Sunoco Agrees to Change Operations on Sections of Mariner East

Sunoco has agreed to change its construction methods at three sections of the Mariner East pipeline in eastern Pennsylvania. The change is being made in order to mitigate any further harm to human and environmental health after a series of accidents on the pipeline.

The new agreement requires Sunoco to use the open trench method of pipeline installation, abandoning the former horizontal directional drilling (HDD) method. The change was agreed upon by both Sunoco Pipeline L.P. and Pennsylvania’s Department of Environmental Protection.

The two methods are fundamentally different. Open trench is a much more invasive method of pipeline installation, requiring heavy machinery to physically dig a hole, or trench, in which the pipe is laid and then covered with earth. Horizontal directional drilling is considered the standard modern method of pipeline installation. HDD uses drilling machinery to bore a hole under the ground where the pipe is then inserted.

When comparing the two methods, HDD is by far the least disruptive method, causing little to no surface damage or disruption. Open trench, on the contrary, is visible and much more disruptive on the surface as it requires long trenches to be dug. In that respect, it is clear as to why HDD has become the default method.

However, in several sections of the Mariner East, using HDD in unstable geological formations resulted in serious damage to the surrounding environment, including sinkholes and spills that have contaminated water sources. For that reason, DEP agreed to open trench construction.

This effort is the latest in the troubled history of the Mariner East project. The 350-mile long pipeline project is being built to move natural gas and gas products from the Marcellus shale basin in southwestern Pennsylvania across the Commonwealth to a terminal in Marcus Hook near Philadelphia. There have been multiple fines issued to Sunoco for previous spills and other violations.

The state Public Utility Commission also recently ordered Sunoco to conduct a public education meeting for residents of Cumberland County in eastern Pennsylvania, where there has been significant opposition to the project. A resident filed a complaint after Sunoco canceled its attendance at a scheduled outreach meeting and failed to send printed materials to the resident as called for its own public awareness program.