Pennsylvania lawmakers on both sides of the aisle are again airing concerns this week about natural gas pipeline projects, calling on Energy Transfer Partners LP (ETP) to halt construction of the Mariner East (ME) 2 and 2X projects, after a gathering system in the western part of the state exploded on Monday.

Democratic state Sen. Andrew Dinniman, who filed a complaint with the Pennsylvania Public Utility Commission (PUC) earlier this year that eventually led to a construction suspension on parts of the ME projects that is partially in effect, said on Twitter the incident in Beaver County’s Center Township is a “chilling reminder” of just how “powerful and dangerous these pipelines can be.”

The infrastructure “shouldn’t be so close to our schools, residential neighborhoods and community centers. Mariner East should be permanently halted until we get real assurance that they’re being installed, inspected and operated with safety as the top priority.”

Dinniman, who represents Chester County where sinkholes formed near the ME project earlier this year, was joined by another lawmaker from the area, Republican state Rep. Chris Quinn, in calling for work to stop.

“While I’m relieved to know that no injuries occured, I also realize that this area of Beaver County is far less dense than the pipeline corridor in Delaware County,” Quinn said of a heavily populated area where the ME system is located. “A similar incident in my district could be even more destructive and have a greater human toll.

“Therefore, I’m calling for an immediate halt to all pipeline construction activities,” Quinn added of the ME project. “This pipeline should not be built until the real and legitimate safety and environmental concerns raised by myself and local residents have been fully addressed.”

Republican state Sen. Tom McGarrigle, who represents constituents near the ME projects, also called on ETP to stop construction until a full investigation of the Beaver County incident has been completed.

A 24-inch diameter segment of ETP’s Revolution system exploded early Monday. The pipeline has been under construction for the last year and was near start up when the incident occurred. The company said it would inspect the entire system following days of heavy rain that likely caused the incident after a landslide.

The PUC, which is leading the investigation, said Wednesday the pipeline is in a Class 3 location, which is based on population density per federal standards. Class 1 lines are in lightly populated areas, while Class 4 lines are in the most densely populated areas.

Regulators said the line was pressure tested last year and this year. ETP officials noted at a press conference earlier this week that the line was nowhere near maximum pressure as it was being commissioned.

The line falls under PUC’s jurisdiction and a 2011 state law that expanded the commission’s authority to enforce federal pipeline safety laws relating to natural gas and hazardous liquids. The PUC’s Bureau of Investigation and Enforcement said it does not comment on the details of investigations until they result in enforcement action or a formal petition or complaint has been filed. Inclement weather and poor on-site conditions have also limited access to the site and slowed the investigation, PUC said.

The pipeline was placed into service last week and is part of the broader Revolution system, which gathers wet gas and also includes 30-inch diameter pipeline and has a capacity of more than 400 MMcf/d. At the time of the blast, the company was in the process of purging and packing the gathering lines that feed ETP’s Revolution Plant in Washington County, where construction was recently completed. The plant would deliver tailgate volumes to affiliate Rover Pipeline’s Burgettstown lateral.

ETP has previously said natural gas liquids from the Revolution Plant could eventually be shipped on its ME system to the Marcus Hook Industrial Complex near Philadelphia. The ME projects have repeatedly been delayed and faced penalties, including a historic $12.6 million fine earlier this year to resolve dozens of violations during construction.

ME 2 is nearly complete. It would run parallel to ME 2X for 350 miles to move ethane, butane and propane from processing facilities in Ohio, Pennsylvania and West Virginia to Marcus Hook.

Monday’s incident was the latest in a series of pipeline incidents in the basin. In June, Leach XPress exploded in West Virginia. About two years ago, a portion of the Texas Eastern Transmission system in southwest Pennsylvania also exploded, destroying a house and severely burning one resident.