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Geologica1Technws Inc Page 2 <br />' Groundwater Monitoring Report <br /> Project No 425 2 <br /> � January 12, 2001 <br /> • 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 <br /> 2 Groundwater Contamination <br /> • Floating product has routinely been detected in MW-2 (located in the area of the <br /> former USTs) during late fall and winter months However it has not been observed <br /> in the last few years <br /> The BTEX contamination previously observed in wells MW-102 and MW-202 has <br />' returned at levels just above the detection limits The wells were non-detect for all <br /> analytes during the three previous sampling events <br /> e The domestic well at 1600"A" Durham Ferry Road had trace concentrations of <br /> benzene during the April 1999 event and contained trace BTEX concentrations for <br /> this event The well has been previously non-detect for all constituents during the <br />' last four monitoring events This well was re-sampled on November 15, 2000, and <br /> was 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 September 20, 2000 was 72 80 feet above <br /> mean sea level and the water table groundwater gradient was 0 0021 ft/ft flowing N32°E A <br /> review of the groundwater gradients shows that the dominant groundwater flow is to the <br />' north with the slope ranging from 0 0012 up to 0 0289 ft/ft Table 1 of Appendix A <br /> summarizes the water table groundwater gradients and levels to date, and Figure 3 illustrates <br /> the historical groundwater directions and gradients <br />' intermediate &Deep Wells <br /> The average groundwater elevation in the intermediate depth wells (MW-102, MW-105 & <br /> MW-107) for September was 72 34 feet above mean sea level and the mterniediate depth <br /> groundwater gradient was 0 027 ft/ft flowing S44°E <br /> Table 2 of Appendix A summarizes the mterniediate depth groundwater gradients and levels <br /> to date Table 2 also summarizes the groundwater level data from the deep well, MW-202 <br /> Figure 2 is a map showing both the water table and intermediate groundwater gradients <br /> 1 <br />