### DEPARTMENT 

### of ENVIRONMENT and NATURAL RESOURCES

PMB 2020 JOE FOSS BUILDING 523 EAST CAPITOL PIERRE, SOUTH DAKOTA 57501·3182 www.state.sd.us/denr

June 1,2011

Carl Daly Director Air and Radiation Program, 8P-AR U.S. Environmental Protection Agency, Region 8 1595 Wynkoop Street Denver, CO 80202-1129

Dear Mr. Daly:

On May 16,2011, Gail Fallon, EPA Region 8, sent the department an email identifying EPA's

comments on South Dakota's Regional Haze State Implementation Plan. The department reviewed and responded to each comment (see Attachment A).

The department discussed EPA's comments with Otter Tail Power Company. Even though the department and Otter Tail Power Company disagree with EPA's comment that the pounds per million Btu emissions limit established for normal operation should include startup and shutdown, Otter Tail Power Company agreed to EPA's request. Otter Tail Power Company's agreement is contingent on EPA agreeing to the 30-day rolling average defined in the drafted revisions of the Regional Haze regulations under the Administrative Rules of South Dakota, chapter 74:36:21 (see Attachment B).

EPA's other item of concern relates to identifying the compliance test method for particulate matter. EPA believes the state has too much director's discretion if we do not specify what EPA approved

test method in the federal rules must be used to demonstrate compliance with the particulate matter limits. DENR disagrees for the reasons specified in the response to comments (see Attachment A).

If EPA is in agreement, the department will move forward with the rule changes and make the appropriate changes to the technical document. After you have had a chance to review the drafted revisions and response to comment, please contact me at (605) 773-3151, to discuss any outstanding issues and the timeline for EPA to approve South Dakota's Regional Haze Program. A timely approval process by EPA will mean Otter Tail Power Company can order and install the required equipment and start, us on our path of achieving natural visibility in our Class I areas.

Sincerely,

AttachmentsA-1 

### Attachment A Response to EPA’s Comments (May 12, 2011)

DENR’s comments are organized in the manne r in which EPA identified them in their

comments.



### A. Emission Limits for Big Stone I

1. The BART Guidelines require emission limits be met on a continuous basis.

EPA’s Comment: South Dakota’s proposed separate pounds per hour startup/shutdown limits have not been adequately justified for nitrogen oxide and sulfur dioxide and therefore, are not acceptable. In addition, the proposed pounds per hour limits are not reflective of the contro l technologies selected.

Response: After going through a case-by-case Be st Available Retrofit Technology (BART) determination, DENR established a BART emission limit for nitrogen oxide representing the installation and operation of a separated over-fire air and selective catalytic reduction system for Otter Tail Powe r Company’s Big Stone I electric coal-fired power plant. The BART emissions limit for sulfur dioxide represents a semi-dry flue gas desulfurization system.

Separated over-fire air is a combustion ai r staging technique aimed at minimizing nitrogen oxide generation during the fuel combustion process. The separated over-fire air system is designed to limit the oxygen (combus tion air) that is ava ilable to react with nitrogen during the combustion process. The combustion air is limited to a value close to the amount stoichiometrically needed to combus t the fuel. This process is achievable at normal operating loads. This process is not achievable at startup and shutdown. During startup and shutdown periods, the National Fire Protection Association requires a minimum of 25% of the full load air flow be established through the boiler before any combustion is initiated and after combustion is terminated. The National Fire Protection Association requirement is a safety practi ce during startup and s hutdown. Therefore, the separated over-fire air system is not effective in contro lling nitrogen oxide emissions during startup and shutdown.

A selective catalytic reduction system uses a catalytic reduction with the use of ammonia injection. Based on reaction ki netics, the target temperatur e window for the reactions is 560 to 780 degrees Fahrenheit. A selective catal ytic reduction system typically operates in the 600 to 750 degree Fahrenheit temperatur e range. These reacti on temperatures are not typical and not achievable during startup and shutdown periods. In addition, injecting ammonia at temperatures below 560 degrees Fahrenheit will coat the catalyst with ammonium salts. This process would re duce catalyst life, increase operation and maintenance cost and may cause fouling of the downstream baghouse.A-2 As noted, the two nitrogen oxide control systems do not operate effectively during periods of startup and shutdown and are una ble to meet the same normal operations emission limits on a pound per million British Thermal Units (Btu) basis during startup and shutdown. Therefore, DENR established a separate pounds per hour emission limit, which includes startup and shutdown, based on the 0.10 pounds per million Btus emission limit for normal operation and the maximum design operating rate for the boiler (e.g., multiply 0.10 pounds per million Btus by 5,609 million Btus per hour which equals 561 pounds per hour). Both limits have to be met on a continuous basis.

Semi-dry flue gas desulfurization systems inj ect an aqueous sorbent slurry. As the flue gas mixes with the slurry solution, water from the slurry is evaporated. The water that remains on the solid sorbent enhances the re action with sulfur di oxide. The process forms a dry waste product which is collected with a standard particulate matter collection device such as a baghouse. The waste produc t can be disposed, sold as a byproduct or recycled to slurry. The performance of a semi-dry system is sensitive to operating conditions, in particular the operating temperatur e. The system needs to operate near the adiabatic saturation temperature to maximi ze the removal of sulfur dioxide. The optimum temperature is 20 to 50 degrees below the saturation temperature. Operations during startup and shutdown are not c onducive to maintaining the appropriate temperature. As such, it is not recomme nded to place the system on line until Otter Tail Power Company can effectively control the ex it temperature within the appropriate range above the adiabatic saturation temperature so Otter Tail Power Company does not have condensation in the baghouse or on th e walls of the semi-dry system.

The sulfur dioxide control system does not ope rate effectively during periods of startup and shutdown and is unable to meet the same normal operations emission limit on a pound per million Btus basis during startup a nd shutdown. Therefore, DENR established a separate pounds per hour emission limit, which includes startup and shutdown, based on the 0.09 pounds per million Btus emission limit for normal operations and the maximum design operating rate for the boile r (e.g., multiply 0.09 pounds per million Btus by 5,609 million Btus per hour which equals 505 pounds per hour). Both limits have to be met on a continuous basis.

DENR is unsure why EPA believes establ ishing two BART emission limits is not adequately justified. It is unrealistic to believe the same emission limit can be established for normal operations when the control equi pment is operational and during startup and shutdown when the control equipment is i noperable or not working efficiently. Therefore, DENR established a limit for norma l operation when the control equipment is operating efficiently and a second limit which includes normal operations and startup and shutdown periods when the control equipment is not working efficiently. The worst case scenario (e.g., operating at maximum capaci ty with an emission limit of 0.10 pounds per million Btus or 561 pounds per hour) was mode led and determined that Big Stone I would not contribute to any vi sibility impairment in any Cl ass I areas in South Dakota orA-3 in other states. This analysis is based on EPA’s guidelines for a BART determination in 40 CFR Part 51, Appendix Y.

EPA also stated the proposed pounds per hour limits were not reflective of the control technologies selected by DENR but did not provide any evidence to support this conclusion. DENR conducted a fi ve factor analysis as speci fied in the federal Regional Haze rules, outlined the five factor analysis in the technical document for South Dakota’s Regional Haze Program and determined th e pounds per hour limits are appropriate.

EPA’s Comment: South Dakota’s limits in pounds per hour are less stringent than the pounds per million Btus limit at any firing rate other than the maximum rated capacity. The more stringent pounds per million Btu limit would supersede the pounds per hour limit overcoming another flaw in that cros s-referenced continuous emission monitoring rules do not indicate how to cal culate a pounds per hour rate.

Response: DENR agrees with EPA that the pou nds per million Btu emission limit is more stringent than the pounds per hour for any firing rate other than the maximum rated capacity since that is how DENR determin ed the pounds per hour emission limit. At the maximum rated capacity, the two limits are equivalent. However, the pound per hour limit applies at all times including start up and shutdown. If Otter Tail Power Company were to operate other than maximum capaci ty during normal operation (e.g., non-startup and non-shutdown periods) the pounds per million Btu limit is applicable and supersedes the pounds per hour limit.

EPA reference to a flaw of the continuous em ission monitoring rules appears to reference the continuous emission monitoring require ments in 40 CFR Part 60 Appendix B and 40 CFR § 60.13, which are referenced in the Admi nistrative Rules of South Dakota (ARSD) chapter 74:36:13 – Continuous Emission Moni toring System. 40 CFR Part 60 Appendix B Performance Specification 6 – Specificati on and Test Procedures for Continuous Emission Rate Monitoring Systems is the sp ecification for a pound per hour monitoring system. In section 3.1, the specification stat es the continuous emission rate monitoring system is the total equipment required for the determining and recording the pollutant mass emission rate (in terms of mass per uni t time). In section 18.0, the flowchart and validation table notes the relative accuracy test audit is to compare the emission rate for the continuous emission monitoring system to the reference method. The table in the regulations provided indicates the units to be in kilogram s per hour and notes that the data needs to be corrected to a consis tent basis for comparison (i.e., moisture, temperature, and pressure conditions). Ther efore, the cross-reference to 40 CFR part 60 Appendix B does specify how to certify the da ta so you can demonstrate compliance with a pounds per hour emission limit.

DENR does agree to change the reference from ARSD chapter 74:36:13 to 40 CFR Part 75 to stay consistent with the Acid Rain pr ogram that Big Stone I is already required to

meet.A-4 EPA’s Comment: EPA comments the separated over fire air system proposed for Otter Tail Power Company should be able to achieve a post combustion emission rate of around 0.50 pounds per million Btus on a 30-day rolling average. EPA believes since a selective catalytic reduction system is capable of achieving greater than 90 percent removal efficiency, then an emission rate of 0.05 pounds per million Btus on a 30-day rolling average is a more than reasonable expectation for the application of selective catalytic reduction system. Therefore, the proposed emission limit of 0.10 pounds per million Btus on a 30-day rolling average provides a more than ample margin to accommodate startup and shutdown

.

Response: DENR has continual discussed in its technical document for South Dakota’s Regional Haze Program and previous response to comments that the control efficiency of a control device is 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. DENR provide d examples in these previous discussions and still consider those discussions valid. To augment those discussions, DENR will use the annual data provided by EPA and presum ptive limits in 40 CFR Part 51 Appendix Y as another method to illustrate why one does not arbitrarily multiply an actual emission rate by an assumed efficiency to establish an emission limit.

40 CFR Part 51 Appendix Y identifies presump tive limits for different boiler design and type of coal burned for electrical genera ting units operating without post-combustion controls (e.g., no selective catal ytic reduction system). If a selective catalytic reduction system is applied and automatically reduces emissions by 90% as indicated by EPA, then the identified boilers should obtain the emission rates identified in Table 1-1. This is the same approach used by EPA when it assumes the separated over-fire air system will achieve a specific emission rate and then automatically multiply by the identified 90% control efficiency.

Table 1-1 – Emission rate af ter selective catalytic reduction (pounds per million Btus) Boiler Type Coal Type Presumptive Limit SCR Efficiency Calculated Emission Rate Dry-bottom wall-fired Bituminous 0.39 90% 0.039 Sub-bituminous 0.23 90% 0.023 Lignite 0.29 90% 0.029 Tangential-fired Bituminous 0.28 90% 0.028 Sub-bituminous 0.15 90% 0.015 Lignite 0.17 90% 0.017

As noted in Table 1-1, the dr y-bottom wall-fired and tangent ial-fired boiler should have actual emissions in the range of 0.02 to 0.04 pounds per million Btus. Table 1-2 compares the “calculated emission rate” in Ta ble 1-1 to the actual emission rates of the units identified by EPA. O nly one of the 14 units identified by EPA has actual emissionsA-5 less than the “calculate emission rate” and this is based on an annual average not a 30-day rolling average.

Table 1-2 – Selective catalytic reductio n comparison (pounds per million Btus) Facility Boiler Type Unit # Actual Emission Rate Calculated Emission Rate Cardinal Dry bottom wall-fired 3 0.05 0.04 Chesapeake Dry bottom wall-fired 3 0.03 0.04 E D Edwards Dry bottom wall-fired 3 0.05 0.04 John E Amos Dry bottom wall-fired 1 0.05 0.04 John E Amos Dry bottom wall-fired 2 0.05 0.04 Mitchell (WV) Dry bottom wall-fired 2 0.05 0.04 Mitchell (WV) Dry bottom wall-fired 1 0.05 0.04 TS Power Plant Dry bottom wall-fired 1 0.05 0.04 Walter Scott Jr. Dry bottom wall-fired 4 0.06 0.04

Chesapeake Tangentially-fired 4 0.04 0.03 Chesterfield Tangen tially-fired 5 0.04 0.03 Chesterfield Tangen tially-fired 6 0.04 0.03

Kingston Tangentially-fired 1 0.05 0.03 Kingston Tangentially-fired 6 0.05 0.03 Kingston Tangentially-fired 8 0.05 0.03 Kingston Tangentially-fired 9 0.05 0.03 Kingston Tangentially-fired 5 0.05 0.03 Kingston Tangentially-fired 2 0.05 0.03 Kingston Tangentially-fired 7 0.05 0.03 W A Parish Tangentially-fired WAP7 0.04 0.03 W A Parish Tangentially-fired WAP8 0.04 0.03

EPA alludes that Otter Tail Power Company should be able to average out the startup and shutdown emissions by using a 30-day rolling average. This comment has several issues. The first issue is the duration and the frequency of startup and shutdown periods. As noted in Tables 1-3, 1-5, 1-6, and 1-7, the emission rate during startup and shutdown periods are greater than the limit. Therefore, the emission calculation must include other operational periods and those operational periods must be lower to offset the emissions during startup and shutdown periods.

By defining the 30-day average as 30-operational days, Otter Tail Power Company is not allowed to take credit for days that it is not operating to average out the startup and shutdownemissions. This leads to the second issue, which is the actual emission rate during nonstartup and non-shutdown periods. As noted in Table 1-1 and 1-2, one cannot automatically assume the actual emissions during non-start up and non-shutdown periods will average less than 0.05 pounds per million Btus (e.g., 50% of the standard) for every 30-day rolling average. Based on the data from the Baldwin En ergy facility and the Kincaid Energy center, which both have cyclone fired boilers with selective catalytic reduction systems, there areA-6 actual 30-day rolling averages (excluding startup and shutdown emissions) that are equal to or greater than 0.07 pounds per million Btus. DE NR disagrees that there is ample room for Otter Tail Power Company to always be able to average out startup and shutdown emissions.

As noted above, the separated over-fire air and selective catalytic reduction system do not operated efficiently during startup and shut down due to technological reasons. DENR pulled hourly nitrogen oxide emissions from EPA’s Clean Air Markets for calendar year 2006, 2007, and 2008 for Otter Tail Power Company’ s Big Stone I facility. To estimate the hourly emissions rates, DENR defined a startup as the time period that indicated emissions and at electrical rate of 0 megawatts to an electrical ra te of 200 megawatts. A shutdown period was defined in the opposite di rection. Table 1-3 indicates the startup and shutdown periods, including the hourly da ta for pounds per million Btus, hourly data for pounds of emissions, hourly electrical loa d, and the average emi ssion rates in pounds per million Btu and pounds per hour for each startup and shutdown episode. Table 1-3 demonstrates and including the diluent appr oach recommended by EPA, Otter Tail Power Company cannot meet the 0.10 pound per million Btu emission limit averaged over the startup and shutdown period. However, Otte r Tail Power Company can generally meet the pound per hour emission limit (e.g., 561 pounds per hour) averaged over the startup and shutdown period

Table 1-3 – Otter Tail Nitrogen Oxide Comparison Time Period Date Hour Operated Operational Load (megawatts) Emission Rate (lbs/MMBtus) Emission (lbs/hour)

Shutdown 02/11/2006 1 173 0.602 1374.125 02/11/2006 2 38 0.382 59.106 02/11/2006 3 0 Startup 02/12/2006 11 0 02/12/2006 12 0 0.017 1.174 02/12/2006 13 0 0.05 10.825 02/12/2006 14 0 0.506 221.729 02/12/2006 15 0 0.583 370.671 02/12/2006 16 1 0.562 427.232 02/12/2006 17 31 0.56 769.328 02/12/2006 18 95 0.55 871.09 Average 0.42 456.14

Shutdown 02/24/2006 15 299 0.814 2845.988 02/24/2006 16 0 Startup 02/24/2006 19 0 02/24/2006 20 0 0.311 18.271 02/24/2006 21 0 0.464 277.286 02/24/2006 22 25 0.494 446.082A-7 Time Period Date Hour Operated Operational Load (megawatts) Emission Rate (lbs/MMBtus) Emission (lbs/hour)

02/24/2006 23 190 0.608 1611.99 Average 0.54 1039.92

Shutdown 06/01/2006 16 93 0.73 921.453 06/01/2006 17 0 Startup 06/11/2006 17 0 06/11/2006 18 0 0.045 6.199 06/11/2006 19 0 0.104 21.882 06/11/2006 20 0 0.32 11.332 06/11/2006 21 0 06/11/2006 22 0 0.549 131.492 06/11/2006 23 0 0.844 435.757 06/12/2006 0 0 0.795 349.8 06/12/2006 1 0 0.747 463.364 06/12/2006 2 14 0.734 568.923 06/12/2006 3 30 0.708 669.98 06/12/2006 4 113 0.674 1117.088 Average 0.57 427.02

Shutdown 06/13/2006 18 77 0.596 551.082 06/13/2006 19 0 Startup 06/14/2006 3 0 06/14/2006 4 0 0.724 100.301 06/14/2006 5 0 0.679 427.974 06/14/2006 6 5 0.723 538.418 06/14/2006 7 132 0.613 1270.197 Average 0.67 577.59

Shutdown 09/29/2006 20 88 0.68 604.077 09/29/2006 21 0 Startup 09/30/2006 18 0 09/30/2006 19 0 0.092 7.888 09/30/2006 20 0 0.362 122.827 09/30/2006 21 0 0.651 381.616 09/30/2006 22 0 0.541 346.294 09/30/2006 23 66 0.467 681.68 10/01/2006 0 194 0.566 1434.98 Average 0.48 511.34A-8 Time Period Date Hour Operated Operational Load (megawatts) Emission Rate (lbs/MMBtus) Emission (lbs/hour)

Shutdown 11/21/2006 21 107 0.656 865.93 11/21/2006 22 0 Startup 11/22/2006 20 0 11/22/2006 21 0 0.065 1.192 11/22/2006 22 0 0.142 40.953 11/22/2006 23 0 0.672 389.491 11/23/2006 0 0 0.733 520.723 11/23/2006 1 1 0.695 265.063 11/23/2006 2 9 0.731 559.434 11/23/2006 3 47 0.632 716.625 11/23/2006 4 186 0.567 1313.852 Average 0.54 519.25

Shutdown 01/02/2007 19 90 0.618 603.57 01/02/2007 20 Startup 01/03/2007 17 01/03/2007 18 0 0.073 9.252 01/03/2007 19 0 0.533 193.053 01/03/2007 20 0 0.733 456.439 01/03/2007 21 10 0.767 597.34 01/03/2007 22 39 0.793 855.25 01/03/2007 23 164 0.526 1137.159 Average 0.58 550.29

Shutdown 01/05/2007 21 94 0.683 751.163 01/05/2007 22 Startup 01/06/2007 16 01/06/2007 17 0 0.099 1.899 01/06/2007 18 0 0.125 23.425 01/06/2007 19 0 0.599 273.204 01/06/2007 20 0 0.644 375.71 01/06/2007 21 13 0.613 534.352 01/06/2007 22 39 0.67 738.742 01/06/2007 23 183 0.523 1227.429 Average 0.49 490.74

Shutdown 03/02/2007 20 107 0.599 722.297 03/02/2007 21 Startup 03/04/2007 17A-9 Time Period Date Hour Operated Operational Load (megawatts) Emission Rate (lbs/MMBtus) Emission (lbs/hour)

03/04/2007 18 0 0.514 27.494 03/04/2007 19 0 0.037 7.659 03/04/2007 20 0 0.513 265.734 03/04/2007 21 0 0.727 421.66 03/04/2007 22 0 0.667 468.568 03/04/2007 23 29 0.679 718.314 03/05/2007 0 123 0.624 1096.68 Average 0.55 466.05

Shutdown 04/24/2007 18 178 0.478 1022.633 04/24/2007 19 87 0.623 677.964 04/24/2007 20 Startup 04/26/2007 19 04/26/2007 20 0 0.018 1.782 04/26/2007 21 0 0.079 20.311 04/26/2007 22 0 0.417 276.93 04/26/2007 23 0 0.426 262.033 04/27/2007 0 0 0.431 269.03 04/27/2007 1 19 0.572 446.314 04/27/2007 2 25 0.502 293.903 04/27/2007 3 131 0.539 1043.019 Average 0.41 431.39

Shutdown 05/24/2007 19 104 0.642 858.323 05/24/2007 20 Startup 05/26/2007 2 05/26/2007 3 0 0.009 0.839 05/26/2007 4 0 0.091 23.687 05/26/2007 5 0 0.423 287.598 05/26/2007 6 0 0.362 194.756 05/26/2007 7 23 0.622 565.274 05/26/2007 8 38 0.748 769.393 05/26/2007 9 164 0.571 1241.068 Average 0.43 492.62

Shutdown 06/09/2007 18 96 0.598 679.388 06/09/2007 19 Startup 06/10/2007 21 06/10/2007 22 0 0.001 0.041A-10 Time Period Date Hour Operated Operational Load (megawatts) Emission Rate (lbs/MMBtus) Emission (lbs/hour)

06/10/2007 23 0 0.031 5.05 06/11/2007 0 0 0.254 140.919 06/11/2007 1 0 0.449 328.354 06/11/2007 2 40 0.665 737.286 06/11/2007 3 115 0.519 843.738 Average 0.36 390.68

Shutdown 10/24/2007 16 75 0.6 620.34 10/24/2007 17 0 0.197 11.194 10/24/2007 18 Startup 12/23/2007 1 12/23/2007 2 0 0.447 120.474 12/23/2007 3 0 0.322 123.712 12/23/2007 4 0 0.322 129.283 12/23/2007 5 0 0.322 135.787 12/23/2007 6 0 0.322 139.523 12/23/2007 7 0 0.322 145.415 12/23/2007 8 0 0.322 152.242 12/23/2007 9 0 0.322 154.785 12/23/2007 10 0 0.322 156.395 12/23/2007 11 0 0.322 154.85 12/23/2007 12 0 0.227 76.885 12/23/2007 13 0 0.213 63.261 12/23/2007 14 0 0.02 1.135 12/23/2007 15 0 0.34 173.842 12/23/2007 16 0 0.303 116.443 12/23/2007 17 0 0.157 34.54 12/23/2007 18 0 0.018 0.965 12/23/2007 19 0 0.033 5.448 12/23/2007 20 0 0.045 9.436 12/23/2007 21 0 0.025 2.915 12/23/2007 22 0 0.024 2.825 12/23/2007 23 0 0.043 8.05 12/24/2007 0 0 0.026 2.426 12/24/2007 1 0 0.023 2.167 12/24/2007 2 0 0.04 7.504 12/24/2007 3 0 0.029 4.045 12/24/2007 4 0 0.023 2.705 12/24/2007 5 0 0.147 38.22A-11 Time Period Date Hour Operated Operational Load (megawatts) Emission Rate (lbs/MMBtus) Emission (lbs/hour)

12/24/2007 6 0 0.285 133.864 12/24/2007 7 0 0.328 175.71 12/24/2007 8 0 0.351 188.873 12/24/2007 9 19 0.47 369.091 12/24/2007 10 35 0.529 520.642 12/24/2007 11 133 0.707 1437.543 Average 0.24 150.63

Shutdown 12/26/2007 3 175 0.504 279.831 12/26/2007 4 Startup 12/26/2007 5 0 0.33 117.488 12/26/2007 6 0 0.389 212.122 12/26/2007 7 96 0.649 1016.529 Average 0.47 406.49

Shutdown 12/29/2007 1 180 0.695 1453.662 12/29/2007 2 34 0.233 31.958 12/29/2007 3 Startup 12/30/2007 19 12/30/2007 20 0 0.026 4.602 12/30/2007 21 0 0.045 10.372 12/30/2007 22 0 0.137 62.623 12/30/2007 23 0 0.432 296.784 12/31/2007 0 17 0.551 472.262 12/31/2007 1 64 0.807 1078.394 12/31/2007 2 139 0.72 1533.816 12/31/2007 3 174 0.636 1602.974 Average 0.43 654.74

Shutdown 01/04/2008 23 105 0.694 737.778 01/05/2008 0 Startup 01/05/2008 20 01/05/2008 21 0 0.013 1.418 01/05/2008 22 0 0.07 17.43 01/05/2008 23 0 0.305 165.249 01/06/2008 0 0 0.396 205.366 01/06/2008 1 0 0.345 200.238 01/06/2008 2 0 0.298 137.497 01/06/2008 3 15 0.458 378.903A-12 Time Period Date Hour Operated Operational Load (megawatts) Emission Rate (lbs/MMBtus) Emission (lbs/hour)

01/06/2008 4 141 0.592 1201.05 Average 0.35 338.33

Shutdown 04/22/2008 23 69 0.746 427.085 04/23/2008 0 Startup 04/24/2008 23 04/25/2008 0 0 0.001 0.142 04/25/2008 1 0 0.049 17.542 04/25/2008 2 0 0.294 188.807 04/25/2008 3 0 0.358 217.986 04/25/2008 4 61 0.654 868.316 04/25/2008 5 188 0.544 1331.658 Average 0.38 435.93

Shutdown 05/21/2008 18 117 0.715 930.358 05/21/2008 19 6 0.044 0.265 05/21/2008 20 Startup 05/30/2008 17 05/30/2008 18 0 0.004 0.416 05/30/2008 19 0 0.014 4.064 05/30/2008 20 0 0.167 77.505 05/30/2008 21 0 0.226 100.819 05/30/2008 22 0 0.36 220.464 05/30/2008 23 0 0.288 163.037 05/31/2008 0 21 0.512 493.363 05/31/2008 1 48 0.638 719.345 05/31/2008 2 182 0.705 1672.33 Average 0.33 398.36

Shutdown 08/05/2008 22 147 0.637 1097.806 08/05/2008 23 64 0.603 410.779 08/06/2008 0 Startup 08/06/2008 20 08/06/2008 21 0 0.008 0.225 08/06/2008 22 0 0.107 27.927 08/06/2008 23 0 0.421 252.263 08/07/2008 0 0 0.419 203.089 08/07/2008 1 7 0.416 93.626 08/07/2008 2 4 0.303 83.096A-13 Time Period Date Hour Operated Operational Load (megawatts) Emission Rate (lbs/MMBtus) Emission (lbs/hour)

08/07/2008 3 38 0.791 820.821 08/07/2008 4 143 0.708 1408.849 08/07/2008 5 195 0.665 1648.734 Average 0.44 494.94

Shutdown 09/15/2008 22 159 0.683 1067.529 09/15/2008 23 Startup 09/17/2008 1 09/17/2008 2 0 0.007 0.161 09/17/2008 3 0 0.014 2.155 09/17/2008 4 0 0.242 102.656 09/17/2008 5 0 0.325 163.962 09/17/2008 6 5 0.533 407.372 09/17/2008 7 31 0.659 591.848 09/17/2008 8 120 0.629 1063.324 Average 0.39 424.88

Shutdown 11/08/2008 15 146 0.572 841.469 11/08/2008 16 44 0.05 2.713 11/08/2008 17 Startup 11/10/2008 1 11/10/2008 2 0 0.006 0.173 11/10/2008 3 0 0.011 2.032 11/10/2008 4 0 0.093 22.878 11/10/2008 5 0 0.472 320.205 11/10/2008 6 0 0.536 363.73 11/10/2008 7 24 0.621 624.043 11/10/2008 8 78 0.667 971.352 11/10/2008 9 195 0.37 921.152 Average 0.34 406.97

Table 1-3 indicates that Otter Tail Power Company’s startup and shutdown periods may have an emission rate of 0.2 to 0.7 pounds per million Btus. Table 1-4 illustrates how many days and how many hours of startup/shutdown periods may occur before an exceedance of the0.10 pounds per million Btu emissions limit occurs assuming the non-startup and nonshutdown periods are at a constant emission rate in pounds per million Btus.A-14 Table 1-4 – 30-Day Startup/Shutdown Com parison (pounds per million Btus) Emissions During Normal Operation Normal Operations Startup/Shutdown Emissions Startup/Shutdown Operations Average Emission Rate 0.05 26 days 0.5 4 days 0.11 0.06 26 days 0.5 4 days 0.12 0.07 27 days 0.5 3 days 0.11 0.08 28 days 0.5 2 days 0.11 0.09 28 days 0.5 2 days 0.12

0.05 27 days 0.6 3 days 0.105 0.06 27 days 0.6 3 days 0.114 0.07 28 days 0.6 2 days 0.105 0.08 28 days 0.6 2 days 0.115 0.09 29 days 0.6 1 day 0.107

0.05 632 hours 0.5 88 hours 0.105 0.06 646 hours 0.5 74 hours 0.105 0.07 661 hours 0.5 59 hours 0.105 0.08 677 hours 0.5 43 hours 0.105 0.09 698 hours 0.5 22 hours 0.105

0.05 648 hours 0.6 72 hours 0.105 0.06 660 hours 0.6 60 hours 0.105 0.07 672 hours 0.6 48 hours 0.105 0.08 685 hours 0.6 35 hours 0.105 0.09 693 hours 0.6 27 hours 0.106

Table 1-4 indicates Otter Tail Power Company would have to limit its startup and shutdown emissions to less than 3% to 13% of its operations. The duration and frequency of the startup and shutdown periods are due to malfunction or planned outages of the emission unit or control device.

The concept of duration and frequency of startup and shutdown periods was a consideration in the consent decree for th e Baldwin facility. The consent decree identifies that the nitrogen oxide emissions occurring during a fift h startup during a 30- day period may be excluded from 30-day ro lling average calcula tions. Table 1-3 indicates a startup and shutdown period c overs approximately 10 hours which could occur over a two day period. Depending on the emission during non-startup and nonshutdown periods, this means Otter Tail Powe r Company could have approximately 1 to 9 startup and shutdown periods before an exceedance would occur.

As indicated by EPA, the emission rate during normal operation will have to be lower than 0.10 pounds per million Btus to account for startup and shutdown periods. Even though theA-15 emission rate (pounds per hour) used in the modeling analysis for visibility would not change, this approach would change the cost analysis for step 4 of the BART determination. The visibility and emission reduction used in the analysis will not change with the change in the emission limit to include startup and shutdown emissions. However, qualitatively, the cost of compliance both on a dollar per ton basis and a dollar per deciview would increase because at a minimum the operation and maintenance cost would increase. In addition, depending on how hard the system is pushed to meet the revised limit, the non-air environmental impacts required in step 4 of a BART determination may be significantly impacted due to the additional raw material used, the degradation of catalysts, etc. that were not accounted for by EPA.

EPA did not provide any evidence that the incr eased costs and non-air environmental impacts were accounted for when EPA identified 0.10 pounds per million Btu, including startup and shutdown in EPA’s BART determination. DENR believes its case-by-case BART determination took all of this in account when determining the BART emission limits during normal operation and operations that include startup and shutdown.

EPA’s Comment: EPA also identified there were two boilers at the Illinois Baldwin power plant burning powder river basin coal with a similar firing design as Otter Tail Power Company and accepted an emission limit 0.10 pound per million Btus on a 30-day rolling average, including startup and shutdown emissions (with limited exceptions).

Response: The Baldwin power plant uses a selective catalytic reduction system to minimize nitrogen oxide emissions

. DENR pulled daily average nitrogen oxide emissions from EPA’s Clean Air Markets for calendar year 2007, 2008, 2009, and 2010 for the Baldwin Power Plant. The Baldwin Power Plan t operates three coal fired boilers. DENR determined that Unit #1 and #2 are cyclone fi red boilers and Unit #3 is a tangential fired boiler. Using the daily information, DENR reviewed the pound per million Btus emission rate associated with startup and shutdown periods for Unit #1 and #2. Table 1-5 and Table 1-6 lists those emission rates and compares them to the nitrogen oxide pound per million Btus emission limit for Otter Ta il Power Company, which excludes startup and shutdown.

Table 1-5 – Baldwin Unit #1 nitrogen oxide comparison (pounds per million Btus) Date Daily Hours Operated Baldwin Emission Rate Otter Tail Limit Compliance Issue? 03/27/2007 1 0.756 0.1 Yes 03/31/2007 14 0.3171 0.1 Yes 04/01/2007 24 0.1157 0.1 Yes 07/27/2007 4 0.241 0.1 Yes 07/29/2007 9 0.2823 0.1 Yes 09/08/2007 5 0.2696 0.1 Yes 09/09/2007 24 0.1755 0.1 Yes 10/27/2007 2 0.343 0.1 YesA-16 Date Daily Hours Operated Baldwin Emission Rate Otter Tail Limit Compliance Issue? 10/28/2007 6 0.2118 0.1 Yes 10/31/2007 21 0.1564 0.1 Yes 11/05/2007 14 0.1258 0.1 Yes 11/08/2007 24 0.2024 0.1 Yes 01/15/2008 24 0.1835 0.1 Yes 03/03/2008 24 0.1945 0.1 Yes 04/05/2008 8 0.1259 0.1 Yes 05/15/2008 9 0.3036 0.1 Yes 05/16/2008 16 0.3736 0.1 Yes 05/17/2008 24 0.3186 0.1 Yes 06/02/2008 24 0.2752 0.1 Yes 06/05/2008 21 0.2018 0.1 Yes 08/21/2008 23 0.1985 0.1 Yes 09/27/2008 2 0.5265 0.1 Yes 09/28/2008 4 0.2725 0.1 Yes 09/29/2008 24 0.1736 0.1 Yes 10/22/2008 22 0.2235 0.1 Yes 11/14/2008 23 0.2243 0.1 Yes 01/15/2009 24 0.2557 0.1 Yes 02/27/2009 24 0.3135 0.1 Yes 04/20/2009 24 0.1993 0.1 Yes 06/11/2009 24 0.1836 0.1 Yes 08/03/2009 22 0.1721 0.1 Yes 08/10/2009 12 0.3396 0.1 Yes 08/15/2009 8 0.4135 0.1 Yes 08/16/2009 4 0.1725 0.1 Yes 08/17/2009 24 0.2097 0.1 Yes 08/30/2009 24 0.1929 0.1 Yes 11/01/2009 22 0.3054 0.1 Yes 02/08/2010 22 0.289 0.1 Yes 04/07/2010 2 0.5705 0.1 Yes 04/11/2010 22 0.2294 0.1 Yes 04/17/2010 3 0.4733 0.1 Yes 04/18/2010 5 0.1856 0.1 Yes 04/19/2010 24 0.1678 0.1 Yes 04/30/2010 1 0.666 0.1 Yes 05/02/2010 22 0.206 0.1 Yes 05/20/2010 5 0.2612 0.1 Yes 05/21/2010 24 0.1395 0.1 Yes 06/07/2010 9 0.3441 0.1 YesA-17 Date Daily Hours Operated Baldwin Emission Rate Otter Tail Limit Compliance Issue? 08/01/2010 6 0.1997 0.1 Yes 08/03/2010 2 0.351 0.1 Yes 08/04/2010 24 0.2099 0.1 Yes 09/15/2010 1 0.356 0.1 Yes 09/16/2010 18 0.3339 0.1 Yes 09/17/2010 15 0.2033 0.1 Yes 11/17/2010 20 0.2565 0.1 Yes 12/19/2010 24 0.2053 0.1 Yes

Table 1-6 – Baldwin Unit #2 nitrogen oxide comparison (pounds per million Btus) Date Daily Hours Operated Baldwin Emission Rate Otter Tail Limit Compliance Issue? 02/08/2007 2 0.606 0.1 Yes 02/14/2007 10 0.2926 0.1 Yes 02/15/2007 24 0.2303 0.1 Yes 06/08/2007 2 0.463 0.1 Yes 06/10/2007 16 0.3688 0.1 Yes 07/27/2007 15 0.2498 0.1 Yes 09/03/2007 23 0.1617 0.1 Yes 11/01/2007 2 0.6675 0.1 Yes 11/04/2007 16 0.2603 0.1 Yes 12/15/2007 8 0.3126 0.1 Yes 12/16/2007 5 0.3124 0.1 Yes 12/17/2007 24 0.2498 0.1 Yes 02/06/2008 3 0.464 0.1 Yes 02/08/2008 6 0.2715 0.1 Yes 02/09/2008 24 0.2022 0.1 Yes 03/07/2008 10 0.2415 0.1 Yes 03/08/2008 24 0.1987 0.1 Yes 04/05/2008 24 0.1901 0.1 Yes 04/27/2008 23 0.2722 0.1 Yes 05/25/2008 14 0.3313 0.1 Yes 05/26/2008 22 0.2946 0.1 Yes 09/20/2008 2 0.637 0.1 Yes 09/22/2008 17 0.3627 0.1 Yes 01/19/2009 10 0.2123 0.1 Yes 01/20/2009 24 0.211 0.1 Yes 02/17/2009 1 0.583 0.1 Yes 02/28/2009 10 0.2059 0.1 Yes 03/01/2009 16 0.3068 0.1 YesA-18 Date Daily Hours Operated Baldwin Emission Rate Otter Tail Limit Compliance Issue? 03/03/2009 21 0.1631 0.1 Yes 04/01/2009 14 0.2911 0.1 Yes 05/16/2009 11 0.2924 0.1 Yes 06/21/2009 4 0.2038 0.1 Yes 06/22/2009 24 0.1917 0.1 Yes 07/11/2009 2 0.551 0.1 Yes 07/12/2009 10 0.2485 0.1 Yes 11/13/2009 2 0.31 0.1 Yes 11/14/2009 16 0.2763 0.1 Yes 11/15/2009 24 0.2673 0.1 Yes 11/16/2009 1 0.259 0.1 Yes 11/17/2009 22 0.2221 0.1 Yes 11/26/2009 1 0.494 0.1 Yes 11/29/2009 13 0.2737 0.1 Yes 12/02/2009 2 0.4035 0.1 Yes 12/04/2009 18 0.1707 0.1 Yes 12/25/2009 3 0.5653 0.1 Yes 12/27/2009 6 0.201 0.1 Yes 02/03/2010 24 0.2168 0.1 Yes 04/03/2010 1 0.465 0.1 Yes 04/04/2010 4 0.1995 0.1 Yes 04/05/2010 24 0.1643 0.1 Yes 07/29/2010 3 0.4413 0.1 Yes 08/01/2010 15 0.2837 0.1 Yes 08/05/2010 24 0.1583 0.1 Yes 09/04/2010 3 0.4367 0.1 Yes 09/07/2010 9 0.1922 0.1 Yes 09/10/2010 24 0.2345 0.1 Yes 10/17/2010 21 0.2178 0.1 Yes 11/06/2010 2 0.2345 0.1 Yes 11/09/2010 24 0.1828 0.1 Yes

Table 1-5 and 1-6 indicates the two cyclone units at the Baldwin Energy facility are unable to meet the emission rate of 0.1 pounds per million Btus during a startup and shutdown period based on a daily average.

2. South Dakota requested information on what other states are meeting nitrogen oxide limits below 0.1 pounds per mil lion Btus and on the diluent cap.

EPA’s Comment: South Dakota’s pounds per million Btus BART limit for nitrogen oxide is higher than other st ates’ and provided examples.A-19 Response: The Clean Air Act provides states, not EPA, with the primary authority to determine BART for sources within their indivi dual states by weighi ng the five statutory criteria set forth in the Clean Air Act. EPA’s attempt to make BART consistent throughout the nation by comparing BART em ission limits and denying a state’s BART determination just because it is not the lo west conflicts with the Clean Air Act and federal regulations. Therefore, EPA should en sure states are following the case-by-case basis BART determination requirements in th e Clean Air Act instead of trying to make every state’s BART determination consistent.

EPA provided a list of coal fi red boilers in an excel spreadsheet representing achievable emission rates. These emission rates represen t boilers with a different firing design than used by Otter Tail Power Company and are not specifically comparable. Regardless, DENR pulled daily average nitrogen oxide em issions from EPA’s Clean Air Markets for calendar year 2009. DENR pulled out the da ys that operated less than 24 hours and assumed these days represented startup and shutdown operations of the boilers. DENR then ranked those daily readings . Table 1-7 identifies the ra nge of the three highest daily average nitrogen oxide emission rates in pound per million Btus and compares them to the nitrogen oxide pound per million Btus em ission limit for Otter Tail Power Company, which excludes startup and shutdown. Table 1-7 indicates that on a day when a startup and/or shutdown period occurs the pound per million Btus emission rates are higher than the limit established for Otter Tail Power Company.

Table 1-7 – Daily Nitrogen Oxide Emission Rate Plant Name Unit Top Three Emission Rate Startup / Shutdown (pound per MMBtus) Otter Tail Limit (pound per MMBtus) Compliance Issue?

Belews Creek 1 0.24 to 0.31 0.1 Yes Belews Creek 2 0.36 to 0.59 0.1 Yes Cardinal 1 0.24 to 0.28 0.1 Yes Cardinal 2 0.29 to 0.49 0.1 Yes Cardinal 3 0.26 to 0.75 0.1 Yes Chesapeake Energy 3 0.08 to 0.17 0.1 Maybe Chesterfield 5 0.18 to 0.39 0.1 Yes Chesterfield 6 0.13 to 0.18 0.1 Yes E D Edwards 3 0.11 to 0.14 0.1 Yes Havana 9 0.24 to 0.31 0.1 Yes John E Amos 1 0.26 to 0.44 0.1 Yes John E Amos 2 0.11 to 0.16 0.1 Yes Kingston 1 0.09 to 0.16 0.1 Maybe Kingston 2 0.13 to 0.23 0.1 Yes Kingston 5 0.07 to 0.13 0.1 MaybeA-20 Plant Name Unit Top Three Emission Rate Startup / Shutdown (pound per MMBtus) Otter Tail Limit (pound per MMBtus) Compliance Issue?

Kingston 6 0.11 to 0.17 0.1 Yes Kingston 7 0.13 to 0.20 0.1 Yes Kingston 8 0.13 to 0.16 0.1 Yes Kingston 9 0.33 to 0.49 0.1 Yes Mitchell (WV) 1 0.23 to 0.41 0.1 Yes Mitchell (WV) 2 0.26 to 0.40 0.1 Yes Pleasant Prairie 1 0.11 to 0.21 0.1 Yes TS Power Plant 1 0.12 to 0.12 0.1 Yes W A Parish WAP7 0.05 to 0.11 0.1 No W A Parish WAP8 0.05 to 0.10 0.1 No Walter Scott Jr. 4 0.05 to 0.09 0.1 No

EPA did not provide any evidence to indica te the sulfur dioxide emission limit was not reflective of the control technology selecte d. Based on DENR’s BART determination, which is a state’s case-by-case evaluation, DENR disagrees with EPA and believes the 0.09 pounds per million Btu limit during normal operation and the 505 pounds per hour limit, which includes startup a nd shutdown periods is BART.

DENR’s BART emission limits were based on a case-by-case BART determination using the five factor analysis. The pounds per hour BART emission limits which represents the worst case scenario were modeled using EPA approved models and determined that Big Stone I would not contribute to any visibility impairment in any Class I areas in South Dakota or in other states. This analysis is based on EPA’s guidelines for a BART determination in 40 CFR Part 51, Appendix Y. Therefore, DENR established BART emission limits that meet the Clean Air Act and Regional Haze program requirements, are being met on a continuous basis, and are enforceable.

3. South Dakota suggested that pounds per million Btu emission limits are not required in a regional haze state implementati on plan, just limits of some form (e.g., pounds per hour) that correspond to modeling results of less than 0.5 deciview impact.

EPA’s Comment: EPA comments that the regulations are clear that the rule intended the enforceable limits for electrical generating units be established on a pounds per million Btus basis using a 30-day rolling average. EPA specifically notes the following:

a. 40 CFR 51.308(e)(1)(ii)(B);A-21 b. The presumptive limits on a pound per million Btu basis as noted in 70 FR 39172 and in particular, the presumptive limit of 0.10 pounds per MMBtu for cyclone units burning subbituminous coal using a sele ctive catalytic re duction system;

c. The rule specifies a 30-day rolling average for electrical generating units and contain a definition of “boiler operati ng” that is consistent with the definition in the proposed revisions to the NSPS for utility boilers in 40 CFR Part 60, Subpart Da; and d. All nitrogen oxide emission limits propos ed for utility boilers under BART, regardless of the state or EPA region, have been in pounds per million Btus.

Response: 40 CFR 51.308(e)(1)(ii)(B) specifies that “the determination of BART for fossil-fuel fired power plants having a to tal generating capacity greater than 750 megawatts must be made pursuant to the guideli nes in appendix Y of this part (Guidelines for BART Determinations Under the Regiona l Haze Rule). Otter Tail Power Company’s Big Stone facility is not gr eater than 750 megawatts. Th erefore, Otter Tail Power Company is not required to follow or im plement the requirements in Appendix Y.

EPA references the presumptive limits and refe renced in the July 6, 2005, federal register notice (Volume 70 pages 39104 through 39172) of the final rules for the Regional Haze Regulations and Guideline for Best Ava ilable Retrofit Technology. The presumptive limits are identified in 40 CF R Part 51 Appendix Y. As noted above Otter Tail Power Company is not applicable to Appendix Y.

In addition, in response to comments EPA not ed in the federal register on page 39108 that “Having carefully consid ered the comments and furthe r reviewed the CAA and the legislative history, we have c oncluded that it would not be a ppropriate for EPA to require States to use the guidelines in making BART determinations for other categories of sources. The better reading of the Act indicat es that Congress inte nded the guidelines to be mandatory only with respect to 750 megawatt power plants. Thus, while we acknowledge the State agency comments a nd the policy reasons support consistency across States, we are not requiring States to use the BART guideline for these other categories. In response to State concerns about equitable applic ation of the BART requirement to source owners with similar s ources in different States, we do encourage States to follow the guidelines for all source categories but are not re quiring States to do so. States should view the guide lines as helpful guidance for these other categories. We disagree with comments that the CAA and the legislative history prohi bit us from issuing guidance for other source categories. As th e guidelines make clear, States are not required to follow the approach in the guide lines for sources other than 750 megawatt power plants. As such, although we believe th at the guidelines provi de useful advice in implementing the BART provisions of the region al haze rule, we do not believe that they hamper State discretion in ma king BART determinations.”

EPA also references the requirements in 40 CFR Part 60, Subpart Da. The reference to 40 CFR Part 60, Subpart Da in the regulati on is identified in 40 CFR Part 51 Appendix Y. As noted above Otter Tail Power Company is not applicable to Appendix Y. InA-22 addition, the reference to Subpart Da is specific to the defi nition of operating day and not the emission limits. However, Subpart Da does not support the requirement that startup and shutdown emissions shall be included in the compliance determination for the pounds per million Btus limit.

40 CFR Part 60 Subpart Da at § 60.48Da (c) sp ecifies that “the PM emission standards under §60.42Da and the NO X emission standards under §60.4 4Da apply at all times except during periods of star tup, shutdown, or malfunction. The sulfur dioxide emission standards under §60.43Da apply at all times ex cept during periods of startup, shutdown, or when both emergency conditions exist and the procedures under paragraph (d) of this section are implemented.”

40 CFR Part 60 Subpart Da at § 60.48Da (g)(1) states “compliance with applicable 30- day rolling average SO 2 and NO X emission limitations is determined by calculating the arithmetic average of all hourly emission rates for SO 2 and NO X for the 30 successive boiler operating days, except for data obt ained during startup, shutdown, malfunction (NO X only), or emergency conditions (SO 2 only).”

40 CFR Part 60 Subpart Da at §60.51Da (b)(5) speci fies “identification of the times when emissions data have been excluded from the calculation of average emission rates because of startup, shut down, malfunction (NO X only), emergency conditions (SO 2 only), or other reasons, and justification for excl uding data for reasons other than startup, shutdown, malfunction, or emergency conditions must be reported to the Administrator for each 24-hour period.”

DENR agrees that the definition of “boiler operating” should be c onsistent with 40 CFR Part 60, Subpart Da and will revise the Regi onal Haze rules. DENR disagrees that the federal rule is clear that the rule intended for enforceable limits be established in pounds per million Btus using a 30-day rolling averag e. DENR would agree it is clear if the federal rules intended for the BART limits to be in pounds per million Btus for sources or all electrical generating units, the federal ru le would have specified this requirement. However, the federal rule is silent on this issue. Therefore, DE NR has the ability to define the emission limit, the averaging pe riod, etc. Even though not specifically commented upon, DENR will revise the rules to define how to calculate the 30-day rolling average.

4. South Dakota explained during the call that startup/shutdown events are rare at Big Stone (only about twice a year) and the po unds per hour limits apply anyway during those events. South Dakota asked where in the rules the pounds per million Btu limits must also apply during startup and shutdown. (Note, for clarity, Big Stone’s pounds per hour limits apply over a 30 day period and include periods of startup and shutdown. Therefore, the startup and s hutdown emissions are average to with normal operating emissions.A-23 EPA’s Comment: The rule states "Section 302(k) of the CAA requires emissions limits such as BART to be met on a continuous ba sis. Although this provision does not necessarily require the use of continuous emissions monitoring (CEMs), it is important that sources employ techniques that ensure compliance on a continuous basis" (70 FR 39172). The rule goes on to state "[m]onitoring requirements gene rally applicable to sources, including those that are subject to BART, are governed by other regulations. See, e.g. , 40 CFR part 64 (compliance assurance monitoring); 40 CFR 70.6(a)(3) (periodic monitoring); 40 CFR 70.6(c)(1) (sufficiency monitoring) (70 FR 39172). Therefore, it is clear that the rule intended for BART emission limits to be met on a continuous basis and did not provide either explicitly or implicitly exceptions for startup and shutdown.

Response: DENR was incorrect in stating that Bi g Stone I only had one or two startup and shutdowns per year. Big St one I has only one or two st artup and shutdown periods for planned routine maintenance. There are other startup and shut downs periods during the year related to the routine operations of the facility.

Section 302(k) of the Clean Air Act states the term “emission limitation” and emission standard” mean a requirement established by the State or th e Administrator which limits the quantity, rate, or concentration of emissi ons of air pollutants on a continuous basis, including any requirement relating to the opera tion or maintenance of a source to assure continuous emission reduction, a nd any design, equipment, work practice or operational standard promulgated under th is act. DENR does not disagree with EPA’s interpretation that 302(k) requires an emission limit to be met on a continuous basis. However, EPA response still does not answer and does not specify why an emission limit in pounds per hour, which includes startup and shutdown, is not an emission limit to be met on a continuous basis, does not meet the requireme nts of the regulations and specifically where it states that an emission limit in pounds per MMBtus must include emissions generated during startup and shutdown.



### B. Monitoring, Recordkeeping and Reporting

1. A compliance test method(s) for PM10 must be specified.

EPA’s Comment: South Dakota’s proposal to review the test protocol prior to testing to determine if the test method proposed is appropriate is an unacceptable form of director’s discretion. In addition, EPA states South Dakota’s performance rules do not specify who makes the determination regarding which of the hundred of test methods is “applicable”. EPA suggests adding the following language “...in accordance with the requirements and procedures set forth in EPA Test Method 5, 5B, 5D, 17, 201, or 201A.”

Response: 40 CFR § 60.8(b) states “performance tests shall be conducted and data reduced in accordance with the test methods and procedures contained in each applicable subpart unless the Administrator (1) specifies or approves, in specific cases, the use of a reference method with minor changes in methodology, (2) approves the use of an equivalent method, (3) approves the use of an alternative method the results of which he has determined to beA-24 adequate for indication whether a specific source is in compliance, (4) waives the requirement for performance tests because the owner or operator of a source has demonstrated by other means to the Administrator’s satisfaction that the affected facility is in compliance with the standard, or (5) approves shorter sampling times and smaller sample volumes when necessitated by process variables or other factors.”

40 CFR § 63.7 (b)(1) states “the owner or operator of an affected source must notify the Administrator in writing of his or her intention to conduct a performance test at least 60 calendar days before the performance test is initially scheduled to begin to allow the Administrator, upon request, to review and approve the site-specific test plan required under paragraph (c) of the is section and to have an observer present during the test.”

40 CFR § 63.7 (e)(2) states “performance tests shall be conducted and data reduced in accordance with the test methods and procedures set forth in this section, in each relevant standard, and, if required, in applicable appendices of parts 51, 60, 61, and 63 of this chapter unless the Administrator (i) specifies or approves, in specific cases, the use of a test method with minor changes in methodology, (ii) approves the use of an intermediate or major change or alternative to a test method, the results of which the Administrator has determined to be adequate for indicating whether a specific affected source is in compliance, (iii) a approves shorter sampling times or smaller sample volumes when necessary by process variables or other factors, or (iv) waives the requireme nt for performance tests because the owner or operator of an affected source has demonstrated by other means to the Administrator’s satisfaction that the affected facility is in compliance with the relevant standard.”

EPA regulations involving performance testing have several “director’s discretion” criteria. DENR performance testing specifies in Administrative Rule 74:36:11:01 stack performance testing or other testing methods – “all stack performance tests or other test methods must be made in accordance with the applicable method specified in 40 CFR § 60.17; Part 60, Appendix A; § 63.14; Part 63, Appendix A; and Part 51, Appendix M (all July 1, 2009). Therefore, the testing must be conducted in accordance with a method that EPA has approved and has completed a rule making process to incorporate that test method.

EPA suggested language contradicts EPA’s position. Each of the test methods specified reference other test methods. For example, EPA’s Method 5 specifies in a note “This method does not include all of the specifications and procedures essential to its performance. Some material is incorporated by reference from other methods in this part. Therefore, to obtain reliable results, persons using this method should have a through knowledge of at least the following additional test methods: Method 1, Method 2, Method 3. EPA language does not list all potentially applicable test methods needed to determine the particulate matter emission

rate.

As a practical matter and as South Dakota revises its regulations, it is easier to revise the performance test requirements in Administrative Rules Chapter 74:36:11 then to update performance testing requirements throughout othe r regulations. Repeating requirements in other sections generates a greater risk of ha ving regulations covering the same topic being different, which causes conflicting requirements.A-25 2. Specific Monitoring, Recordkeeping and Repo rting language must be incorporated into the State Implementation Plan.

EPA’s Comment: South Dakota’s Regional Haze program does not contain the elements necessary to make BART limits practically en forceable. The proposed State Implementation Plan contains controls, emission limits and general schedules but does not include specific averaging times, recordkeeping, monitoring, and schedules for compliance. The Clean Air Act requires that State Implementation Plans, including the Regional Haze State Implementation Plan, contain elements sufficient to ensure emission limits are practically enforceable. It is not sufficient to include thes e elements in a separate permit or agreement that is not made part of th e State Implementation Plan. EPA provided language DENR could use to address th e monitoring, recordkeeping and reporting requirements.

Response: DENR does not agree that the BART limits are not enforceable. Administrative Rules of South Dakota section 74:36:21:06 establishes the BART emission limits. In addition, it indicates compliance with the particul ate matter limit be based on an annual stack performance tests and the average of three 1-hour test runs. It also indicates compliance with the sulfur dioxide and nitrogen oxide limits shall be based on continuous emission monitoring equipment and a 30-day rolling average. DENR does agree the boiler operating and 30-day rolling average should be defined and will revise the Regional Haze rules appropriately. DENR also disagrees that the monitoring, recordkeeping, and reporting requirements are not specified since DENR referenced the same monitoring, recordkeeping and reporting language in DENR’s EPA approved Title V air quality permit program. DENR does agree to incorporate similar language pr oposed by EPA in the Regional Haze rules to address this concern.

3. Additional suggested improvements which South Dakota may opt to address and which EPA strongly encourages.

EPA’s Comment: EPA recommends South Dakota incorporate a Compliance Assurance Monitoring plan into the Regional Haze State Implementation Plan.

Response: A Compliance Assurance Monitoring plan is a requirement under 40 CFR Part 70 which is the Title V air quality permit requirements. A facility that must submit a compliance plan must establish operational limitations in which it can operate and stay in compliance with its permit limits. The operational limits are based on the facilities actual operations. In addition, typically if a facility installs continuous emission monitoring equipment it has satisfied the requirements under the Compliance Assurance Monitoring plan. Therefore, the only pollutant this would have to be developed for is for particulate matter. Requiring a Compliance Assurance Monitoring plan before the facility has installed and operated the new control devices would be unrealistic. Theref ore, DENR will establish the Compliance Assurance Monitoring plan when DENR incorporates the BART requirements in Big Stone I’s Title V air quality permit.A-26 EPA’s Comment: EPA recommends DENR reference 40 CFR Part 75 for the continuous emission monitoring systems instead of 40 CFR Part 60.

Response: DENR agrees and will revise the Regional Haze rules appropriately.



### C. Reasonable Progress Fo ur-Factor Analysis

1. Selective Non-Catalytic Reduction system must be carried through the 4-factor analysis for GCC Dacotah.

EPA’s Comment: WRAP’s report stated the Selective Non-Catalytic Reduction system is not applicable to long wet and dry kilns is out of date. EPA indicates the Selective NonCatalytic Reduction system is being used for wet cement kilns in Europe and Ash Grove Cement’s wet kiln in Midlothian, Texas was authorized to test a Selective Non-Catalytic Reduction system. Ash Grove Cement installed a full scale Selective Non-Catalytic Reduction system on one of its wet kilns and the system has been running for several months and achieving 35 to 40% nitrogen oxide reductions on a consistent basis.

Response: Although DENR does not agree that one plant operating for several months constitutes the system is capable, DENR will include a Selective Non-Catalytic Reduction system in the 4-factor analysis for GCC Dacotah.

2. Make necessary edits for correction of WRAP CMAQ modeling results.

EPA’s Comment: EPA is requesting that Table 7-1(a) for Badlands be revised in the technical document to reflect the correcti on of WRAP’s Plan02d CMAQ modeling results.

Response: DENR believes this revision can be made during the 5-year review but since DENR is already making changes to the technical document, DENR will review WRAP’s results and update the technical document appropriately.



### D. Reasonably Attributable Visibility Impairment

1. EPA is requesting that DENR reconsider ad opting the Reasonably Attributable Visibility Impairment rules which are currently under a Federal Implementation Plan.

EPA’s Comment: The Reasonably Attributable Visibility Impairment may be handled through South Dakota adopting it under its State Implementation Plan, revising the Regional Haze State Implementation Plan to clarify its in tention to coordinate the Regional Haze State Implementation Plan with EPA’s Federal Implementation Plan, or South Dakota does nothing and the burden remains with EPA to ensure proper coordination between the two implementation plan’s long term strategies occurs.A-27 Response: DENR plans on coordinating with EPA to ensure the long term strategies requirements are met for each program. DENR does agree to reconsider the first option once the Regional Haze State Implementation Plan has been approved by EPA and DENR has a chance to determine if it has the resources necessary to implement the Reasonably Attributable Visibility Impairment under its State Implementation Plan.B-1 ATTACHMENT B

ARTICLE 74:36

AIR POLLUTION CONTROL PROGRAM

Chapter 74:36:01 Definitions. 74:36:02 Ambient air quality. 74:36:03 Air quality episodes. 74:36:04 Operating permits for minor sources. 74:36:05 Operating permits for Part 70 sources. 74:36:06 Regulated air pollutant emissions. 74:36:07 New source performance standards. 74:36:08 National emission standards for hazardous air pollutants. 74:36:09 Prevention of significant deterioration. 74:36:10 New source review. 74:36:11 Performance testing. 74:36:12 Control of visible emissions. 74:36:13 Continuous emission monitoring systems. 74:36:14 Variances, Repealed. 74:36:15 Open burning, Transferred or Repealed. 74:36:16 Acid rain program. 74:36:17 Rapid City street sanding and deicing. 74:36:18 Regulations for state facilities in the Rapid City area. 74:36:19 Mercury budget trading program, Repealed. 74:36:20 Construction permits for new sources or modifications. 74:36:21 Regional haze program.

CHAPTER 74:36:21

REGIONAL HAZE PROGRAM

Section 74:36:21:01 Applicability. 74:36:21:02 Definitions. 74:36:21:03 Existing stationary facility defined. 74:36:21:04 Visibility impact analysis. 74:36:21:05 BART determination. 74:36:21:06 BART determination for a BART-eligible coal-fired power plant. 74:36:21:07 Installation of controls based on visibility impact analysis or BART determination. 74:36:21:08 Operation and maintenance of controls.B-2 74:36:21:09 Monitoring, recordkeeping, and reporting. 74:36:21:10 Permit to construct. 74:36:21:11 Permit required for BART determination. 74:36:21:12 Federal land manager notification and review.

74:36:21:01. Applicability. The provisions of this chapter a pply to the owner or operator of a new major source, modification to a major sour ce, and a BART-eligible source. The provisions of this chapter do not apply to a major source or major modification to an existing source applicable to chapters 74:36:09 and 74:36:10.

Source: 37 SDR 111, effective December 7, 2010. General Authority: SDCL 34A-1-6. Law Implemented: SDCL 34A-1-6.

74:36:21:02. Definitions. Unless otherwise specified, the terms used in this chapter mean:

(1) "Adverse impact on visibility," visib ility impairment that interferes with the management, protection, preservation, or enjoyment of the visitor's visual experience of the mandatory Class I federal area. Adverse impact on visibility shall be based on a case-by-case basis taking into account the geographic extent, intens ity, duration, frequency, and time of visibility impairment, and how these factors correlate with times of visitor use of a mandatory Class I federal area and the frequency and timing of natural conditions that reduce visibility;

(2) "BART," best available retrofit technology;

(3) "Best available retrofit technology" an emission limitation based on the degree of reduction achievable through the application of th e best system of continuous emission reduction for each pollutant that is emitted by an existing st ationary facility. The emission limitation must be established, on a case-by-case basis, taking into c onsideration the technology available, the costs of compliance, the energy and nonair quality envi ronmental impacts of compliance, any pollution control equipment in use or in existence at the s ource, the remaining useful life of the source, and the degree of improvement in visibility that may r easonable be anticipated to result from the use of such technology;

(4) "BART-eligible source," an existing stationary facility;

(5) "Coal-fired power plant," any pe rson, corporation, limited liability company, association, company, partnership, political subdivi sion, municipality, rural electric cooperative, consumers power district, or a ny group or combination acting as a unit, owning or holding under lease, or otherwise real property used, or intended for use, for the conversion of coal into electric

power;

(6) "Contribute to adverse impact on visibility," a change in visibility impairment in a mandatory Class I federal area of five-tenths deciviews or more, based on a 24-hour average, above the average natural visibility baselin e. A source exceeds the threshold if the 98 th percentileB-3 (eighth highest value) of the modeling results , based on one year of the three years of meteorological data modeled, equals or exceeds five-tenths deciviews;

(7) "Major source," as defined in § 74:36:01:08(2) and (3);

(8) "Mandatory Class I federal area," any ar ea identified in 40 C.F.R. § 81, Subpart D (July 1, 2009); and

(9) "Visibility impairment," any human per ceptible change in visibility such as light extinction, visual range, contrast, coloration, from that which would have existed under natural conditions ; and

(10) “30-day rolling average,” shall be e xpressed as pounds per million Btus and pounds per hour and calculated in accordance with the following procedures:

(a) Sum the total pounds of pollutant in que stion emitted from a unit during an operating day and the previous 29 operating days;

(b) Sum the total heat input to the unit in million Btus during the operating day and the previous 29 operating days;

(c) Sum the total hours the unit operated in hours during the day and the previous 29 operating days;

(d) For pounds per million Btus, divide th e total number of pounds of the pollutant emitted during the 30-day operating days by the total heat input during the 30-day operating days;

(e) For pounds per hour, divide the total number of pounds of the pollutant emitted during the 30-day operating days by the total hours operated during the 30-day operating days

.

A new 30-day rolling average shall be calculate d for each new operating day. Each 30-day rolling average shall include all emissions that occur during periods of startup and shutdown.

(11) “Operating day,” means a 24-hour pe riod between 12 midnight and the following midnight during which any fuel is combusted at any tim e in the unit. It is not necessary for fuel to be combusted the entire 24-hour period.

Source: 37 SDR 111, effective December 7, 2010. General Authority: SDCL 34A-1-6. Law Implemented: SDCL 34A-1-6.

74:36:21:03. Existing stationary facility defined. An existing stationary facility is any of the following stationary sources of air pollutants, including any reconstructed source that was not in operation before August 7, 1962, and was in existence on August 7, 1977, and has the potential to emit 250 tons per year or more of any air po llutant. In determining potential to emit, fugitive emissions, to the extent quantifiable, must be counted for:B-4 (1) Fossil-fuel fired steam electric plants of more than 250 million British thermal units per hour heat input; (2) Coal cleaning plants (thermal dryers); (3) Kraft pulp mills; (4) Portland cement plants; (5) Primary zinc smelters; (6) Iron and steel mill plants; (7) Primary aluminum ore reduction plants; (8) Primary copper smelters; (9) Municipal incinerators capable of charging more than 250 tons of refuse per day; (10) Hydrofluoric, sulfuric, and nitric acid plants; (11) Petroleum refineries; (12) Lime plants; (13) Phosphate rock processing plants; (14) Coke oven batteries; (15) Sulfur recovery plants; (16) Carbon black plants (furnace process); (17) Primary lead smelters; (18) Fuel conversion plants; (19) Sintering plants; (20) Secondary metal production facilities; (21) Chemical process plants; (22) Fossil-fuel boilers of more than 250 million British thermal units per hour heat input; (23) Petroleum storage and transfer facilities with a capacity exceeding 300,000 barrels; (24) Taconite ore processing facilities; (25) Glass fiber processing plants; and (26) Charcoal production facilities.

Source: 37 SDR 111, effective December 7, 2010. General Authority: SDCL 34A-1-6. Law Implemented: SDCL 34A-1-6.

74:36:21:04. Visibility impact analysis. The owner or operator of a new major source or modification to a major source shall demonstrate to the department that the potential to emit from the new major source or modification to a major source will not contribute to adverse impact on visibility in any mandatory Class I federal area. The demonstration shall be based on visibility models approved in 40 C.F.R. § 51, Subpart W (July 1, 2009).

Source: 37 SDR 111, effective December 7, 2010. General Authority: SDCL 34A-1-6. Law Implemented: SDCL 34A-1-6.

74:36:21:05. BART determination. The owner or operator of a BART-eligible source that emits any air pollutant which may reasonably be anticipated to contribute to adverse impact on visibility in any mandatory Class I federal ar ea shall submit a BART determination. The BART determination shall follow the procedures outlined in 40 C.F.R. § 51, Subpart Y (July 1, 2009) and must be based on an analysis of the best system of continuous emission control technologyB-5 available and associated emission reductions achie vable for each BART-eligible source. In this analysis, the BART determination must take into consideration the technology available, the costs of compliance, the energy and nonair quality envi ronmental impacts of compliance, any pollution control equipment in use at the source, the remain ing useful life of the s ource, and the degree of improvement in visibility that may reasonably be anticipated to result from the use of such technology. The BART determination shall be subm itted within nine months after being notified by the department that the existing stationary s ource is reasonably anticipated to contribute to adverse impact on visibility in any mandatory Class I federal area.

Source: 37 SDR 111, effective December 7, 2010. General Authority: SDCL 34A-1-6. Law Implemented: SDCL 34A-1-6.

74:36:21:06. BART determination for a BART-eligible coal-fired power plant. The owner or operator of a BART-eligib le coal-fired power plant may not cause or permit emissions of the following regulated air pollutant in excess of the following amounts:

(1) PM10 emissions in excess of 67.3 pounds per hour, which includes periods of startup and shutdown;

(2) PM10 emissions in excess of 0.012 pounds per million Btus, which includes periods of startup and shutdown;

(3) Sulfur dioxide emissions in excess of 505 pounds per hour, which includes periods of startup and shutdown;

(4) Sulfur dioxide emissions in excess of 0.09 pounds per million Btus, which does not include includes periods of startup and shutdown;

(5) Nitrogen oxide emissions in excess of 561 pounds per hour, which includes periods of startup and shutdown; and

(6) Nitrogen oxide emissions in ex cess of 0.10 pounds per million Btus, which does not include includes periods of startup and shutdown.

Compliance with the PM10 emission limits shall be based on an annual stack performance test using the performance testing methods in § 74:36:11 and using the average of three 1-hour test runs. Compliance with the sulfur dioxide and nitrogen oxide emission limits shall be based on using continuous emission monitoring systems and a 30-day rolling average.

Source: 37 SDR 111, effective December 7, 2010. General Authority: SDCL 34A-1-6. Law Implemented: SDCL 34A-1-6.

74:36:21:07. Installation of controls based on visibility impact analysis or BART determination. The owner or operator of a new major sour ce, modification to a major source, or a BART-eligible source that emits any air polluta nt which may reasonably be anticipated toB-6 contribute to adverse impact on visibility in a ny mandatory Class I federal area shall install, operate, and maintain the controls establishe d in a visibility impact analysis or BART determination. The owner or operator of a new major source or modification to a major source must install and operate the controls established in a visibility impact analysis at initial startup. The owner or operator of a BART-eligible source re quired to install BART must install, operate, and demonstrate compliance with BART as expeditiously as practicable, but no later than five years from EPA's approval of the state implementation plan for regional haze.

Source: 37 SDR 111, effective December 7, 2010. General Authority: SDCL 34A-1-6. Law Implemented: SDCL 34A-1-6.

74:36:21:08. Operation and maintenance of controls. The owner or operator required to install and operate controls established in a visib ility impact analysis or BART determination shall establish written procedures to ensure the contro l equipment is properly operated and maintained. The written procedures shall include, at a minimum, the following:

(1) A maintenance schedule for each cont rol device that is consistent with the manufacturer's instructions and recommendations for routine and long-term maintenance; (2) Procedures for the proper operation and maintenance of each control device; and (3) Parameters to be monitored to determine each control device is being operated properly.

Source: 37 SDR 111, effective December 7, 2010. General Authority: SDCL 34A-1-6. Law Implemented: SDCL 34A-1-6.

74:36:21:09. Monitoring, recordkeeping, and reporting. The owner or operator required to install and operate controls established in a visibility impact analysis or BART determination shall conduct periodic monitoring, recordkeeping, and reporting. All sulfur dioxide and nitrogen oxides emissions from the BART-eligible source sh all be routed to the main stack of a BARTeligible source. Monitoring of sulfur dioxide a nd nitrogen oxide emissions from the main stack of a BART-eligible source shall be conducted using a continuous emission monitoring system which complies with the continuous emission monitoring requirements in chapter 74:36:13 40 C.F.R. Part 75 (July 1, 2009) . Monitoring and related recordkeeping and reporting requirements for other air pollutants from a BART-eligible source or fr om a major source or modification of a major source shall consist of at least the following: be in accordance with § 74:36:05:16.01(9). Recordkeeping and reporting shall comply with the requirements in § 74:36:05:16.01(9)

.

(1) All emissions monitoring and analysis pr ocedures, alternative approved methods or test methods required in determining compliance with §§ 74:36:21:04 and 74:36:21:06;

(2) As necessary, documentation of the use, ma intenance, and if appropriate, installation of monitoring equipment or methods;

(3) Documentation of the following:

(a) The date, place, and time of sampling or measurements;B-7 (b) The date or dates analyses were performed; (c) The company or entity that performed the analyses; (d) The analytical techniques or methods used; (e) The results of such analyses; and (f) The operating conditions as existing at the time of sampling or measurement;

(4) Recordkeeping and reporting requirements that comply with the following:

(a) Submission of reports of any require d monitoring must occur at least every six months. Reports must clearly identify all exceedances with §§ 74:36:21:04 and 74:36:21:06. All required reports must be certified by a responsible official; and (b) Exceedances of §§ 74:36:21:04 and 74:36:21:06, including those attributable to upset conditions, the probable cause of such exceedan ce and any corrective actions or preventive measures taken must be promptly reported and certified by a responsible official; and

(5) Requirements for retention of monitoring records and all supporting documentation for at least five years from the date of the monitoring sample, measurement, report, or application.

Source: 37 SDR 111, effective December 7, 2010. General Authority: SDCL 34A-1-6. Law Implemented: SDCL 34A-1-6.

74:36:21:10. Permit to construct. The owner or operator subject to this chapter may be issued a permit to construct in accordance with ch apter 74:36:20 if the department determines that the new major source or modification to a major source does not contribute to adverse impact on visibility at a mandatory Class I federal area.

Source: 37 SDR 111, effective December 7, 2010. General Authority: SDCL 34A-1-6. Law Implemented: SDCL 34A-1-6.

74:36:21:11. Permit required for BART determination. The owner or operator of a BART-eligible source shall submit an applicati on in accordance with chapter 74:36:20 to include the controls, emission limits, monitoring, recordk eeping, and reporting requirements identified in the BART determination and approved by the department.

Source: 37 SDR 111, effective December 7, 2010. General Authority: SDCL 34A-1-6. Law Implemented: SDCL 34A-1-6.

74:36:21:12. Federal land manager notification and review. The department shall provide written notice to the federal land mana ger of a BART determination or any permit application for a new major source or modification to a major source if the emissions from which may contribute to adverse impact on visibility at a mandatory Class I federal area, except for an application submitted in accordance with chapte r 74:36:09 or 74:36:10. A no tification of a BART determination shall include a copy of the BART determination and must be submitted within 30 days of receipt of a complete BART determination. The department shall consider an analysisB-8 performed by the federal land manager submitted within 60 days of the federal land manager being notified of a BART determination or by the end of the public participation process, whichever is later. A permit application for a new major source or modification to a major source shall include a copy of the permit application and visibility impact analysis. The department shall consider an analysis performed by the federal land manager submitted within 30 days of the federal land manager being notified of a visibility impact anal ysis or by the end of the public participation process, whichever is later. The department shall follow the procedures outlined in chapter 74:36:09 or 74:36:10 for an application submitted in accordance with chapter 74:36:09 or 74:36:10.

Source: 37 SDR 111, effective December 7, 2010. General Authority: SDCL 34A-1-6. Law Implemented: SDCL 34A-1-6.