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Geo6gccaI Tecluucs t1 c Page 2 i Groundwater Monitoring Report Project No 770 2 May 28,2003 ' history of variable groundwater flow direction GTI's monitoring efforts confirin that groundwater direction varies from quarter to quarter at the site / 1 1.0 GROUNDWATER MONITORING 1.1 H dro eolo of Site Y g gY tThe site exhibits a pnmanly silty/clayey geology with minor sand layers/lenses, pebbles, black organics and iron staining occasionally present The water table well groundwater ' elevation on January 28, 2003 averaged —39 43 feet mean sea level (MSL) or —63 feet below grade surface (bgs) For the February 6 event, the water table well groundwater elevation increased to an average of—39 24 feet MSL or —63 feet bgs On March 19, 2003 ' the averaged depth to groundwater in the water table wells was again approximately 63 feet bgs and elevation averaged —38 72 feet MSL This represents a cumulative increase of approximately 1 67 feet since the December 2002 monitoring event Groundwater gradient calculations indicate that the flow in the water table wells was S47°E with a slope of 0 001 ft/ft on January 28, 2003 On February 6, 2003 the water table well M gradient was S62°E with a slope of 0 001 ft/ft, and on March 19, 2003 it was S66°E with a slope of 0 001 ft/ft The groundwater gradient in the deeper aquifer monitored by wells MW-104, 105 & 106 was also calculated for the three sounding events On January 28 the deeper aquifer gradient was N89°E with a slope of 0 0018 ft/ft, on February 6 it was N66°E with a slope of ' 0 0013 ft/ft, and on March 19 it was N81°E with a slope of 0 0034 ft/ft ' Groundwater elevation and gradient data are summarized in Tables 1 and 2, Appendix A Water table well gradient directions are shown on Figure 2A, 3A & 4A for the January, February and March 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 events are illustrated in Figures 2B, 3B and 4B ' The historical water table gradients are illustrated in Figure 5A & 5B /Groundwater Gradient Rose Diagrams for Water Table and Deep Wells, respectively The site's shallow ' aquifer displays highly variable shifts in groundwater direction It is noted that groundwater direction has been predominantly to the southeast since additional wells were installed in May 2002 The deeper aquifer flow has been consistently to the east for the events it has ibeen monitored i