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SVE Svstein installation and Efficiency Report Canepa s Car Wash(Pacific Avenue) June 25, 1999 Pagc -2 ' 3 0 SITE BACKGROUND Canepa's Cat Wash consists of an automated car washing facility, a fuel station, and a convenience store ' (Figure 2, Appendix A) The car wash and fuel station have been to operation for than two decades In the Spring of 1993, three underground storage tanks (USTs), fuel Imes and dispensers were removed ' and replaced with a double walled system The USTs consisted of two 12,000-gaIlon gasoline USTs and one 5,000-gallon diesel UST Upon removal of the USTs and piping, it was discovered that the fuel Imes had leaked and that the USTs had been overfilled Approximately 600 cubic yards of soil were removed ' from the UST excavation area Beginning in March, 1993, one soil boring and an array of nine soil vapor extraction (SVE) wells were ' drilled and installed in the area of the fuel dispenser islands Between September, 1993, and March, 1994, eight monitoring wells (MW-1 through MW-8) were installed In March, 1994, a soil vapor extraction system was installed and operated In the Fall of 1996, it was determined that the SVE system ' was inadequate and operation of the system was terminated Condor has conducted Quarterly Groundwater Monitoring activities at the site since August, 1996 ' Analyses of groundwater samples collected from selected SVE wells(SVE-1, 2, 3, 4, 5, 7, 8,and 9) indicate that high concentrations of benzene, toluene, ethyl benzene, and total xylenes (BTEX), total petroleum hydrocarbons quantified as gasoline (TPH-G), and methyl tertiary-butyl ether (MTBE) are present in the former location of the fuel dispenser islands Prior to granting approval for installation of a new SVE system, the Underground Storage Tank Clean-Up ' Fund indicated the need for additional investigation Condor subsequently conducted the installation and sampling of two sot] borings (SB-1 and S13-2) adjacent to the SVE well array The investigation included soil vapor screening using a Simulprobe sampling device in soil vapor collection mode and the collection ' and laboratory analyses of soil and groundwater samples The results indicate high levels of volatile organic compounds are present in the soil vapor and groundwater at the site The laboratory analytical results of the soil and groundwater samples collected during the investigation are presented in Repos t—Soil ' and Gr-oundwaler Investigation,dated June 12, 1998 A detailed Site History is included in Appendix B 4.0 SITE GEOLOGY ' On May 6 and 7, 1998, a Condor geologist supervised the installation of two soil borings (SB-I and SB-2 referenced above in Section 3 0) in the vicinity of the existing SVE wells (east of the former location of the USTs) Inter-bedded clay, silt, and sand are present in the shallow subsurface of the Canepa's Car ' Wash site From the surface to a depth of approximately 8 feet bgs, a black, organic-rich clay was encountered Below the clay, sandy clays, and clayey silts were encountered Beginning at approximately 23 5 feet bgs and extending down to between 33 and 38 feet are silty-sand lenses, which ' appear to be discolored to bluish-gray The discoloration is possibly due to the presence of petroleum hydrocarbons Below the discolored silty-sand and extending down to 70 feet were inter-bedded clay, Silt and sand with a moderate to strong gasoline odor Groundwater was encountered at approximately 16 40 feet bgs Gioundwater yields are greater in the inter-bedded silt-v and sandy sequences from 40 feet to at least 70 feet bas (total drilling depth) In soil boring SB-2 clean quartz rich sand was encountered beginning at approximately 70 feet A cross-section of the site is shown in Figure 3 and the Soil Boring Logs for SB-I and SB-2 arc, included to Appendix B ' `� CONDOR