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r r Mr John Benedict Project 880039 1A February 22, 2002 Page 2 soil bonng s were converted to dual completion vapor extraction wells VW-1 through VW-3, and p P 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 r 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 nullion 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 MWA R 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 GROUNDWATER MONITORING: FOURTH QUARTER 2001 On November 15, 2001, an IT technician was on-site to measure depth to groundwater and collect a groundwater samples from wells MW-1R, VW-2 and VW3 for subjective and laboratory analyses IT has attempted to coordinate point quarterly sampling with the former ARCO facility 2168, 1 located east and downgradient of the subject site but has not gotten a response from their consultant The data presented on Figure 2 for the former ARCO facility 2168 was collected on August 16, 2001 Floating product was not observed in groundwater monitoring wells (see Table 1 and Appendix A) TT 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 rThe groundwater samples were analyzed at Sequoia Analytical in Sacramento, California, 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 all three wells TPH-g was detected in MW-1R, VW-2 and VW-3 at concentrations of 310, 42,000, and 9,600 micrograms per liter (gg/L), respectively Benzene was reported in MW-R1, VW-2 and VW-3 at 13, 3,800, and 1,200 gg/L, respectively MTBE was reported in groundwater at VW-3 at IT CORPORATION SAC 111SACRFPIICOMMON\sacDP120021PRJ\PJ81880\8800391 A 2aa doe-001st 3 (01010000) 1