DAQ-2024-008116

DAQE-GN121030023-24

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Dani Baldwin
MountainWest Pipeline, LLC
P.O. Box 45922
Salt Lake City, UT 84145
[e-mail]

Dear Mr. Checketts:

RE: Replacement-in-Kind Determination for the Oak Spring Turbine Compressor Station

This letter is in response to the notification submitted on January 1, 2024, concerning the exchange of
Unit T-3 (7,684 hp rated) at the Salt Lake Station. Utah Division of Air Quality has determined that the
exchange of Unit T-3 meets the Replacement-In-Kind rule R307-401-11.

MountainWest Pipeline shall notify the Director in writing when the installation of the exchanged Unit
T-3 has been completed and is operational. An initial compliance test is required within 180 days of
installation. A notification shall be submitted at least 30 days prior to conducting any testing. To ensure
proper credit when notifying the Director, send your correspondence to the Director, attn: NSR Section.

The replacement of Unit T-3 shall operate under the conditions listed in Approval Order
DAQE-AN121030019-20.

Please direct any technical questions regarding this letter to Mr. Tad Anderson, who may be reached at
[phone].

Sincerely,

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Jon L. Black, Manager
New Source Review Section

JLB:TD:jg
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195 North 1950 West • Salt Lake City, UT
Mailing Address: P.O. Box 144820 • Salt Lake City, UT 84114-4820
Telephone [phone] • Fax [phone] • T.D.D. [phone]
www.deq.utah.gov
Printed on 100% recycled paper
State of Utah

SPENCER J. COX
Governor

DEIDRE HENDERSON
Lieutenant Governor

Department of
Environmental Quality

Kimberly D. Shelley
Executive Director

DIVISION OF AIR QUALITY
Bryce C. Bird
Director

* ) ' & — 4 @ D v A ? A C ? G w A G ˜
May 15, 2024
Via USPS Mail

January 11, 2024

Utah Division of Air Quality
Director, Air Quality Division
P.O. Box 144820, Salt Lake City, Utah 84114-4820

RE: MountainWest Pipeline, LLC - Oak Spring Turbine Compressor Station
Approval Order DAQE-AN0121030019-20
Turbine Core Exchange for T-3 - Request for Substantial Equivalency Determination

Dear Division:

Upon receipt of a determination of substantial equivalency, MountainWest Pipeline, LLC will
exchange the core with a replacement-in-kind for the Solar Taurus 60-7800S (SN OHE20-T9062)
turbine, T-3, at the Oak Spring Turbine Compressor Station. The proposed rebuilt core unit is
from the Solar Turbines overhaul fleet exchange with identical horsepower, heat rate and
emissions. The turbine is equipped with dry low NOx combustion technology and the
replacement unit will be identical to the existing core unit with the exception of the combustion
unit’s serial number. The turbine core replacement is scheduled for July 2024. The core exchange
follows the routine schedule for major maintenance under the fired-hour maintenance
agreement with Solar Turbines.

T-3 is subject to 40 Code of Federal Regulations Part 60 (NSPS), Subpart GG. Performance testing
will be performed in accordance with NSPS Subpart GG and Approval Order DAQE-
AN0121030019-20. An initial compliance test will be conducted within 180 days of installation.
A notification will be submitted at least 30 days prior to testing. The test results will be submitted
within 60 days of testing.

As it pertains to R307-401-11(2), MountainWest Pipeline, LLC requests written concurrence from
the Division that additional permitting actions or requirements are not required for the turbine
core replacement-in-kind for T-3. Questions regarding this submittal should be referred to Dani
Baldwin at [phone] or [e-mail].

Sincerely,

Dani Baldwin
Environmental Specialist
MountainWest Pipeline, LLC
P.O. Box 45922
Salt Lake City, Utah 84145