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1 <br /> ' 14 GROUND WATER HYDROLOGY <br /> During drilling activities, ERM typically encountered ground water in <br /> ' borings at depths between 30 and 40 feet bgs The ground water <br /> potentiometric surface at the property ranges from approximately <br /> 31 to 35 feet bgs <br /> ERM evaluatedound water flow a <br /> gn' t the former UST location using the <br /> ' three on-site monitoring wells Table 1 presents the ground water <br /> elevations recorded during quarterly sampling events Ground water flow <br /> direction in the aquifer beneath the site fluctuates, although the majority of <br /> ' monitoring events indicate a northwestern trend of flow The most recent <br /> ground water elevation contour map, along with a rose diagram displaying <br /> historical ground water flow direction, is shown on Figure 5 An <br />' anomalous ground water flow direction to the east was observed during <br /> ground water monitoring conducted on 22 June 2000 After reviewing the <br /> data, it should be noted that the difference m ground water elevation <br /> between the three wells was 0 06 feet, a very flat gradient for the site based <br /> on historical data Also of note, during the monitoring on 22 June 2000, it <br />' was noted that MW-1 was under pressure when the monitoring well cap <br /> was removed to measure the ground water level The water level was <br /> allowed to equilibrate for over an hour prior to measuring, however, it is <br />�. possible that the ground water level had not fully equilibrated prior to <br /> measurement If the ground water level had not equilibrated fully, the <br /> ground water level may have risen higher, which may have changed the <br />' ground water flow to a more northerly gradient <br /> Ground water wells are a common source of potable water in the Great <br /> Valley geomorphic province, however, no water supply wells exist within <br /> a 2,000-foot radius of the site A copy of the Environmental Data Resources <br />' (EDR) Radius Map has been included as Figure 6 The wells shown on <br /> Figure 6 within a 2,000-foot radius of the site have all been abandoned <br /> This information satisfies Item #1 of the PHS/EHD checklist <br /> I <br /> ERM 3 <br /> 43435a/uPaa/o2/i 3/03 <br />