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i butyl ether (MTBE), di-isopropyl ether (DIPE), ethyl tertiary butyl ether (ETBE), tertiary amyl methyl ether (TAME), and tertiary butanol (TBA) 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 Iocal groundwater flow direction and hydraulic gradient Groundwater at the site was measured at depths between 67 07 to 80 00 feet below ground surface (bgs) The groundwater potentiometric surface elevation averaged approximately 28 22 feet bgs during this monitoring event The groundwater elevation has decreased approximately 0 59 feet since the last sampling event in December 1999 The groundwater flow direction during this reporting period is toward the southwest with a hydraulic gradient of approximately 0 03 ft /ft A summary of data regarding groundwater levels measured through Feburary 17, 2000 is presented in Table 1 Copies of field observations documenting work performed at the site is presented in Attachment I Groundwater Analytical Results The distribution of groundwater sample analytical results obtained from monitor wells at the site on February 17, 2000, is presented on Figure 3 and summarized in Table 2 TPHg and BTEX were present at detectable concentrations in eight 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 1,150 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-7 Benzene concentrations ranged from below the laboratory method detection limit in monitor wells MW-2,MW-5 through MW-8, and MW-10,to 144 ug/L in MW-3 MTBE concentrations in groundwater samples ranged from below the laboratory method detection limit in monitor wells MW--2,MW-3 and MW-7 through MW-10,to 10 1 ug/L in a sample collected from monitor well MW-4 Attachment H contains photocopies of the laboratory analytical report and the chain-of-custody form Approximately 4 79 feet of liquid phase hydrocarbon (LPH) was detected in MW-1 during this monitoring event The physical appearance (clear) and its presence in the subsurface vapor extraction piping suggest that the LPH is the result of condensed soil vapor Asa precaution,the site inventory records and leak detection systems were checked, and a visual comparison was made between the LPH and all three grades of gasoline currently dispensed at the site Inventory records and leak detection systems were normal and the LPH did not visually match the colored grades of gasoline dispensed at the site The LPH is currently being removed from MW-I by hand bailing methods and the use of a passive, down-hole petroleum skimmer C Slime O1Rfne4efordQ100 a SECOR 077 41737 003 ApH3 24 2000