Innovative Cover Design Construction Completed Successfully

Much of the remediation at RMA is clean-up and on-site disposal of hazardous waste.  In the U.S. there are strict requirements for how that waste is disposed and covered. Methods that use synthetic covers have been the accepted standard, but at RMA an innovative alternative cover system was developed by the Army, with detailed involvement by EPA including engineering support and technical analysis from PWT and geotechnical/civil engineering expertise from PWT partners Steve Dwyer and Jorge Zornberg under the leadership of Dorthea Hoyt. This innovative solution underwent eight years of design, testing, and negotiations with regulatory agencies, and construction of 453 acres of the “RCRA-equivalent Covers” was completed between 2005 and 2010.

The professional publication, Civil Engineering, published this paper in January 2011. See the published paper.

PCE Groundwater Treatment

Bountiful, Utah

A migrating plume of Perchloroethylene (PCE) from a dry cleaning business in Bountiful, Utah contaminated groundwater, affected residents and livestock, and necessitated an EPA remedial action. PWT designed an innovative remedial  groundwater treatment system to address the contamination that reduced physical impact, improved operating efficiency, and reduced costs.

As part of the unique design, PWT incorporated pipe-hole boring techniques that eliminated the physical impacts of surface soil removal consistent with traditional trenching techniques for piping installation. In order to keep bentonite mud from contaminating the surrounding aquifer, PWT used sonic drilling. The sonic drilling technique had the added value of eliminating the need for geophysical logging since direct logging of geological data could be performed. This made the process more efficient since tertiary steps and the indirect geophysical logging methods were able to be eliminated. PWT also engineered a safe and effective alternative to double containment piping, saving about 20% of the total project cost.

All work on this RAC2 project was performed on time, within budget, and we are proud to state that the EPA team rated PWT with “Excellent” performance ratings in all service areas on the prime contract.

California Gulch- OU 11 Superfund Site

California Gulch OU11Leadville, Colorado:

PWT used value engineering and sustainable design to remediate toxic metal-contaminated soils in former mining sites near Leadville, Colorado. In operable unit 11 of the site, PWT managed an innovative environmental remediation project to treat and re-vegetate 150 acres of irrigated meadows pastureland and 18 acres of fluvial deposits that bordered approximately 3,000 feet of the Arkansas River.

The design incorporated a unique remediation process. It included the application of a lime-based amendment that is a by-product of sugar beet processing: the first large-scale application of this type of in-situ soil treatment. In order for this amendment to work, it was important to thoroughly incorporate the lime mixture into the contaminated soil. A state-of-the-art soil mixer was incorporated into the design, making the process more efficient. The time and cost savings for this value-engineered process allowed an expansion of two acres of treatment and covered the subsequent year’s costs. It also saved the energy and environmental pollution impacts of the traditional method of extensive soil removal.

This unique process is helping to create healthy soils that support the germination of new vegetation. Based on this data, the EPA is considering using the same method to treat the Clark Fork River NPL Site, a much larger site in Montana.

See an EPA report about California Gulch at