Mariner East 2 Hazards Quantification

The Mariner East 2 pipeline is proposed to carry Highly Volatile Liquids (artificially liquefied Ethane, Propane, Butane gas) through several densely populated areas in Southeastern Pennsylvania. Much of route through Chester and Delaware counties would be considered Class 4 High Consequence Areas by Natural Gas standards. However, these artificially liquefied gases have hazards greater than traditional Natural Gas. “Natural Gas Liquids”, or “NGLs” are maintained in an artificially liquefied state inside the pipeline. This liquid state is a higher energy state containing more combustion energy than the ambient state these gases have in the natural environment. If leaked, highly condensed liquids rapidly convert back to a gas, expanding by hundreds of times in volume into a highly explosive gas cloud. These gases are naturally odorless, colorless, and heavier-than-air. The heavier-than-air characteristic allows these gases to migrate in unpredictable ways that are highly dependent on wind conditions and topography. The gases, being heavier-than-air, remain low to the ground, will settle in low lying areas, can enter sewer systems or porous rock and use them as conduit to migrate indeterminate distances from a leak site. These gases only require a 3% gas-to-air ratio to remain combustible. A model has been developed to quantify the hazards for the proposed Mariner East 2 pipeline carrying artificially liquefied ethane, propane, and butane from Houston, PA to Marcus Hook, PA. The model focuses on the heavily populated segment between the pumping station in Derry Township, Dauphin County, PA and the pipeline terminus in Twin Oaks, Delaware County, PA. Methane Natural Gas hazards model is shown for reference and comparison throughout the modeling process. Data for this assessment utilizes results from an independent Hazards Study performed by Oklahoma-based Quest Consultants. Quest ran several simulations of ME2 pipeline ruptures using liquefied Ethane as the piped material. A summary of their results is shown: