NOREAS designed, installed, and has been operating a 200 CFM soil vapor extraction (SVE) system to remediate soil, soil vapor, and groundwater impacted with chlorinated solvents associated with historical dry cleaning operations at the site. The system includes a series of 9 SVE wells and 16 vapor monitoring probes connected to the central treatment system via a network of underground and aboveground piping. Because the site is located in a highly congested area of Los Angeles that is zoned for mixed use (commercial and residential), several critical technical factors were considered during the project design. In particular, the system design and construction were customized to minimize the project footprint and allow for minimal disruption to the busy operations of the current business (auto repair facility). Furthermore, the proximity of the site to adjacent residential properties required additional system controls to maintain acceptable noise levels during operations.
System monitoring data indicate a reduction of more than 90% in VOC concentrations in soil vapor across the site after the first 6 months of SVE operations. As a result, the SVE operations are expected to be completed ahead of estimated schedule and within the project budget. A pilot test for enhanced in situ bioremediation (EISB) of groundwater is scheduled, followed by full-scale implementation of the groundwater remedy. Current design for the full-scale EISB remedy includes the injection of a sufficient electron-donor substrate into a series of 36 multi-depth wells located at the downgradient edge of the dissolved VOC plume. Determination of remedial cleanup goals is based on extensive risk assessment efforts using site-specific conditions, such as need for cleanup goals to be protective of nearby residential occupants. Based on current status, site closure is anticipated for 2014.