# Appendix 10.13

Table 10-16

Reference 12: Table 3-8 on page 18 and Table 6-7 on page 87 of "S outh Dakota’s Regional Haze State Implementation Plan."

# SOUTH DAKOTA’S

REGIONAL HAZE

STATE IMPLEMENTATION PLAN

South Dakota Department of Environment and Natural Resourc es17

Table 3-7 – Baseline versus Natural Background (Deciviews) Class I Baseline Natural Difference Baseline Natural Difference Area 20% Least Impaired Days 20% Most Impaired Days Badlands 6.91 2.32 4.59 17.16 7.44 9.72 Wind Cave 5.16 2.29 2.87 15.93 7.41 8.52

3.2.4 Refined Natural Conditions EPA identifies any refined approach for determining natura l visibility conditions should be based on accurate, complete, and unbiased information and should be developed using a high degree of scientific rigor. The refined natural concentration estimates must retain the distinction between natural and anthropogenic components. For example, just like EPA’s default natural concentrations, the refined natural concentrations shou ld not exceed actual measured concentrations of that species over a 5-year period

. EPA indicates additional information will become available over the years to improve on the default natural concentrations such as the following: 1. Implementation of a coordinated fire data system o r fire tracking system; 2. The collection of multiple years of speciated parti culate matter data in mandatory Class I areas and the assessment of potential contributions by natural fire events using data from the fire tracking system; 3. Development of chemical analysis techniques to identi fy carbon attributed to fire versus other sources; 4. Development of improved emissions factors and tracking of fire activity levels; and 5. Improved regional scale fire modeling or remote sensi ng tools to retrospectively determine whether smoke from a fire impacted a Clas s I area air shed. DENR agrees more refined natural species concentrati ons will be developed in the coming years that are more specific to a national park and will re view this new information as it periodically reviews its Regional Haze State Implementation Plan

. 3.3 Uniform Rate of Improvement In accordance with 40 CFR § 51.308(d)(2)(iv)(A), the initi al implementation plan shall address the difference between the baseline and natural conditions for the 20% most impaired and 20% least impaired days. In accordance with 40 CFR § 5 1.308(d)(1)(i)(B), the state is required to determine the rate of progress needed to attain natural visi bility conditions by the year 2064. The rate of progress is based on the difference bet ween the baseline visibility conditions and the natural visibility conditions for 20% most impaired days for each Class I area. The uniform rate of visibility improvement, measured in deciviews, is determined by taking the difference between the baseline visibility conditions an d the natural visibility conditions and dividing by 60 years, which is the time frame for a ttaining natural visibility conditions by 2064. The uniform rate of improvement is required to be c onsidered as the state establishes its reasonable progress goals for attaining natural visibilit y conditions. The uniform rate of18

improvement for the Badlands and Wind Cave National Parks is based on the formula in Equation 3-7 and the baseline and natural backgroun d valued in Table 3-7. The results are displayed in Table 3-8. The uniform rate of improv ement was calculated for the 20% most impaired days for each national park. Equation 3-7 – Uniform Rate of Progress



## ! 60 Pr "

# $ Natural Baseline ogress of Rate Uniform
Table 3-8 – Annual Uniform Rate of Improvement Description Badlands Wind Cave Annual Improvement 0.1620 deciviews 0.1420 deciviews The uniform rate of improvement was used to establish the slope of reduction necessary to achieve the natural visibility conditions in 2064. The slope of reduction for the 20% most impaired days for the Badlands and Wind Cave National Parks a re displayed in Figure 3-5. The improvement needed by 2018 was calculated based on the an nual uniform rate of improvement identified for each Class I area. The baseli ne is based on calendar years 2000 through 2004. Therefore, there are 14 years from the baseline to the first planning period or 2018. The improvement needed for the 20% most impaired days by calendar year 2018 for each Class I area was determined by multiplying the annua l uniform rate of improvement by 14 years then subtracting that from the baseline value for the 20% most impaired days in Table 3-7. The result is displayed in Figure 3-5. Figure 3-5 – Uniform Rate of Improvement (a) Badlands National Park

0.00 3.00 6.00 9.00 12.00 15.00 18.00

2000 2004 2008 2012 2016 2020 2024 2028 2032 2036 2040 2044 204 8 2052 2056 2060 2064 YearDeciviews

Reasonable Progress 2018 (14.89 deciviews) Natural (7.44 deciviews)19

(b) Wind Cave National Park

0.00 3.00 6.00 9.00 12.00 15.00 18.00

2000 2004 2008 2012 2016 2020 2024 2028 2032 2036 2040 2044 204 8 2052 2056 2060 2064 YearDeciviews

Reasonable Progress 2018 (13.94 deciviews) Natural (7.41 deciviews)



### 4.0 IMPROVE Data for Class I Areas The data from the IMPROVE monitoring sites identifi es the composition of the pollutants impacting our Class I areas and consists of ammonia sulfates fine (ammSO4f), ammonia nitrates fine (ammNO3f), organic mass carbon (OMC), elemental carbo n fine (Ecf), soil, coarse mass (CM), and sea salt. The IMPROVE data has been collected at th e Badlands National Park since 1988 and the Wind Cave National Park since 2000. DENR is using the IMPROVE data to help determine what air pollutants are causing or contributing to visibility impairment in the Class I areas and assist in evaluating if each state is ach ieving the reasonable progress goals.

4.1 Aerosol Concentrations The average aerosol concentration (micrograms per cub ic meter (ug/m 3 )) and visibility (deciviews) per year during the baseline period (20 00-2004) for the 20% least (P10) and 20% most (P90) impaired days are summarized in Table 4- 1 for the Badlands National Park and Table 4-2 for the Wind Cave National Park. The last line in ea ch Table provide the default natural conditions that should be achieved for the 20% most impai red days by 2064.

The baseline aerosol concentrations at the Badlands and Wind Cave Nat ional Parks during the 20% most impaired days are all similar and within 22% or less of each other except for the coarse mass and sea salt. If you neglect sea salt, the aerosol with the greatest dissimilarity is coarse mass with the Badlands National Park’s coarse mass b aseline concentrations being greater than at the Wind Cave National Park. This would be expe cted because of the drier conditions associated with the Badlands National Park. Coarse mass is t ypically generated from crushing or grinding operations, dust from paved or unpaved roads, windblown dust, etc.86

Emerging control technologies such as Enviroscrub, Electro catalytic oxidation , and the Airborne process have not been commercially available and have no t been demonstrated for long-term levels of performance. As noted in 40 CFR Part 51, A ppendix Y, a control technology needs to be commercially available to be considered technica lly feasible. As such these emerging technologies are not considered technically feasible options for Otter Tail Power Company. DENR determined that the following sulfur dioxide control technologies were feasible for Otter Tail Power Company: 1. Semi-dry flue gas desulfurization; and 2. Wet flue gas desulfurization. 6.3.2.3 Sulfur Dioxide Control Effectiveness Step 3 requires the evaluation of control effectiveness for each control technology. DENR evaluated the control effectiveness by comparing the effect iveness in Table 6.6. Table 6-6 – Comparison of Control Effectiveness for Sulfur Dioxide Controls

Emission Rate Control Efficiency Otter Tail 1 RBLC 3 Basin 4 EPA 5 Rank Control (lbs/MMBtus) 2 (lbs/MMBtus) 2 (lbs/MMBtus) 2 (%) #1 Wet Flue Gas Desulfurization 0.043 to 0.15 0.1 to 0.167 0.05 90 to 98

#2 Semi-Dry Flue Gas Desulfurization 0.09 to 0.15 0.038 to 0.16 0.07 80 to 90

1 – The identified emission rates were identified in Otter Tail Power Company’s BART analysis; 2 – “lbs/MMBtus” means pounds per million British th ermal units; 3 – The identified emission rates were obtained from EPA’s Reasonable Achievable Control Technology, Best Available Control Technology, and Lowest Achievable Emission Rate Clearinghouse (RBLC) considering data for permits i ssued after calendar year 2000; 4 – The emission rates are based on the BACT analysi s provided by Basin Electric Power Cooperative’s proposed NextGen project in South Dak ota; and 5 – The control efficiencies, in percent removal, ar e from EPA’s “Air Pollution Control Technology Fact Sheet on Flue Gas Desulfurization Systems”. 6.3.2.4 Sulfur Dioxide Control Technology Impacts Step 4 requires DENR to look at impacts associated with the control alternativ es such as cost of compliance, energy impacts, non-air quality environm ental impacts, and the remaining useful life of the project. These impacts are intended to provide ratio nal in choosing between the alternative control options when determining what is consi dered BART.87

Otter Tail Power Company identified cost estimates for each of the control options. In addition, Otter Tail Power Company identified cost estimated for two different operating scenarios for each of the two control alternatives. Table 6-7 summari zes Otter Tail Power Company’s estimated costs. In 40 CFR Part 51, Appendix Y – Guidelines for BART Determinat ion Under the Regional Haze Rule, in the section titled “How should I determine vis ibility impacts in the BART determination” it notes that the model should use the 24-ho ur average actual emission rate from the highest emitting day of the meteorological period model ed (for the pre-control scenario). The 18,000 tons per year of sulfur dioxide is based on t he highest average 24-hour average emission rate (4,832 pounds per hour) for calendar years 2001 through 2003 and operating 85% of the time or 7,746 hours per year. Based on the BART guid elines, the baseline emissions are 18,000 tons per year. Table 6-7 – Comparison of Control Effectiveness for Sulfur Dioxide Controls Control Option Capital Cost O&M 1 Annual Cost 2 Reduction 3 Cost Effectiveness 4 WFGD #1 5 $171,800,000 $9,600,000 $29,050,000 17,100 $1,699 WFGD #2 6 $171,800,000 $9,490,000 $28,900,000 14,870 $1,944 SDFGD #1 7 $141,300,000 $7,660,000 $23,570,000 16,120 $1,462 SDFGD #2 8 $141,300,000 $7,480,000 $23,330,000 14,870 $1,569 1 – O&M represents the operational and maintenance c ost estimate for the control alternative; 2 – Annual cost is the annualized cost for each cont rol alternative taking into account both the capita l and operational and maintenance costs; 3 – Reduction represents the amount of sulfur dioxid e reduced in tons per year annual from the baseline level of 18,000 tons of sulfur dioxide per year; 4 – Cost Effectiveness represents the annualized cos t divided by the identified emission reductions (dollar per ton); 5 – WFGD #1 represents a wet flue gas desulfurizatio n system meeting an emission rate of 0.043 pounds per million British thermal units; 6 – WFGD #2 represents a wet flue gas desulfurizatio n system meeting an emission rate of 0.15 pounds per million British thermal units; 7 – SDFGD #1 represents a semi-dry flue gas desulfur ization system meeting an emission rate of 0.9 pounds per million British thermal units; and 8 – SDFGD #2 represents a semi-dry flue gas desulfur ization system meeting an emission rate of 0.15 pounds per million British thermal units. Otter Tail Power Company did not identify the cost ef fectiveness on a dollar per visibility reduction. DENR considered this cost effectiveness i n Step 5 of the analysis. Otter Tail Power Company identified the energy impacts cost associated for each of the control options. Table 6-8 summarizes Otter Tail Power Company’s est imated energy impacts.88

Table 6-8 – Estimated Energy Impacts for Sulfur Dio xide Controls Control Energy Demand Percent of Generation Wet Flue Gas Desulfurization 9,500 kilowatts 2.0 percent Semi-Dry Flue Gas Desulfurization 3,325 kilowatts 0.7 percent The non-air quality environmental impacts of the tw o control alternatives include the solid and aqueous waste streams. The semi-dry flue gas desulfurizati on system would be installed upstream of the existing baghouse. The baghouse wo uld be used to collect the injected lime and reacted sulfur dioxide emissions along with other existing particulate matter emissions. Otter Tail Power Company did not identify how much additional parti culate matter would be collected by the baghouse due to the use of the semi-dry flue gas desulfurization system. At this time, it is assume the additional material collected in the baghouse is negligible compared to the existing collection. Otter Tail Power Company estimates that the wet flue gas desulfurization system would generate an additional 44,700 tons of gypsum solids which would need to be properly disposed. In conducting its cost analysis, Otter Tail Power C ompany used 30 years as the life expectancy averaging period for the control alternatives. Since the usef ul life of Otter Tail Power Company’s Big Stone I facility is expected to be longer than 30 years, there is no difference between the control options based on useful life. 6.3.3 Nitrogen Oxide BART Review 6.3.3.1 Nitrogen Oxide Control Technologies Step 1 requires the identification of all available retrofit control technologies. Otter Tail Power Company identified the following control options for nit rogen oxide: 1. Low-nitrogen oxide burners (LNBs); 2. Over-fire air (OFA); 3. Separated over-fire air (SOFA); 4. Selective non-catalytic reduction (SNCR); 5. Rich reagent injection (RRI); and 6. Selective catalytic reduction (SCR). DENR also identifies the following control technologi es that may be used to control nitrogen oxide emissions: 1. Flue-gas recirculation; 2. Oxygen enhanced combustion; 3. Catalytic absorption/oxidation; 4. Gas reburn; and 5. Emerging control technologies such as Enviroscrub, Ele ctro-catalytic oxidation, NOxStar, and Cascade processes.