Case Study of Selected Technologies to Remediate Soil and Groundwater at Natural Gas Compression Facilities, West Panhandle Field, Texas

Michael A. Jacobs, P.G.¹, J. David Mohrbacher P.E.², Brent Miller, P.E.³, and Kyle Hughes⁴,

¹Pioneer Natural Resources USA Inc, Midland, Texas, ²URS Corporation, Denver, Colorado

³ERM Corporation, Seattle, Washington, ⁴Eco-Logical Environmental Services, Amarillo, Texas

In 2001, Pioneer Natural Resources USA Inc. conducted an environmental assessment of soil and groundwater contamination associated with natural gas production.  The gas compression and production facilities are located in the West Panhandle Field, Moore and Potter Counties, Texas, and have been in operation since the 1930s. Shallow and/or deep soil contamination, primarily from used lube oil and natural gas condensate, was discovered at most of the gas compression facilities.  Limited amounts of non-aqueous phase liquids (NAPL) were observed on shallow perched water- bearing zones at two sites, and dissolved phase (BTEX) plumes with benzene concentrations exceeding drinking water standards were observed at a total of six sites. The depths to the shallow perched water-bearing zones at these sites varied from approximately 20 to 40 feet below ground surface.

Pioneer Natural Resources USA, Inc. implemented a program of restoration and remediation at these sites as part of the Operator and Voluntary Cleanup Programs (OCP/VCP) administered by the Railroad Commission of Texas.  Pioneer initiated a variety of bio-vent, air sparging and high vacuum dual phase vapor extraction system approaches to achieve cleanup of soil and groundwater.  To date 133 wellhead compressor sites, 72 mercury meter sites and 5 field compressor sites have been closed.  In 2005, the remediation program was nominated by the Texas Railroad Commission for the Interstate Oil and Gas Compact Commission’s Environmental Stewardship Award and received Honorable Mention.