The former Motor Fuels Corporation refinery in Levelland, Texas used to produce all grades of gasoline, tractor fuels, diesel, distillate products, and fuel oils prior to the plant’s closure in 1954 after 15 years of operation.

All refinery equipment was removed by 1958, and the property has since been redeveloped, but the groundwater in the area contains a plume of benzene and 1.2-dichloromethane (DCA), which is contaminating the groundwater that supplies the city of Levelland with around 33% of its drinking water.

The plume is approximately 1.6 kilometres wide and extends around 2.4 kilometres from the former refinery. While the EPA has established a maximum contaminant level of 5 ppb in drinking water for both benzene and DCA concentrations, samples collected during onsite investigations put maximum benzene concentrations at 19,000 ppb and maximum DCA concentrations at 380 ppb.

The EPA committed approximately $5.2 million for clean-up activities at the site in 2008, and this led to 21 groundwater extraction wells, 10 monitoring wells, 4 injection wells and 62 soil vapour extraction (SVE) wells being installed. A treatment plant was also built to house a combined groundwater and soil vapour treatment system.

Two QED 24-tray E-Z Tray® Air Stripper units were installed in the treatment plant to remove VOCs in the groundwater; dissolved metals are treated with chemical precipitation. A C3 unit that uses cryogenic compression and condensation to recover contaminant vapour as a liquid collects the vapour from the Air Stripper and SVE system. Downstream, is a Zeolite Condenser absorbs benzene allowing 90% of the air stream to be released to the air; this concentrated air is then desorbed and passed onto the C3 unit, which compresses the gas into pure product that can be sold.

“QED did some fine engineering to put an induced vacuum on the E-Z Tray Air Strippers to make the exhaust stream compatible with the Zeolite Condenser. The humidity and temperature are critical to the functioning of the Condenser,” said Mike Lindstrom of USA Environment who subcontracted the installation of the piping and equipment for the project. “QED did the calculations to meet the design criteria, and to meet a very demanding schedule.”

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