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Mr Kyle Christie Project 0805-146 01 February 13, 1995 Page 2 motutorung well MW-2 Fecal and total coliform bacteria were not detected in the sample collected from well MW-3 In January 1993, RESNA observed drilling of seven soil borings (B-13 through B-19) and the installation of two groundwater monitoring wells (MW-4 and NIW-5) and four vapor extraction wells (VW-4 through VW-7) Results of this assessment were reported in RESNA's first quarter 1993 status report(RESNA, June 9, 1993, Report 31009-7) Analytical data indicated that hydrocarbons present in soil below 26 feet and to groundwater were probably from an off-site source Therefore, ARCO requested that an investigation of soil and groundwater be performed off site and upgradient of the ARCO station to evaluate whether hydrocarbons were present upgradient of the site In October 1993, RESNA observed drilling of two soil borings (1320 and B21) and the installation of two groundwater monitoring wells (MW-6 and MW-7) Analytical data indicated that residual and dissolved hydrocarbons are present to wells MW-6 and MW-7 (RESNA, February 15, 1994, Report 31009-9) GROUNDWATER MONITORING: FOURTH QUARTER 1994 Groundwater Technology, Inc , (GTI) of Concord, California, was contracted by ARCO to conduct the field work at the site, GTI subsequently forwarded their field notes and the laboratory reports to EMCON Field work included measuring depths to water and collectmg groundwater samples for subjective and laboratory analyses EMCON used these data to evaluate the direction and gradient of groundwater flow beneath the site On December 1, 1994, a technician from GTI measured depths to water and collected groundwater samples from wells MW 1 through MW-7 for subjective and laboratory analyses Floating product was not noted in samples from the wells (see Table 1) However, a sheen was observed to well MW-3, f MW-4 and MW-6 and threrefore groundwater samples for laboratory analysts were not collected (see Table 1) The wellhead elevations of the site monitoring wells were previously surveyed by Tom O Morrow Inc The surveyed elevations and the depth to groundwater measurements, summarized to Table 1, were used to evaluate the potentiometnc surface beneath the site The direction of groundwater flow on December 1, 1994, was northeast with a hydraulic gradient of 0 003, as shown on Figure 3 The gradient is consistent with pervious data. Groundwater elevations have decreased approximately 019 foot since the last sampling event(September 1994) Groundwater samples from wells MW-1, MW-2 and MW-5 and MW-7 were analyzed for total petroleum hydrocarbons as gasoline (TPHG) using Environmental Protection Agency (EPA) Methods 5030/8015 and benzene, toluene, ethylbenzene and total xylenes (BTEX) using EPA Methods 5030/8020 prescribed by the state of California Samples were also analyzed for halogenated volatile SAC/N 1pj010805108051460 Icm-95/main 5