Articles & Case Studies

E-Z Trays an Integral Part of Levelland's Groundwater Treatment

Posted: Wednesday 4th January 2017

The refinery at the former Motor Fuels Corporation produced all grades of gasoline, tractor fuels, diesel, distillate products, and fuel oils. It closed in 1954 after 15 years of operation, and the refinery equipment was removed by 1958. The property has since been redeveloped, but the groundwater contains a plume of benzene and 1,2-dichloromethane. This plume is now contaminating the groundwater that supplies the city of Levelland, Texas with one-third of its drinking water.

The plume extends approximately one and a half miles from the former refinery, and is approximately one mile wide. Analyses of samples collected during ongoing site investigations indicate maximum benzene concentrations of 19,000 ppb and maximum DCA concentrations of 380 ppb. The EPA has established a maximum contaminant level of 5 ppb in drinking water for both of these contaminants.

In 2008, the EPA obligated approximately $5.2 million for cleanup activities at the site. Since then, 21 groundwater extraction wells, 10 monitoring wells, 4 injection wells and 62 soil vapor extraction (SVE) wells have been installed, and a treatment plant was built to house a combined groundwater and soil vapor treatment system.

Two QED 24-tray E-Z Tray® (U.S. Patent Number 5,518,668) Air Stripper units, each with a 30 horsepower blower and a combined flow rate of 500 gpm, were installed in this treatment plant to remove VOCs in the groundwater; dissolved metals are treated with chemical precipitation. A C3 unit, which uses cryogenic compression and condensation to recover the contaminant vapor as a liquid, is collecting the vapor from the Air Stripper and SVE system. The downstream equipment is a Zeolite Condenser, which absorbs benzene so that 90% of the air stream can be released to the air. The concentrated air is then desorbed and passed onto the C3 unit, which compresses the gas into pure product that can be sold by the customer.

“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.”

Dave Fischer, Vice President of Engineering at QED notes that, “The reason to use induced vacuum is to avoid any temperature rise through the blower that would change the dew point enough to cause any condensation in the downstream equipment and piping.”

The Levelland system generates 1,000 gallons of product per week, which contributes about $10,000 per month towards payback on the system.




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December 2018

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