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S E C 0 R -- - - -- - - - Ms Anastasia Duarte-Wilkinson October 22,2003 Page 2 Groundwater at the site was measured at depths between 71 67 to 92 91 feet below ground surface(bgs) The groundwater potentiometnc surface elevation averaged approximately 23 71 feet bgs during this monitonng event The groundwater elevation decreased approximately 0 44 feet since the last sampling event in May 2003 The groundwater flow direction during this reporting period was predominantly toward the south/southwestwith a hydraulic gradient of 0 05 feet per foot (ft/ft) A summary of data regarding groundwater levels measured through July 24,2003 is presented in Table 1 Copies of field observations documenting work performed at the site are presented in Attachment 1 GROUNDWATER ANALYTICAL RESULTS The distnbution of groundwater sample analytical results obtained from monitor wells at the site on July 24, 2003 is presented on Figure 3,and summarized in Tables 2 and 3 The highest concentrations of petroleum hydrocarbons were reported in monitor well MW-1 TPHg concentrations were below method detection limits in all but one well, MW-1,during this monitoring event,which reported a concentration of 1,000 micrograms per Irter(ug/L) With the exception of benzene concentrations in MWA (0 9 ug/i)and MW-9(0 7 ug/L),benzene was reported below method detection limits in all other wells sampled MTBE was reported below method detection limits in all but two wells, MWA reported a concentration of MTBE at 0 5 ug/L, and MW-9 reported a concentration of MTBE at 1 1 ug/L Attachment 2 contains photocopies of the laboratory analytical report and the chain-of-custody form LPH is monitored and removed (if necessary) from MWA by hand bailing methods and the use of a passive, down-hole petroleum skimmer A total of approximately 62 gallons of LPH has been removed from MW-1 since its detection in February 2000 LPN has not been detected in MW-1 since July 2002 PURGE WATER Purge water generated dunng groundwater purging is currently contained on-srte in Department of Transportation rated 55-gallon drums pending removal to a disposal/recycling facility SiTE REMEDIATION Construction of a soil and groundwater remediation system was completed at the site in December 1999 The remediation system consists of seven SVE wells (W-1, W-3 through W-8), two groundwater monitor wells modified for SVE(MW-1 and MW-3),and four AS 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)approved an air permit for the site SOIL VAPOR EXTRACTION The system was steadily operational throughout the quarter During semi-monthly site visits,SECOR monitored system parameters Influent air samples were collected on a monthly basis on July 8, August 19, and September 2,2003 Based on the influent soil vapor sample analytical results,approximately 16 7 pounds of gasoline were removed and treated at an average extraction rate of 44 scfm for this reporting penod Atotal of approximately 38,894 pounds of gasoline has been removed and treated at the site since the SVE system . began operation SVE system performance data, which includes soil vapor analytical results and system I Mme OillockefordlQMRs12001-20031Lockeford 03-03 doe SECOR Intematonallncorporated