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1 Pilot Testing Report and Conceptual Corrective Action Plan November 22, 1994 Executive Summary Page 2 Manna Pro Corporation, Stockton, CA. Based on these pilot tests, Groundwater Technology was able to make the following conclusions: • Groundwater extraction at a rate of 2.2 gallons per minute (gpm) (calculated based upon aquifer test data) from each of three groundwater extraction wells located within the impacted groundwater zone can be expected to provide hydraulic control of the hydrocarbon plume in groundwater. • High Vacuum Extraction (HVE) applied to groundwater extraction wells in combination with groundwater pumping using a centrifugal pump resulted in an elevated per well groundwater extraction rate of approximately 3.75 gpm. HVE applied to groundwater extraction wells is expected to enhance groundwater recovery and decrease cleanup time. • A venting radius of influence of approximately 18 feet was calculated for a single vapor extraction point with a flow rate of 15 standard cubic feet per minute (SCFM) at a vacuum of 148.5 inches of water. Significant hydrocarbon concentrations observed in soil vapor extracted during pilot testing indicates soil venting would be an appropriate remedial technology for the site. • A reduced venting radius of influence was observed during the HVDPE test when the centrifugal pump was not used to pump water from the well. This technology was considered less desirable than combined groundwater extraction and HVE for the site conditions. Based on these conclusions, a Conceptual Corrective Action Plan (CCAP) was developed for the site. The CCAP for the Manna Pro site involves designing, installing and operating a soil and groundwater remedial action program. The conceptual design of the program involves three groundwater extraction wells located within the impacted groundwater zone and approximately 20 vapor extraction points located within the impacted vadose (unsaturated) zone. Specific details of this conceptual design will be further verified during the final design process. Extracted groundwater and soil vapor will be treated using appropriate abatement technologies based upon cost effectiveness and ability to meet applicable discharge standards. The details of the remedial systems will be set forth in the final design. The remedial systems will be permitted and installed following approval of the final design by SJCPHS. The remedial action program will be operated and maintained until the sooner to occur of: 1) the time at which soil and groundwater have been remediated in compliance with law; or 2) the time at which further operation of the remedial system will no longer result in significant additional remediation of the site. Thereafter, a closure report will be prepared and submitted to SJCPHS for approval. —P,GROUNDWATER z_. TECHNOLOGY,INC.