ARCHIVED REPORTS XR0010526 - Laserfiche WebLink

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California for treatment The excavation was backfilled with imported soil and crushed rock, which was compacted in accordance with County regulations After all laboratory work was complete, Upgradient Environmental submitted the Site Remediation Report in December 1995 Residual hydrocarbons were detected in two of the sidewall samples from the west wall, where further excavation was precluded because of the proximity of the service station building Total Petroleum Hydrocarbons (gasoline) were detected at 9 mg/kg (parts per million) in sample JL-P-13 in a clay layer at a depth of 25 feet and at 4,200 mg/kg in sample JL-P-15 in a sand layer at 12 5 feet (Figure 3) No hydrocarbons were detected in samples below the clay layer, and because organic vapor concentrations (PID readings) declined rapidly below this layer, Upgradient Environmental interpreted the clay as a confining layer that inhibited downward migration of gasoline In July 1996,PHS/EHD requested further investigation of the residual contamination that was detected in samples JL-P-13 and JL-P-15 However, no work was performed until Mr Fisk discussed the matter with representatives of the CVRWQCB in mid-2001 These discussions led to the July 2001 request by Mr Marty Hartzell of the CVRWQCB for a drilling investigation work plan Mr Fisk again retained Upgradient Environmental to perform the work, which was completed in June 2002 Three monitoring wells were installed, and groundwater samples were collected for analysis Those results were presented in the Second Quarter 2002 Report Groundwater was again monitored during _. the third quarter, and the results are reported here 3.0 PROCEDURES, Groundwater monitoring was conducted on August 19 The wells were opened and the water level was allowed to equilibrate with atmospheric pressure for approximately 15 minutes before the depth to water was measured The relative elevation of the top of the well casing was surveyed for each well, and a water level meter accurate to 0 01 feet was used to measure the water depth (Appendix A) Each well was then purged of approximately 6 gallons of water, and temperature and electrical conductivity were measured at 2-gallon intervals to confirm that the standing water had been removed and these parameters had stabilized , ) Water samples were collected by lowering a disposable Teflon® bailer to the water table Three 40-m1 vials and one 1-liter bottle were collected from each well and preserved in a cooled ice chest The water samples were shipped to McCampbell Analytical Laboratory in Pacheco, where they were analyzed for Total Purgeable and Extractable Petroleum Hydrocarbons in the gasoline and diesel ranges (TPH-g and TPH-d), Benzene, toluene, ethylbenzene, and xylene (BTEX), and for five gasoline oxygenates and dichloroethane (1,2-DCA) The laboratory report is included in Appendix B, and the results are discussed in section 4 0 3