# ~~/g~~-DAKOTA ADivision ofMDUResources Group, Inc. 400North Fourth Street Bismarck, ND58501 (701)222·7900 June 14,2011


## u.s. Environmental Protection Agency Region VIII 1595 Wynkoop Street Denver, CO 80202-1 129 Attention: Vanessa Hinkle, 8P-AR Re: Updated Response to Request for Additional Reasonable Progress Information for tbe Montana-Dakota Utilities Company, Lewis and Clark Generating Station, Pursuant to Section 114(a) ofthe Clean Air Act (42 U.S.c. Section 7414(a» DearMs. Hinkle: Montana-Dakota Utilities Co. respectfully submits the enclosed emission control analysis for Lewis & Clark Generating Station's Unit I in response to the EPA request issued on November 5, 2010 as an update to the analysis previously submitted on February II, 20I I. The analysis has been updated to revise priorreported costs associated with the NOx control costs and the hydrated lime use costs for SO, control based on additional information which became available after the initial due date for the analysis. The report is being supplied in its entirety and serves to replace the previously filed February 2011 version ofthe report. Forease in identifying the changes to the report, the tables ofinterest(Table 2 and Table 5 ofthe analysis) have been reproduced below to illustrate, in red, the values that have been updated. Whilethe costs increased on an absolute basis, none ofthe conclusions on the comparative cost basis have changed sincethe February submittal. Table Z. SO, Control CostSummary Installed Annualized Pollution Incremental Capital Cost Operating Cost Control Cost Control Cost Control Technology (MM$) (MM$/yr)

### * ($Iton)

### ** ($Iton)*** SDA with Baghouse $66.34 $10.05 $11,825 $13,220 Existing ScrubberMod. $0.27 $0.14 $1,383 NA DSI with Baghouse $15.75 $2.84 $28,347 NA 

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# .. ••• Pnorreported: SDA with Baghousc, $9.68: EXlstmg ScrubberMod., SO. 10: OSl wuh Baghollse S2.80. Prior reported: SDA with Baghouse, $11,390: Existing Scrubber Mod., $1.015; OSI with Baghouse 527,912. Priorreported (Slton): SDA with Baghollse. S12,776
.Vanessa Hinkle June 8,2011 Page 

### 2 Table 5. NOx Control CostSummary

PrIor reported. SNCR wuh SOFAlLNB, S>.69, SOFAlLNB, 51.». Priorreported: SNCR with SOFAlLNB, $0.96; SOFAlLNB, SO.23
. Priorreported: SNCR with SOFAlLNB, $2,395; SOFAlLNB, $1,213
. Priorreported: SCR, $18,786 

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# .. ... ..... Installed Annualized Pollution Incremental Capital Cost Operating Cost Control Cost Control Cost ControlTechnology (MMS)* (MMS/yr)** (S/ton)*** (S/ton)·*** SCR $38.98 $6.98 $9,680 $18,368 SNCR with SOFAlLNB $4.53 $1.09 $2,729 $7,279 SOFAlLNB $2.20 $0.36 $1,213 NA SNCR $2.43 $0.76 $2,533 NA SNCR(low load) $2.43 $0.56 $9,817 NA
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A statement ofcenification for the enclosed analysis is provided with this cover letter. No claim ofconfidential business information is being assened for the enclosed repon. In addition to the electronic submittal, two (2) paper copies ofthis correspondence and the analysis have been mailed to yourattention. Ifyou have any questions about this submittal, please contactJon Madison at 701-222-7835. Sincerely,

# Ct/~~ Ms. Abbie Krebsbach Environmental Manager Montana-Dakota Utilities Co.
Enclosure: Updated Emissions Control Analysis for Lewis and Clark Station Unit I
cc: Mr. Joel Trinkle, 

### Barr Engineering CompanyVanessa Hinkle June 8, 2011 Page 3 STATEMENT OF CERTIFICATION I certify underpenalty oflaw that I have personally examined and am familiar with the information submitted in this document and all attachments and that, based on my inquiry of those individuals immediatelyresponsible for obtaining information, I believe that the information is true, accurate, and complete. I am aware that there are significantpenalties for submitting false information, including the possibility offine or imprisonment.

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