Major Modification – HDD 290 | Energy Transfer

Mariner East 2 Project Modification HDD 290 Upper Uwchlan Township, Chester County

Sunoco Pipeline, a subsidiary of Energy Transfer, is seeking approval from the Pennsylvania Department of Environmental Protection to change the installation method for a portion of the 20-inch pipeline located in Upper Uwchlan Township, Chester County.

The company proposes to change from a horizontal directional drill (HDD) to an open cut on a section of the route spanning approximately 2,700 feet, south of and parallel to Little Conestoga Road and through the intersection of Little Conestoga and Milford Roads.

The modification would also change the pipeline route slightly on a 1,400-foot section of the route, running south of the original path.

The proposed change to the Mariner East 2 pipeline installation method adapts to the local geology and maximizes public and environmental safety. This change would eliminate the potential for inadvertent returns of water and clay drilling fluid. Once work begins, installation will take approximately 5 to 10 weeks.

This is one of the last sections of the 20-inch Mariner East 2 pipeline to complete in Chester County; the 16-inch Mariner East 2X pipeline has already been installed in this area.

NOTE: Construction methods, completion times and exact locations are subject to change due to the inherent fluidity of the construction process and outside factors. The 16-inch Mariner East 2X pipeline is already installed in this area.

Screen Shot 2021 04 12 at 10.50.10 AM 1 - Major Modification - HDD 290

Our goal is safe, time-efficient pipeline installation

This location is the site of an inadvertent return that occurred at Marsh Creek Lake on Aug. 10, 2020. An inadvertent return is when non-toxic drilling mud rises to the surface through preexisting cracks in the rock and soil during the HDD process. Energy Transfer’s engineers and environmental consultants evaluated numerous options to modify the originally permitted route and method. This change to the construction method is the best overall option, catering to the local geology to maximize safety and efficiency during the installation of the Mariner East 2 pipeline. Overall, the modification directs work further away from Marsh Creek Lake and will eliminate the potential for inadvertent returns of water and clay drilling fluid. Click here to read more about Marsh Creek remediation and restoration efforts and to learn more about inadvertent returns.

What Is a Major Modification?

This is classified as a “major modification,” which is a change to an existing environmental permit issued for pipeline construction that exceeds a minor revision. It could be a change in the construction method, the specific pipeline route or the workspace within the right-of-way. In the case of Mariner East 2, such environmental permits are issued by the Pennsylvania DEP.

Installation Methods

Building on the success of the HDD 280 Major Modification nearby, this modification will change the construction method from HDD to open cut installation. Where workspace and enough land access are available, open trench installation is the typical method used for construction, repair and replacement of various utilities, such as pipelines and sewer and water lines. Open trench installation excavation consists of: digging a trench with backhoes or wheel ditchers; lowering the pipe into the trench; and backfilling the subsoil and separated topsoil, where applicable.

Open Cut Installation - Major Modification - HDD 290

For additional information, please check out our fact sheet

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