Collection of Contaminated Groundwater
Piketon, OH: Shallow Soil Mixing/Soil Vapor Extraction
Geo-Con implemented the first full-scale project to use Shallow Soil Mixing (SSM)/Thermally Enhanced Vapor Extraction (TEVE) and Soil Vapor Extraction (SVE) to remove Volatile Organic Compounds (VOCs) contamination from a waste disposal area. The site is at the Portsmouth Gaseous Diffusion Plant in Piketon, Ohio and was contaminated to a depth of 22 feet. The cleanup was completed without excavation and the soils remained in place after treatment in accordance with Ohio EPA approvals. SSM was performed with 8 to 12 feet diameter-mixing tools.
The site consisted of primarily silty and clayey soils with a groundwater table 15 feet below the surface. Trichloroethylene (TCE) contamination was spread over the site at levels, which varied from 1 to 500 ppm. The VOCs were mobilized by SSM and TEVE and removed through a SVE treatment unit.
Considerable experimentation was required in auger/mixer designs, procedures, additives, and equipment during the work. Hydrogen peroxide was experimentally used during part of the process. Much of the work was performed in harsh winter conditions. Work was performed around the clock, seven days per week to avoid state-mandated liquidated damages. Geo-Con completed the project on time and removed 200% of the planned amount of VOCs.
The specified objective of the Work Plan was to remove or destroy a minimum of 70 percent of the VOCs. Over 90% of the VOCs were removed. This project was the first full-scale implementation of SSM/SVE and is being used as the model for future DOE cleanups.