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CJeo(o,yw-qf 'echnw-s Inc Page 2 ' Groundwater Monitonng Report Project No 724 2 . October 3,2002 1.0 GROUNDWATER MONITORING ' 1.1 Hydrogeology of Site Site-specific groundwater gradients and bearings for water table and intermediate wells ' were calculated utilizing computer generated contours On June 21, 2002, the gradient in water table wells MW-4, MW-5, MW-6 and MW-7 was ' flowing S57°E at 0 0057 ft/ft This is the steepest gradient yet observed at the site Figure 2 illustrates the water table groundwater gradient map for the monitoring event The average elevation of groundwater under the site was —19 29-feet (below) msl The water level has ' risen significantly at the site since October of 1992 when groundwater was—39 feet msl Figure 3 is an intermediate well groundwater gradient map for the June 2002 event In the intermediate wells (water above the screened interval of the well) MW-1 through MW-3, MW-106 and MW-107, groundwater flowed due east at a gradient of 0 0017 ft/ft Deep ' well MW-104 is not screened across similar elevations so a deeper gradient was not calculated for the event Table 1 in Appendix A contains the shallow groundwater elevations and gradients for all events since the start of this project in October 1992 Table 2 in Appendix A contains the historical intermediate/deep groundwater elevations ' Historical groundwater gradient data are illustrated in Figure 4, Groundwater Gradient Rose Diagram Vertical Groundwater Gradients Under vertical groundwater flow conditions, the water level in a monitoring well is a function of the length of the well screen and its depth or vertical position in the aquifer As with horizontal flow conditions, the diameter of the well or piezometer is immaterial ' The following procedure is used to calculate the vertical groundwater gradient • Determine vertical distance between the two measuring devices by the distance from the ' mid-point between the top and bottom seal of the deep well (MW-104, MW-106, MW- 107) and the mid-point between the groundwater elevation and the bottom seal in the shallow well (MW-4, MW-6, MW-7) • Measure the head in both wells used in the calculations • If the lateral distance between the well pair is greater than a few feet, then calculations ' must be made to correct the down-gradient piezometnc head to account for the sloping water table between the wells The calculation considers the slope of the water table and the distance in a down-gradient direction between the two wells used in the calculations r