Xcel Energy·M 

October 19, 2015 

Mr. Guy Donaldson 

EPA's South Central Region (Region 6) 

Air Planning Section (6PD-L) 

Environmental Protection Agency 

1445 Ross Avenue 

Suite 1200 

Dallas, Texas 75202-2733 

Docket No. EPA-R06-0AR -2014-07 54 

Re: Proposed Approval/Disapproval of Texas and Oklahoma Regional Haze State 

Implementation Plans; Federal Implementation Plan for Regional Haze 

Dear Mr. Donaldson: 

Over the past several months, EPA Region 6 has requested that Southwestern Public Service 

Company ("SPS ") d/b/a Xcel Energy ("Xcel Energy") respond to multiple information requests 

regarding water use at its Tolk Station and the impact on water use of the possible requirement to install 

dry scrubbers at Tolk Station. The multiple requests suggest that EPA has not fully understood the 

information that SPS has provided. SPS respectfully submits the following information regarding water 

availability and use at Tolk Station to provide a simple and clear explanation about the impact on water 

usage of requiring dry scrubbers at Tolk Station. 

Based on an engineering study of the Tolk units that SPS provided to EPA in 2014, SPS 

estimates that the use of dry scrubbers at Tolk Station will require 1,046 gallons per minute (gpm) of 

water to operate the scrubber systems for both units. 1 The average blowdown for the facility, i.e. water 

that is removed from the boiler to maintain the water quality chemistry needed for operation, is between 

300 to 350 gpm. We have estimated that approximately 70% of this blow down could be used for the 

operation ofthe scrubber. The remaining 30% must be sent to the evaporation ponds and cannot be used 

for dry scrubber operation due to water chemistry and quality. Using 70% of the blowdown yields 210 

to 245 gpm ofblowdown for use. 

300 gpm X .7 = 210 gpm 

350 gpm X .7 = 245 gpm 

1 Phase 1 AQCS Engineering Services Project Study- Harrington Generating Station Unit 1, 2 & 3 and Tolk Generating 

Station Units 1&2, November 2011 -Response to EPA Request for Information Pursuant to Section 114 of the Clean Air Act 

Regarding Xcel Energy's Tolk Generating Station dated July 2, 2014 (SPS provided this study to EPA as a public document 

in its response to the Section 114 request). 
Mr. Guy Donaldson 2 October 19, 2015 

SPS believes that a reasonable estimate to reflect this range would be use of an average volume 

of230 gpm of available blowdown water. Subtracting that amount (230 gpm) from the dry scrubber use 

total requirement (1,046 gpm) leaves a balance of 816 gpm of additional fresh water that must be 

obtained to operate the dry scrubbers. 

1,046 gpm- 230 gpm = 816 gpm 

816 gpm converts into 428,889,600 gallons per year of additional fresh water needed for dry 

scrubber operation: 

816 gpm X 60 min X 24 hrs X 365 days= 428,889,600 gallons/year 

Talk Station historically has a capacity factor of 88%. Taking the total required water arid 

multiplying by the capacity factor for the facility yields 377,422,848 gallons of additional fresh water 

needed per year (approximately 380 million gallons) for dry scrubber operation. 

428,889,600 gallons/year X .88 capacity factor = 377,422,848 gallons/year or 380 million 

gallons (mg) per year 

Convetiing the additional required fresh water makeup to acre feet yields a total of 1,166 acrefeet of additional fresh water required each year for operation of the dry scrubbers at Talk Station. 

380 MG /325,851 gallons/acre-feet= 1,166 acre-feet per year 

As a result of the calculations shown above, Talk Station will be required to obtain 1,166 acrefeet of additional water per year to operate a dry scrubbing system on both units. This additional water 

cost and acquisition was not included in EPA's cost estimates in the proposed rule. 

Xcel Energy appreciates EPA's consideration of this response to EPA's informat.ion request in 

its efforts to finalize the rule. Additionally, Xcel Energy formally requests this response be placed in 

Docket No. EPA-R06-0AR-2014-0754. If you should have any questions, please contact me at 303-

571-2762 or Ann Seha at 612-215-4619. 

Very truly yours, fit ~---------= JeffWest 

Senior Director, Environmental 

~ Services 

Xcel Energy Inc.