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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

combusti on engirres wi th two natural gas fueled turbines and made appropriate

changes to the permit. Sfnce these changes did not resul t in any emissi on

increase and Best Ava; 1abl e Control Technology will be util ized for the gas

turbines, the modifications are being made as an administrative change.

Appropriate changes have been made to Conditi ons #1, #2, and #3 in the

enclosed permit. The enclosed permit will replace the February 2, 1987 permit.

This revised conditi onal permi t shall become effective i nmediately unl ess

you notify us otherwise (see Section IV of the permit). Construction and

operation may not take place if this permit or any part thereof is rejected.

If yoo have any questions, please contact John Dale of nrt staff .at

(303) 293-1886.

Enclosures

cc: Burnell Cordner, Director

Bureau of Air Quality Utah Department of t-eal th

Arlene Luther, Navajo Nation RECEIVED

AIR QUALITY

NOV 10 1981
CONDITIONAL PERMIT TO

CCMt1ENCE CONSTRUCTION AND OPERATE

40 CFR 52.21

Preventi on of

Significant Deterioration of Air Quality

Mob il Oi 1 Corporati on

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, Regi on VII I (herei na fter liE PAil ) a Preventi on of Signifi cant

Deterioration (PSD) application to construct the proposed modification

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 and issue a conditional air quality

permit for the source and provided opportunity for publ ic 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 Qual ity in

Salt Lake Ci~ and the EPA Region VIn office in Denver. The only conments

concerning the permit were received fran the Appl icant and contained only

minor clarifications.

On September 1, 1987, the Appl i cant submi tted a letter requesti ngto repl ace

the three reci procating internal corrbustion engines wi th 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. FIND INGS

On the basis of information in the administrative record, EPA has determined

that:

1. The Applicant is a major source and this 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 believe that the Applicant can comply with the

conditions of this 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. CONOI TIONAL PERMIT TO CONSTRUCT AND OPERATE

c. November 4, 1986 - Supplementary information correcting VOC

emi ss'ton rates.

d. September 1, 1987 - Letter requesting to replace three

reci procating internal combusti on 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 NOx emission 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

mal functi on, owners and operators shall maintain and operate the

facility in a manner consistent with good air pollution control

practi ces for minimizing emi ssi ons, Oetermi nati on of whether

acceptable operating and maintenance procedures are being used will

be based on information available to the Administrator, which may include, but not be limi ted to, monitoring resu1 ts, review of

operating and maintenance 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 mal functions, 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. The identity 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 1imitati ons -descrtbed in this permi t will be considered a

violation of the permit.

6. This permit shall expire if construction 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. A test protocol outl ining a plan for the initi a1 canpl i ance

demonstrati on tests shall be submi tted to EPA 45 days in advance of

any scheduled testing.

9. EPA and its authorized representatives may inspect the permitted

facil ity during normal business hours for purposes of ascerta""ing

compliance with all conditions of this permit.

10. Nothing in this approval shall excuse the Appl icant, the owner,

and/or operator fran complying with all other appl icab1e Federal,

State and local regulati ons.
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

modi fy 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 and is 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:~~~' I rwi n L. D1 ckstein, D1 rector

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 a

3216 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.