SO2 NOx PM FinePM Coarse3 SO2 NOx PM 98th Percentile Impact (dv) 98th Percentile

Improvement (dv) Class I

Area Meterological

Year Modeling performed by Basin Electric1 Precontrol 5970.0 813.0 16.5 138.7 No control Existing LNB Existing ESP 2.539 NA TRNP-SU 2002 Run 1 905.0 760.4 23.1 194.0 FGD at 90% Presumptive Existing ESP 0.832 1.707 TRNP-SU 2002 Run 2 633.5 760.4 23.1 194.0 FGD at 93% Presumptive Existing ESP 0.796 1.743 TRNP-SU 2002 Run 3 452.5 760.4 23.1 194.0 FGD at 95% Presumptive Existing ESP 0.627 1.912 TRNP-SU 2002 Run 4 905.0 603.0 23.1 194.0 FGD at 90% SOFA Existing ESP 0.703 1.836 TRNP-SU 2002 Run 5 633.5 603.0 23.1 194.0 FGD at 93% SOFA Existing ESP 0.662 1.877 TRNP-SU 2002 Run 6 452.5 603.0 23.1 194.0 FGD at 95% SOFA Existing ESP 0.524 2.015 TRNP-SU 2002 Supplemental4 452.5 441.0 23.1 194.0 FGD at 95% SOFA+SNCR Existing ESP 1.610 NA TRNP-SU 2002 1See Appendix C.4 of SIP.

4Represents the modeled impact from Units 1 and 2 combined. Individual unit impacts for the SOFA+SNCR control option were not supplied by NDDH. Scenario

3Emission rates reflecting PM control options were not modeled. Instead, the PM emission rate reflects control with the existing ESP. **Leland Olds Unit 1 CALPUFF Modeling** Emission Rate (lbs/hr)2 Control Option

2The precontrol emission rate reflects actual operation from the highest emitting day of the years 2000-2002 (meteorological period modeled per the NDDH BART protocol). By contrast, the control scenario emission rates assume operation at the boiler potential-to-emit heat input capacity of 2622 lb/MMBtu. In addition, the SO2 precontrol emission rate is based on a fuel sulfur content of 2.76 lb/MMBtu, while the SO2 control scenario emission rates are based on an assumed fuel sulfur content of 3.43 lb/MMBtu.

7/14/2011SO2 NOx PM FinePM Coarse3 SO2 NOx PM 98th Percentile Impact (dv) 98th Percentile

Improvement (dv) Class I

Area Meterological

Year Modeling performed by Basin Electric1,4 Precontrol 12205.0 3959.0 26.9 226.3 No control No control Existing ESP 4.924 NA TRNP-SU 2002 Run 1 885.3 1359.5 45.6 383.0 FGD at 95% ASOFA+RRI+SNCR Existing ESP 0.961 3.963 TRNP-SU 2002 Run 2 885.3 1559.5 45.6 383.0 FGD at 95% ASOFA+SNCR Existing ESP 1.050 3.874 TRNP-SU 2002 Run 3 885.3 2462.0 45.6 383.0 FGD at 95% ASOFA Existing ESP 1.445 3.479 TRNP-SU 2002 Modeling performed by ND Dept. of Health2,5 ND Run 1 880.5 395.9 45.6 383.0 FGD at 95% ASOFA+SCR Existing ESP 0.531 4.393 TRNP-SU 2002 1See Appendix C.4 of SIP. 2See Appendix B.4 of SIP.

5NDDH applied the assumed percent NOx reduction for the control scenario to the precontrol emission rate. 4The precontrol emission rate reflects actual operation from the highest emitting day of the years 2000-2002 (meteorological period modeled per the NDDH BART protocol). By contrast, the control scenario emission emission rates assume operation at the boiler potential-to-emit heat input capacity of 5130 MMBtu/hr. In addition, the SO2 precontrol emission rate is based on a fuel sulfur content of 2.76 lb/MMBtu, while the SO2 control scenario emission rates are based on an assumed fuel sulfur content of 3.43 lb/MMBtu. 3Emission rates reflecting PM control options were not modeled. Instead, the PM emission rate reflects control with the existing ESP. Control Option **Leland Olds Unit 2 CALPUFF Modeling**

Scenario Emission Rate (lbs/hr)

7/14/2011