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3.0 INVESTIGATIVE RESULTS 3.1 LABORATORY ANALYSIS PROGRAM All of the soil and groundwater samples collected during this investigation were submitted for chemical analysis to Sunstar Laboratories, Inc. of Tustin California, a California Department of Health Services, Environmental Laboratory Accreditation Program certified laboratory. The soil ' samples were analyzed for volatile organic compounds (VOCs) according to EPA Method 8260B and for TPH as Gasoline (TPH-G), TPH as Diesel (TPH-D) and TPH as Motor Oil (TPH-MO) according to EPA Method 8015M. The groundwater sample was analyzed for VOCs and TPH-G. ' Sample extraction and analysis were performed in accordance with the extraction and hold times specified in the EPA Methods. A copy of the laboratory report and chain of custody record are included in Appendix C. 3.2 CHEMICAL ANALYSIS RESULTS The results of the soil analyses indicated the following: ' • TPH-G was detected in each of the soil samples with the maximum concentration being 49 mg/kg in the soil sample collected at 20 feet bgs in boring B1. ' • TPH-D was detected in each of the soil samples with the maximum concentration being 29 mg/kg in the soil sample collected at 10 feet bgs in boring B1. • None of the soil samples had detectable concentrations of VOCs or TPH-MO. ' The results of the groundwater analyses indicated the following: ' • None of the groundwater samples had detectable concentrations of TPH-G or TPH-D. • The only VOC detected was tert-Butyl benzene at 2.3 micrograms per liter. ' A summary of the laboratory results is presented in Tables 1 and 2. The soil sample results were compared to the ESLs with none of the samples having TPH-G or TPH-D concentrations above their respective ESI-s. The groundwater sample results were compared to the ESLs, however tert-butyl benzene does not have an ESL. The tert-butyl benzene concentration was compared to the EPA Region IX Preliminary Remediation Goal (PRG) ' for tap water. The PRG for tert-butyl benzene is 61 micrograms per liter, therefore the concentration detected (2.3) was below the PRG. ' 6