DAQ-2025-000689

DAQE-GN121030024-25

Dani Baldwin
MountainWest Pipeline, LLC
650 South Main Street, 3rd Floor
Salt Lake City, UT 84101
[e-mail]

Dear Dani Baldwin:

RE: Replacement-in-Kind Determination for Turbine T-2 at Oak Spring Turbine Compressor Station
Project Number: N121030024

The Utah Division of Air Quality (UDAQ) received your notification, dated December 17, 2024,
concerning Replacement-in-Kind (RIK) of a Solar Taurus 60-7800S Turbine, Turbine T-2 at the Oak
Spring Turbine Compressor Station. The Utah Division of Air Quality has determined that the
replacement of the Turbine T-2 satisfies the eligible criteria outlined in R307-401-11.

MountainWest Pipeline, LLC shall notify the director in writing when the installation of the exchanged
unit 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 Turbine T-2 shall operate under the conditions listed in Approval Order
DAQE-AN121030019-20.

The charge for the review done in making this change is a flat fee plus a filing fee as authorized by the
Utah Legislature. You will receive an invoice for these charges shortly. If you have any questions, please
contact Jacob Hurley, who can be reached at [phone] or [e-mail].

Sincerely,

Jon L. Black, Manager
New Source Review Section

JLB:JH:jg

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

* ) ' & — B v A ? A D @ B w ? E ˜
02/03/2025
Via Certified Mail

December 17, 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-2 - Request for Substantial Equivalency Determination

Dear Mr. Bird:

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 turbine, T-2, 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 core
replacement is scheduled for April 2025. The core exchange follows the routine schedule for
major maintenance under the fired-hour maintenance agreement with Solar Turbines.

Turbine T-2 is subject to 40 Code of Federal Regulations Part 60 (NSPS), Subpart KKKK.
Performance testing will be performed in accordance with NSPS Subpart KKKK and DAQE-
AN0121030019-20. The 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 turbine T-2. Questions regarding this submittal should be referred
to Dani Baldwin at [phone] or [e-mail].

Sincerely,

Dani Baldwin
Environmental Specialist
MountainWest Pipeline, LLC
650 South Main Street, 3rd Floor
Salt Lake City, Utah 84101