In southwestern Virginia lies an abandoned landfill that had been placed on the nation’s list of the worst hazardous waste sites. The landfill received more than 850,000 tons of hazardous wastes that were buried at depths up to 80 feet. These materials include oils contaminated with polychlorinated biphenyls, aluminum sludges, asbestos, and medical wastes.

Tetra Tech was tasked by the U.S. Environmental Protection Agency (EPA) to address problems posed by the landfill and to design solutions to alleviate risks to the environment. Tetra Tech completed the design of several solutions to address the landfill problems. With an assembled team of 30 engineers, our remedial design was divided into three components, including a 27-acre landfill cap, a gas/leachate collection system, and upgrades to an existing sanitary sewer system and sewage treatment plant. All design engineering work was completed within six months and the project was $150,000 under budget.

Tetra Tech incorporated several unique features that provided cost-effective engineering solutions, including a leachate collection trench that used an innovative biopolymer construction technique; leachate force main sewers installed using directional drilling; and a 250,000 gallon sequencing batch reactor upgrade for the sewage treatment plant. A special engineering study was performed that saved more than $140,000 of construction costs compared to traditional techniques.

Highlight:
EPA consistently recognized Tetra Tech’s superior performance throughout the project and noted: "Tetra Tech demonstrated a thorough knowledge of the design process and project needs and was able to identify many of the potential issues various stakeholders might have and preempted their concerns by presenting a solution to these problems.”