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S E C O R - - -- -- - -- -- - • Ms Anastasia Duarte-Wilkinson April 4, 2003 Page 2 The groundwater elevation decreased approximately 0 55 feet since the last sampling event in November 2002 The groundwater flow direction during this reporting period is toward the south/southwest with a hydraulic gradient of approximately 0 03 ft/ft A summary of data regarding groundwater levels measured through January 16,2003,is presented in Table 1 Copies of field observations documenting work performed at the site are presented in Attachment 1 GROUNDWATER ANALYTICAL RESULTS The distribution of groundwater sample analytical results obtained from monitor wells at the site on January 16, 2003, is presented on Figure 3 and summarized In Tables 2 and 3 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 during this monitoring event, with the exception of MW-1 MTBE concentrations ranged from 1 5 micrograms per litter(ug/L)in MW-1 to below method detection limits in monitor wells MW-2 through MW-8 and MW-10 this quarter Attachment 2 contains photocopies of the laboratory analytical report and the chain-of-custody form On January 16, 2003, LPH was not detected in MW-1 during this monitoring event and therefore 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 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 SITE REMEDIATION Construction of a sod and groundwater remediation system was completed at the site in December 1999 The remediation system consists of seven sod 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 SOIL VAPOR EXTRACTION During site visits, SECOR monitored system parameters and collected appropriate influent soil vapor samples Air samples were collected on January 7,2003, February 4,2003,and March 5,2003 Based on the influent sod vapor samples analytical results, approximately 55 5 pounds of gasoline were removed and treated at an average extraction rate of 48 scfm for this reporting period A total of approximately 38,841 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 efficiency results, is included in Attachment 3 • 1 Mme OE1LockefordUMfti-ockeford Q1-03 doc SECOR Intemadonal Incorporated