Prevention of Significant Deterioration Permit

Pio Pico Energy Center – PSD Permit SD 11-01

Fact Sheet Addendum – Revised PM, PM10 and PM2.5 BACT Analysis for the

Combustion Turbines

Section 1.0: Background 

Section 1.1: Environmental Appeals Board Decision

On November 19, 2012, the United States Environmental Protection Agency, Region 9 (Region 9 or the Region) 

issued a Clean Air Act Prevention of Significant Deterioration (PSD) permit (Permit No. SD 11-01) to Pio Pico, 

LLC (PPLLC or applicant) authorizing construction of the Pio Pico Energy Center (PPEC or Project). Region 9’s 

November 19, 2012 final permit decision granted conditional approval, pursuant to the PSD regulations (40 

CFR 52.21), to the applicant to construct and operate a 300 megawatt (MW) electric generating facility. The 

Project consists of three General Electric (GE) LMS100 natural gas-fired combustion turbine-generators (CTs) 

operating in simple cycle with a total net generating capacity of 100 megawatts each. 

Three individuals and entities filed petitions for review of the Region’s November 19, 2012 permit decision for 

the PPEC with EPA’s Environmental Appeals Board (EAB or Board). Collectively, the petitioners raised eleven 

issues for Board resolution. 

On August 2, 2013, the Board issued a decision remanding in part and denying review in part of the Region’s 

November 19, 2012 PSD permit decision for the PPEC.1 The Board remanded to Region 9 the emission limits 

for the three CTs for particulate matter (PM), which includes total particulate matter, particulate matter 10 

micrometers (μm) in diameter and smaller (PM10), and particulate matter 2.5 μm in diameter and smaller 

(PM2.5). The Project is subject to best available control technology (BACT) requirements for total PM, PM10, 

and PM2.5. The Region made one BACT determination that represented the Region’s determination for total 

PM, PM10, and PM2.5, which was referred to by the Board as the “PM BACT analysis.” The Board directed 

Region 9 to prepare a revised PM BACT analysis for the CTs and to make a new PM BACT determination for the 

CTs after consideration of all relevant information. The Board also directed Region 9 to reopen the public 

comment period to provide the public with an opportunity to comment on the revisions to its PM BACT 

analysis for the CTs. The EAB denied review of all other issues.2 

With respect to its remand concerning Region 9’s BACT analysis and determination for PM for the CTs, the 

Board specifically directed the Region to: 

 

1

 This decision, In re: Pico Pico Energy Center (“In re: Pio Pico”), PSD Appeal Nos. 12-04 through 12-06, slip op. (EAB Aug. 2, 2013), 

can be found on the Board’s website at the following address: 

http://yosemite.epa.gov/oa/EAB_Web_Docket.nsf/PSD%20Permit%20Appeals%20(CAA)/A73AC96F4C0E14CE85257BBB006800F2/$

File/Pio%20Pico...36.pdf. 

2

The Board’s decision also stated that once Region 9 issues a final permit decision following the public comment period required by 

the Board’s remand, the Region’s final permit decision and the Board’s decision in this matter become final agency action subject to 

judicial review per 40 CFR 124.19(l). The Board’s decision further stated that the Board is not requiring, and will not accept, an 

appeal to the Board of the final permit decision for the Project following remand in this case. In re: Pio Pico, slip op. at 116-17.
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Pio Pico Energy Center 

1. Consider emission data and BACT limits from the Panoche and CPV Sentinel facilities in its BACT 

analysis and document whether the limits or emission rates observed at these facilities can or cannot 

be achieved at the PPEC; 

2. Explain whether a two-tier load-based approach is typical for similar facilities, and if not, why such an 

approach is appropriate in this case. If a load-based approach continues to be Region 9’s choice, Region 

9 must: 

a. Provide a rationale explaining any specific load level selected; and 

b. Provide record support for the emission limits selected as BACT for high and low loads 

consistent with this direction. 

3. Reopen the public comment period to provide the public with an opportunity to review and comment 

on this analysis. 

In re: Pio Pico, slip op. at 101-02. Consistent with the Board’s remand order, Section 2.0 below contains 

Region 9’s revised PM BACT analysis and determination for the CTs. This analysis supplements the PM BACT 

analysis and determination in the Fact Sheet and AAQIR issued in June 2012 for the PSD permit action for the 

PPEC and the responses provided by the Region related to the PM BACT determination for the CTs in the 

Response to Comments issued by the Region in November 2012 for this action. 

Section 1.2: Environmental Justice Analysis

As further background, we also note that in its August 2, 2013 decision, the Board upheld Region 9’s decision 

to accept late comments from one individual on the Environmental Justice Analysis (EJ Analysis) for the 

Region’s PSD permit decision for the PPEC without reopening the comment period to the public, after 

considering the applicable legal principles and the particular circumstances presented in this matter. In re: 

Pico Pico, slip op. at 28-33. In this context, the Board also stated: 

[B]ecause of the confusing language the Region used to accept late comments, the Region should 

consider providing other members of the public the same two-week opportunity to submit late 

comments on the EJ Analysis as it gave Mr. Sarvey. As explained in more detail later in this decision, 

because the Board is separately remanding the permit on another issue to allow public comments, this 

might provide an opportunity to allow additional late comments on the EJ Analysis. 

In re: Pico Pico, slip op. at 32. 

Region 9 has carefully considered the Board’s suggestion in this regard, and has determined that it will not 

reopen the public comment period to take additional comment on the EJ Analysis for its PSD permit decision 

for the PPEC, for the following reasons. 

First, the Region previously extended the public comment period to all members of the public for all issues 

related to its proposed PSD permit decision for the PPEC. The public comment period opened on June 20, 

2012 and was extended until September 5, 2012. This afforded a substantial length of time during which the 

public could comment on the EJ Analysis, which was posted in the electronic docket for the Region’s proposed 

permit decision for the PPEC starting on June 20, 2012. Second, only one commenter, the individual who was 

allowed to submit late comments on the EJ Analysis, submitted comments on the EJ Analysis for the PPEC. 
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Pio Pico Energy Center 

Region 9 thoroughly considered, and provided a detailed response to, all comments on the EJ Analysis 

submitted by this individual. Third, the Region provided the public with an additional method of commenting 

on the EJ Analysis when it held a public hearing for its proposed PSD permit decision for the PPEC on July 24, 

2012. No one offered any oral comments at this public hearing, and the only set of written comments that 

was submitted at the public hearing – which was also submitted to the Region via email -- did not concern the 

EJ Analysis. Fourth, no commenters other than the individual who was allowed to submit a late comment 

requested additional time to comment specifically on the EJ Analysis, or approached the Region with a 

situation similar to that of this individual, or otherwise submitted a request for additional time to comment 

following the original extension of the public comment period. Fifth, PSD permits are time-sensitive because 

new source construction cannot begin prior to receiving a final permit, and because PSD permit applications 

must be granted or denied within one year of application completeness. CAA 165(a), (c), 42 USC 7475(a), (c). 

Offering the public an additional opportunity to comment on the EJ Analysis at this time could result in 

additional delay in the Region’s issuing a final permit decision in this matter given the Region’s need to take 

additional time to consider and appropriately respond to any such comments. Last, the Region is aware of no 

other information indicating that reopening the public comment period to take additional late comments on 

the EJ Analysis is necessary, given the opportunities for public comment on the EJ Analysis that have already 

been provided. Considering all of these factors, the Region has determined that offering further opportunity 

for public comment on the EJ Analysis for its PSD permit decision for the PPEC is not warranted. 

Section 1.3: Comment Period, Procedures for Final Decision, and EPA Contact

Region 9 is issuing a supplemental public notice requesting public comment on the Region’s revised 

particulate matter BACT analysis for the CTs for the Project and the related proposed revisions to the PSD 

permit’s PM conditions. Region 9 is now taking comment solely on these matters, and a written response to 

these comments will be provided with Region 9’s final permit decision for the Project. Region 9 is not 

reopening the comment period generally or soliciting comment at this time on any issues other than those 

described in this paragraph. 

Any interested person may submit written comments on Region 9’s revised PM BACT analysis for the CTs for 

the Project and proposed revisions to the particulate matter PSD permit conditions for the Project. All written 

comments on Region 9’s proposed action must be received by Region 9 via email by December 17, 2013, or 

postmarked by December 17, 2013. Comments must be sent or delivered in writing to Lisa Beckham at one of 

the following addresses: 

E-mail: R9airpermits@epa.gov

U.S. Mail: Lisa Beckham (AIR-3) 

 U.S. EPA Region 9 

 75 Hawthorne Street 

 San Francisco, CA 94105-3901 

 Phone: (415) 972-3811 

Alternatively, written or oral comments may be submitted to EPA at the Public Hearing for this matter that will 

be held on December 17, 2013, as described below. 
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Pio Pico Energy Center 

Attendance at the hearing is not required in order to submit written comments. At the public hearing, any 

interested person may provide written or oral comments, in English or Spanish, and data pertaining to Region 

9’s revised PM BACT analysis for the CTs and related proposed revisions to the PM permit conditions for the 

Project. The public hearing will be held as follows: 

Date: December 17, 2013 

Time: 6:30 p.m. – 8:00 p.m. 

Location: San Ysidro Middle School 

Multi-Cultural Center (MCC) 

4345 Otay Mesa Road 

 San Ysidro, California 92173 

English-Spanish translation services will be provided at the Public Hearing. 

If you require a reasonable accommodation, by December 10, 2013 please contact Philip Kum, EPA Region 9 

Reasonable Accommodations Coordinator, at (415) 947-3566, or kum.philip@epa.gov. 

Information available as part of the administrative record for Region 9’s current action includes: Region 9’s 

revised particulate matter BACT analysis for the CTs, the related proposed revisions to the PSD permit’s 

particulate matter conditions, information submitted by the applicant in response to the EAB’s remand, and 

certain other supporting information. This information, and certain other information relating to Region 9’s 

decision for this PSD permit application, is available through the EPA Region 9 website at 

http://www.epa.gov/region09/air/permit/r9-permits-issued.html#pubcomment. The administrative record for 

Region 9’s PSD permit decision for the Project may be viewed in person, Monday through Friday (excluding 

federal holidays) from 9:00 AM to 4:00 PM, at the EPA Region 9 address above. Due to building security 

procedures, please call Lisa Beckham at (415) 972-3811 at least 48 hours in advance to arrange a visit. Hard 

copies of the administrative record can be mailed to individuals upon request in accordance with Freedom of 

Information Act requirements as described on the EPA Region 9 website at http://www.epa.gov/region9/foia/.

Region 9’s proposed revisions to the PSD permit for the Project and the accompanying revised PM BACT 

analysis for the CTs are available for review at the following locations: San Diego Air Pollution Control District, 

10124 Old Grove Road, San Diego, CA 92131, (858) 586-2600; San Ysidro Public Library, 101 W. San Ysidro 

Boulevard, San Diego, CA 92173, (619) 424-0475; Chula Vista Public Library, Civic Center Branch, 365 F Street, 

Chula Vista, CA 91910, (619) 691-5069; Otay Mesa-Nestor Library, 3003 Coronado Avenue, San Diego, CA 

92154 (619) 424-0474; San Diego Central Library, 820 E Street, San Diego, CA 92101, (619) 236-5800; National 

City Public Library, 1401 National City Boulevard, National City, CA 91950, (619) 470-5800. 

All comments that are received will be included in the public docket without change and will be available to 

the public, including any personal information provided, unless the comment includes Confidential Business 

Information (CBI) or other information whose disclosure is restricted by statute. Information that you consider 

CBI or otherwise protected should be clearly identified as such and should not be submitted through e-mail. If 

you send e-mail directly to Region 9, your e-mail address will be automatically captured and included as part 

of the public comment. Please note that an e-mail or postal address must be provided with your comments if 

you wish to receive direct notification of EPA’s final decision regarding the permit. 
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Pio Pico Energy Center 

If you have questions, or if you wish to obtain further information, please contact Lisa Beckham at (415) 972-

3811, via email at R9airpermits@epa.gov, or at the mailing address above. If you would like to be added to our 

mailing list to receive future information about this proposed permit decision or other PSD permit decisions 

issued by EPA Region 9, please contact Lisa Beckham at (415) 972-3811 or send an email to 

R9airpermits@epa.gov, or visit EPA Region 9's website at http://www.epa.gov/region09/air/permit/psdpublic-guidelines.html. 

EPA’s Final Permit Decision: Region 9 will consider all substantive written and oral comments submitted 

during the public comment period on the topics on which comment is currently being solicited before taking 

final action on the PSD permit application, and will send notice of the final permit decision to each person who 

submitted comments and contact information during the public comment periods for this permit decision or 

requested notice of the final permit decision. Region 9 will respond to all such substantive comments in a 

document accompanying the final permit decision and will make the Public Hearing proceedings available to 

the public, if applicable. 

Region 9’s final permit decision will become effective 30 days after service of notice of the decision unless (1) 

a later effective date is specified in that decision, or (2) no comments request a change in the proposed 

revised permit conditions that are announced in this Fact Sheet Addendum and the accompanying public 

notice, in which case the permit will become effective immediately upon issuance. In addition, following the 

final permit decision, Region 9 will publish a notice in the Federal Register announcing the decision, which will 

discuss the opportunity to seek judicial review of this decision. 

If EPA issues a final decision granting the PSD permit application for the Project, then construction of the 

Project may commence upon the date on which EPA’s decision becomes effective, subject to the conditions of 

the PSD permit and other applicable permit and legal requirements. 

Section 2.0: Revised PM, PM10, and PM2.5 BACT Analysis for the CTs

Section 2.1: Region 9’s Initial PM BACT Analysis for the CTs

Region 9’s initial PM BACT analysis for the PPEC’s CTs, which was included in the June 2012 Fact Sheet and 

AAQIR, used EPA’s well-established case-by-case top-down procedure to determine BACT for PM, PM10 and 

PM2.5 for the CTs. Region 9 conducted one analysis to apply to PM, PM10, and PM2.5 emissions, collectively 

referred to as “PM”, because the PSD permit application for the PPEC assumes that all PM is PM2.5. In addition, 

the PM analysis included the consideration of condensable and filterable particulate matter emissions. 

Region 9’s initial analysis concluded that BACT for PM for the CTs is low sulfur Public Utilities Commission 

(PUC)-quality natural gas and good combustion practices. In the PSD permit issued on November 19, 2012, 

Region 9 set a fuel sulfur content limit for natural gas of 0.25 grains per 100 dry standard cubic feet (dscf) on a 

12-month rolling average and a sulfur content of 1.0 grains per 100 dscf that is not be exceeded at anytime. 

These portions of the Region’s PM BACT determination for the CTs were not within the scope of the issues 

that the EAB directed the Region to address on remand; therefore, Region 9 is not reconsidering or revising its 

determination for this portion of the PM analysis. 
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Pio Pico Energy Center 

The PSD permit decision issued by Region 9 on November 19, 2012 also included two PM emission limits for 

the CTs: (1) a limit of 5.5 lb/hr and (2) a limit of 0.0065 lb/MMBtu that applied only at loads of 80% or higher. 

Consistent with the Board’s remand order, Region 9 has conducted a supplemental PM BACT analysis for the 

CTs to further examine the basis for these particular emission limits. This supplemental BACT analysis focused 

on BACT limits and emissions data from other facilities similar to the PPEC, including the Panoche Energy 

Center and the CPV Sentinel facility, and considered whether the limits or emission rates observed at these 

facilities can be achieved at the PPEC. Using this information, Region 9 considered whether to revise the lb/hr 

and lb/MMBtu limits that were included in the November 19, 2012 PSD permit for the Project. Consistent with 

the Board’s order, Region 9 also considered whether separate emission limits should be established at 

different load levels for each unit. 

Section 2.2: Additional Information Provided by the Applicant

In a letter dated August 15, 2013, PPLLC provided additional information and emissions data in response to 

the Board’s decision. The information included numerous stack test data from the Panoche Energy Center, 

CPV Sentinel, and the Walnut Creek Energy Center, all of which employ the same model of gas turbine as the 

PPEC and operate in simple-cycle mode.3 

Using the test data provided, the applicant conducted its own statistical analysis, and proposed revised PM 

emission limits of 5.0 lb/hr and 0.0053 lb/MMBtu4 that apply at all times for the PPEC’s CTs. The applicant’s 

statistical analysis looked at the results of 38 test runs for PM emissions from the three facilities and 

determined the average and standard deviation of both the lb/hr and lb/MMBtu results. Assuming normal 

distribution, the applicant concluded that 98% of test runs are expected to be within 2 standard deviations of 

the mean (i.e., multiply the standard deviation by two and add it to the average). The applicant further applied 

an additional 20% margin to “account for the fact that these data are for new units, which will inevitably suffer 

diminished performance over time....so that the BACT emission limitation can be met over the units’ entire 

useful lifetime.” The applicant further stated that such a safety factor is warranted because no data exists for 

LMS100 units nearing the end of their useful life. 

The applicant proposed that these limits apply at all times, under all allowable operating loads, and that the 

limits be enforced based on the test methods specified in the November 19, 2012 PSD permit for the PPEC. 

Section 2.3: Summary of Recent PM BACT Determinations

Table A-1 provides a summary of recent PM BACT/Lowest Achievable Emission Rate (LAER) determinations for 

simple-cycle natural gas-fired CTs similar to those of the PPEC. 

The majority of PSD permits for these facilities set only a lb/hr PM emission limit, and several do not apply any 

numerical PM emission limit at all, instead relying solely on low sulfur fuel and good combustion practices as 

 

3 We note that, of this performance test data, only certain data for the Panoche Energy Center was available prior to Region 9’s 

issuance of the November 19, 2012 permit decision for the PPEC. The Walnut Creek Energy Center and CPV Sentinel did not conduct 

initial compliance demonstration stack testing until 2013. 

4

In an August 27, 2013 letter, PPLLC notified EPA of a typographical error in its August 15, 2013 letter. In its August 27 letter, PPLLC 

clarified that the August 15, 2013 letter had inadvertently proposed a limit of 0.0053 lb/MWh instead of PPLLC’s intended proposed 

limit of 0.0053 lb/MMBtu. 
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Pio Pico Energy Center 

BACT. When using a lb/hr emission limit it is not possible to directly compare permit limits for units of varying 

sizes, because the lb/hr emission rate varies directly with the size of the CT – meaning that larger units have 

higher potential PM emissions, on a lb/hr basis, than smaller units. As such, for determining a lb/hr emission 

limit, we have only further considered CTs of similar size (80-120 MW). We note that the Dayton Power & 

Light facility, which has four 80 MW units, is the only facility identified in Table A-1 that has a lb/MMBtu limit. 

The lowest BACT or LAER permit limits we have identified for a CT of a size similar to that of the CTs for the 

PPEC are 6.0 lb/hr for the Panoche Energy Center and 0.0130 lb/MMBtu at the Dayton Power & Light facility. 

These limits are higher than the PM emission limits in Region 9’s November 19, 2012 PSD permit for the PPEC, 

and higher than the 5.0 lb/hr and 0.0053 lb/MMBtu permit limits proposed by the applicant in its August 2013 

submittals to EPA. 

We further note that neither the CPV Sentinel permit nor the Walnut Creek Energy Center permit, which are 

for facilities using the same turbine model as those for the PPEC, contains a lb/hr or lb/MMBtu BACT/LAER 

limit. While the permits for these two facilities do contain an 11 lb/hr limit, that limit is based on a local rule 

requirement and not on a BACT/LAER determination. BACT for both the CPV Sentinel facility and the Walnut 

Creek Energy Center was determined to be good combustion practices and low sulfur fuel, which is consistent 

with the BACT determination for the PPEC. Both of these permits contain a requirement that limits total PM10

emissions on a monthly basis, but this is not part of the BACT/LAER determination for these facilities.5 The 

monthly limits were based on an emission factor of 5 lb/hr at the CPV Sentinel facility and 6 lb/hr at the 

Walnut Creek Energy Center. Initially, the pounds of PM10 per month limit for the CPV Sentinel facility was 

based on a 6 lb/hr emission factor, but the applicant subsequently requested to lower the PM10 limit to a value 

based on a 5 lb/hr emission factor. This permit change was made in a determination by the South Coast Air 

Quality Management District (SCAQMD) in March of 2010. Region 9 does not consider the 5 lb/hr and 6 lb/hr 

values used in these permitting decisions to be enforceable permit limits for the purposes of reviewing past 

BACT/LAER determinations when setting a new BACT limit. We note that our response to comments that 

accompanied our November 19, 2012 permit decision for the PPEC erroneously referred to the 5 lb/hr value as 

a permit limit for CPV Sentinel. However, these values are emission factors and are not, in fact, included in the 

permits as enforceable conditions. As such, the permittees could have actual emissions greater than these 

factors and still be able to comply with the lb/month PM10 limits in their permits. While we believe it would 

generally be reasonable to further consider these emission factors in our analysis as potential BACT emission 

limits, we do not consider them to be more stringent than the values proposed in the applicant’s August 2013 

letters.6 Thus, while further analysis of the basis for these emission factors would be needed in order to 

consider them for purposes of setting BACT limits, we do not believe it is necessary in this case given that the 

applicant’s proposed limits are more stringent than these emission factors. We note that we also considered 

the available PM emission data for these two particular facilities (CPV Sentinel and Walnut Creek Energy), as 

discussed in Section 2.4 below. 

 

5

Condition A63.1 of the Walnut Creek Energy Center permit has a limit of 2,592 pounds of PM10 per month, and Condition A63.1 of 

the CPV Sentinel permit has a limit of 2,425 pounds of PM10 per month. 

6

 The 5.0 lb/hr limit proposed by the applicant in its August 15, 2013 letter is slightly more stringent than either of these values. We 

consider the 5.0 lb/hr limit to be more stringent than 5 lb/hr because it has more significant figures making the value more precise. 

For example, a stack test average of 5.459 lb/hr rounds to 5 lb/hr when demonstrating compliance with a 5 lb/hr limit, but rounds to 

5.5 when demonstrating compliance with a 5.0 lb/hr limit. 
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Pio Pico Energy Center 

In summary, the PM BACT emission limits of 5.5 lb/hr and 0.0065 lb/MMBtu that were established in Region 

9’s November 19, 2012 PSD permit for the PPEC are the lowest permitted emission limits for similarly sized 

natural gas-fired CTs that we have found, and the 5.0 lb/hr and 0.0053 lb/MMBtu permit limits proposed by 

the applicant in August 2013 for the PPEC are lower than any existing BACT/LAER permit limits we have found 

for similarly sized CTs. 

Section 2.4 Review of Available Stack Test Data

Region 9 reviewed the following PM stack test data for three facilities with GE LMS100 turbines to assist with 

determining appropriate PM emission limits for the PPEC’s CTs. These three facilities are the only facilities 

Region 9 is aware of that use the GE LMS100 turbines and are currently in operation. The 2010, 2011, and 

2012 test reports for the Panoche Energy Center were obtained from the San Joaquin Valley Unified Air 

Pollution Control District and the applicant provided the other test results.7

· Panoche Energy Center – Units 1 through 4 – 2009 Initial Compliance Demonstration 

· Panoche Energy Center – Units 1 through 4 – 2010 Annual Compliance Demonstration 

· Panoche Energy Center – Units 1 though 4 – 2011 Annual Compliance Demonstration 

· Panoche Energy Center – Units 1 though 4 – 2012 Annual Compliance Demonstration 

· Walnut Creek Energy Park – Units 1 through 5 – 2013 Initial Compliance Demonstration 

· CPV Sentinel – Units 1 through 8 – 2013 Initial Compliance Demonstration 

In evaluating this data in the context of setting BACT emission limits for PM for the PPEC’s CTs, Region 9 

considered a number of technical factors with the potential to impact the reliability and usefulness of the data 

in projecting achievable emissions for the PPEC, as discussed below. 

As a preliminary matter, we note that there are no reasonable methods, beyond good combustion practices 

and the low sulfur fuel requirements already required by the PSD permit, that the permittee could employ to 

adjust its operations to account for the inherent variability of PM emissions from CTs in order to be able to 

comply with the emissions limits that will be selected. For this reason, as noted above, many NSR permits for 

similar facilities do not include any numerical PM emission limits as a component of their PM BACT/LAER 

requirements. However, we believe PM emissions limits are warranted, particularly to ensure compliance with 

the NAAQS – a required element of our approval. 

In light of the permittee’s limited ability to adjust its operations to address the inherent variability of PM 

emissions from CTs, we need to be particularly careful to ensure that the BACT limit that is selected is 

technically feasible to meet on an ongoing basis for the life of the facility. Accordingly, potential variability in 

stack test data for the same turbine model is a significant concern when we consider setting a BACT limit 

based on such data. 

An additional consideration in our evaluation of existing performance data is the fact that in December 2010, 

EPA revised its PM test method for condensable PM – Method 202 (see 75 FR 80118 on December 21, 2010). 

EPA’s November 19, 2012 PSD permit for the PPEC requires the use of this method for measuring condensable 

PM emissions (along with the use of EPA Method 5 for measuring filterable PM). As explained in the 

 

7

The applicant also provided summaries of the 2010 and 2011 Panoche Energy Center test data, but not the full stack test reports. 
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Pio Pico Energy Center 

December 21, 2010 Federal Register notice, the final amendments to Method 202 revised the sample 

collection and recovery procedures of the method to reduce the formation of reaction artifacts that could lead 

to inaccurate measurements of condensable particulate matter. Additionally, the final amendments 

eliminated most of the hardware and analytical options in the previous version of the method, thereby 

increasing the precision of the method and improving the consistency in the measurements obtained between 

source tests performed under different regulatory authorities. 

In light of the above considerations, in our initial review of the stack test data for the three facilities, we 

looked first at the test methods that were used to determine PM emissions from these CTs. In order to 

measure PM emissions it is necessary to determine filterable and condensable PM emissions. The majority of 

the available stack test data for the GE LMS100 turbines was not obtained using the current version of EPA 

Method 202 for condensable PM.8 

The 2009 and 2010 Panoche Energy Center data used the older version of EPA Method 202. The 2011 and 

2012 testing for Panoche Energy Center used SCAQMD Method 5.1 to measure condensable PM rather than 

revised EPA Method 202.9

 SCAQMD Method 5.1 is not an approved EPA test method.10 

The CPV Sentinel test data for condensable PM was also not conducted using EPA Method 202. Instead, PM 

testing was conducted using SCAQMD Method 5.1. 

The PM testing for the Walnut Creek Energy Park used EPA Method 202 (condensable PM), EPA Method 201A 

(filterable PM2.5), and SCAQMD Method 5.1 (filterable and condensable PM). While Method 201A is intended 

to measure filterable PM2.5 and not total filterable PM, the applicant has assumed for the purposes of the PSD 

application that all PM is PM2.5. In addition, the stack test report contains the necessary information to 

determine the total filterable PM emissions. 

Although there are differences in the PM test methods used at these three facilities, we have concluded that it 

is reasonable to rely on the available source test data in considering emission limits for BACT purposes. 

However, this is only reasonable if we account for the greater potential for variability in future test results that 

stems from the fact that consistent test methods were not used. While the particular test method that is used 

does not change the actual emissions from the equipment, it is important to rely on data from a consistent 

method or to correct for differences between test methods in order to reasonably and confidently compare 

data when attempting to predict achievable emission levels for purposes of setting a BACT limit. 

Thus, in Section 2.5 below, we discuss a number of variables that must be taken into account when using the 

stack test data to determine an appropriate PM BACT limit for the PPEC CTs. 

Section 2.5 Summary of Analysis of PM Data

 

8 While much of the data for filterable PM also did not use the EPA test method for filterable PM, EPA Method 5, the method that 

was used is not significantly different from EPA Method 5. 

9

SCAQMD Method 5.1 is used to measure both filterable and condensable PM. 

10 The main difference between the two methods is directly related to the changes EPA made to its method in 2010, which were 

intended to address the formation of reaction artifacts that could create a positive bias for results from the test method. (That is, 

actual emissions were not as high as the older version of Method 202 reported them to be). The changes made by EPA in its 

revisions to EPA Method 202 to address this issue are not included in SCAQMD Method 5.1. 
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Pio Pico Energy Center 

While Region 9 believes it is reasonable to consider the available stack test data in determining achievable PM 

BACT limits for the CTs, we must take into consideration the following issues in reviewing this data: 

1. EPA must set a PM limit that is technically feasible to meet on an ongoing basis for the life of the 

equipment. The available data that we reviewed spans only 5 years – when CTs are expected to last 

more than 20-30 years. It is unclear how much PM emissions will vary as the equipment ages and 

therefore it would be inappropriate to rely heavily on this emissions data in setting a limit that is 

achievable on an ongoing basis over the life of the equipment. 

2. It is not appropriate to set the PM limit based on the lowest emission rate measured during a single 

source test because we must be able to account for inherent variability that the permittee cannot 

control. 

3. While we have data from more than a single source test, it is not representative of a multitude of 

operating conditions. Much of the data is from initial compliance demonstrations, which, for example, 

would not account for the potential SCR catalyst degradation overtime or the presence of lubricating 

oils as maintenance is performed over the life of these CTs. 

4. The available data does not address our concerns related to potential spikes in sulfur content of the 

fuel, which the permittee cannot control. The permittee must be able to meet the emission limit even 

during short term spikes in fuel sulfur content (as allowed within the limits of the permit). 

5. PM emissions vary even on identical turbine models due to different operating conditions at the time 

of each stack test. The available data demonstrate enough variability that it is impractical to set a BACT 

limit based simply on average emissions from stack test data – as the limit must be met at all times 

under all conditions. This variability is demonstrated by test averages ranging from 0.64 lb/hr to 4.97 

lb/hr and 0.00092 lb/MMBtu to 0.00533 lb/MMBtu, as well as by high relative standard deviations11 of 

59% and 52%, respectively. 

We also note that the data reviewed by the applicant did not include the stack test data from the 2012 

Panoche Energy Center stack testing. In addition, the applicant appeared to use the Walnut Creek Energy Park 

data for SCAQMD Method 5.1 instead of EPA Methods 5 and 202. So, we recalculated the emissions limits 

(using the method proposed by the applicant) to include the 2012 Panoche Energy Center data and the EPA 

Method 201A12 and 202 data for Walnut Creek Energy Park. See Tables A-2 and A-3. The results of our 

calculations – 5.1 lb/hr and 0.0055 lb/MMBtu – are slightly higher than those proposed by the applicant. We 

believe these differences in calculations to be insignificant and believe the applicant’s proposed limits are 

achievable given the many uncertainties for which the calculation method accounted. 

Regarding the applicant’s calculation method – adding two standard deviations plus 20% to the average – 

Region 9 would typically only add 2 standard deviations (98% confidence level) when reviewing stack test data 

and not add an additional 20%. However, in this case, given the many variables that cannot be adequately 

accounted for, as discussed above in this section and in Section 2.4, the applicant’s approach of adding an 

additional 20% seems reasonable in this case. 

 

11 Relative standard deviation is a measure of the reliability of the data. The closer the value is to 0% the greater the reliability. 

12 In addition, we used the information available in the stack test report to calculate total filterable PM and not just filterable PM2.5. 
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Pio Pico Energy Center 

In summary, we are proposing to revise the PM BACT emission limits for the PPEC to those proposed by the 

applicant in August 2013: 5.0 lb/hr and 0.0053 lb/MMBtu. These limits are lower than any of the PM limits in 

recent PM BACT/LAER determinations for similar simple-cycle natural gas-fired CTs, and lower than the limits 

of 5.5 lb/hr, and 0.0065 lb/MMBtu at loads greater than 80%, in EPA’s November 19, 2012 PSD permit 

decision for the PPEC. We are proposing that these PM emission limits apply at all times. 

Section 2.6 Consideration of Separate Emission Limits for Different Load Levels

The EAB’s remand order instructs Region 9 to explain whether a two-tier load-based approach to BACT is 

typical for similar facilities, and if not, why such an approach is appropriate in this case. The Board further 

stated that if a load-based approach continues to be Region 9’s choice, Region 9 is to: 

a. Provide a rationale explaining any specific load level selected; and 

b. Provide record support for the emission limits selected as BACT for high and low loads consistent with 

the Board’s order. 

Region 9 first notes for clarification that the 5.5 lb/hr PM emission limit in the November 19, 2012 PSD permit 

for the PPEC would have applied at all times so it was not a load-based limit. We are not changing our 

determination that the lb/hr PM emission limit will apply at all times in this revised BACT determination, 

although we are proposing to lower the lb/hr PM limit proposed as BACT for the PPEC, as discussed above. 

In response to the Board’s directive, we were not able to find another permit limit for a similar source that 

applied only to certain load levels. Thus, we do not believe that it is typical practice for permitting authorities 

to set PM lb/hr BACT limits for simple cycle CTs based on particular load levels. In Region 9’s experience, PM 

emissions are typically tested only at or near the maximum operating capacity. The CPV Sentinel test data is 

the only test data for a similar facility that we are aware of that includes results from testing at load levels 

other than at or near 100% load; this is atypical in our experience of reviewing PM test data for simple cycle 

CTs. 

Likewise, based on our review of other permits, we do not believe that it is typical practice for permitting 

authorities to set lb/MMBtu PM BACT limits for simple cycle CTs based on particular load levels. We found 

only one other similar facility that had a lb/MMBtu PM BACT limit (see Table A-1 below). The permitting 

authority did not specify that the limit only applied to certain load levels, so we assume that it applies at all 

times. 

With regard to the lb/MMBtu PM limit, we are no longer proposing a load-based approach, as the lb/MMBtu 

PM limit will apply at all times, as stated above. While the applicant had previously stated its belief that at low 

loads (50% load), the expected PM emission rate from the PPEC would be 0.01 lb/MMBtu, the applicant is now 

proposing that the 0.0053 lb/MMBtu limit apply at all times. While it is likely that emission levels in lb/MMBtu 

differ between higher load levels and lower load levels, there is insufficient data available to determine a 

particular emission limit that should apply at differing load levels. The CPV Sentinel test data has a very limited 

set of test runs at lower load levels that show that emissions were not significantly higher at lower loads than 

higher loads. So, while some degree of variation is expected we believe the calculation method for the 

proposed emission limits is conservative enough to account for this potential variation. Therefore, we are 
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Pio Pico Energy Center 

proposing to remove the load-based criterion in the PPEC PSD permit, which applied the lb/MMBtu limit only 

to loads above 80%.13 

Further, as stated above, like many other PSD permits for natural gas-fired turbines, our BACT determination 

focuses primarily on meeting the fuel sulfur limits and good combustion practices. We are aware of no other 

available and economically feasible technologies or work practice standards that the permittee could use to 

reduce PM emissions from the CTs. We are also not aware of additional actions that the permittee could take 

that would cause the facility to not meet good combustion practices and the fuel sulfur limits at low operating 

loads but still meet those requirements at higher operating loads. 

For all of these reasons, we find no need for setting different BACT limits that would apply at different 

operating load levels. 

Section 2.7 Revisions to Required Sample Volume for PM Testing

Based on our review of the available test data, and because PM emissions from gas-fired CTs are so low, we 

are concerned that the current permit requirement for the PPEC’s CTs to obtain 90 standard cubic feet (SCF) 

during each test run is not sufficient to produce reliable test data. Therefore, we are also proposing to revise 

the testing requirements for PM such that at least 120 SCF of sample volume (instead of 90 SCF) is obtained. 

This change is intended to increase the accuracy of the PM test results. 

3.0 Conclusion

In response to the Board’s remand order, Region 9 has reviewed stack test results for various facilities 

employing the GE LMS100 turbine, PM BACT/LAER determinations for turbines at similar facilities, and the 

lower PM emission limits proposed by the applicant in August 2013. Based on our review of this information 

and related considerations, we are proposing to lower the PM BACT emission limits for the PSD permit for the 

PPEC to the limits of 5.0 lb/hr and 0.0053 lb/MMBtu as proposed by the applicant in August 2013. In addition, 

we are proposing to revise the permit to apply both PM limits at all times, and to modify the testing 

requirements for PM such that at least 120 SCF of sample volume is obtained. 

 

13 We also note that the San Diego County Air Pollution Control District (District) provided comments on Region 9’s initial PM BACT 

analysis and noted that a one-hour source test of a large combined cycle turbine during a cold startup at about 10% load resulted in 

a particulate emission factor of 0.021 lb/MMBtu while the annual compliance test for the same turbine at full load had a particulate 

emission factor of 0.0034 lb/MMBtu. Based on this, the District recommended a lb/hr limit instead of a lb/MMBtu limit. The 

information provided by the District was not for a facility similar to the PPEC and, as such, should not be used in determining the PM 

BACT limit for the PPEC. We do not believe further review of this issue is warranted in this revised analysis as the applicant is now 

proposing limits that apply at all times. 
Table A-1 Summary of Recent PM BACT Limits for Simple Cycle Combustion Turbines, Natural Gas-Fired 

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Pio Pico Energy Center 

Facility Turbine

Size PM BACT/LAER Limit Averaging Period Source Location Permit Date

Pioneer Generating Station ~50MW 5.4 lb/hr 1-hr RBLC North Dakota 5/14/2013

R.M. Heskett Station ~85 

MW) 

7.3 lb/hr average of three test 

runs 

RBLC North Dakota 2/22/2013

Blank Hills - Cheyenne Prairie 40 MW 4.0 lb/hr 3-hr average RBLC Wyoming 8/28/2012

Calcasieu Plant 160 MW 17 lb/hr Not applicable RBLC Louisiana 12/21/2011

Sabine Pass LNG Terminal ~35 MW 2.08 lb/hr hourly maximum RBLC Louisiana 12/6/2011

Mariposa Energy 50 MW fuel sulfur content and good 

combustion practices 

Not applicable Permit California 11/24/2010

PSEG Fossil Kearny Generating 

Station 

43 MW 6.0 lb/hr average of three tests RBLC New Jersey 10/27/2010

Howard Down Station 64 MW 5.0 lb/hr average of three test 

runs 

RBLC New Jersey 9/16/2010

Dahlberg Combustion Turbine 

Elec Gen Facility 

190 MW 9.1 lb/hr 3-hr average RBLC Georgia 5/14/2010

Dayton Power & Light 80 MW 0.0130 lb/MMBtu Not listed RBLC Ohio 12/3/2009

Bayonne Energy Center 64 MW 5.0 lb/hr Not listed RBLC New Jersey 9/24/2009

CPV - Sentinel 100 MW fuel sulfur content and good 

combustion practices 

Month Permit California 8/29/2009

Canyon Power Project 50.95 

MW 

fuel sulfur content and good 

combustion practices 

Month Permit California 6/24/2009

Shady Hills Generating Station 170 MW none (opacity and fuel sulfur content) Not applicable RBLC Florida 1/12/2009

Orange Grove 50 MW 3.0 lb/hr average of three test 

runs 

Permit California 4/8/2009

Green River Energy - Elk Creek 

Station 

175 MW No limits Not applicable RBLC Minnesota 7/1/2008

Walnut Creek Energy Park 100 MW fuel sulfur content, good combustion 

practices 

Month Permit California 2/27/2008

Panoche Energy Center 100 MW 6.00 lb/hr one hour Permit California 12/19/2007
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Pio Pico Energy Center 

Table A-2 Stack Test Data for Total PM Emissions 

Walnut Creek Energy Center

Year Unit Test Average, lb/hr Test Average, lb/MMBtu

2013 1 1.6617 Data Not Reported 

2013 2 0.7023 0.00098 

2013 3 1.0570 0.00146 

2013 4 0.8760 0.00123 

2013 5 1.9787 0.00307 

CPV Sentinel

Year Unit Test Average, lb/hr Test Average, lb/MMBtu

2013 1 0.718 0.00114 

2013 2 0.628 0.00092 

2013 3 1.733 0.00232 

2013 4 2.307 0.00334 

2013 5 0.903 0.00157 

2013 6 1.307 0.00200 

2013 7 0.740 0.00120 

2013 8 1.430 0.00213 

Panoche Energy Center

Year Unit Test Average, lb/hr Test Average, lb/MMBtu

2009 1 2.527 0.00267 

2009 2 2.687 0.00300 

2009 3 4.973 0.00533 

2009 4 4.627 0.00500 

2010 1 2.240 0.00220 

2010 2 1.375 0.00134 

2010 3 1.724 0.00164 

2010 4 2.559 0.00252 

2011 1 2.388 0.00242 

2011 2 2.649 0.00254 

2011 3 4.557 0.00446 

2011 4 1.834 0.00183 

2012 1 1.367 0.00131 

2012 2 1.417 0.00137 

2012 3 1.397 0.00135 

2012 4 2.200 0.00215 

Table A-3 Combined Statistics – Total PM Emissions 

 Test Average, lb/hr Test Average, lb/MMBtu

Average (Mean) 1.95 0.00223 

Standard Deviation 1.146 0.00116 

Relative Standard Deviation 59% 52% 

Average + 2 Stan Dev + 20% 5.1 0.0055
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Pio Pico Energy Center 

References:

Pio Pico Energy Center PSD Permit Application, PM BACT Determination, Sierra Research August 15, 2013. 

Pio Pico Energy Center PSD Permit Application, PM BACT Determination Correction of Typographical Error, Sierra 

Research, August 27, 2013. 

Excerpts of PM Emission Test Data Reviewed, EPA Region 9, November 2013. 

Methods for Measurement of Filterable PM10 and PM2.5 and Measurement of Condensable PM Emissions From 

Stationary Sources; Final Rule, 75 Fed. Reg. 80118, December 21, 2010, http://www.gpo.gov/fdsys/pkg/FR-2010-

12-21/pdf/2010-30847.pdf.