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I - Mr Kyle Christie Project 0805-142 01 February 13, 1995 Page 2 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 2, 1994, a technician from GTI measured depths to water and collected groundwater samples from wells MW-1 through MW-3 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 Tom O Morrow The surveyed elevations and the depth-to-groundwater measurements (summarized in Table 1) were used to evaluate the potentlometrrc surface beneath the site The groundwater flow direction on December 2, 1994, was to the south with a hydraulic gradient of 0 002 (see Figure 3) Groundwater elevation data are presented on Figure 3 and in Table 1 Groundwater elevations increased approximately 2 55 feet from the previous sampling event (September 1994) Groundwater samples were analyzed for total petroleum hydrocarbons as gasoline (TPHG), total petroleum hydrocarbons as diesel (TPHD) using Environmental Protection Agency (EPA) Method 5030/8015 and 351018015, respectively, total oil and grease (TOG) using EPA Method 5520 B and F, and benzene, toluene, ethylbenzene, and total xylene (BTEX) isomers using EPA Methods 5030/8020 These samples were analyzed at National Environmental Testing Inc , In Santa Rosa, California The results of analyses are summarized in Table 1 Copies of the laboratory analysis reports are presented in Attachment A TPHG concentrations were below laboratory detection limits in wells MW-2 and MW-3, however, TPHG concentrations were detected in well MW-1 at 110 parts per billion (ppb) Concentrations of benzene were below detection limits in. all wells TPHG and benzene concentrations are shown on Figure 2 TOG was not detected in groundwater samples collected from all wells TPHD was detected in all wells at concentrations ranging from 110 ppb(well MW-3)to 170 ppb(MW-2 } ACTIVITIES PERFORMED DURING THE FOURTH QUARTER A One of the access agreement forms to install one vapor extraction well was obtained from Pamela Martinez(property owner north of the site) o Miguel Guerrero (property owner west of the site) was contacted by an EMCON representative regarding the access agreement form sent to hum on October 24, 1994, for the installation of one vapor extraction well on his property However, EMCON has not received the signed form. SAC/SAC/PJM0805108051420 IBM-94 PAS 3