls

... ion Ii IIlII'> in m:wn.larKc**\~** itll thc**~,,"I~** ( IlUpilall"S; ,\"urUlKC "'hll11hlnJll.! (CAM! plan Yl'\do! ,J anJ IppOl\,l'd In**:(~lrd,II\(':** \\ ilh 

### ·m (TR 

### pan M. A test protocol shall be submiued fo r Div i sion approval prior to testing and a written report of the test results shall be submiued to th\! Division, Testing requ i red by t h e WAQSR Chapter 6, Section 3 operating permit may be submitted to s<l tisfy the testing required.**I~kll'** Ihe pnnr 'I.'nl 'lrr lll!'.b...d.!l rl'lh:

... 10.11. lhl ')PCratlll).; J}C.mil rl.;u!...L[IOn", l1u-.ncI.'J" [n be replaced "itll a pro", Itln that \\ill be III 

## 1'_ sU'

The State of Wyoming**prn!lll~'** performance tests and com p l i ance with the BART limits for**NO~** be determined for Units 3 and 4 

### using a continuous em i ssions monitoring system (CEMS). clll1,j

.. jellt

.... uh Ih\' pnwi"lun" in Iht-. "ccUlm certi fied in accordanc e with 40 CFR part 60 and dutu from the CEMS**~hall** meet th\' requi re nwnh !!1 40 CFR part 75. Th e State of Wyuming**~** :..... performance tests for compHance with the BART limits lo r PMIPM 10 conducted annually following 40 CFR 60.46 and EPA Reference Test Metho d s 1 -4 and 5. 

### fJ',

. .l**1!I~l** III ill II ,I fP,\ .\/t-I}wd), 5/J. 50. II! J .1'.\ (//l(Irflmilli • ..ll! 

### I.'} erR (Jllrl**~m** 

# ,\

\ ,I ,h!ll '11 ,I ,f 

### III! \' ,un

.. "'Hh**~'jk:h** run .It :"t 120 I!!!!!J III til f 'n .lIlll .Ich run

Il.**~** m.:')1 flOor",

.. tanJ;Jru ,:uhic fecI. Testing r equired by the WAQSR Chapter 6. Section 3 operating pennit may Ix submitted to satisfy the testing requ i re d. Ikktc [hl

Ir III nt, I h.**I~I_K '-'rt!n~t!_I()**  all the 

## "r aim!! QCmH! rc 'ui ItlHn,,-,J hi'**lic~d."** [ulll'

1\,'**~** hAl....o!' 'iun that ",III "'-: In**jhe_SIl~**

II. SIP E l ements that must be added:

• I**~II'** lilli" 'IX,\'I" the J.\e"u!l!li! lim, II the**~t.!J.i!u, ~**  .. Iun limih ulI:luJJIIg )1\1

• SIP must contain monitoring and compliance detcmlination speCifics. 

### I See Section at the end of this analysis J

• T he SIP must also contain the specific recordkccping and reporting n.'quirements, (See Footnote I lor suggested language)

• T he SIP must explicitly state those records the sources are required to keep to assess compliance for the time frame specified in the SIP, Records must be commensurate wilh regulatory requirements. Records must be available for ex amina t ion upon request. (See Footnote I for suggested language)

• The S IP must give reporting schedules and reponing formats,

• Recordkceping

o The recordkeeping must be required such that failure to d o so would be a scpamte violation.

o Preferably. the SIP should specify that records must be kept for at least five years '

I**Sugge ~tcd**  l anguage. Owner/oper,l1or sh:!11 maintain the foUowin : re co rds for at**[ea.~t** [ i v( Y(itfS. and thc:y
must**~** ava il ahk on requesl: 1. All CEMS data. Slack tcst dala. and data coll(Cted pursuant 10 the C AM plan. i n cluding the date. place, and tin'K! of sampling. m(asurement. or tcsting: parameters samp l ed. mca..urcd. or test(l[ and results: lh( company. entity. or jl(rson Ihat performed the**te.~ ing,**  i f applicab l e: and any lield dam sheets from testing

.• The SIP should require periodic rcporting. 2

• The S IP should require timely deviation reporting. H

• Include definitio n s for: ( I ) boiler openlting da/; (2) CEMS 6 ; and (3) substitute hourly emission rates 7

Suggested language for monitoring and compliance determinations: I. Pounds Per Hour And Tons Per Year L imits

For any hour in which fuel is combusted in the boiler. owner/opercltor shall calculate hourly S02 and NOx emissions in pounds at the CEMS in accordance with the monitoring procedures and requirements of 40 CFR part 75. In calculating hourly mass emissions and em i ssions nltes, owner/operator shall use the conversion procedures specified in 40 CFR part 75. Appendix F. For any hour that valid. quality assured CEMS data are unavailable, emissions shall be calculated in accordance with the missing da ta substitution procedures in 

### 40 CFR part 75

. subpart D. These hourly values shall then be used to determine compliance in accordance with Ihe particular limit's averaging period,

as foHows:

2, Records of quality us.

.. urance and quality control activities fo r emissions measuring**system~** including. but notlimjtoo to. any records required by 40 CFR Pan 75. J. Records of all majo r maintenunce activities conducted on em i ssion units, air pollution control equipment. a n d CEMS. 4, Any other records**requir~d** by 4{) CFR pan$ 64 and 75.**~** Suggest ed language · OWller/openllor s hall also su bmit quanerly CEMS performance rcpons. to include dates and dur.llion of each period during which the CEMS was inoperative (ellcepl for zero and span adjustments and calibration checks), rea,;on{sJ why the CEMS was i noperative and steps taken to prevent

recurrence. any periods for which missing data substitution procedures were used. any CEMS repairs or adjustments. and res ult s of any CEMS performance tests re4uired by 40 CFR pan 15 (Relative Accuracy T est Audits, Relative Accuracy Audits. and Cylinder Gas Audits)

.

.l Su gg ested language

. Owner/operator shall submit quanerly ellccss emissions repuns no late r than the ': W

Lh day following the e nd of each calendar quaner.**Ellces.~ emi~sions**  me:IOS emissio ns that exceed the**emission.~** l imits specified in

_ _ above.

,**Sugge ~ted**  language· Owner/operator sh:1I1 also submit quanerly rcpons uf any exceedances or excursions under the approved CA:vI pl an, and steps taken to correct the excet..'<iances or cxcur:;itlns. in accordance with 4() crR 64.lJ(a).**~** Define boiler operating day as "any 2J.

· hour period between J 2:00 midnight and the following midnight during which any fud is COl11busted at any time at the s tea m generating uni!." See. 4() CFR pan 51. Appt:ndill y, section V.**"Sugge.~ted** language· Continuous**emis.~ion** monitoring system" or ''CEMS'' means the equipment requi red by [ Ih is Sttlio n ll o sample. anaIY7.e, measure

. and provide. by means of readings recorded at least**un~'e** every 15 minutes !using an automated data acqui s ition and h andling system (DAHSj). a pcnnancnt record of SO:! or NOli**emis.~i on** **.** other pollutant emissions. diluent. or stack gas volumetric flow rate

.

7 Suggestoo language

. "Substitute hourly emission rates" or "substitute hourly emiss i on values" mcans any hourly emission nues (l r values calculated in accordance with the missing data substitutiun pmcedures of 40 CFR pan 75

. .**~ubp.1tt** D, wh ere valid. quality a

.. sured CEMS dat a for that hour are unavailable.a. Pound

.. Per Hour Limit". If the limit Un T able _(cross-ref BART limit table)Jis e)(prcssed as a Ib/hr limit, owner/operato r shall calculate average Iblhr emis.

.. ions

over the appropriate averaging period. as follows:

i. Limits with a 30-day averaging period : Emissions shall be calculated on a 30-day rolling average basis. At the end of each boiler openlting day, owner/operator shall calculate a new 30

- day rolling averJge emission nne in Iblhr from the arithmetic
average of all valid and substitute hourly emission values from t he CEMS for the most
recent JO boiler operating days

ii. Limits with a 12-month averaging period: emissi ons shaH be calculated

on a 12-month rolling average basis. At the end of each month. owner/operator shall calculate a new 1 2-month rolling avcmge emission rate in Iblhr from the arithmetic
average of all valid and substitute hourly emission values from the CEMS for the mos t rt..'Ccnt 12 months.

h. Tons Per Year Limits. If the limit [in Table _(cruss-ref BART limit table)lis c)(presscd as a tons/yr limit, rolling 1 2

- month lo ta l. total emissions in tons/yr shall be calcuillted on a 12-month rolling basis. At the end of cach month

. owner/operator shall calculate a new 12-month emissions total. in tons/yr, using all vnlid and substitute hourly emis s ion valw!s from th e CEMS for the most re<..'Cnt 12 months.

2. Pounds P er Million Btu Limits

For any hour in w h ich rud is combusted in the boiler. o wner/operator shall calculate hourly average 502 and NO)( eoncentrJtions in pounds per million Btu at the CEM5 in u(,'Cordance with the requirements of 40 CFR pan 75. For any hour that val id. quality assured CEMS data are unavailable, emissions shall be calculated in accordance with the missing data substitution procedures in 40 CFR part 75 subpart D. These hourly
averages shall then be used to detennine compliance in accordance wi th the particular limit's averaging period. as follows:

a. Limi ts with a 3-hour averaging period: emissions s hal l be calculated on a 3-hour rolling avemge basis. At the end of each hour, owner/operator shall calcu l at e a new 3- hour average emission rate in IblMMBtu from the arithmetic averugc of the valid and substitute hourly emission ra tes from the CEMS for the most recent three hours.

b

. Limits with a 30-day averaging period: emissions sh.11I be calculated on a 30-day rolling average basis. At the end of each boiler operating day, owner/operator shall calculate a new JO

- day rolling average emission ra te in IblMMBtu from th e arithmetic averJge of all valid and substitute hourly emission mtcs from the CEMS for the most
recent 30 boiler operating days.

c. Limits with a 9O-day averaging period: emissions shall be calculated on a 9O

- day rolling avcmge basis. At the end of each boiler operating day. owner/opcrntor shallcalculate a new 90-day roUing av e rage emission ra te in Ib/MMBtu from the arithme ti c avemge of all valid and substitute hourly emission rates f rom the CEMS fo r the most
recent 90 boi l e r operat i ng days.

d. Limits with a 1 2-month avemging per iod: emissions shall he ca lc ulated on a 1 2

- month rolling average basis. At the end of each month, oW
, ner/operator shall calculate a

new 12-month rolling average! emission mtc in Ib/MMBtu from the arithmet i c avcmge of all valid and substitute hourl y emiss ion ra tes from the CEMS for the most recent 12 months.

e. Li mits w i th an annua l calendar averaging p eriod: em i ssions sha ll be calculated on

a calendar year bas i s. At the end of each ca l endar year, owner/operator shall calcu l a te a

new emissio n rate in Ib/MMBtu from the arithmetic average of all va l id and s ubstitute hourly emission rates from the C E MS for the preceding year

.ENCLOSURE 3

DRAFT COMPLIANCE DETERMINATION LANGUAGE FOR COLORADO BART LIMITS 

### 2111110

I. Monitoring, Recordkecping, and Reporting

A. Dctinitions

"BART unit" means any unit subject to a BART emission lim i t in Table

__ _

"Boiler operating day" means any twenty

- fouf-hour period between midnight and the following midnight during which any fuel is combustcd at any time in a BART unit.

"Cont inuous emission monitoring system " or "CEMS" means the equipment
requ ired by Ithi s section I to sample. analyze, measure, and provide
, by means of readings recorded at least once every J 5 minutes (using an automated data acquisition and handling system (DAHS)

. a permanent record ofS02 or NOx emissions, other 

### pollutant emissions, diluent, or stack gas volumetric flow ratc.

"Substitute hourly emission rates" or "substitute hourly emission values" means any hourly emission rates or values calculated in a ccord a nce with the missing data substitution procedures of 40 CFR part 75
, subpart D, where valid, quality assured CEMS data for that hour arc unavailable.

B. Monitoring/Compliance Determination: S02 and NOx BART Limits

At all times after the compliance deadline s pecified in 

### " specify sectionlJ
, the owner/operator of each BART unit shall maintain, calibrate, and operate a CEMS, in full compliance with the requirements found at 40 CFR part 75, to accurately measure S02, NOx, diluent, and stack gas volumetric flow rate from each BART unit. The CEMS shall be used to determine compliance with the S02 and NOx BART emission limits for each BART unit.

In determining compliance with the S02 and NOx BART limits. all periods of emissions shall be included, including startups, shutdowns, emergencies, and malfunctions.

NOTE: Per section 302(k) of the CAA, BART limits must be met continuously. The 

### BART limits section of the SIP and Reg. 3 need to state that the BART limits apply
at all times, including periods of SSM.

I. Pounds Per Hour And Tons Per Year Limits

For any hour in which fuel is combusted in the boiler
, owner/operator shall calculate hourly S02 and NOx emissions in pounds at the CEMS in accordance with the monitoring procedures and requirements of 40 CFR part 75. In calculating hourly mass

### emissions and emissions r ates , owner/operator shall use the conversion procedures
spe cified in 40 CFR part 75, Appendix F, For any hour that valid
, quality assured CEMS data are unavailable, emissions shall 

### be calculated in accordance with the m i ssing data substitution procedures in 40 CFR part 75
, subpart 

### D. These hourly values shall then be used to detennine compliance in accordance with the particular limit's averaging period,

as follows:

a. Pounds Per H our L imits. If the limit [in Table

_ (cross

- refBART limit table)Jis expressed as a Iblhr limit, owner/operator shall calcu la te ave r age Ib/hr emissions

over the appropriate averaging period
, as follows:

i. Limits with a 30-day averaging period: Emissions shall be calculated on a 3D

- day rolling average basis. At the end of each boiler operating day
, owner/operator shall calculate a new 3D

- day rolling average emission rate in Iblhr from the arithmetic
average of all valid and substitute hourly emiss i on values from the CEMS for the most recent 30 boiler operating days

ii. Limits with a 12-month averaging period: emissions shall be calculated

on a 12-month rolling average basis. At the end of each mon th, owner/operator shall calculate a new 12-month rolling average emission rate i n Iblhr from the arithmetic
average of all valid and substitute hourly emission values from the CEMS for the most recent 12 months.

b. Tons Per Year Limits

. If the limit lin Table

_ (cross

- ref BART limit table)Jis expressed as a tons/yr limit. rolling 12

- month total, total emissions in tonslyr shall be calculated on a 12-month rolling basis. At the end of each month

. owner/operator shall calculate a new 12

- month emissions total
, in tons/yr, using all valid and substitute hourly emission values from the CEMS for the most recent 12 months.

2. Pounds Per Million Btu L imits

For any hour in which fuel is combusted in the boiler, owner/operator shall calculate hourly average S02 and NOx concentrations in pounds per million Btu at the CEMS in accordance with the requirements of 40 CF R part 75. For any hour that valid
, quality assured CEMS data are unavailable
, emissions shall be calculated in accordance with the missing data substitution procedures in 4D CFR part 75
, subpart 

### D. These hourly
averages shall then be used to determine compliance in accordance with the particular limit's averaging period. as follows:

a. Limits with a 3

- hour averaging period: emissions shall be 

### calculated on a 3-hour rolling average basis. At the end of each hour, owner/operator shall calculate a new 3- hour average emission ra te in Ib/ MMBtu from the arithmetic average of the valid and substitute hourly emission rates from the CEMS for the most recent three hours.

b. Limits w ith a 30

- day averaging period: emissions shall be calculated on a 3D

- day rolling average basis. At t he end of each boiler operating day, owner/operator shall



### 2

### calculate a new 30 -day rolling average emission rate in IblMMBtu from the arithmetic
average of all valid and subst itute hourly emission rates from the CEMS for the most recent 30 boiler operating days.

c. Limits with a 90

- day averaging period: emissions shall be calculated on a 90

- day rolling average basis. At the end of each boiler operating day, owner/operator sha ll calculate a new 90 -d ay rolling average emission rate in Ib/MMBtu from the arithmetic
average of all valid and subs titu te hourly emission rates from the CEMS for the most recent 90 boiler operating days.

d

. Limits with a 12

- month avemging period: emissions shall be calculated on a 12

- month rolling average basis. At the end of each month, owne r /operato r sha ll calculate a

new 12

- month rolling average emission rate in Ib/MMB t u from the arithmetic average of all valid and substitu t e hourly emission rates from the CEMS for the most recent 1 2 months.

e. L imit s with an annual calendar averaging period: emissions shall be calculated on

a calendar year basis. At the end of each calendar year, owner/operator shall calculate a

new emission rate in Ib/MMBtu from the arithmet i c average of all valid and subs titu te hourly emission rates from the CEMS for the preceding year. IINeed to address bubbled units.1I

C. 

### Monitoring/Compliance Determination: Particulate BART Lim it s

I. EGU Particulate BART Limits.

Compliance with the particulate BART emission limi ts for each EGU BART unit shall be determined from annual performance stack tests. Within 60 days of the compliance deadline specified in
, and on at least an annual basis thereafter, the owner/operator of each EGU BART unit shall conduct a stack test on each unit to

measure particulate emissions using EPA Method 5
, 58, 5D
, or 17. as appropriate, in 40 CFR part 60, Appendix A. 

### A test shall consist of th ree runs, with each run at least 120 minutes in duration and each run collecting a minimum samp le of 60 dry standard eubic feet.



### In addition to annual stack tests, owner/operator shall monitor particula te emissions for compliance with the BART emission limits in accordance with the applicable Comp liance Assurance Monitoring (CAM) p l an developed and approved in accordance with 40 CFR part 64.

2. CEMEX Particulate BART Limits. /lNeed to address CEMEX particulate limits

- 20% opacity and Iblton of dry feed.1I

D. Recordkeeping

Owner/operator shall maintain the following records for at least five years:



### 3

### I

. All CEMS data, stack test data, and data collected pursuant to the CAM plan, including the date, place
, and time of sampling, measurement, or testing; paramete r s sampled
, measured
, or tested and results; the company, entity, or person that performed the testing, if applicable; and any field data sheets from testing.

2. Records of quality assurance and quality control activities for emissions measuring systems including, but not limited to, any records required by 40 CFR Part 75.

3. Records of all major maintenance activities conducted on emission units, air pollution control equipment, and CEMS.

4. Any other records required by 40 CFR parts 64 and 75

.

E

. Report ing requirements

Owner / operator shall submit quarterly excess emissions reports no later than the 30 lh 

### day following the end of each calendar quarter. Excess emission s means emissions that exceed the emissions limits specified in

__ above. Owner/operator shall submit reports of any required performance stack tests for particu l ate matter, within 60 calendar days after completion of the test. Owner / operator shall a lso submit quarterly reports of
any exceedances or excursions under the approved CAM plan
, and steps taken to correct the exeeedances or excursions, in accord a nce with 40 C F R 64.9(a).

Owner / operator shall also submit quarterly C E MS performance reports , to include dates and duration of each period during which the CEMS was inoperative (except for

zero and span adjustmen t s and calibration checks)
, rea s on(s) why the CE MS was inoperative and steps taken to prevent recurrence, any periods for which missing data substitution procedures were used, any CE MS repairs or adjustments
, and result s of any CEMS performance tests required by 40 CFR part 75 (Relative Accuracy T es t Aud its, Relative Accuracy Audit s, and Cylinder Gas Audits).

4

### 1

September 14, 2010

Rick Boddicker, Environmental Senior Scientist South Dakota Department of Environment and Natural Resourc es 523 East Capital, Joe Foss Building Pierre, South Dakota 57501

Re: Comments on the South Dakota Draft Regional Haze SIP Re: Comments on the South Dakota Draft Regional Haze SIP Re: Comments on the South Dakota Draft Regional Haze SIP

Dear Mr. Boddicker:

Sierra Club, the National Parks Conservation Association , and Plains Justice respectfully submit the following comments on South Dakota’s draft regional haze plan. South Dakota’s draft plan represents a good start to a rule that will protect nearby Class I areas from haze-causing pollution. However, the state’s pla n could, and must, go further still to ensure the goal of natural visibility by 206 4.
Best Available Retrofit Technology (BART) Determination for Big Stone Power Plant

Federal regulations mandate that states’ regional haze SI Ps include emission limitations representing BART for each BART-eligible sourc e. 40 C.F.R. §51.308(e). Best available retrofit technology or BART is defined as follows :
Best Available Retrofit Technology (BART) means an emissionlimitation based on the degree of reduction achievable through the applica tion of the best system of continuous emission reduction for each pollu tant which is emitted by an existing stationary facility. The emission limitation must be established, on a case-by-case basis, taking into consid eration the technology available, the costs of compliance, the energy and nonair quality environmental impacts of compliance, any pollution control equipment in use or in existence at the source, the remaining useful lif e of the source, and the degree of improvement in visibility which may reasonably be a nticipated to result from the use of such technology.

40 C.F.R. § 51.301.

BART is to be determined based on a five factor analysi s. 40 C.F.R. Part 51, Subpart Y, Section I.F.1. EPA’s five factor analysis r equirements stems from statutory and regulatory requirements regarding how BART is to be determin ed. Specifically:

### 2

The determination of BART must be based on an analysis of the best system of continuous emission control technology available and associ ated emission reductions achievable for each BART-eligible source that i s subject to BART within the State. In this analysis, the State must ta ke into consideration the technology available, the costs of compliance, the energy an d nonair quality environmental impacts of compliance, any pollution control equipment in use at the source, the remaining useful life of the source, and the degree of improvement in visibility which may reasonably be antici pated to result from the use of such technology.
40 C.F.R. § 51.308(e)(1)(ii)(A). See also § 169A(g) of the Clean Air Act

South Dakota’s draft regional haze plan states that, bec ause Big Stone I has a generating capacity less than 750 MW, the state is not required to follow the BART Guidelines in 40 C.F.R. Part 51, Subpart Y. South Da kota Draft Regional Haze Plan at 82. Specifically, the South Dakota Regional Haze Plan states “... in identifying the available control technologies, DENR is not listing any of the perm utations of the control levels for each identified control technology as suggested by EPA’s gui dance.” Id.

While the Federal regional haze regulations mandate that BART for units of 750 MW or greater must follow the BART Guidelines, the fact t hat Big Stone I has a generating capacity less than 750 MW does not mean South Dakota does not have to follow a reasoned analysis in evaluating BART and setting BART emission limitations. The state’s BART requirements still must comply with BART as defined at 40 C.F.R. § 51.301 and, in evaluating the “best system of continuous emission reduct ion,” the state must include the top level of pollutant removal efficiency of the control bein g evaluated. This would include evaluation of emission limits required as lowest achievabl e emission rate (LAER) and best available control technology (BACT), and must also inclu de the top levels of pollution control achieved at facilities anywhere including outside the United States. Thus, there is no justification for the state to ignore the fact that poll ution controls can be designed and operated at varying levels of control efficiency. If the sta te does not consider the capabilities of the various pollution controls evaluated i n the case by case BART analysis, its cost impacts analysis will be skewed in favor of th e lowest capital cost equipment rather than properly evaluating cost impacts in terms of amount of pollution reduced. Thus, South Dakota must consider the varying levels of control ef ficiency of pollution controls in the BART analyses for Big Stone.

A A . BART for Sulfur Dioxide (SO2 . BART for Sulfur Dioxide (SO2 . BART for Sulfur Dioxide (SO2) Emissions at Big Stone Emissions at Big Stone Emissions at Big Stone

The BART analysis for SO2 at Big Stone I is flawed beca use Otter Tail and the state failed to consider the level of control achievable with wet and dry scrubbers and because it is based on coal with higher uncontrolled SO2 emissions tha n Otter Tail has historically burned at Big Stone I. Further, DENR and Otter Tail fa iled to consider the other environmental benefits of a wet scrubber.

1. A 1. Analysis of BART Emission Limits Achievable Must Be on Current Coal nalysis of BART Emission Limits Achievable Must Be Basedon Current Coal Characteristics Characteristics.

### 3

Based on the percent removal assumed for the wet and dry sc rubbers and the proposed emission limits, it is clear that Otter Tail as sumed an uncontrolled SO2 emission rate of approximately 0.86 lb/MMBtu. 1 This is what Otter Tail claimed was the highest 24- hour average rate of SO2 emitted by Big Stone I during 20 01-2003. Table 1.2-1 of Otter Tail’s November 2009 BART Submittal to DENR. While the BART guidelines require use of highest daily emissions in the visibility modeling analysis, that is not an appropriate starting point for setting a BART emission limit that i s supposed to reflect BART, especially given that the BART emission limits apply on a30 day average basis.

A review of the annual average SO2 emission rates from Bi g Stone I over the last 10 years from EPA’s Clean Air Markets Database shows that the highest annual average SO2 emission rate was no higher than 0.70 lb/MMBtu. This e missions rate reflects the uncontrolled SO2 emissions from Big Stone I since it curr ently has no SO2 controls. DENR should have used this emission rate, or, at worst, determi ned the highest 30 day average uncontrolled SO2 emission rate, in setting the BART emissionlimit for Big Stone based on the control efficiency of the SO2 controls evaluated.

2. DENR and Otter Tail Failed to Evaluate the Highest SO2 Removal Efficiencies Achievable with a State Achievable with a State-

- of - the - Art Wet Scrubber. Art Wet Scrubber. Art Wet Scrubber.

DENR assumed a wet scrubber would achieve 95% control f rom the worst case daily SO2 emission rate at Big Stone of 0.86 lb/MMBtu. Usingthe highest uncontrolled SO2 emissions from the past 10 years of 0.70 lb/MMBtu, the BART emission limit with a 95% efficient wet scrubber should be no higher than 0.035 lb/MMBtu.

Further, wet scrubbers can achieve higher removal efficienc y, as high as 99%. A prime example is the Chiyoda CT-121 FGD. Vendor inform ation for this technology indicates that this scrubber has achieved 98-99% SO 2 removal even with low sulfur coal. 2 For example, the Chiyoda’s bubbling jet reactor has consi stently achieved >99% SO 2 removal during long-term operation at the Shinko-Kobe power plant in Japan. This facility consists of two 700-MW coal-fired utility boilers. The w et FGD was designed to achieve 0.014 lb SO2/MMBtu (9 ppmv at 3% oxygen) on an instant aneous basis and has consistently exceeded this level of control while treating ga ses with inlet SO 2 concentrations of 1.78 lb/MMBtu. 3 This technology has been guaranteed by Chiyoda to achieve 99% SO 2 removal on three coal-fired boilers in Japan. 4It also has been demonstrated in the U.S. at the University of Illinois’s Abbott power plant, Georgia Power’s Plant Yates 5 , Dayton

1 

### For example, Otter Tail’s BART analysis assumed a controlled SO2 emission r ate of 0.043 lb/MMBtu with a wet scrubber at 95% control. Table 3.3-1 of Otter Tail’s November 2009 BART Submittal to DENR. This reflects an uncontrolled SO2 emission rate of 0.86 lb/MMBtu. 2 

### See Black & Veatch vendor brochure on CT-121, Ex 1.

3 

### Yasuhiko Shimogama, Hirokazu Yasuda, Naohiro Kaji, Fumiaki Tanaka, and David K. Harris
, Commercial Experience of the CT-121 FGD Plant for 700 MW Shinko-Kobe Electric Powe r Plant, Paper No. 27, presented at MEGA Symposium, Air & Waste Management Associati on, May 19-22, 2003, Ex.2.

4 

### CT-121 FGD Process – Jet Bubbling Reactor, http://www.bwe.dk/fgd-ct121.html

. 5 

### Emission-control Technologies Continue to Clear the Air, Power , May/June 2002.

### 4

Power & Light’s Killen Unit 2, 6and Plant Bowen Unit 3. 7 It has also been licensed for installation on several additional units in the US, inclu ding the other three units at Plant Bowen in Georgia, the other units at Dayton Power & Light’s Killen plant, Dayton Power & Light’s Stuart plant, and AEP’s Big Sandy Unit 2, C onesville Unit 4, Cardinal Units 1 and 2, and Kyger Creek, among others. 8Black & Veatch and Southern Company are both U.S. licensees. Further, this technology also has shown to be v ery effective in removing fine particulates, oxidized and elemental mercury, and acid gases, and the technology uses less energy compared to traditional wet scrubbers.

Further, Mitsubishi, a vendor of scrubber systems, reports it has guaranteed SO 2 removal efficiencies up to 99.8 percent, including for coal- fired boilers. 9, 10, 11

Finally, a recent Lake Michigan Air Directors Consorti um (“LADCO”) and the Midwest Regional Planning Organization (“MRPO”) presentat ion indicated that advanced FGD technologies could achieve 99.5% control for $1,240 to $2,875 per ton of SO 2 removed and wet FGD could achieve 99% SO 2 control for $1,881 to $3,440 per ton of SO 2 removed. Ex. 8 These costs are well within the range that EPA normally considers cost effective in best available control technology (BACT) analyses.

In addition, the Georgia Environmental Protection Division r ecently issued a PSD permit for Plant Washington which will burn Powder RiverBasin coal as its primary coal, and this permit requires a 97.5% SO2 removal efficiency to be achieved on a 30 day rolling average basis. A copy of that permit is attached as E xhibit 9.

An annual average was compiled of SO 2 emission rates for 2008 using data submitted to the Clean Air Markets website by similar c oal-fired electric generating units. The annual average SO 2 emission rates were ranked from low to high to identify the best performing similar sources. This analysis is shown in Ex. 10. The best performing similar source in 2008 was Pleasant Prairie Units 1 and 2 in W isconsin. The 2008 annual average achieved at Unit 1 was 0.021 lb/MMBtu and at Unit 2, 0.027 lb/MMBtu. These units are equipped with a wet limestone scrubber and burn a low su lfur Powder River Basin Coal.

6 

### See Black & Veatch, First Black&Veatch/Chiyoda Wet Flue Gas Desulf urization System in North America Successfully Goes Operational, Ex. 3.
7 

### Blankinship, Steve, Go Take a Bath, Power Engineering, October 2008, available at http://pepei.pennnet.com/display_article/342997/6/ARTCL/none/none/1/Go-Take-a-Bath/. 8 

### Chiyoda Licenses Its Flue Gas Desulfurization Technology in USA Newly f or 5 Coal-Fired Generation Units, Press Release, May 2, 2005, Ex. 12; Chiyoda Licenses its Flue Ga s Desulfurization Process in USA for Georgia Power Owned 4 FGD Units, January 26, 2005, E x. 4.

9 

### Jonas S. Klingspor, Kiyoshi Okazoe, Tetsu Ushiku, and George Munson, High Efficiency Double Contact Flow Scrubber for the U.S. FGD Market, Paper No. 135 presented at MEGA Symposium, Air & Waste Management Association, May 19-22, 2003, p.8, Table 4, Ex. 5.

10 

### Yoshio Nakayama, Tetsu Ushiku, and Takeo Shinoda, Commercial Experience and ActualPlant-Scale Test Facility of MHI Single Tower FGD, Ex. 6.

11 

### Mitsubishi High SO2 Removal Experience, Ex. 7.

### 5

Similar data for the first six months of 2009 indicat e that other units are currently achieving even lower SO 2 emissions, including Iatan Unit 1 at 0.0051 lb/MMBtu ; Muscatine Unit 9 at 0.013 lb/MMBtu; Hammond Unit 2 at 0.016 lb /MMBtu; Gorgas Unit 10 at 0.017 lb/MMBtu; Prairie Creek Unit 4 at 0.019 lb/MMBtu; Hopew ell Power Station Units 1 and 2 at 0.020 lb/MMBtu; and Centralia Unit BW22 at 0.021 lb/MMBtu.

Thus, the Big Stone I BART Analysis should have evaluatedthese levels of control based on the actual uncontrolled SO2 emissions emitted by t he unit over a 30 day average basis in its evaluation of a wet scrubber for BART.

3. DENR and Otter Tail Failed to Evaluate the Highest SO2 Removal Efficiencies Achievable with a State Achievable with a State-

- of - the - Art Dry Scrubber. Art Dry Scrubber. Art Dry Scrubber.

DENR assumed only 90% control with a dry scrubber at Bi g Stone I and proposed an emission limit of 0.09 lb/MMBtu, which reflects somewhat less than 90% SO2 removal efficiency from the worst case 24-hour SO2 emissions of 0.8 6 lb/MMBtu. Using the highest uncontrolled SO2 emissions from the past 10 years of 0.70 lb/MMBtu, the BART emission limit with a 90% efficient dry scrubber should be no h igher than 0.07 lb/MMBtu. DENR and Otter Tail thus should have evaluated this SO2 emis sion rate achievable with a dry scrubber in the BART analysis.

There have been several proposed coal-fired power plants burni ng low sulfur Powder River Basin coal that have proposed to use dry scrubbers to meet PSD requirements and that are subject to higher control efficiency requirements a nd/or lower SO2 BACT limits than 0.09 lb/MMBtu. Those facilities include the Newm ont Nevada TS power plant, the proposed White Pine power plant, the proposed Toquop power plant, and the Dry Fork power plant. The Newmont Nevada power plant is subject to a minimum 95% SO2 removal efficiency requirement when burning coal with a sulfur cont ent equal to or greater than 0.45% and is subject to a minimum 91% SO2 removal ef ficiency when burning coal with sulfur content less than 0.45%. 12 This facility is currently operating in compliance wit h its limits. The Newmont Nevada is also subject to an SO2 BA CT limit of 0.065 lb/MMBtu when burning coal with less than 0.45% sulfur content. The proposed Toquop permit included an SO2 BACT limit of 0.06 lb/MMBtu on a 24-hraverage basis. 13 The Dry Fork power plant in Wyoming, which is also currently under c onstruction, will burn Powder River Basin coal, will be equipped with a dry scrubber, a nd is subject to an SO2 BACT limit of 0.07 lb/MMBtu. 14

Thus, the Big Stone I BART Analysis should have evaluatedthese levels of control based on the uncontrolled SO2 emissions emitted by the unit overa 30 day average basis.

4. DENR’s Determination of Cost Effectiveness of a Wet Sc rubber is within the Range of the Costs of Other SO2 Range of the Costs of Other SO2 BART Determinations. BART Determinations. BART Determinations.

12 

### See Section V.A.2.a.8. of Newmont Nevada Permit, Ex. 11.

13 

### See Section V.A.2..a.(8) of draft Toquop permit, Ex. 12. 14 

### See Dry Fork PSD Permit, Ex. 13.

### 6

Even if we ignore the fact that DENR and Otter Tail failed to evaluate the control efficiencies and emission rates achievable with a wet s crubber at Big Stone I, DENR’s cost effectiveness calculation of the wet scrubber at an SO2 emission rate of 0.043 lb/MMBtu of $1,699/ton is a reasonable cost when compared to other SO2 BART determinations. According to a spreadsheet put together by the National Par k Service with cost information for BART determinations, the average cost effectiveness of SO2 BART controls is $1,571 lb/ton, the mean cost effectiveness is $1,966/ton, and the highest cost required to meet SO2 BART was $7,309 lb/MMBtu. Because similar facilities will have to incur similar costs to meet BART, DENR has no justification to discount install ation of a wet scrubber based on costs.

5. DENR and Otter Tail Did Not Adequately Eval 5. DENR and Otter Tail Did Not Adequately Evaluate th e Other Environmental uate the Other Environmental Benefits of a Wet Scrubber. Benefits of a Wet Scrubber.

DENR and Otter Tail did not fully evaluate the environmenta l impacts of a wet scrubber versus a dry scrubber. Specifically, the high er SO2 removal efficiencies and very low SO2 emission rates, on the order of single digit par ts per million (ppm) concentrations, will be needed for the effective removal of carbon dioxide ( CO2) from the gas stream. Many of the amine-based CO 2 control methods currently under development are very sensitive to sulfur and thus require very low SO 2 inlet concentrations, on the order of 1 to 2 ppm. 15 This will require 98-99%+ SO2 removal or an outlet SO2 of 0.01 lb/MMBtu. It will be more cost effective and operationally simpler to design and install controls in one retrofit program.

It is well recognized that it is not a matter of if but when Congress and/or EPA will mandate CO2 reductions from industrial sources such a s Big Stone. Thus, if an SO2 control technology will better prepare Big Stone to be able to e ffectively remove CO2 in the future, that must be taken into account in the BART an alysis as another environmental benefit from a wet scrubber versus a dry scrubber. Indeed, as described above, there are wet scrubber technologies available that can remove 99+% of the SO2. Dry scrubbers do not achieve as high levels of SO2 emission reduction.

Another environmental benefit of wet scrubbers versus dry scr ubbers is greatly improved removal of hydrogen chloride (HCl) and hydrogen fluor ide (HF) as compared to a dry scrubber. Actual measurements have demonstrated t hat very high HCl and HF control efficiencies, 99.7% to 99.9% for HCl and 99.8% to 99.9 % for HF, are being achieved at wet scrubbed plants. 16Such high levels of HCl and HF removal have not been sh own for coal fired boilers controlled with dry scrubbers. Tests at the r ecently constructed Wygen II, an electrical generating unit burning subbituminous coal fr om the Powder River Basin and equipped with a spray dryer absorber, showed only 49% removal of HF and 58% removal of HCl. According to the Institute of Clean Air Companies , “wet scrubbers also provide significant removal of arsenic, beryllium, cadmium, chr omium, lead, manganese, and mercury from flue gas.” 17

15 

### Chuck Dene, Lesley A. Baker, and Robert J. Keeth, FGD Performance Capability, Me ga 2008, Ex. 14. 16 

### See 10/14/08 Letter from Alstom to Duke Energy, Exs. 15A and B.

17 

### See http://www.icac.com/i4a/pages/index.cfm?pageid=3401.

### 7

Further, lower emissions of SO2 that are achievable wit h a wet scrubber also equate to lower PM2.5 concentrations since there will be less SO2 in the air to contribute to sulfate formation. And studies have demonstrated that sulfate ad dition to sulfate-limited water bodies or wetlands can increase the transformation of mercury to its neurotoxic form, methylmercury. 18Thus, with lower SO2 emissions from Big Stone via t he use of a wet scrubber as compared to a dry scrubber, the result shou ld be less sulfate deposition which should decrease methylization of mercury.

These environmental benefits must also be considered in evalua ting the environmental benefits of the SO2 control options for BART at Big Stone I.
B. BART for Nitrogen Oxides (NOx) Emissions at Big Ston e.
The BART analysis for NOx at Big Stone I is flawed becau se Otter Tail and the state failed to consider the level of control achievable with the p roposed selective catalytic reduction (SCR) at Big Stone I.

DENR has proposed a NOx emission limit of 0.10 lb/MMBt u, on a 30 day average, based on the use of separated overfire air and installation of SCR. The Big Stone I boiler has already been modified to use overfire air as a NOx control

. 19 A review of monthly average NOx emission rate data from EPA’s Clean Air Mar kets Database shows that the highest monthly emission rate of NOx in 2009 was 0.71 l b/MMBtu. DENR’s proposed 0.10 lb/MMBtu NOx emission rate therefore reflects 85.9% NOx control with the SCR. However, SCR systems can achieve 90+% reductions in NOx. The em ission limit reflective of a 90% reduction in NOx would be 0.071 lb/MMBtu. This level of emissions has commonly been required as BACT in the last decade for numerous coal-firedboilers. In more recent years, lower levels of NOx have been required as BACT.

A review of recent SCR retrofits definitively shows that very high levels of NOx removal are being achieved by recent SCR retrofit installa tions. NOx emission rates less than 0.05 lb/MMBtu are routinely achieved, and NOx removalefficiencies are typically around 90%. 20 Permitting agencies have required lower NOx limits in r ecent BACT determinations, with many proposed and required BACT limi ts of 0.05-0.06 lb/MMBtu and at least one NOx BACT limit as low as 0.035 lb/MMBtu. 21

18 

### See, e.g. , Jeremiason, Jeff D. et al., Sulfate Addition Increases Methylmercury P roduction in an Experimental Wetland, Environ. Sci. Technol., 2006, 40, 3800-3806, Ex. 16; Krabbenhoft, David P. et al ., Unravelling the Complexities Mercury Methylation in the Everglades: TheUse of Mesocosms to Test the Effects of “New” Mercury, Sulfate, Phosphate, and Dissol ved Organic Carbon, available at http://sofia.usgs.gov/projects/merc_carbon/hgmeso_ge er03abs.html.

19 

### Terry Graumann of Otter Tail testified that the overfire air systemhad already been installed at Big Stone I to comply with acid rain requirements in the Big Stone Title V permit contested case hearing, in testimony given August 21, 2008. 20 

### See Erickson, Clayton A. et al., Selective Catalytic Reduction System Performance and Reliability Review, The 2006 MEGA Symposium, Paper # 121, Ex. 17.

21 

### The Plant Washington Permit has a NOx limit of 0.050 lb/MMBtu on a 30 day rolling aver age

### 8

Thus, the proposed NOx BART limit of 0.10 lb/MMBtu fa ils to reflect emissions level achievable with the proposed BART controls (i.e., separat ed overfire air and SCR). DENR must evaluate this lower level of NOx emissions in its BART analysis for Big Stone.

C. BART for PM at Big Stone. C. BART for PM at Big Stone.

DENR has proposed as BART for PM an emission limit of 0. 012 lb/MMBtu and the use of a fabric filter baghouse. However, baghouses can a chieve much lower emission rates, and permitting authorities have required lower limits as BACT. For example, the Plant Washington permit has a filterable PM limit of 0.010lb/MMBtu. Ex. 9. Thus, DENR must lower the PM BART emission limit of 0.010 lb/MMBtu if notlower.

In addition, EPA’s BART Guidelines require that, becau se BART limits must be met on a continuous basis, there must be adequate provisions ensu ring compliance with BART on a continuous basis. Yet, DENR has only proposed an an nual stack test to demonstrate compliance with its proposed PM BART limit. DENR cou ld require a PM continuous emission monitoring system (CEMS) to ensure continuous comp liance with the BART limit, such as is required by the Plant Washington permit to m eet a 0.010 lb/MMBtu emission limit. Alternatively, DENR should impose an opacity l imit reflective of BART, which should be a limit of no more than 10% opacity. Given tha t Big Stone already has continuous opacity monitoring (COMs), the opacity limit would help ensure continuous compliance with the PM BART limit.

Many coal plant permits include stringent opacity limit s as part of the BACT limits for those facilities. The MidAmerican facility in Counc il Bluffs, Iowa, has an opacity limit of 5 percent. The Plum Point facility in Osceola, Arkansas , has a BACT limit of 10 percent opacity. The Wisconsin Department of Natural Resources s et a 10 percent opacity limit as BACT for the Fort Howard (Fort James) Paper Company’s 500 MW CFB boiler. The Desert Rock permit has a 10% opacity limit.

In summary, DENR must impose a PM BART limit reflectiv e of the best system of continuous emission reduction, and limits lower than 0. 012 lb/MMBtu can be met with a baghouse. DENR should require either PM CEMS or set anopacity limit reflective of BART in addition to a lb/MMBtu limit and use COMs to ens ure continuous compliance with the opacity limit and use that data as an indicator of continuous compliance with the PM BART limit.

D. There Should Be No Exemptions from BART Emission Lim its During Startup and Shutdown. Shutdown.

As EPA has said in the BART Guidelines, BART emission l imitations must be met on a continuous basis pursuant to section 302(k) of the Clean Air Act. Yet, DENR has proposed to exempt Big Stone from meeting the lb/MMBtu BART emission limits during startup and shutdown. Startup and shutdown are part of the normal operations of a power plant like Big Stone, and startup and shutdown emission s impact visibility and regional



### and 0.030 lb/MMBtu on a 12 month average when burning Powder River Basin coal. See Ex. 9.

### 9

haze. So DENR’s proposed BART limits must include peri ods of startup and shutdown. Further, there is no justification to exempt Big Stone from meeting BART limits during startup and shutdown. Numerous permitting authorities ha ve issued as stringent if not more stringent BACT limits for coal-fired boilers with no ex emptions for startup and shutdown. Further, during the 2008 contested case h earing for the Big Stone II permit, Otter Tail’s Terry Graumann made clear that they were no t requesting exemptions from emission limits during periods of startup or shutdown, a nd Otter Tail’s Mark Rolfes indicated the pollution controls would operate during startu p and shutdown. 22

Thus, not only is continuous compliance with BART limit s required under federal rules, but there is no technical justification for exempt ions from BART limits during startup and shutdown. Thus, these BART exemptions must be deleted.

E. The State’s Proposed BART Regulation M E. The State’s Proposed BART Regulation Must Make Clea r that the Emission Limitations ust Make Clear that the Emission Limitations Apply to Big Stone I. Apply to Big Stone I.

The EPA’s BART Guidelines require that the state impose BART through enforceable requirements and that the enforceable requirements r equire that BART be met as expeditiously as practicable but no later than 5 years from the date EPA approves the state’s regional haze SIP. DENR has proposed a state r egulation to make these requirements enforceable at ARSD 74:36:21:06-09. However, the regulation specifying the emission limits fails to specify that Big Stone is subjec t to these emission limits. The regulation must identify the source that is subject to these emission limits ensure enforceability of the BART limits.

Second, regarding the compliance timeframe, the BART regul ation should require compliance with the PM BART limit now given that Big S tone has already installed a fabric filter baghouse and can comply with the BART limit now.

Given that South Dakota is not meeting its “glide path” milestones to natural visibility conditions by 2064, it is imperative that DENR require Big Stone to install the most effective BART controls and meet stringent emissionlimits. We appreciate your consideration of our comments.

Sincerely,

Holly Bressett Project Attorney Sierra Club Environmental Law Program 85 Second St., 2nd Floor San Francisco, CA 94105 (415) 977-5646 (phone) (415) 977-5793 (fax)

Lynn McClure Midwest Regional Director National Parks Conservation Association

22See Big Stone Contested Case Hearing Transcript, A ugust 2008, at 617-618, 679 and 602-603.

### 10

8 South Michigan Ave., Suite 2900 Chicago, IL 60603 312-263-0111 office 312-343-7216 cell
www.npca.org
Carrie La Seur, D.Phil., J.D., LEED A.P. President & Founder Plains Justice 310 N. 27th St., Ste. 12 Billings, MT 59101 http://www.plainsjustice.org/ 406-696-8700 866-484-2373 (fax)

Exhibits215 South Cascade Street PO Box 496 Fergus Falls, Minnesota 56538-0496 218 739-8200 www.otpco.com

August 31, 2010

Mr. Rick Boddicker Senior Environmental Scientist South Dakota Department of Environment and l'Jatural Resources 523 East Capitol Joe Foss Building Pierre, SD 57501-3181

Dear Mr. Boddicker:

Subject: Connnent

- Proposed Regional Haze Program Chapter 74:36,21 

## RECEIVED 

## SEP 022010

AIR QUALITY

PROGRAM



# C»**OriER~;;:rIIJ=L=** POWER COMPANY

The following connnent is offered by Otter Tail Power Company as operating agent for Big Stone Plant. Big Stone Plant is co-owned by NorthWestern Corporation d/b/a NorthWestern Energy, Montana-Dakota Utilities Co, A Division ofMDU Resources Gronp, Inc" and Otter Tail Power Company, a wholly owned subsidiary of Otter Tail Corporation.

Otter Tail suggests the following clarifying revision to ARSD 74:36:21: 11:

74:36:21:11. Permit meaifieatieB required for BART determination. The owner or operator of a BART-eligible source shall submit an application in accordance with § 74:36:20 to modify its operations to include the controls, emission limits, monitoring, recordkeeping, artd reporting requirements identified in the BART determination and approved by the department in aeeordanee with 

### § 74 :36:20.

Thank you for your consideration of our connnent.

Manager, Environmental Services

An Equal Opportunity Employer AN**~** OTTERTAIL COMPANY