Site Background
MarkWest Liberty Midstream & Resources LLC (MarkWest) is currently authorized to operate its Harmon Creek Gas Plant under GP5-63-01011B and Plan Approval 63-01011.
The Harmon Creek Gas Processing Plant is located at 123 Point Pleasant Road in Smith Township, Washington County.
What’s New
On March 11, 2025, DEP held a public hearing to receive public comments on its intent to issue air quality plan approval [PA-63-01011B]. More information on the hearing is available in the Public Participation section.
On March 7, 2026, DEP published notice of its intent to issue a natural minor State-Only Operating Permit [PA-63-01011]. More information on the plan approval application and draft are available in the Permitting/Approvals section.
Permitting/Approvals
GP- 5 is a general plan approval and/or general operating permit for natural gas compression and/or processing facilities. This general permit applies to mid-stream natural gas gathering, compression and/or processing facilities that are minor air contamination sources or facilities.
On June 29, 2022, DEP authorized the facility to operate under GP5-63-01011B (AG5-63-00011A).
Air quality plan approval is required for the applicant to commence construction of an air contamination source and may allow for temporary operation. A plan approval is not the same as an operating permit, which is required for long-term operation. Publication of a draft air quality plan approval and notice of intent signals that DEP has performed its evaluation of the application and begins the regulatory public participation process.
On June 29, 2022, DEP received an air quality plan approval application from MarkWest.
On July 8, 2022, DEP deemed the application to be administratively incomplete and noted technical deficiencies. On July 11, 2022, DEP received a response from MarkWest. On July 13 and 14, 2022, DEP received responses to technical deficiencies. On July 21, 2022, DEP deemed the application to administratively complete.
On September 1, 2022, DEP requested a more detailed BAT analysis that DEP received on October 17, 2022. DEP received additional revised technical information on the following dates: October 19, October 31, November 1, November 3, November 4, November 10, November 17, and November 21, 2022.
- BAT Analysis Request (9-1-2022) (PDF)
- MarkWest information submission (10-17&19-2022) (PDF)
- MarkWest information submission (10-20-2022) (PDF)
- MarkWest information submission (10-31-2022) (PDF)
- MarkWest information submission (11-1-2022) (PDF)
- MarkWest information submission (11-3-2022) (PDF)
- MarkWest information submission (11-4-2022) (PDF)
- MarkWest information submission (11-10-2022) (PDF)
- MarkWest information submission (11-17-2022) (PDF)
- MarkWest information submission (11-21-2022) (PDF)
On November 23, 2022, DEP issued a draft plan approval.
- Review Memo (11-23-2022) (PDF)
- Draft Plan Approval (PDF)
On December 3, 2022, DEP published notice of its intent to issue the air quality plan approval in the Pennsylvania Bulletin.
- Pennsylvania Bulletin Notice (starts on page 7434)
On April 12, 2023, DEP issued the air quality plan approval.
- Final Plan Approval (PDF)
- Comment and Response Document (PDF)
On March 7, 2026, DEP published notice of its intent to issue a natural minor State-Only Operating Permit [PA-63-01011] in the Pennsylvania Bulletin.
Air quality plan approval is required prior to the start of construction of an air contamination source and associated air cleaning device(s) and will allow for temporary operation. A plan approval is not the same as an operating permit, which is required for long-term operation. Publication of a draft air quality plan approval and notice of intent signals that DEP has performed its evaluation of the application and begins the regulatory public participation process.
On January 19, 2024, DEP received MarkWest’s application for air quality plan approval to construct and temporarily operate air contamination sources and air cleaning devices associated with the proposed DeEthanizer II and 330 MMscfd Cryo II projects at its Harmon Creek Gas Processing Plant. On January 31, 2025, DEP determined the application to be administratively complete. On May 28, 2024, DEP identified technical deficiencies. On November 12, 2024, DEP issued a second technical deficiency letter.
- Technical Deficiency Letter (PDF)
- Second Technical Deficiency Letter (PDF)
- Technical Deficiency Response (PDF)
- Revised Plan Approval Application (PDF)
- Updated BAT Analysis (PDF)
- Proposed Emission Reductions (PDF)
- Valve Extensions Information (PDF)
- Method 21 Proposal (PDF)
On February 8, 2025, DEP published notice of its intent to issue a draft plan approval to allow the construction and initial temporary operation of new air contamination sources.
- Proposed Air Quality Plan Approval (PDF)
- Review Memo (PDF)
Public Participation
Public Notice and Comment Period
On December 3, 2022, DEP published notice of its intent to issue the air quality plan approval [PA-63-01011] in the Pennsylvania Bulletin, which commenced a 30-day public comment period.
- Pennsylvania Bulletin, Vol. 52, No. 49 (begins on page 7434)
On February 8, 2025, DEP published notice of its intent to issue the air quality plan approval [PA-63-01011B] in the Pennsylvania Bulletin, which commenced a 30-day public comment period.
- Pennsylvania Bulletin, Vol. 55, No. 6 (begins on page 1328)
On March 7, 2026, DEP published notice of its intent to issue a natural minor State-Only Operating Permit [PA-63-01011] in the Pennsylvania Bulletin. This notice also commences a 30-day public comment period, which expires Monday, April 6.
- Pennsylvania Bulletin, Vol. 56, No. 10 (begins on page 1321)
Public Hearing – March 11, 2025
Burgettstown Area Middle/High School Campus, Burgettstown, PA 15021
Compliance/Enforcement
On October 5, 2022, DEP and MarkWest Liberty Midstream & Resources, LLC executed a consent assessment of civil penalty (CACP) to resolve violations 2021 of visible emissions from flaring.
- CACP (10-5-2022) (PDF)