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San Joaquin County Environmental Health Department DIRECTOR Donna Heran, REFS r. 600 East Main Street Stockton , California 95202 -3029 PROGRAM COORDINATORS Robert McClellon, REHS - - Jeff Carruesco, RENS, RDI Linda Website: www.sjgov. org/ehd LFoley, RENS FOR Phone: (209) 468-3420 Linda Turkatte, REFS Fax: (209) 464-0138 June 28 , 2011 Mr. David Atwater Van De Pol Enterprises, Incorporated Post Office Box 1107 Stockton , California 95201 Subject: Pacific Pride — South EI Dorado Street 3147 South EI Dorado Street Stockton, CA 95206 Dear Mr. Atwater: The San Joaquin County Environmental Health Department (EHD) has received and reviewed Dual Phase Extraction Pilot Test Report — February 2011 (report), dated 13 May 2011 , prepared by your consulting firm , Advanced GeoEnviron mental, Inc. (AGE), on your behalf for the above-referenced site. In the report, AGE documents the results from a 24-hour dual phase extraction (DPE) pilot test involving the simultaneous extraction of groundwater and soil vapor from monitoring well MW-7 located approximately 31 feet down-gradient of the former underground storage tank area . AGE describes how soil vapor and groundwater samples were collected and analyzed for chemicals of concern at designated times throughout the pilot test. note that high concentrations of TPH-g and TPH-d were detected in soil samples collected from P- 1 at 20 feet below surface grade (bsg) and high soil gas concentrations were detected in P-7. AGE induced and sustained a cone of groundwater depression of 38 . 5 feet below surface grade (bsg) at MW-7, noting that the static water level measured from MW-7 prior to the DPE test was approximately 24 bsg . AGE monitored wells MW-1 , MW-2, MW-4, MW-6, and VW-1 through VW-3 for induced groundwater draw-down levels while extracting groundwater from MW-7 at a rate of approximately 1 . 8 gallons per minute; the maximum induced groundwater drawn-down was 0 . 32 feet measured from MW- 1 . A total of 2,592 gallons of water were extracted between 01 and 02 February 2011 , and approximately 0. 1 pounds (equivalent to 0.012 gallons) of total petroleum hydrocarbons as gasoline (TPH-g) were removed over the 24-hour period . Once the water level was sustained at 38. 5 feet bsg in MW-7, AGE induced a vacuum in the vadose zone and monitored VW-1 through VW-3 and MW-4 . The greatest induced vacuum measurement was 0 . 23 inches of water measured from VW-2 located 32 feet from extraction well MW-7 . The effective radius of influence was projected to be approximately 53 feet at a vacuum potential of 0 . 1 inches of water. AGE calculated the mass and volume of soil vapor hydrocarbons extracted during the DPE pilot test to be approximately 15 . 1 pounds of gasoline (equivalent to 2.4 gallons of gasoline) .