Bachman. Tom A.

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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: Scan to Email from 2142mr

Terry: Enclosed are pages 46-49 ofthe Colorado draft BART. These pages were referred to in EPA's 9/3 letter.

Brenda L. Morris, Senior Enforcement Attorney 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

----- Forwarded by Brenda Morris/R8/USEPA/US on 09/13/2010 02:52 PM

From: Mail R8Printer/R8/USEPA/US@EPA

To: Brenda Morris/R8/USEPA/US@EPA

Date: 09/13/2010 01 :57 PM

Subject: Scan to Email from 2142mr

This document was digitally sent to you using an HP Digital Sending device.(See attached file: Document.pdf)

1

6.4.3 Overview of the BART Determinations and the Five Factor Analyses for

Each BART Source

This section presents an overview of the BART determinations for the subject to BART

sources.

The Regional Haze rule requires states to make determinations about what is

appropriate for BART, considering the five statutory factors:

(1) The costs of compliance,

(2) The energy and non-air quality environmental impacts of compliance,

(3) Any existing pollution control technology in use at the source,

(4) The remaining useful life of the source, and

(5) The degree of visibility improvement that may reasonably be anticipated from the

use of BART.

The rule gives the states broad latitude on how the 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 under the rule, other than to

consider the 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

For the purposes of the 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 other sources 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 for these sources, largely because

significant NOx add-on controls are not the norm for Colorado electric generating units,

and to afford a degree of uniformity in the consideration of BART for these sources.

With respect to 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 of the Regional Haze rule,

which the state has considered. However, Colorado also notes that Appendix Y is expressly not

mandatory with respect to EGUs of less 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 below this 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 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

Proposed ReVisions to Chapter 6 • August 5, 2010

46
cases for over twenty years. The LSD has notable advantages in Colorado given the

non~air quality consideration of its relatively lower water usage in reducing 302

emissions in the state and other non-air quality considerations. Each of these systems

will meet EPA's presumptive limits, and in some cases surpass those Iimits.4 The

Division has determined in the past that these 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 of the emissions control technology, the state has assessed

S02 emissions control technologies and/or emissions rates for BART sources, as

necessary, on a case by case basis in making its BART determinations.

With respect to PM emissions, fabric filter baghouses and appropriate PM emissions

rates are in place at all power plants in Colorado. Fabric filter 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 of the

emissions control technology, the state has assessed PM emissions control

technologies and/or emissions rates 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 of the appropriateness of employing such

post-combustion technology at these sources for implementation of the 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 new facility (Public Service Company

of Colorado, 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 for visibility improvement

under the regional haze rule, the state has considered the five statutory factors in each

instance. Based on its authority, discretion and policy jUdgment to implement the

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 greater than 750 MW. including sources greater than 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

Document for BART NOx Limits for Electric Generating Units and Technical Support Document for BART

NOx Limits for Electric Generating Units Excel Spreadsheet, Memorandum to Docket OAR 2002-0076,

April 15, 2006: Technical Support Document for BART S02 Limits for Electric Generating Units,

Memorandum to Docket OAR 2002-0076, April 1, 2006; and Regulatory Impact Analysis for the Final

Clean Air Visibility Rule or the Guidelines for Best Available Retrofit Technology (BART) Determinations

Under the Regional Haze Regulations, U.S. EPA, June 2005.

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

Colorado Dept. ofPublic. Health and Environment, Air Pollution Control Division

Proposed Revisions to Chapter 6· August 5,2010

47
Regional Haze rule, the state has determined that costs and the anticipated degree of

visibility improvement are the factors that should be afforded the most weight. 5 In this

regard, the state has utilized screening criteria as a means of generally guiding its

consideration of these factors. More specifically, the state finds most important in its

consideration and determinations: (i) the cost of controls as appropriate to achieve the

goals of the 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 air quality 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.

For the 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 by the state's calculation, and which provide a modeled visibility benefit

on 0.50 tldv or greater at the primary Class I Area affected, that level of control is

generally viewed 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 of 0.20 tldv or greater at the 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 consistent with 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 order to: (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 Visibility and Regional Haze State Implementation Plan for 12 Mandatory Class I Federal Areas 48

Colorado Dept. ofPublic Health and Environment, Air Pollution Control Division

Proposed Revisions to Chapter 6 • August 5, 2010
$5,000/ton criterion is also consistent and within the range of the state's implementation

of reasonably achievable control technology (RACT), as well as best achievable control

technology (BACT) with respect to 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 of state 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 of control 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 or exceed $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 by the different

types of control technologies is pertinent to its assessment and determination.

Considering costs for the highest-performing add-on NOx controls (i.e., SCR), the state

anticipates a direct level of visibility improvement contribution, generally 0.50 t.dv or

greater of visibility improvement at the primary affected Class I Area. 1o For the lesserperforming add-on NOx controls (e.g., SNCR), the state anticipates a meaningful and

discernible level of Visibility improvement that contributes to broader visibility

improvement, generally 0.20 Mv or greater of Visibility improvement at the primary

affected Class I Area. 11

and, (iii) for the DMA/NFR nonattainment area, reducing precursor emissions from RICE directly tied to

exceedance levels of ozone.

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

10 The EPA has determined that BART-eligible sources that affect visibility above 0.50 tidv are not to 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 subject to BART. See, Air Quality Control

Commission Regulation No.3, Section III.B.1.b. ThUS, a visibility improvement of 0.50 tidv or greater will

also provide significant direct progress towards improving visibility in a Class I Area from that facility.

II The state finds that an improvement of 0.20 tidv or greater will meaningfully contribute to improving

visibility in Class I Areas. It is pertinent to the state that a modest number of facilities, for example five

facilities, providing this level of visibility improvement are able to afford 1.0 Mv of visibility 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 Visibility and Regional Haze State Implementation Plan for 12 Mandatory Class I Federal Areas

Colorado Dept. of Public Health and Environment, Air Pol/ution Control Division

Proposed Revisions to Chapter 6 - August 5, 2010

49