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GeofogtcafTechnzcs 2nc Page 2 <br /> Groundwater Monitoring Report <br /> Project No 770 2 <br /> Apn1 11,2001 <br /> 1.0 GROUNDWATER MONITORING <br /> 1.1 Hydrogeology of Site <br /> The site exhibits a primarily clayey geology with minor sand layers/lenses, pebbles, black <br /> ' organics, and iron staining occasionally present The average groundwater elevation on <br /> March 15, 2001 averaged —3143 feet below MSL (-56 feet bgs) This represents an <br /> increase of 126 feet since the December 2000 monitoring event <br /> A groundwater gradient was calculated for the March 2001 groundwater monitoring event <br /> and found to be flowing S 18°W at 0 0019 ft/ft Groundwater elevation and gradient data is <br /> summarized in Table 1, Appendix A Gradient direction is show on Figure 2 Gradient <br /> Map The historical gradients are illustrated in Figure 3 Groundwater Gradient Rose <br /> ' Diagram <br /> Vertical Groundwater Gradients <br /> ' Under vertical groundwater flow conditions, the water level in a monitoring well is a <br /> function of the length of the well screen and its depth or vertical position in the aquifer As <br /> with horizontal flow conditions, the diameter of the well or piezometer is immaterial <br /> r' The following procedure is used to calculate vertical groundwater gradient <br /> • Determine vertical distance between the two measuring devices by the distance from the <br /> mid-point between the top and bottom seal of the deep well (MW-105) and the mid- <br /> point between the groundwater elevation and the bottom seal in the shallow well (MW- <br /> 5) <br /> ' • Measure the head in both wells used in the calculations <br /> • 1f the lateral distance between the well pair is greater than a few feet, then calculations <br /> ' must be made to correct the down-gradient piezometnc head to account for the sloping <br /> water table between the wells The calculation considers the slope of the water table and <br /> the distance in a down-gradient direction between the two wells used in the calculations <br /> Figure 2 shows the location of the well cluster used for calculating vertical groundwater <br /> gradient in this report, MW-5 and MW-105 Tables 1 and 2 show Summary of Water Level <br /> ' and Gradients Slope and Bearing, and Table 3 shows the calculated vertical gradients The <br /> information used in the calculations is shown below <br /> 1 <br />