Leidy South Expansion Project

Quick Facts

  • New facilities associated with the Leidy South project are located primarily along existing pipeline corridors.
  • The project application was filed with the FERC on July 31, 2019. It was assigned Docket Number CP19-494-000.
  • Once complete, the project will expand the Transco pipeline’s Marcellus and Utica takeaway capacity by 582,400 dekatherms per day.


The Leidy South Project is a proposed expansion of Williams’ existing Pennsylvania energy infrastructure to further connect robust supplies of natural gas in northern and western Pennsylvania with growing demand centers along the Atlantic Seaboard in time for the 2021-22 winter heating season.

The project will help the existing Transco pipeline system transport an additional 582,400 dekatherms of natural gas supply per day – enough natural gas to meet the daily needs of approximately 2.5 million homes.

Impact & Benefits

Pennsylvania is the second-largest natural gas producing state in the U.S., producing a record 6 trillion cubic feet of gas in 2018. The Commonwealth accounted for 19% of total U.S. marketed natural gas production in 2017 and produced more natural gas than any other state except Texas.

While Pennsylvania produces record volumes of natural gas, insufficient pipeline infrastructure continues to limit consumer access to the state’s supplies, resulting in production curtailments and shut-in production.

Williams’ Transco pipeline has executed commitments with Seneca Resources Company, LLC, Cabot Oil & Gas Corporation and UGI Utilities for 100 percent of the firm transportation capacity under its proposed Leidy South project. Once complete, the project will further expand the Transco pipeline’s Marcellus and Utica takeaway capacity from the Leidy Hub and Zick interconnect.

According to third-party researchers, construction of the Leidy South Project’s two greenfield compressor facilities is estimated to generate $100 million in economic activity within Pennsylvania, supporting 680 jobs with combined earnings of $28 million, and produce $1.3 million in state tax revenue.


The design of the Leidy South Project limits environmental impacts by maximizing the use of existing energy infrastructure. The proposed facilities include:

  • Replacement of 6.3 miles of Transco’s existing 24-inch Leidy Line A with 36-inch pipe in Clinton County, Pennsylvania (Hensel Replacement)
  • 2.4 miles of 36-inch pipeline loop in Clinton County, Pennsylvania (Hilltop Loop); and
  • 3.5 miles of 42-inch pipeline loop in Lycoming County, Pennsylvania (Benton Loop);
  • Compressor Station 605 – Uprate the two existing electric motor driven compressors from 15,000 horsepower (“hp”) to 21,000 hp each at Transco’s existing Compressor Station 605 in Wyoming County, Pennsylvania;
  • Greenfield Compressor Station 607 – Install two turbine driven compressor units and cooling in Luzerne County, Pennsylvania;
  • Compressor Station 610 – Add one turbine driven compressor unit and cooling at Transco’s existing Compressor Station 610 in Columbia County, Pennsylvania;
  • Greenfield Compressor Station 620 – Install one turbine driven compressor unit in Schuylkill County, Pennsylvania;
  • Appurtenant underground and above-ground facilities.


  • November 2018 - Pre-filing process begins
  • December 2018 / February 2019 - Open Houses
  • July 2019 - Submit 7(c) Application to FERC
  • Early 2021 - Anticipated Construction Start
  • Winter 2021 - Target In-Service

Regulatory Process

Interstate natural gas pipelines are regulated by the Federal Energy Regulatory Commission (FERC). As such, FERC requires pipeline operators to obtain a federal Certificate of Public Convenience and Necessity, in addition to various state permits, before any pipeline facilities can be built.


The FERC pre-filing process -- which began in November 2018 -- is intended to solicit early input from citizens, governmental entities and other interested parties to identify and address issues with potential facility locations (the project was assigned pre-filing docket number PF19-1; view the submital here). The company will host a series of public open houses in the affected areas to formally introduce the proposal to the public and solicit feedback. Public input is important to us and can help shape the final project scope.

Certificate Application

Following the pre-filing period, Williams filed its Certificate Application with the FERC on July 31, 2019, seeking approval to construct the Leidy South Project. You may access all project-related documentation at the FERC website by referencing the docket number assigned to the project (Docket Number CP19-494-000).

Among other things, the Certificate Application contains a description of the new facilities, need for the project, detailed maps, schedules, and various environmental reports. This information details the various studies and analyses that have been conducted to determine what effect construction and operation could potentially have on the environment and community.

Environmental Evaluation

FERC will prepare an environmental evaluation using information included in the Certificate Application, supplemental information that may be provided by the company upon request, information assembled by FERC staff, as well as information provided by state and federal agencies and the public. The evaluation will describe the proposed project and alternatives, as well as identify existing environmental conditions and potential impacts from the project.

If FERC determines that the project is environmentally acceptable – and is satisfied the project is in the public interest – it will issue an Order granting a Certificate of Public Convenience and Necessity.

Contact Us

Questions related to the project can be directed to PipelineExpansion@williams.com

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