# Xcel

# Energy·M

October 19, 2015 Mr. Guy Donaldson EPA's South Central Region (Region 6) Air Planning Section (6PD-L) Environmental ProtectionAgency 1445 Ross Avenue Suite 1200 Dallas, Texas 75202-2733 DocketNo. EPA-R06-0AR-2014-0754 Re: Proposed Approval/Disapproval ofTexas and OklahomaRegional Haze State ImplementationPlans; Federal Implementation Planfor Regional Haze DearMr. 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 ofthe 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 informationregarding water availability and use at Tolk Stationto provide a simple and clear explanation about the impact on water usage ofrequiring 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 ofdry 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 boilerto maintainthe water quality chemistry needed for operation, is between 300 to 350 gpm. We have estimated that approximately 70% ofthis blow down could be used for the operation ofthe scrubber. The remaining 30% mustbe sentto the evaporationponds and cannotbe used for dry scrubber operation due to water chemistry and quality. Using 70% ofthe blowdown yields 210 to 245 gpm ofblowdown for use. 300 gpm X .7 = 210 gpm 350 gpm X .7 = 245 gpm

1Phase 1AQCSEngineering Services Project Study- Harrington Generating Station Unit 1, 2 & 3 andTolk Generating StationUnits 1&2, November 2011 -Responseto EPA Request for InformationPursuantto Section 114 ofthe Clean AirAct Regarding XcelEnergy's Tolk Generating Station dated July 2, 2014 (SPS providedthis studyto EPA as apublic document inits 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 ofan average volume of230 gpm ofavailable blowdownwater. Subtracting that amount (230 gpm) from the dry scrubberuse total requirement (1,046 gpm) leaves a balance of 816 gpm of additional fresh water that must be obtainedto 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 minX 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 ofadditional fresh waterrequired each year for operation ofthe dry scrubbers at Talk Station. 380 MG/325,851 gallons/acre-feet= 1,166 acre-feetperyear As a result ofthe calculations shown above, Talk Station will be required to obtain 1,166 acrefeet ofadditional water per year to operate a dry scrubbing system on both units. This additional water cost and acquisition was not included inEPA's cost estimates inthe proposed rule. Xcel Energy appreciates EPA's consideration ofthis 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. Ifyou should have any questions, please contact me at 303- 571-2762 or Ann Seha at 612-215-4619. Verytruly yours,



# fit**~---------=** JeffWest

# ~ Senior Director, Environmental Services Xcel Energy Inc.