### Bachman. Tom 

### A.

From: Sent: To: Subject: Attachments:



### FYI O'Clair, Terry

### L. Monday, September 13, 2010 4:01 PM Bachman, Tom A. FW: Scan to Email from 2142mr Document.pdf



### -----Original Message----- From: Morris.Brenda@epamail.epa.gov [mailto:Morris.Brenda@epamail.epa.gov] Sent: Monday, September 13, 2010 3:55 PM To: O'Clair, Terry 

### L. Cc: Buenning.Hans@epamai1.epa.gov Subject: Fw: Scanto Email from 2142mr

Terry: Enclosed arepages 46-49 ofthe Colorado draftBART. Thesepages werereferredto inEPA's 9/3 letter.

Brenda 

### L. Morris, SeniorEnforcementAttorney U.S. EPA, Region 8 1595 Wynkoop Street (ENF-L) Denver, CO 80202-1129

Tel: 303-312-6891 Fax: 303-312-6953

morris.brenda@epa.gov

----- ForwardedbyBrendaMorris/R8/USEPA/US on09/13/2010 02:52 PM

From: Mail R8Printer/R8/USEPA/US@EPA To: BrendaMorris/R8/USEPA/US@EPA Date: 09/13/2010 01 :57 PM Subject: Scanto Email from 2142mr

This documentwas digitally sentto you using an HP Digital Sendingdevice.(See attachedfile: Document.pdf)

1

### 6.4.3 Overviewofthe BARTDeterminations andthe Five FactorAnalyses for Each BARTSource


### This section presents an overview ofthe BART determinations forthe subject to BART
sources. The Regional Haze rule requires states to make determinations aboutwhat is appropriate for BART, considering the five statutory factors: (1) The costs of compliance, (2) The energy and non-air quality environmental impacts ofcompliance, (3) Any existing pollution control technology in use atthe source, (4) The remaining useful life ofthe source, and (5) The degree ofvisibility improvementthat may reasonably be anticipated from the
use of BART.
The rule gives the states broad latitude on howthe five factors are to be considered to determine the appropriate controls for BART. The Regional Haze rule provides little, if any, guidance on specifically how states are to use these factors in making the final determinations regarding what controls are appropriate underthe rule, otherthan to considerthe five factors in reaching a determination. 1 

### The manner and method of consideration is left to the state's discretion; states are free to determine the weight and significance to be assigned to each factor.2


### Forthe purposes ofthe five factor review for the three pollutants that the state is assessing for BART, where pertinent, S02 and PM have been assessed utilizing the five factors on a case by case basis to reach a determination. This is primarily because the top level controls for 802 and PM are already largely in use on electric generating units in the state, and certain othersources require a case by case review because of their unique nature. For NOx controls on BART electric generating units, for reasons described below, the state is employing guidance criteria to aid in its assessment and determination of BART using the five factors forthese sources, largely because significant NOx add-on controls are notthe norm for Colorado electric generating units, and to afford adegree of uniformity in the consideration of BART forthese sources. With respectto 802 emissions, there are currently ten lime spray dryer (LSD) S02 control systems operating at electric generating units in Colorado. 3 

### There are also two wet limestone systems in use in Colorado. The foregoing systems have been successfully operated and implemented for many years at Colorado sources, in some

1 The EPA "BART Guidelines" provide information relating to implementation ofthe Regional Haze rule, which the state has considered. However, Colorado also notes thatAppendix Y is expressly not mandatorywith respectto EGUs ofless than 750 MWs in size, and Craig Station (Tri-State Generation and Transmission) is the only such BART electric generating unit in the state. See 70 Fed. Reg. at 39108. Thus, the state has substantial discretion in how it considers and applies the five factors (and any other factors that it deems relevant) to BART electric generating units in the state that are belowthis megawatt threshold, and for non-EGU sources. See, e.g., id. at 39108, 39131 and 39158.

2 See, e.g., 70 Fed. Reg. at 39170 and 39137.

3 EGUs with LSD controls include Cherokee Units 3 & 4, Comanche Units 1, 2 & 3, Craig Unit 3, Hayden Units 1 &2, Rawhide Unit 1, Valmont Unit 5.

Colorado VisibilityandRegionalHaze State Implementation Plan for12 MandatoryClass I FederalAreas Colorado Dept. ofPublic Health andEnvironment, AirPollution ControlDivision ProposedReVisions to Chapter6 • August5, 2010 46cases forovertwenty years. The LSD has notable advantages in Colorado given the**non~air** quality consideration ofits relatively lowerwater usage in reducing 302 emissions in the state and other non-airquality considerations. Each ofthese systems will meet EPA's presumptive limits, and in some cases surpass those Iimits.4 The Division has determined in the past thatthese systems can be cost-effective for Colorado's BART sources, and the Air Quality Control Commission approved LSD systems as BART for Colorado Springs Utilities' Martin Drake Units #6 and #7 in 2008. With this familiarity and use ofthe emissions control technology, the state has assessed S02 emissions control technologies and/oremissions rates for BART sources, as necessary, on a case by case basis in making its BART determinations.
With respectto PM emissions, fabric filter baghouses and appropriate PM emissions rates are in place at all power plants in Colorado. Fabricfilter baghouse systems have been successfully operated and implemented for many years at Colorado sources. The state has determined that fabric filter baghouses are cost effective through their use at all coal-fired power plants in Colorado, and the Air Quality Control Commission approved these systems as BART in 2007. With this familiarity and use ofthe emissions control technology, the state has assessed PM emissions control technologies and/or emissionsrates for BART sources, as necessary, on a case by
case basis in making its BART determinations.
With respect to NOx emissions, post-combustion controls for NOx are generally not employed in Colorado at BART or other significant**coal~fired** electric generating units. Accordingly, this requires a direct assessment ofthe appropriateness ofemploying such post-combustion technology at these sources for implementation ofthe Regional Haze rule. There is only one coal-fired electric generating unit in the state that is equipped with a selective catalytic reduction (SCR) system to reduce NOx emissions, and that
was employed as new technology designed into a newfacility (Public Service Company ofColorado, Comanche Unit#3, operational 2010). There are no selective non-catalytic reduction (SNCR) systems in use on coal-fired electric generating units in the state to reduce NOx emissions.
In assessing and determining appropriate NOx BART controls forvisibility improvement under the regional haze rule, the state has considered the five statutory factors in each instance. Based on its authority, discretion and policyjUdgmentto implementthe

4 In preparing Appendix Y, EPA conducted extensive research and analysis of emission controls on BART sources nationwide, including all BART EGU sources in Colorado. See 70 Fed. Reg. at 39134. Based upon this analysis, EPA established presumptive limits that it deems to be appropriate for large EGU sources of greaterthan 750 MW. including sources greaterthan 200 MW located at such plants. EPA's position is that the presumptive limits are cost effective and will lead to a significant degree of visibility improvement. ld. See also, 69 Fed. Reg. 25184, 25202 (May 5, 2004); Technical Support DocumentforBARTNOxLimits forElectric Generating Units and TechnicalSupportDocumentforBART NOxLimits forElectric Generating Units ExcelSpreadsheet, Memorandum to Docket OAR 2002-0076, April 15, 2006: TechnicalSupportDocumentforBARTS02 Limits forElectric Generating Units, Memorandum to Docket OAR 2002-0076, April 1, 2006; and RegulatoryImpactAnalysis forthe Final Clean AirVisibilityRule orthe Guidelines forBestAvailable Retrofit Technology (BART) Determinations Underthe RegionalHaze Regulations, U.S. EPA, June 2005.

Colorado VisibilityandRegionalHaze State Implementation Plan for12 MandatoryClass IFederalAreas Colorado Dept. ofPublic. Health andEnvironment, AirPollution ControlDivision ProposedRevisions to Chapter6· August5,2010 47Regional Haze rule, the state has determined that costs and the anticipated degree of visibility improvement are the factors that should be afforded the mostweight.5 In this regard, the state has utilized screening criteria as a means of generally guiding its consideration ofthese factors. More specifically, the state finds most important in its consideration and determinations: (i) the cost ofcontrols as appropriate to achieve the goals ofthe regional haze rule (e.g., expressed as annualized control costs for a given technology to remove a ton of Nitrogen Oxides (NOx) from the atmosphere, or 

### $/ton of NOx removed); and, (ii) visibility improvement expected from the control options analyzed (e.g., expressed as visibility improvement in delta deciview (tldv) from CALPUFF airquality modeling). Accordingly, as part of its five factor consideration the state has elected to generally employ criteria for NOx post-combustion control options to aid in the assessment and determinations for BART- a $/ton of NOx removed cap, and two minimum applicable Mv improvement figures relating to CALPUFF modeling for certain emissions control types, as follows.
Forthe highest-performing NOx post-combustion control options 

### (i.e., SCR systems for electric generating units) that do not exceed 

### $5,OOO/ton of pollutant reduced bythe state's calculation, and which provide a modeled visibility benefit
on 0.50 tldv orgreater atthe primary Class I Area affected, that level of control is generallyviewed as reasonable.
For lesser-performing NOx post-combustion control options 

### (e.g., SNCR technologies for electric generating units) that do not exceed $5,000Iton of pollutant reduced by the state's calculation, and which provide a modeled visibility benefit of0.20 tldv or greater atthe primary Class I Area affected, that level of control is generally viewed as reasonable.
The foregoing criteria guide the state's general approach to these policy considerations. They are not binding, and the state is free to deviate from this gUidance criteria based upon its consideration of BART on a case by case basis.
The cost criteria presented above is generally viewed by the state as reasonable based
on the state's extensive experience in evaluating industrial sources for emissions controls. For example, the $5,OOO/ton criterion is consistentwith Colorado's retrofit control'decisions made in recent years for reciprocating internal combustion engines (RICE) most commonly used in the oil and gas industry.6 In that case, a $5,000/ton threshold, which was determined by the state Air Quality Control Commission as a notto-exceed control cost threshold, was deemed reasonable and cost effective for an initiative focused on reducing air emissions to protect and improve public health.7 The

5 See 70 Fed. Reg. at 39170 and 39137.

1,Air Quality Control Commission Regulation No.7, 5 C.C.R. 1001-9, Sections XVII.E.3.a.(ii) (stateWide RICE engines), and XVI.CA (8-Hour Ozone Control Area RICE engines).

7 The RICE emissions control regulations were promulgated by the Colorado Air Quality Control Commission in orderto: (i) reduce ozone precursor emissions from RICE to help keep rapidly growing rural areas in attainment with federal ozone standards; (ii) for reducing transport of ozone precursor emissions from RICE into the Denver Metro Area/North Front Range (DMAINFR) nonattainment area; Colorado VisibilityandRegionalHaze State Implementation Plan for 12 Mandatory Class IFederalAreas 48 Colorado Dept. ofPublic Health andEnvironment, AirPollution ControlDivision ProposedRevisions to Chapter6 •August5, 2010

### $5,000/ton criterion is also consistent and within the range ofthe state's implementation of reasonably achievable control technology (RACT), as well as best achievable control technology (BACT) with respectto new industrial facilities. Control costs for Colorado RACT can be in the range of 

### $5,OOO/ton (and lower), while control costs for Colorado**B~CT** 

### can be in the range of$5,OOOlton (and higher). For a primarily aesthetic environmental standard

- visibility improvement and protection to be achieved over a long planning horizon

- as contemplated in the Regional Haze rule, the state finds that this 

### $5,000/ton criterion is appropriate, and as a matter ofstate policy to require emissions reduction control costs above this level would be too costly and overly burdensome, and thus generally not reasonable for this Regional Haze planning period.
In addition, as it considers the pertinent factors for regional haze, the state believes that the costs ofcontrol should have a relationship to visibility improvement The highestperforming post-combustion NOx controls, 

### i.e., SCR, has the ability to provide significant NOx reductions, but also has initial capital dollar requirements that can approach orexceed $100 million per unit. 8 

### The lesser-performing post-combustion NOx controls, e.g., SNCR. reduce less NOx on a percentage basis, but also have substantially lower initial capital requirements, generally less than $10 million.9 

### The state finds that the significantly different capital investment required bythe different types ofcontrol technologies is pertinentto its assessment and determination. Considering costs for the highest-performing add-on NOx controls (i.e., SCR), the state anticipates adirect level ofvisibility improvement contribution, generally 0.50 t.dv or greater ofvisibility improvement at the primary affected Class I Area.

### 1o Forthe lesserperforming add-on NOx controls (e.g., SNCR), the state anticipates a meaningful and discernible level ofVisibility improvementthat contributes to broadervisibility improvement, generally 0.20 Mv or greater ofVisibility improvement atthe primary affected Class I Area. 11

and, (iii) for the DMA/NFR nonattainment area, reducing precursoremissions from RICE directly tied to exceedance levels ofozone.

8 See, e.g., Appendix C, reflecting Public Service of Colorado, Comanche Unit #2, $83MM; Public Service of Colorado, Hayden Unit #2, $72MM; Trl-State Generation and Transmission, Craig Station Unit #1, $210MM.

9 See, e.g., Appendix C, reflecting CENC (Tri-gen), Unit #4. $1.4MM; Public Service Company of Colorado, Hayden Unit #2, $4.6MM; Tri-State Generation and Transmission, Craig Station Unit #1, $13.1MM

10The EPA has determined that BART-eligible sources that affect visibility above 0.50 tidv are notto be exempted from BART review, on the basis that above that level the source is individually contributing to visibility impairment at a Class I Area. 70 Fed. Reg. at 39161, The state relied upon this threshold when determining which Colorado's BART eligible sources became subjectto BART. See, Air Quality Control Commission Regulation No.3, Section III.B.1.b. ThUS, avisibility improvement of0.50 tidv orgreaterwill also provide significant direct progress towards improving visibility in a Class I Area from thatfacility.

II The state finds that an improvement of 0.20 tidv or greaterwill meaningfully contribute to improving visibility in Class I Areas. It is pertinent to the state that a modest number offacilities, for example five facilities, providing this level ofvisibility improvement are able to afford 1.0 Mv ofvisibility benefit. Below this minimum level, for example 0.10 Mv, would take twice as many facilities to afford a similar collective visibility Mv benefit.

Colorado VisibilityandRegionalHaze State Implementation Plan for12 Mandatory ClassIFederalAreas Colorado Dept. ofPublic Health andEnvironment, AirPol/ution ControlDivision ProposedRevisionsto Chapter6 - August5, 2010 49