ARCHIVED REPORTS XR0001799 - Laserfiche WebLink

Home Browse Search

r ' Mr Kyle Christie Project 0805-142 01 November 14, 1994 Page 2 subjective and laboratory analyses EMCON used these data to evaluate the direction and gradient of groundwater flow beneath the site On September 27, 1994, a technician from GTI measured depths to water and collected groundwater ' samples from wells MW-I 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 potentiometnc surface beneath the site The groundwater flow direction on September 27, 1994, was to the southeast with a hydraulic gradient of 0 002 (see Figure 2) Groundwater elevation data are presented on Figure 2 and in Table 1 Groundwater ' elevations decreased approximately 2 58 feet from the previous sampling a,,ent (June 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 3510/8015, 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 I Copies of the laboratory analysis reports are presented ail Attachment A TPHG concentrations ranged from 130 parts per billion ([ppb] well MW-2) to 380 ppb (well MW-3), and concentrations of benzene ranged from below detection limits (wells MW-2) to 4 5 ppb (well MW-1) TPHG and benzene concentrations are shown on Figure 1 TOG was not detected in groundwater samples collected from all wells TPHD was detected in well MW-1 at a concentration of 140 ppb, but was not detected in the other wells i WORK IN PROGRESS 1 At the request of San Joaquin County Public Health Service information during site investigations conducted at ARCO service stations Nos 760 and 548 (1612 Hammer Lane in Stockton, California) were reevaluated in an effort to assess which site warrants the next available San Joaquin County designated ARCO vapor extraction treatment unit The results of this evaluation was presented in a ' report dated September 14, 1994 ARCO will continue quarterly monitoring. The next sampling event is tentatively scheduled for the month of December 1994 ' Access agreements were mailed to Pamela Martinez (property owner north of the site) and Miguel Guerrero (property owner west of the site) on October 24, 1994 Once access has been obtained, EMCON will conduct further off-site assessment, which will include installation of two vapor ' extraction wells ' SAC/pj0"05\08051420 lass-94lik 4