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Ge0(09w lTTecfa1tcs 2nc Page 2 Groundwater Monitoring Report Project No 724 2 March 7,2002 1.0 GROUNDWATER MONITORING 1.1 Hydrogeology of Site Site-specific groundwater gradients and bearings for water table and intermediate wells rwere calculated utilizing computer software generated contours On December 6, 2001, the gradient in water table wells MW-4, MW-5, MW-6 and MW-7 was flowing S48°E at 0 0019 ft/ft, which is the southern most direction noted during the course of the investigation The average elevation of groundwater under the site was—19 60 feet (below) msl The water level has risen significantly at the site since October of 1992 when groundwater was —39 feet msI Figure 2A is a water table well groundwater gradient map for the December 6, 2001, monitoring event ' Figure 2B is an intermediate well groundwater gradient map for the 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 S84°E at a gradient of 0 0016 ft/ft Deep well MW-104 is not screened across similar elevations so a deeper gradient was not calculated for the event On December 20, 2001, the wells were re-surveyed in accordance with the Geotracker requirements by Thompson-Hysell Engineering of Modesto, CA The wells were also sounded during that task and the average groundwater elevation at the site was ---19 57 feet msl with the groundwater flowing S69°E at 0 0034 ft/ft This represented an increase of 0 59 feet since the previous event (data normalized to the December 20, 2001, survey) In the intermediate wells (water table is above the screened interval of the well) MW-I through MW-3, MW-106 and MW-107, groundwater flowed S83°E at a gradient of 0 0016 ft/ft As noted above deep well MW-104 is not screened across similar elevations so a deeper gradient was not calculated for the event The gradient directions for the water table and intermediate wells on December 20, 2001, are shown in Figures 3A and 313, respectively 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, Appendix A contains the ' historical inten-nediate/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