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_ tt Sf 11 Mr John Benedict Project 880-039 lA October 22, 2001 Page 2 ' Station (located at the corners of Charter Way and Lincoln Street), residual and dissolved hydrocarbons have been detected beneath these facilities Between September 17 and October 11, 1996, EMCON/OWT observed the drilling of six soil borings (BAR 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 ' 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 a TPH-g, benzene, toluene, ethylbcnzene, and total xylenes (BTEX) isomers, and methyl tert-butyl ether (MTBE) were detected in the groundwater sample collected ' from monitoring well MW-I 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: THIRD QUARTER 2001 On September, 17, 2001, an IT technician was on-site to measure depth to groundwater and collect groundwater samples from wells MW-1R, VW-2, and VW3 for subjective and laboratory analyses IT has attempted to coordinate joint quarterly sampling with the former ARCO facility 2168, 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) 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 tThe 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 IT CORPORATION SAC 111SACRFPIICOMMON\..DP120011PRY%P18Y880039M]ab dm-Wat 1 (01010000)