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    Southwest Community Information

    MarkWest Harmon Creek Gas Plant

    This page was last updated on February 10,  2025

    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 January 19, 2024, DEP received MarkWest’s application for air quality plan approval [PA-63-01011B] 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 February 8, 2025, DEP published notice of its intent to issue a draft plan approval [PA-63-01011B]. More information on the plan approval application and draft are available in the Permitting/Approvals section.

    On March 11, 2025, DEP will hold 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. 

    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.

    On November 23, 2022, DEP issued a draft plan approval.

    On December 3, 2022, DEP published notice of its intent to issue the air quality plan approval in the Pennsylvania Bulletin.

    On April 12, 2023, DEP issued the air quality plan approval.

    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.

    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.

    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. This notice also commences a 30-day public comment period.

    On February 8, 2025, DEP published notice of its intent to issue the air quality plan approval [PA-63-01011B] in the Pennsylvania Bulletin. This notice also commences public comment period.  

    Public Hearing – March 11, 2025

    On March 11, 2025, DEP will hold a public hearing to receive public comments on its intent to issue air quality plan approval [PA-63-01011B].

    March 11, 2025 from 6:30 to 8:30 PM
    Burgettstown Area Middle/High School Campus
    LGI Room
    100 Bavington Road
    Burgettstown, PA 15021

    Members of the public will have the opportunity to present up to three minutes of oral testimony relevant to the draft plan approval.

    Those wishing to register for the public hearing must contact Emily Green, Southwest Regional Environmental Justice Coordinator, by email at emgreen@pa.gov or by calling 412-442-4042 at least 24 hours before the hearing. Testimony is limited to three (3) minutes in length. DEP requests that organizations designate one spokesperson to present testimony on their behalf. Individuals should provide a copy of their testimony and exhibits for submission to DEP at the hearing. Submitted materials are not limited in length and must include the name, address, and phone number of the person submitting them and identification of the proposed Plan Approval (PA-63-01011B). DEP will equally consider all comments, whether delivered orally during the hearing or submitted in writing.

    Individuals wishing to attend who require an auxiliary aid, service, or other accommodations to participate should contact Emily Green. The Pennsylvania AT&T Relay Service is available by calling 1-800-654-5984 (TTD users) or 1-800-654-5988 (voice users) and request that the call be relayed to Emily Green at 412-442-4042

    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.