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APPENDIX G <br />GROUNDWATER DIRECTION AND FLOW RATE CALCULATION1 <br />The groundwater monitoring network consists of eight monitoring wells and a piezometer. Two <br />water -bearing zones are monitored. To monitor the shallow, perched aquifer, MW -4, MW -5, <br />SB -1, PZ -1, MW -8 MW -9A, MW -10A, MW -11 A are used. Well SB -1 was originally installed <br />to provide additional water level data. SB -1 was added to the monitoring well network on <br />December 2, 1996. Piezometer PZ -1 was added July 30, 2003. Water elevations taken at these <br />five points are used to define the direction and gradient of groundwater flow in the vicinity of <br />CHLF. The average groundwater velocities in this water bearing zone were calculated using the <br />following equation (Darcy's Law): <br />V= Ki <br />n <br />V = maximum linear velocity <br />K = permeability <br />i = hydraulic gradient <br />n =porosity <br />K = 8.11 x 10-5 centimeters per second (cm/s) <br />= 83.69 feet per year (ft./yr) <br />i = 0.04 foot per foot (ft/ft) northeasterly <br />n = 0.30 <br />The northeasterly groundwater flow velocity 11.16 ft/yr was calculated as follows: <br />V = 83.69 ft/yj: (0.04 ft/ft) = 11.16 ft/yr <br />0.30 <br />The hydraulic conductivity was determined with a slug test in well MW -4 to be 8.11 x 10-5 cm/s <br />in the perched water -bearing zone beneath the landfill. An average porosity value of 0.30 was <br />used, based on published porosity values for similar geologic materials. <br />The deep water -bearing zone is monitored by wells MW -1, MW -2, MW -6, and MW -7. Wells <br />MW -1 and MW -2 were dry. MW -6 and MW -7 were installed in 2003 and water elevations were <br />used to calculate groundwater flow and generate a groundwater contour map. The average <br />groundwater velocity was also calculated using the equation based on Darcy's law: <br />K = 8.1 lx 10-5 centimeters per second (cm/s) <br />= 83.69 feet per year (ft./yr) <br />i = 0.005 foot per foot (ft/ft) northeasterly <br />n = 0.30 <br />The northeasterly groundwater flow velocity of 1.39 ft/yr from well MW -7 to MW -6 was <br />calculated as follows: <br />V = 83.69 ft/yr (0.005 ft/ft) = 1.39 ft/yr <br />0.30 <br />Corral Hollow Landfill G-1 Department of Public Works/Solid Waste <br />3rd Quarter 2012 Groundwater Monitoring County of San Joaquin — October 30, 2012 <br />