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UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

REGION IX 

75 Hawthorne Street 

San Francisco, CA 94105·3901 

November 8, 2006 

Patrick E .. Flynn 

Environmental Health & Safety Manager 

Resolute Natural Resources Company 

1675 Broadway, Suite 1950 

Denver, CO 80202 

OFFICE OF THE 

REGIONAL ADMINISTRATOR 

Re: Revised Application for a Prevention of Significant Deterioration Permit for 

McElmo Creek Main Flare 

Dear Mr. Flynn: 

This letter is in response to the submittal by ExxonMobil of a revised application 

for a Prevention of Significant Deterioration (PSD) permit for the Main Flare at 

ExxonMobil's McElmo Creek gas compression facility. This revised application, 

received by EPA, Region 9 on October 3, 2006, provides supplemental data in response 

to a letter from EPA dated May 22, 2006 informing ExxonMobil that the initial permit 

application was administratively incomplete . 

. We appreciate the many revisions that have been made thus far to the application; 

most of the areas originally identified by EPA in its May 22, 2006 letter as 

administratively incomplete have been adequately addressed in the revised application. 

However, upon review of the revised application in accordance with 40 CFR § 124.3, 

EPA has determined that the application remains administratively incomplete for PSD 

purposes with respect to emissions data and the BACT analysis. These areas are 

discussed below. 

Emissions Data 

In our May 22, 2006 letter, we requested that ExxonMobil provide pre- and postproject actual emissions, as well as pre-project estimates of the potential to emit for all 

criteria pollutants. We stated that, for purposes of the PSD permit application, pre-project 

means before the gas plant was dismantled in 1997, and post-project means after the gas 

plant was dismantled. As requested, ExxonMobil provided this data, using the limits from 

the Consent Decree for Civil Action Case United States v. Mobil Exploration and 

Production U.S. Inc. as the post-project PTE. In order for EPA to be able to properly 

calculate the cost-effectiveness of the various control options discussed in the revised 

application, the permit application must include the maximum PTE for all criteria 

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pollutants following the dismantling of the gas plant, but prior to the imposition of the 

Consent Decree limits. 

BACT Analysis 

Also in our May 22, 2006 letter, we requested that the application address means 

to reduce the occurrence of flaring, considering, among other things, methods to improve 

the efficiency, reliability, and/or capacity of the gas compressors (including replacing the 

compressors), and any other methods that may reduce the frequency of flaring and the 

quantity of gas flared. In response, the permit application has been revised to analyze 

compressor engine modifications per EPA's top-down BACT methodology. The revised 

application discusses options for improving the· reliability of the existing compressor, 

replacing the compressor, and other compressimi operations changes. The application 

states that "Implementing these options [options to improve compressor operations] is 

assumed to achieve a minimum decrease of75% of base emissions of each pollutant." As 

noted in the application, step 3 of EPA's top-down methodology is to rank all technically 

feasible control options by control effectiveness. However, the application does not 

contain a basis for the 75% control efficiency assumed for compressor improvements. 

The application must be revised to include the technical basis for this assumed control 

efficiency. Where a range of control efficiencies is expected to exist, the top down 

analysis should examine the maximum possible control efficiency first. If the maximum 

efficiency is eliminated based on technical infeasibility, then the application should 

explain the basis. The maximum technically.:achievable control efficiency should also be 

considered in the cost effectiveness analysis of any control option, rather than only the 

minimum as is currently used. 

Should you have any questions concerning the review of your application, or if 

you would like to arrange for a meeting or conference call to discuss your application, 

please contact me at (415) 972-3974. 

Sincerely, 

j~ 

·'G:~ C. Rios 

Chief, Permits Office 

cc: Randy Cleaveland, ExxonMobil 

Torn Hormel, McVehil-Monnett Associates, Inc. 

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