Laserfiche WebLink
ARCO Station 548 E Q R <br /> 1612 West Hammer Lane,Stockton <br /> Remedial Action Plan <br /> May 31,2006 <br /> 6.0 REMEDIAL ACTION PLAN <br /> 6.1 Evaluation of Remedial Alternatives <br /> The goal'of this remediation effort is (1) removal and/or in-situ biodegradation of dissolved <br /> petroleum hydrocarbons, benzene, and MtBE in on-site groundwater to concentrations below <br /> applicable cleanup goals, and (2) to prevent further off-site migration of the dissolved plume. <br /> The extent of dissolved petroleum hydrocarbons, benzene, and MtBE beneath the site and the <br /> results of remedial feasibility testing performed on site are the basis for evaluating the feasibility <br /> of proposed remedial alternatives. The proposed remedial alternatives evaluated herein <br /> include: <br /> • No Action/Monitored Natural Attenuation <br /> • Soil Vapor Extraction <br /> • Groundwater Extraction and Treatment <br /> • Dual Phase Extraction <br /> • In situ Biologic and/or Chemical Treatment <br /> 6.1.1 No Action/Monitored Natural Attenuation <br /> Under this alternative, no remedial action, other than monitoring of groundwater, is <br /> . undertaken. Given that the dissolved petroleum hydrocarbon concentrations beneath the site <br /> are higher than maximum contaminant levels (MCLS) following remedial action and <br /> groundwater monitoring activities, this alternative may not be viable. The no action <br /> alternative is implementable and cost effective, but may not be viable to meet current <br /> remedial objectives. <br /> 6.1.2 Soil Vapor Extraction <br /> SVE involves extracting vapors from the vadose zone, combined with treatment of the extracted <br /> air using granular activated carbon (GAC), an internal combustion (IC) engine, a <br /> catalytic/thermal oxidizing (CatOx) unit, or other method, followed by discharge of the treated <br /> vapor stream to ambient air, under permit from the overseeing air quality board. <br /> Based on the results of the past remedial activities, SVE appears to be capable of removing <br /> '7 dissolved petroleum hydrocarbons and MtBE concentrations from the soil zone beneath the site, <br /> but would have limited impact on groundwater contamination. However, the increase in <br /> groundwater elevations at this site has caused the impacted soil to become submerged. <br /> Therefore, the impacted soil is no longer accessible by SVE. SVE is not an implementable <br /> remedial alternative due to the rising water table. <br /> 6.1.3 Groundwater Extraction and Treatment System <br /> Remediation using a groundwater extraction and treatment system (GETS) is a well <br /> documented procedure. Submersible (electric or solar) or centrifugal pumps are placed in <br /> . one or more groundwater monitoring or extraction wells. Extracted groundwater is routed to <br /> an on-site treatment system via subsurface piping, and discharged under permit to the <br /> sanitary sewer or the storm drain. Common and cost-effective technologies used in treating <br /> I:IBP-ARC0104 BP Valley Portfolio15481Reports\RAP1548 RAP.doc 9 <br />