Mariner East pipeline construction caused spills
Construction of the Mariner East II pipeline has resulted in dozens of spills of drilling fluid in 10 counties, including Westmoreland, since April, according to documents released by the state Department of Environmental Protection.
The documents, released as part of litigation by the Philadelphia-based Clean Air Council, show that the spills have not been limited to southeastern Pennsylvania, as previously reported.
Of the 61 spills documented between April 25 and June 17, 25 occurred in the southwestern part of the state, 29 in the south central region and seven in the southeastern region.
Westmoreland County had 11 reported spills, the second-highest number after Cumberland County. The Westmoreland spills occurred in Derry (three), Hempfield (one) and the Loyalhanna Lake National Recreation Area (seven), according to the documents.
Officials with Sunoco Logistics Partners LP, builder of the 350-mile pipeline, described the spills as “inadvertent returns” of a drilling fluid composed of bentonite, a nontoxic clay and water. The fluid is used as a drill-bit lubricant during horizontal directional drilling, said company spokesman Jeff Shields.
Horizontal drilling is used to lay pipe under roads, waterways, wetlands, wildlife habitats and other “sensitive areas,” Shields said. Fluid returns occur when drilling mud seeps to the surface through underground fissures.
Such spills, although not unexpected, can get into local well water, Shields said. The phenomenon can result in a loss of water pressure and water clouding.
“It's not something you want with waterways. You want to have minimal impact on waterways,” he said.
Shields said Sunoco Logistics has been following its contingency plan for inadvertent releases, which is part of its DEP water crossing permits. Those permits are being challenged before the Pennsylvania Environmental Hearing Board.
“Any ingredients in the drilling fluid must be approved by the DEP and meet safe drinking water standards, and that is specifically in case the fluid escapes through a seam in the geology and into the environment,” Shields said. “As part of our permits with the DEP, we have plans to monitor for inadvertent returns, contain any bentonite and water, and recover it.”
Construction on the Mariner East II pipeline began soon after the state DEP issued its final permits in February. In Westmoreland County, the pipeline traverses Sewickley, Hempfield, Penn, Salem, Loyalhanna and Derry townships.
Other affected municipalities include Jeannette, Export, Delmont and Murrysville.
The 20- and 16-inch pipelines will be able to carry 275,000 barrels of liquid natural gas a day and cross 270 properties over 36 miles in Westmoreland County. The new pipelines will run parallel to the existing Mariner East I line.
The DEP documents can be viewed at StateImpact Pennsylvania .
Stephen Huba is a Tribune-Review staff writer. Reach him at 724-850-1280, shuba@tribweb.com or via Twitter @shuba_trib.
