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i Mr Kyle Christie Project 0805-114 03 April 4, 1995 . Page 2 In June 1994, RESNA prepared and submitted a problem assessment report (PAR) and a final remediation plan to the county and state regulatory agencies The reports indicated additional subsurface investigation is required and will include additional air sparge wells, monitoring air sparge well, vapor extraction wells and one additional off-site monitoring well. During fourth quarter 1994, EMCON has submitted access agreements to the property owner north of the site to install one monitoring well. The well is necessary to fully delineate hydrocarbons in groundwater Access from the property owner has not been obtained 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 collecting 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—we-ffi-MVT through MW-8 and MW-10 for subjective and laboratory analyses Floating product or product sheen was not noted in samples from the wells (see Table 1) The wellhead elevations of the monitoring wells at the site were previously surveyed by Morrow Surveying of West Sacramento, California The surveyed elevations and the depth to groundwater measurements, summarized in Table 1, were used to evaluate the potentiometric surface beneath the site The groundwater flow direction on December 1, 1994, was to the southeast with a hydraulic gradient of 0 O (see Figure 3) The groundwater flow direction in the past has generally been towards the east to southeast Groundwater elevation data are presented on Figure 3 and in Table 1 Groundwater elevations increased 103 feet from the previous sampling event performed in September 1994 Groundwater samples collected from wells MW-1 through MW-8 and MW-10 were analyzed for total petroleum hydrocarbons as gasoline (TPHG) and benzene, toluene, ethylbenzene, and total xylene isomers (BTEX) using Environmental Protection Agency (EPA) Method 5030/8015 and EPA Methods 5030/8020 These samples were analyzed at National Environmental Testing, Inc , in Santa Rosa, California (Hazardous Waste Testing Laboratory Certificate No 1386) The results of analyses are summarized in Table 2 Copies of the laboratory analysis reports are presented in Attachment A. TPHG concentrations ranged from below limits MW-3, MW-f, and MW-7) to 1 0�arts per billion ([ppbj MW-4), benzene concentrations ranged from below detection limits (MW-10) to 400 ppb (MW-4) Benzene was detected in well MW-3 and MW-6 at a concentration of 0 8 ppb TPHG isand benzene concentrations are shown on Figure 2 sAC/N\PJ"8055080511403AM-95\NAM t