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' G o e toccal recus/nc 8 kn Page e 2 g Groundwater Momtonng Report Project No 770 2 March 31, 2004 April and May 2003 sounding events and GTI's monitoring efforts confirm that groundwater direction varies from month to month at the site There are numerous agricultural, commercial and residential wells near the Marcl parcel and the influences from these wells are the probable cause for the groundwater direction fluctuations ' 1.0 GROUNDWATER MONITORING ' 1.1 Hydrogeology of Site The site exhibits a primarily silty/clayey geology with minor sand layers/lenses, pebbles, ' black organics and iron staining occasionally present The groundwater monitoring schedule was modified to include monthly depth to groundwater measurements in 2002 ' This was necessary to better define the gradients that have varied greatly in the past The water table well groundwater elevation on October 20, 2003, averaged —41 95 feet mean. sea level (MSL) or —66 feet below grade surface (bgs)XFor the November 25 event, the water table well groundwater elevation decreased to an average of—42 05 feet MSL '�On December 16, 2003 the average depth to groundwater in the water table wells was again approximately 66 feet bgs and elevation averaged —42 06 feet MSL A net decrease of 0 22 feet in groundwater elevation was recorded between the September and December 2003 sounding events Groundwater gradient calculations indicate that the flow in the water table wells was S70°E with a slope of 0 001 ft/ft on October 20, 2003 On November 25, 2003 the water table well ' gradient was S77E with a slope of 0 001 ft/ft, and on December 16, 2003 it was S57°E with a slope of 0 001 ft/ft r The groundwater gradient to the deeper aquifer monitored by wells MW-104, 105 & 106 was also calculated for the three sounding events On October 20, 2003, theqeeper aquifer gradient was S89°W with a slope of 0 0012 ft/ft, on November 25 it was S83° ith a slope +))5)s� ' of 0 001 ft/ft, and on December 16 it was S87°E with a slope of 0 0011 ft/ft Groundwater elevation and gradient data are summarized in Tables 1 and 2, Appendix A r Water table well gradient directions are shown on Figure 2A; 3A & 4AJfor the October, November and December 2003 events, respectively Wells MW-4 and MW-5 are excluded ✓ ' from the contouring due to anomalous values that contort the contours in the central portion of the site The deep well gradient directions for the same events are illustrated in Figures _ 213, 3B and 413, respectively 1 The historical water table gradients are illustrated in Figure SA & SB Groundwater Gradient Rose Diagrams for Water Table and Deep Wells, respectively The site's shallow