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ATC Associates Inc. <br /> VITC <br /> 1117 Lone Palm Avenue, Suite B <br /> Modesto,California 95351 <br /> 209-579-2221 <br /> Fax: 209-579-2225 <br /> A S S O C I A T E S I N C . <br /> The groundwater samples from borings GPI, GP2, GP3, and CPT] were analyzed by Argon <br /> Laboratories for TPHg and BTEX by EPA methods 8015B/8021B. The groundwater samples <br /> were also analyzed for MTBE and oxygenate fuel additives by EPA method 8260B. The <br /> groundwater samples collected from borings GPI and GP2 contained detectable concentrations <br /> of TPHg and BTEX. The groundwater sample collected from boring GP3 contained no <br /> detectable concentrations of TPH or BTEX. The groundwater sample from boring CPT1 at <br /> approximately 19 feet bgs contained detectable concentrations of TPHg and BTEX. The <br /> groundwater sample from boring CPT] at approximately 52 feet bgs contained no detectable <br /> concentrations of TPHg or BTEX. MTBE and fuel oxygenates were below stated method <br /> detection limits for the groundwater samples collected from borings GPI, GP2, GP3, and CPTI. <br /> The results of the March-April, 2004 subsurface investigation are summarized in ATC's <br /> Summary Report of Additional Subsurface Investigation 7675 West Eleventh Street Tracy, <br /> California dated April 11, 2004. <br /> On March 6, 2006, ATC submitted the Risk Assessment of the Fayette Manufacturing <br /> Corporation Site, 7675 West Eleventh Street, Tracy, California as requested by the EHD. The <br /> report summarized risk assessment modeling and comparative analysis performed for target <br /> analytes detected in soil and groundwater samples associated with the site using: Version 9, <br /> October 2004 EPA Region IX Preliminary Remediation Goals (PRGs), San Francisco Bay <br /> RWQCB (Region I1) Environmental Screening Levels (ESLs) for Deep Soils (>3m bgs), <br /> Johnson Ettinger Soil Gas Modeling, and California Human Health Screening Levels (CHHSLs). <br /> Soil concentrations used for comparison were derived from the most recent soil investigation, <br /> which was performed on April 05, 2004 during ATC's Additional Subsurface Investigation <br /> summarized in the report dated August 11, 2004. <br /> In response to ATC's Risk Assessment of the Fayette Manufacturing Corporation Site, 7675 <br /> West Eleventh Street, Tracy, California dated March 6, 2006, the EHD directed additional site <br /> activities summarized in correspondence dated August 29, 2006. The letter cited discussions <br /> between the EHD and the Central Valley Regional Water Quality Control Board that denied site <br /> closure and that further site activity would be necessary. Recommendations by the EHD <br /> included additional subsurface investigation within known areas of elevated adsorbed <br /> hydrocarbon (BTEX and TPHg) impact (i.e. surrounding former UST #1 and UST #2; and <br /> around MW2 and MW3) with hydrocarbons, an in situ soil gas investigation within this <br /> impacted area, application of vapor intrusion modeling and regulatory comparative analyses of <br /> historic and recent soil data from the shallow soil horizon (0 to approximately 9 feet bgs and <br /> above the capillary fringe of the first water bearing zone beneath the site), and review of <br /> dissolved hydrocarbon analyses and historic trends with future groundwater analyses to be <br /> Page 5 el-IV TC <br /> w:\17861\WP for Additional Subsurface Investigation ( - % <br /> Soil Vapor Study,and Modeling .... <br /> .•O L i 4... <br /> •• .wL <br />