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1 k''q KLEINFELDER 6 DISCUSSION OF FINDINGS A total of four soil samples and one groundwater sample were submitted under chain-of-custody procedures to Sequoia Analytical Laboratory of Sacramento, California Sequoia is a State of California Department of Health Services (DHS) certified laboratory for the analyses requested No unusual odors or discoloration was noted in soil samples collected at five foot depth intervals in boring B1/TW-1 PID readings recorded from the samples collected ranged from 4 0 to 30 ppmv and increased with depth Given that laboratory results show that hydrocarbon concentrations decreased with depth, the PID readings likely increased due to increasing soil moisture 1 The four soil samples and one groundwater sample were analyzed for petroleum constituents The four soil samples submitted for analyses from B1/TW-1 were collected at depths of about 8, 12'/2, 13, and 18-feet bgs The soil samples selected for analysis were based on, field observations, and the objectives of the scope of work For additional information, see the laboratory data sheets and Chain-of-Custody records in Appendix D ' The four soil samples and one groundwater sample were analyzed for the following • Total Petroleum Hydrocarbons as referenced to Diesel [TPH-D] by EPA Method 3510/8015M • Total Purgeable Petroleum Hydrocarbons as referenced to Gasoline [TPH-G] by EPA Method 8015M + Benzene, Toluene, Ethylbenzene, Xylenes [BTEX] by EPA Method 8020 • Oxygenates by EPA Method 8260 • Methanol by EPA Method 8015M The samples were analyzed on a normal laboratory schedule requiring approximately two weeks (ten working days) For a summary of the results obtained, please refer to Tables 5-1 and 5-2 in Section 5 of this report Of the requested analytes only TPH-D was detected in three soil samples and one groundwater sample TPH-D concentrations in soil ranged from 5 34 to 168 mg/kg The highest concentration of TPH-D was detected in a soil sample collected at about 8 feet bgs , while the lowest concentration above laboratory reporting limits was 5 34 mg/kg at about 13 feet bgs A soil sample collected from approximately 18 feet bgs was non-detect for the requested analytes, ' but appears to be within the shallow groundwater table The single groundwater sample was found to contain 0 389 mg/l (389 µg/1) TPH-D According to a memorandum from the California Regional Water Quality Control Board, Central Valley Region (RWQCB), from Jon Marshack to Technical Staff, dated May 17, 1995, recommended limits for diesel in water is 100 µg/1 This recommended limit is referenced to a "taste and odor 20-1311-40 E0112019R039 Page 10 of 13 O 1999,Klemfelder,Inc January 20, 1999