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1 well casing elevations, representing an average increase in the water table elevation of <br /> approximately 0 35 feet since August 1995 The water level data were used to develop the <br />' groundwater elevation contour map (Figure 2) Assuming that horizontal isotropic conditions <br /> prevail, groundwater to the uppermost aquifer beneath the site flowed towards the southeast with a <br />' slight mounding effect noted in the vicinity of well MW-2 The average hydraulic gradient on <br /> January 12, 1996 was calculated to be 0 009 ft/ft or approximately 48 ft/mile A summary of <br /> groundwater monitoring data is presented in Table 2 <br /> CONCLUSIONS <br /> Petroleum hydrocarbon constituents remained non-detectable in the groundwater sample collected <br /> from wells MW-1, MW-2, MW-4 and MW-5 Concentrations of petroleum hydrocarbon <br />' constituents generally decreased, even one to two orders of magrutude, in the groundwater <br /> samples collected from wells MW-3 and MW-6 since the last monitoring episode in August 1995 <br />' The extent of groundwater contamination has been fully delineated in the south and east directions but <br /> not in the northeast direction due to concentrations of petroleum hydrocarbons detected in wells on the <br /> northeast corner of the property <br />' The direction of groundwater flow and the magnitude of hydraulic gradient are consistent with the <br /> previous quarter Groundwater elevations have risen due to seasonal conditions <br />' RECOMMENDATIONS <br /> Based on the results of the first quarter 1996 monitoring episode, we recommend the following <br /> o Continued quarterly monitoring of depth to water in all wells on site. <br />' o Continued quarterly sampling of wells MW-3, MW-4, MW-5 and MW-6 <br />' o A reduction in sampling of wells MW-1 and MW-2 to semiannual, dunng first and <br /> third quarters. Well MW-1 has never contained detectable concentrations of petroleum <br /> hydrocarbons since monitoring began Well MW-2 has not contained detectable <br />' concentrations of petroleum hydrocarbons for the last three quarters of sampling. <br /> Smith Environmental is in the process of preparing a workplan for investigation of the extent of <br /> groundwater contamination northeast of the site <br /> 3 SNRN <br /> 1506781QUARTLYIIQR-1996 doc <br />