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Mr John Benedict Project 880039 1A January 26, 2001 Page 2 1 soil bonngs were converted to dual completion vapor extraction wells VW-1 through VW-3, and one soil boring was converted to a single vapor extraction well VW-4 (EMCON, Preliminary Investigation and Evaluation Report, February 5, 1997) The results of this investigation indicated the following • With the exception of soil samples collected from boring B-6R, residual hydrocarbons were detected in each boring The highest concentrations were detected approximately ' 10 feet below ground surface (bgs) near the former USTs Total oil and grease was detected in the soil sample collected near the former UST cavity (located near the building) at a concentration of 10,000 parts per million Polychlorinated biphenyls, ' TPH-d, and chlorinated hydrocarbons were below laboratory detection limits in all soil samples analyzed from soil borings B-2R and B-6R ' • TPH-g, benzene, toluene, ethylbenzene, and total xylenes (BTEX) isomers, and methyl tert-butyl ether (MTBE) were detected in the groundwater sample collected from monitoring well MW-1R TPH-g and benzene were detected at concentrations of ' 33,000 parts per billion (ppb) and 1,400 ppb, respectively MTBE was detected at a concentration of 550 ppb NGROUNDWATER MONITORING: FOURTH QUARTER 2000 ' On October 31, 2000, an IT technician was on-site to measure depth to groundwater and collect a groundwater sample from well MW-IR for subjective and laboratory analyses Floating product was not observed in groundwater monitoring well MW-1R(see Table 1 and Appendix A) IT used ' these data to evaluate changes in concentrations of dissolved gasoline hydrocarbons in the groundwater IT's sampling and analysis procedures are presented in Appendix B The groundwater sample collected from monitoring well MW-lR was analyzed at Sequoia Analytical in Sacramento, California The groundwater sample was analyzed for TPH-g using U S Environmental Protection Agency (USEPA) Modified Methods 8015, and for BTEX ' and MTBE using USEPA Method 8020 Copies of the chain-of-custody records and laboratory analysis reports are presented in Appendix C ' The results of laboratory analyses indicated that dissolved hydrocarbons were present in the monitoring well TPH-g was detected at a concentration of 234 micrograms per liter (pg/L), ' toluene and ethylbenzene constituents were detected at concentrations of 0 598 µg/L and 2 0 µg/L, respectively, benzene, total xylenes and MTBE were below laboratory reporting limits Results of laboratory analyses are summarized in the Table 1 As requested by the SJCPHS Environmental Health Division, fourth quarter monitoring data from the former ARCO facility located to the east of the site was obtained The former ARCO IT CORPORATION SAC W\sacDP120011PRJWJ81880039 la laa doc-001ta 1 (01010000)