Appendix 10.13 

Table 10-16 

Reference 4: 

Page 79 of "Colorado Visibility and Regional Haze State 

Implementation Plan for 12 Mandatory Class I Federal Areas", January 

7, 2011 
Colorado Visibility and Regional Haze State Implementation Plan for 12 Mandatory Class I Federal Areas 

Colorado Dept. of Public Health and Environment, Air Pollution Control Division 

Approved January 7, 2011 

1 

Colorado Visibility and Regional Haze 

State Implementation Plan for the 

Twelve Mandatory Class I Federal 

Areas in Colorado 

Colorado Air Pollution Control Division 

Revised Regional Haze Plan

Air Quality Control Commission, approved 01/07/2011 
Colorado Visibility and Regional Haze State Implementation Plan for 12 Mandatory Class I Federal Areas 

Colorado Dept. of Public Health and Environment, Air Pollution Control Division 

Approved January 7, 2011 

79 

Drake Unit 7 - SO2 Cost Comparison 

Alternative Emissions 

Reduction (tpy) 

Annualized Cost 

($) 

Cost Effectiveness 

($/ton) 

Baseline 0 $0 $0 

DSI 2,657 $3,723,826 $1,405 

Dry FGD (LSD) @ 82% control 

(0.15 lb/MMBtu annual average) 

3,632 $8,216,863 $2,263 

Dry FGD (LSD) @ 85% control 

(0.12 lb/MMBtu annual average) 

3,764 $8,829,321 $2,345 

Dry FGD (LSD) @ 90% control 

(0.08 lb/MMBtu annual average) 

3,986 $9,898,382 $2,483 

The energy and non-air quality impacts of the remaining alternative are as follows: 

 DSI - reduced mercury capture in the baghouse, fly ash contamination with 

sodium sulfate, rendering the ash unsalable as a replacement for concrete and 

rendering it landfill material only 

 Dry FGD – less mercury removal compared to unscrubbed units, significant water 

usage 

There are no remaining useful life issues for the alternatives as the sources will remain 

in service for the 20-year amortization period. 

The projected visibility improvements attributed to the alternatives are as follows: 

SO2 Control 

Method

Drake – Unit 5 Drake – Unit 6 Drake – Unit 7 

SO2 

Emission 

Rate 

(lb/MMBtu) 

98th 

Percentile 

Impact 

(Δdv)

SO2 

Emission 

Rate 

(lb/MMBtu) 

98th 

Percentile 

Impact 

(Δdv)

SO2 

Emission 

Rate 

(lb/MMBtu) 

98th 

Percentile 

Impact 

(Δdv)

Daily Max (3-yr) 0.94 1.00 0.99 

DSI (annual 

avg.) 

0.25 0.12 0.33 0.18 0.33 0.29 

Dry FGD (LSD) 

(annual avg.) 

Not 

feasible 

0.12 0.24 0.12 0.39 

Dry FGD (LSD) 

(annual avg.) 

Not 

feasible 

0.07 0.26 0.07 0.41 

Based upon its consideration of the five factors summarized herein and detailed in 

Appendix C, the state has determined that SO2 BART for Unit 5 is the following SO2 

emission rate: 

Drake Unit 5: 0.26 lb/MMBtu (30-day rolling average) 

The state assumes that the BART emission limit can be achieved through the 

installation and operation of dry sorbent injection. Other alternatives are not feasible. 

 Unit 5: $1,760 per ton SO2 removed; 0.12 deciview of improvement 
Colorado Visibility and Regional Haze State Implementation Plan for 12 Mandatory Class I Federal Areas 

Colorado Dept. of Public Health and Environment, Air Pollution Control Division 

Approved January 7, 2011 

80 

Based upon its consideration of the five factors summarized herein and detailed in 

Appendix C, the state has determined that SO2 BART for Unit 6 and Unit 7 is the 

following SO2 emission rates: 

Drake Unit 6: 0.13 lb/MMBtu (30-day rolling average) 

Drake Unit 7: 0.13 lb/MMBtu (30-day rolling average) 

The state assumes that the BART emission limits can be achieved through the 

installation and operation of lime spray dryers (LSD). A lower emissions rate for Units 6 

and 7 was deemed to not be reasonable as increased control costs to achieve such an 

emissions rate do not provide appreciable improvements in visibility (0.02 delta deciview 

for both units respectively).

These emission rates for Units 6 and 7 provide 85% SO2 emission reduction at a 

modest cost per ton of emissions removed and result in a meaningful contribution to 

visibility improvement.

 Unit 6: $2,808 per ton SO2 removed; 0.24 deciview of improvement 

 Unit 7: $2,345 per ton SO2 removed; 0.39 deciview of improvement 

Particulate Matter BART Determination for Martin Drake - Units 5, 6 and 7 

The state determines that the existing regulatory emissions limit of 0.03 lb/MMBtu 

(PM/PM10) for the three units represent the most stringent control options. The units 

are exceeding a PM control efficiency of 95%, and the emission limits are BART for 

PM/PM10. The state assumes that the BART emission limit can be achieved through the 

operation of the existing fabric filter baghouses. 

NOx BART Determination for Martin Drake - Units 5, 6 and 7 

Ultra low NOx burners (ULNB), ULNB including OFA, SNCR, SNCR plus ULNB, and 

SCR were determined to be technically feasible for reducing NOx emissions at Drake 

Units 5, 6 and 7. 

The following tables list the emission reductions, annualized costs and cost 

effectiveness of the control alternatives: 

Drake Unit 5 - NOx Cost Comparison 

Alternative Emissions 

Reduction (tpy) 

Annualized 

Cost ($) 

Cost 

Effectiveness 

($/ton) 

Baseline 0 $0 $0 

Overfire air (OFA) 154 $141,844 $923 

Ultra-low NOx burners (ULNBs) 200 $147,000 $736 

ULNBs + OFA 215 $288,844 $1,342 

Selective Non-Catalytic Reduction (SNCR) 231 $1,011,324 $4,387 

ULNB/SCR layered approach 626 $4,467,000 $7,133 

Selective Catalytic Reduction (SCR) 626 $4,580,000 $7,314