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i ! . Groundwater Elevation Data Depth to groundwater was obtained from the existing groundwater monitor wells at the site using a water level indicator graduated to 0 01 foot The depth to groundwater measurement was converted to a groundwater elevation for each well and used to construct a groundwater elevation contour map (Figure 2), and calculate the local groundwater flow direction and hydraulic gradient Groundwater at the site was measured at depths between 68 90 to 76 94 feet below ground surface (bgs) The groundwater potentiometric surface elevation averaged approximately 26 85 feet bgs during this monitoring event The groundwater elevation has decreased approximately 145 feet since the last sampling event in April 2001 The groundwater flow direction during this reporting period is toward the southwest with a hydraulic gradient of approximately 0 02 ft/ft A summary of data regarding groundwater levels measured through August 20, 2001 is presented in Table 1 Copies of field observations documenting work performed at the site are presented in Attachment I Groundwater Analytical Results The distribution of groundwater sample analytical results obtained from monitor wells at the site on August 20,2001,is presented on Figure 3 and summarized in Table 2 Due to the presence of liquid phase hydrocarbon (LPH),the highest concentration of petroleum hydrocarbons is in the vicinity of monitor well MW-1 TPHg and benzene concentrations were below method detection limits for all wells sampled during this monitoring event MTBE concentrations were below method detection limits for all wells sampled except MW-4 (1 1 ug/1) during this monitoring event Attachment H contains photocopies of the laboratory analytical report and the chain-of-custody form iApproximately 0 52 feet of LPH was detected in MW-1 during this monitoring event The LPH is currently being removed from MW-1 by hand bailing methods and the use of a passive, down-hole petroleum skimmer on a weekly basis The LPH thickness has generally decreased in MW-1 since it was first observed in February 2000 A total of approximately 55 gallons of LPH has been removed from MW-1 since its detection in February 2000 Purge Water Purge water generated dunng groundwater purging is currently contained on-site in Department of Transportation rated 55-gallon drums and will be removed to a disposal/recycling facility during November 2001 SITE REMEDIATION Construction of a soil and groundwater remediation system was completed at the site in December 1999 The remediation system consists of seven soil vapor extraction (SVE) wells (W-1, W-3 through W-8), two groundwater monitor wells modified for SVE (MW-1 and MW-3) and four air sparge wells (AS-1 through AS-4) with catalytic oxidation treatment A Site Plan depicting the locations of the remediation wells, subsurface piping, and remediation equipment compound is included as Figure 4 Initial start-up air discharge compliance testing was completed on December 13, 1999 The San Joaquin County Valley Air Pollution Control District(SJVAPCD)has approved an air permit for the site During site visits, SECOR monitored system parameters and collected C 171me OiN.ockefordQ301 2 SECOR 077 41737 003 November 8,2001