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Geofogicaf7ecfinics Inc Page 2 <br /> Groundwater Momtoi ing Report <br /> Project No 425 2 <br /> April 23,2001 <br /> I • Vertical groundwater gradients do exist at the site and range from 2 to 20 times the <br /> magnitude of the horizontal gradient At times the site has experienced both a <br /> negative and positive vertical gradient No clear trend has been recognized to <br /> account for these differences but variations in community groundwater pumping and <br /> rainfall may be causal factors Thus during low pumping demand, the vertical _ <br />'IF groundwater gradient would be expected to be upward, and the inverse would also <br /> be expected <br /> 2 Groundwater Contamination <br /> I <br /> • During late fall and winter months floating product has routinely been detected in <br /> MW-2 (located in the area of the former USTs) However it has not been observed <br /> Isince February 1998 <br /> • BTEX contamination has been previously observed in deep-screened wells MW-102 <br /> and MW-202 but the wells were non-detect for the second consecutive cvcnt <br /> • The domestic wells associated with the site were non-detect for all constituents <br /> 1.0 GROUNDWATER MONITORING <br /> 1.1 Hydrology of Site <br /> 1.1.1 Horizontal Groundwater Gradients <br /> Water Table Wells <br /> The average water table elevation at the site on March 6, 2001 was 72 00 feet above mean <br /> sea level This represents a decrease of 0 06 feet since the December 2000 monitoring <br /> event The water table groundwater gradient was 0 0044 ft/ft flowing S27°E A review of <br /> the groundwater gradients shows that the dominant groundwater flow during the last two <br /> years is to the north-northeast with the slope ranging from 0 0015 up to 0 0044 ft/ft Table <br /> 1 of Appendix A summarizes the water table groundwater gradients and levels to date, and <br /> Figure 3 illustrates the historical groundwater directions and gradients <br /> 14 <br /> Intermediate & Deep Wells <br /> The average groundwater elevation in the mterrnediate depth wells (MW-102, MW-105 & <br />' MW-107) for December was 71 92 feet above mean sea level and the intermediate depth <br /> groundwater gradient was 0 0018 ft/ft flowing N8 8'E <br />' Table 2 of Appendix A summarizes the intermediate depth groundwater gradients and levels <br /> to date Table 2 also summarizes the groundwater level data from the deep well, MW-202 <br /> The water table and intermediate groundwater gradients are included in Figure 2 <br />