Laserfiche WebLink
I ME <br /> 5-2 <br /> soil <br /> The May 26, 1987, soil samples collected at 5.5 to 11.5 feet <br /> below ground surface show significant hydrocarbons in the soil <br /> beneath the site. These samples show high concentrations of EPA 8015 <br /> and EPA 8020 constituents at the depth interval of 10.0 to 11.5 feet <br /> below ground surface in Boreholes AS-1, AS-3, AS-4, AS-5, AS-6, and <br /> AS-7. Borehole AS-2 showed no detectable hydrocarbon product. No <br /> detectable hydrocarbon product was found at the depth intezval of 5.0 <br /> to 6.5 feet' below ground surface. <br /> Recovery Systems <br /> IA Although in-place, the recovery s'ustem at the site does not <br /> appear to have been operational since late March ot: eazly Iipril <br /> 1987. GR's March 31, 1987, reading of the system was 19,842,796 <br /> gallons. The free floating product has been successfully removed <br /> from the groundwater surface, and approxim.ateiy 19,842,800 gallons of <br /> product and groundwater have been removed from the shallow aquifer <br /> system. <br /> The recovery system pumped 6ontinuously, except for brief, minor <br /> breakdowns from the time of its installation in April 1984, to March <br /> 1987. Because of this continual pumping and the nearly flat ground- <br /> water gradient of 0.003 feet per mile, groundwater and dissolved <br /> hydrocabons have probably not migrated very far off site. <br /> The discharge permit for the water pumped by the recovery system <br /> into the sanitary sewer system was approved and obtained from the <br /> City of Stockton Regional Wastewater Control Facility (RWCF) in <br /> August 1984. The permit expired in August 1985, and for unknown <br /> reasons, the permit was not renewnd. <br /> Monitoring Wells <br /> According to an article written by G. W. Schmidt, "The Use of PVC <br /> Casing and Screen in the Presence of Gasolines on the Groundwater <br /> Table," spring 1187, the polyvinyl chloride (PVC) well casing is <br /> sound in the presence of hydrocarbon product (i.e.,. gasoline) , This <br /> article is included as Appendix C. The groundwater. monitoring wells <br /> ac the site are yielding and recovering properly, and appear to be <br /> structurally sound. <br /> RECOMMEINDATIONS <br /> 7� <br /> Based on our contAusions, the following recommendations for site <br /> remediation and additional investigative work are made for ARCO <br /> Station 2133, Stockton. <br />