i
;!.: UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION VIII 99918th STREET-SUITE 500 DENVER, COLORADO 80202·2405 

### OCT 2? 

### !Sa7 REF: 8AT-AP 1

Mr. D.C. Forbes' Environmental/Regulatory Manager Mobil Exploration 

### &Producing U.S. Inc. P.O. Box 5444 Denver, Colorado 80217-5444' Dear Mr. Forbes: This letter is in response to your september 1, 1987 letter requesting changes to the Prevention of Significant Deterioration of Air Quality (PSD) permit that EPA issued on February 2, 1987 forrt:E1mo Creek Unit Gas Plant. We revieWed your request to replace the three reciprocating internal combustion engirres with two natural gas fueled turbines andmade appropriate changes to the permit. Sfnce these changes did not result in any emission increase and Best Ava;1abl e Control Technologywill beutilized for the gas turbines, the modifications are being made as an administrative change. Appropriate changes have been made to Conditions #1, #2, and#3 in the enclosed permit. The enclosed permit will replace the February 2, 1987 permit. This revised conditional permit shall become effective inmediately unless you notify us otherwise (see Section IV of the permit). Construction and operation may not take place if this permit or anypart thereof is rejected. Ifyoo have any questions, please contactJohn Dale of 

### nrt staff.at (303) 293-1886.

Enclosures cc: Burnell Cordner, Director Bureau of Air Quality Utah Department of t-ealth Arlene Luther, Navajo Nation 

### RECEIVED AIRQUALITY 

### NOV 10

### 1981CONDITIONAL PERMIT TO CCMt1ENCE CONSTRUCTION AND OPERATE 40CFR 52.21 Prevention of Significant Deterioration of Air Quality Mobil Oi1 Corporation P.O. Box 5444 Denver, Colorado 80217-5444

1. INTRODUCTION
Mobil Oil Corporation (hereinafter lithe Applicant") proposes to construct and operate a modification to Mobilis rt:Elmo Creek Unit on the Navajo Indian Reservation in San Juan county, Utah. On May 13, 1986, the Applicant submitted to the U. S. Environmental Protection Agency, Region VIII (hereinafter liEPAil) a Prevention of Significant Deterioration (PSD) application to construct the proposedmodification pursuant to 40 CFR 52.21.

. . The EPA issued a public notice on December 17,1986, in the san Juan Record and the Salt Lake Tribune, newspapers of general circulation in the area. The notice proposed to approve the application andissue a conditional air quality permit for the source and provided opportunity for public conments during the ensuing 30 calendar days. The permit application, the proposed permit, and its supporting analysis were available for public inspection at the Office of the san Juan**Coun~** Clerk in rt>nticello, the Utah Bureau of Air Quality in Salt Lake**Ci~** and the EPA Region VIn office in Denver. The only conments concerning the permit werereceived fran the Applicant andcontained only minor clarifications. On September 1, 1987, the Applicant submitted a letter requestingto repl ace the three reciprocating internal corrbustion engines with two natural gas fueled turbines. These changes did not result in an emission increase and Best Available Control Technoloty (BACT) will be utilized for the gas turbines. II. FINDINGS 

### On the basis of information in the administrative record, EPA has determined that: 1. The Applicant is a major source andthis modification will result in a significant emission increase of oxides of nitrogen (NOx) and volatile organic compounds (VOC). 2. The Applicant will meet all of the applicable requirements of the PSD regulations. 3. 

### No applicable emission standard, ambient air quality standard, or maximum allowable increase, will be violated by pollutant emissions fran this source.

### 4. EPA has good reason to believethat the Applicant can comply with the conditions ofthis permit. However, if the conditions of this permit are not met by the Applicant, EPA does not assume any risk of loss which may occur as a result of the commencement of construction and operation by the Applicant. I II. CONOITIONAL PERMIT TO CONSTRUCT AND OPERATE

c. November 4, 1986

- Supplementary information correcting VOC emiss't

### on rates. d. September 1, 1987

- Letter requesting to replace three reciprocating internal combustion engines with two 

### natural gas fueled turbines. 2. The owner or operator shall limit emissions from the modification to 

### those shown in Table 1. Each of the two 3216 hp gas turbines shall be limited to a maxil1lJl11 NOxemission rate of 150 ppmv at 15% oxygen on a dry basis. 3. Stack testing for NOx shall be performed according to Method 20 in 40

## crn 60, App. A. 4. At all times, including periods of start-up, shutdown, and equt

### paent malfunction, owners and operators shall maintain and operate the facility in a manner consistent with good air pollution control practices for minimizing emissions, Oetermination of whether acceptable operating and maintenance procedures are being usedwill be based on information available to the Administrator, which may include, but not be limi ted to, monitoring resu1ts, review of operating andmaintenance procedures, and inspection of the source.5. The**~p1icant** shall notify EPA not more than 48 hours after discovery (or as soon as possible) of excess emissions during periods of start-up, shutdown, equtjment malfunctions, or process upset. Not more than 10 days after discovery, all of the following shall be provided to EPA in writing:

a. The identity of the stack or other emi.ssion point where excess emissions occurred.

. b. The magnitude of excess emissions expressed in terms of permit conditions.

c. Pertinent operating data during the time of upset. d. The time and duration of excess emissions.

e. Theidentity of the equtpnent or process causing the upset and the suspected reasons for the upset. f. Steps and procedures taken during the upset period to minimize excess emissions. g. Steps and procedures taken or anticipated to be taken to prevent recurrence of the upset conditions. h. If the Pdministrator determines that the information submitted does not evidence malfunction or upset conditions, failure to meet 1imitations -descrtbed in this permit will be considered a violation of the permit. 6. This permit shall expire ifconstruction is not commenced within the time specified, or once commenced, construction is delayed for the time specified in 40 CFR 52.2l(r)(2). 7. All performance testing required pursuant to this permit shall be conducted in accordance with the time schedules and procedures contained in 40 CFR 60.8. Performance test results shall be submitted not more than 45 days after the testing date. 8. Atest protocol outlining a plan for the initia1 canpl i ance demonstration tests shall be submitted to EPA 45 days in advance of any scheduled testing. 9. EPA and its authorized representatives may inspect the permitted facility during normal business hours for purposes of ascerta""ing compliance with all conditions of this permit. 10. Nothing in this approval shall excuse the Applicant, the owner, and/or operator fran complying with all other applicab1e Federal, State and local regulations.

### IV. GENERPL This permit is issued in reliance upon the completeness and accuracy of the information set forth in the Applicant's application to 

### EPA for permission to 

### modify their M:

### Elmo Creek plant. On 

### -the effective date of this permit, the conditions herein become enforceable by EPA pursuant to any remedies it now has or may have in the future under the Clean Air Act. Each and every condition of this permit is a material part hereof andis not severable. This permit is immediately effective, unless you notify this Regional Office, in writing (Attention: Mr. 

### Marius J. 

### Gedgaudas, Air Programs Branch, 8AT-AP), that this permit or a term or condition of it is rejected. Such notice should be made not more than ten nO} days after recei pt of the permit and should include the reason or reasons for rejection.
UNITED STATES ENVIROtlt1ENTAL PROTECTION AGENCY REGION VIII

# BY:~~~' Irwin L. 

### D1ckstein, D1rector Air and Toxics Division

. 

### OCT 27

# mr DATE:TABLE 1 MOBIL HcELMO CREEK UNIT STAGE 2 ESTIMATED EMISSION CHARACTERISTICS
EXIT NO CO SOa VOC HEIGHT TEMP VELO. DIA U'IH COORDlAN'IES ( NO. SOURCE HP tlyr n 

### ill t/yr gls t/yr gls tly sIs (ft) (OF) (ft/s) (ft) East Nord 14**~4500** a3216 74.6 2.15 17.0 0.49 0.05 0.001 4.0 0.12 20 834 331 2.5 65.9.02 4125.0f 15 T4500 3216 74.6 2.15 17.0 0.49 0.05 0.0001 4.0 0.12 20 834 331 2.5 659.08 4125 '"



### --- a Total 6432 149.2 34.0 0.1 8.0

Significant Emission Rate 40 100 40 40

1 T4500

- Solar Turbines Incorporated, Hodel: Centaur T4500 HD a 1730 hp was at 4,800 ft and 90°F, 3216 hp is at ISO. Eqiv 3216 hp at 4,800 ft and 90°F is 2852 hp or 5702 hptotal.