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APPENDIX G <br /> GROUNDWATER DIRECTION, FLOW RATE CALCULATIONS, AND <br /> HYDROGRAPHS <br /> Groundwater elevations in the monitoring wells were obtained this semester. These <br /> measurements were used to define the direction and gradient of groundwater flow in the vicinity <br /> of the North County Sanitary Landfill. The groundwater flow direction is to the southwest. The <br /> average groundwater velocity in this area was calculated using the following equation (Darcy's <br /> Law): <br /> V= Ki <br /> n <br /> V=maximum linear velocity <br /> K=permeability <br /> i=hydraulic gradient <br /> n =porosity <br /> K=9.8 x 10-3 centimeters per second (cm/s) <br /> = 10,100 feet per year(ft/yr) <br /> i =0.00037 foot per foot (ft/ft) <br /> n =0.30 <br /> The groundwater flow velocity was 12.456 ft/yr for the second quarter and was calculated as <br /> follows: <br /> V= 10_,100 ft/yr(0.00037 ft/ft) <br /> 0.30 <br /> = 12.456 ft/yr <br /> Permeability coefficients determined with a slug test in well G-1 ranged from 8.3 x 10-3 to 9.8 x <br /> 10-3 cm/s in the water-bearing zone beneath the landfill. The highest measured permeability <br /> value of 9.8 x 10-3 cm/s was selected because it would produce the greatest groundwater <br /> velocity. The hydraulic gradient was calculated by dividing the difference in groundwater <br /> elevations between contour lines -34.20 and-34.80 by the lateral distance between the two <br /> elevations in the direction of groundwater flow (1600 ft). An average porosity value of 0.3 was <br /> used, based on published porosity values for similar geologic materials. <br /> North County RCSL Public Works/Solid Waste <br /> 1st Semester 2006 Groundwater Monitoring G-1 County of San Joaquin—July 31,2006 <br />