ARCHIVED REPORTS XR0001188 - Laserfiche WebLink

Home Browse Search

1 1n the sort sample collected from boring BAR at a concentration of 2,000 ppm, but was below laboratory detection limits in the sora sample collected from boring B-6R Copies of ' the laboratory analysis reports are presented in Appendix C Chromium, Lead, Nickel, and Zoic were detected at low concentrations in soil samples ' collected from sort borings B-2R and B-6R However, these concentrations are within background levels (Dragon 19$$) Cadmium was below laboratory detection limits in all soil samples analyzed Analytical results are presented in Table 2 ' Composite soil sample SP-1 was below detection limits for TPHG and BTEX Total lead was detected at a concentration of 6 2 ppm 5.3 Distribution of Hydrocarbons in Groundwater ' TPHG was detected in the groundwater sample collected from monitoring well MW-1R at a concentration of 33,000 parts per billion (ppb) Benzene, toluene, ethylbenzene and total xylenes were also detected in the groundwater sample from monitoring well MWA R at concentrations of 1,400 ppb, 6,200 ppb, 700 ppb, and 2,500 ppb, respectively MTBE was detected at a concentration of 550 ppb The results of groundwater analyses are summarized in Table 4 Copies of the laboratory analysis reports are presented in Appendix C 5.4 Groundwater Flow Direction and Gradient ' The wellhead elevations of the monitoring wells at the site were surveyed by Tom O Morrow, Inc , of West Sacramento, California Typically, the surveyed elevations and the depth to groundwater measurements would be used to evaluate the potentiometric ' surface beneath the site, but because only one groundwater monitoring well is present at the site, the potentiometric surface could not be evaluated However, based on groundwater data collected on August 22, 1996, at the ARCO Service Station ' (downgradient), groundwater flow was towards the northeast with a hydraulic gradient of approximately 0 002 (see Appendix D) A copy of the ARCO Service Station ' groundwater contour map is presented in Appendix D Groundwater elevations are consistent with groundwater elevations measured at the former ARCO Service Station and Texaco Service Station 5.5 Remediation Feasibility Based on the vapor extraction test conducted at the former ARCO Service Station, which the geology is similar to that observed at the subject site, vapor extraction is a feasible method to remove hydrocarbons from soil (RESNA, December 18, 1992) RESNA ' SAC1N\PJ'Z\2613\2613 i000 I BB-9NIb 2 Rev 0 215197 22613 100 001 5-2