The Leidy South expansion project is a proposed natural gas pipeline expansion project to increase the transportation capacity of the existing Transco natural gas pipeline in the US by 582,400 dekatherms of per day (Dth/day).

Williams’ subsidiary Transcontinental Gas Pipe Line Company (Transco) is executing the project to boost natural gas supplies from Marcellus and Utica in Pennsylvania to serve the growing demand centres of the Atlantic Seaboard region on Cape Town's western coastline by the 2021-22 winter heating season.

Williams filed the expansion proposal for the Leidy South pipeline with the US Federal Energy Regulatory Commission (FERC) in August 2019 and received approval for the same in July 2020.

The Leidy South project will expand Transco’s existing transportation capacity from Leidy Hub and Zick interconnection points downstream to Transco’s Zone 5 and 6 market areas.

Construction on the Leidy South pipeline expansion project is expected to commence in the second half of 2020, with the completion targeted for December 2021. 

Leidy South expansion corridor

 The Leidy South expansion pipeline will cover the corridor across two Pennsylvania Department of Environmental Protection (DEP) regions, US. It will cover three counties in the northcentral region and the other three in the northeast region. 

The project aims to minimise the environmental impacts through utilisation of existing facilities.

The project aims to replace approximately 10km of Transco’s existing 24in Leidy Line A with 36in pipe in Clinton County, Pennsylvania.

The pipeline expansion facility will consist of Hilltop loop and Benton loop in Pennsylvania. While Hilltop loop involves the construction of 3.86km of 36-inch pipeline loop in Clinton County, the Benton loop will include 5.63km of 42-inch pipeline loop in Lycoming County.

The project will also involve underground and above-ground facilities along with a 90ft tall communication tower. The other equipment will include mainline valves, cathodic protection, pig receivers and pig launchers. 

Leidy South expansion design details

The facilities under the expansion project will be built within the existing compressor station areas located within property boundaries of Dominion Transmission (DTI) or the Leidy Storage facility, which is a partnership between DTI, Williams pipeline and Spectra Energy.

The compressor station 605 with existing 15,000hp electric motor driven compressors will be uprated to 21,000hp compressors in the Wyoming County of Pennsylvania.

The greenfield compressor station 607 will involve the installation of two turbine driven compressor units along with cooling facility. This infrastructure will be located in Luzerne County along with installation of a 190ft tall free-standing communication tower.

Compressor station 610 will feature an additional turbine driven compressor unit along with cooling system in Columbia County.

A new turbine driven compressor will be installed at greenfield compressor station 620 of Schuylkill County.

Off-take agreements

In October 2018, Williams entered into 15-year binding agreements with Seneca Resources Company (330,000Dth/d), Cabot Oil and Gas (250,000Dth/d) and UGI Utilities (2,400Dth/d) for off-take of natural gas from the Leidy South expansion project. 

Contractors involved

Goodwin and Associates were involved in the archaeological survey of Leidy South expansion project. 

Leidy South pipeline expansion project background

The Leidy South expansion is an enhancement to the existing Leidy South pipeline developed by Dominion Transmission in October 2017. The existing Leidy South project was constructed with the aim to transport 0.155 billion cubic feet (bcf) per day of natural gas to the Mid-Atlantic region.

Williams entered a capacity lease agreement with National Fuel Supply Corporation to connect the Leidy South expansion pipeline with Clermont, Pennsylvania. The company will lease Meade Pipeline’ undivided stake in Central Penn Line from Zick to River Road regulator station.