ARCHIVED REPORTS_XR0007138 - Laserfiche WebLink

Home Browse Search

S E c o R -- - --- - - --- - Ms Anastasia Duarte-Wilkinson July 23, 2003 Page 2 The groundwater elevation decreased approximately 0 12 feet since the last sampling event in January 2003 The groundwater flow direction during this reporting period is toward the south/southwest with a hydraulic gradient of approximately 0 05 ft/ft A summary of data regarding groundwater levels measured through May 15,2003, 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 May 15, 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 concentrations were below method detection limits in all but two wells during this monitoring event,MW-1 at 4,300 micrograms per litter(ug/L)and MW-10 at 120 ug/L Benzene concentrations were below method detection limits for all wells during this monitoring event, with the exception of MW-1 (1 2 ug/L) MTBE concentrations ranged from 1 5 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 May 15, 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 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 f=igure 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 April 1, 2003, May 2, 2003, and June 5, 2003 Because of the decline of influent vapor concentrations, the SVE system was shut down between May 2, 2003 and June 5, 2003, to evaluate if a significant change of soil vapor concentrations would occur Based on the laboratory analytical results collected before shutdown(28 ppmv TPHg)and after restarting the SVE system (5 4 ppmv TPHg), a continued decline of soil vapor concentrations was observed Based on the influent soil 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 i Mme OIilLockeford%QMRslLockeford Q2-03 doc SECOR lntematlona!lnoorporated