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40 Groundwater Elevation Data Depth to groundwater was obtained from the existing groundwater monitor wells at the site using a water level indicator graduated to 0 01 foot The depth to groundwater measurement was converted to a groundwater elevation for each well and used to construct a groundwater elevation contour map (Figure 2), and calculate the local groundwater flow direction and hydraulic gradient Groundwater at the site was measured at depths between 66 75 to 76 87 feet below ground surface (bgs) The groundwater potentiometnc surface elevation averaged approximately 28 03 feet bgs during this monitoring event The groundwater elevation has decreased approximately 0 22 feet since the last sampling event in.lune 2000 The groundwater flow direction during this reporting period is toward the southwest with a hydraulic gradient of approximately 0 02 ft /ft A summary of data regarding groundwater levels measured through August 18, 2000 is presented in Table 1 Copies of field observations documenting work performed at the site are presented in Attachment I Groundwater Analytical Results The distribution of groundwater sample analytical results obtained from monitor wells at the site on August 18, 2000, is presented on Figure 3 and summarized in Table 2 TPHg and BTEX were present at detectable concentrations in five of the nine samples submitted for analysis Chemical analytical results indicate the highest concentrations of TPHg and benzene are in the vicinity of monitor wells MW-3 and MW-4 TPHg concentrations in groundwater samples ranged from 384 micrograms per liter(ug/L)in monitor well MW-3, to less than detectable levels in samples collected from monitor wells MW-2,and MW-5 through MW-10 Benzene concentrations ranged from below the laboratory method detection limit in monitor wells MW-2,MW-6 through MW-8,and MW-10, to 74 2 ug/L in MW-3 MTBE concentrations in groundwater samples ranged from below the laboratory method detection limit in monitor wells MW-7 through MW-l 0,to 6 6 ug/L in a sample collected from monitor well MW-5 Attachment II contains photocopies of the laboratory analytical report and the chain-of-custody form Approximately 0 01 feet of liquid phase hydrocarbon (LPH) was detected in MW-I during this monitoring event In general,the LPH thickness has decreased in MW-1 after vapor extraction was temporarily discontinued at this well The physical appearance (clear) and its presence in the subsurface vapor extraction piping suggest that the LPH is the result of condensed soil vapor The LPH is currently being removed from MW-1 by hand bailing methods and the use of a passive, dawn-hole petroleum skimmer on a weekly basis A total of approximately 34 gallons of LPH has been removed from MW--I since its detection in February 2000 C%Time O( .oCWOrdQ'IOQ 077 44 731 003 Oclphtr 17 2�0a