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Mr John Benedict Project 880039 October 17, 2000 Page 2 Between September 17 and October 11, 1996, IT (formerly EMCON) observed the drilling of six ' soil borings (B-ZR through B-6R) One soil boring was converted to monitoring well MW-1R, three soil borings 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 Polychlonnated biphenyls, ' TPH-d, and chlonnated 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 ter(-butyl ether (MTBE) were detected in the groundwater sample collected from monitoring well MW-1R TPHG 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 GROUNDWATER MONITORING: THIRD QUARTER 2000 ' On August 16, 2000, an IT technician was onsite to measure depth to groundwater and collect a groundwater sample from well MW-1R 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 1T's sampling and analysis procedures are presented in Appendix B ' The groundwater sample collected from monitoring well MW-1R was analyzed at Sequoia Analytical in Sacramento, California The groundwater sample was analyzed for TPHG using U S Environmental Protection Agency (USEPA) Modified Methods 8015, and for BTEX ' and MTBE using USEPA Method 802.0 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 299 micrograms per liter (µg/L), BTEX constituents were detected at concentrations of 114 pg/L, 14 0 µg/L, 3 32 pg/L, and 10 9 µg/L, ' respectively, and MTBE was below laboratory detection limits at <2 5 pg/L using USEPA Method 8020 Results of laboratory analyses are summarized in the Table 1 SAC\MACRFPI\COMMON\Consulting\data\Shared\Projects\misc18800391A ab doc-00\ta 1 rrcoA+oPAnon (41010000) I