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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 70 74 to 78 66 feet below ground surface (bgs) The groundwater potentiometric surface elevation averaged approximately 26 95 feet bgs during this monitoring event The groundwater elevation was adjusted approximately 2 75 feet since the last sampling event in March 2002 as a result of the wells being resurveyed The groundwater flow direction during this reporting period is toward the southwest with a hydraulic gradient of approximately 0 03 ft/ft A summary of data regarding groundwater levels measured through May 16, 2002 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 May 16, 2002, is presented on Figure 3 and summarized in Table 2 The highest concentration of petroleum hydrocarbons is in the vicinity of monitor well MW-1 TPHg concentrations were below method detection limits (MDL) for all wells sampled during this monitoring event except MW-1 Benzene concentrations were below MDLs for all wells this quarter MTBE concentrations ranged • from 16 micrograms per litter(ug/L) in MW-4 to below method detection limits in monitor wells MW-1,MW-3, MW-6, MW-8 and MW-10 Attachment II contains photocopies of the laboratory analytical report and the chain-of-custody form LPH was not detected in MW-1 during this monitoring event and therefore the well was sampled LPH continues to be monitored and removed(if necessary)from MW-1 by hand bailing methods and the use of a passive,down-hole petroleum skimmer on a weekly basis A total of approximately 62 gallons of LPH has been removed from MW-1 since its detection in February 2000 Purge Water Purge water generated during groundwater purging is currently contained on-site in Department of Transportation rated 55-gallon drums pending removal to a disposal/recycling facility during 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 C Mme OiALockotordQ202 2 SECOR 770T 41737 00 0003