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APPENDIX G <br /> GROUNDWATER DIRECTION AND FLOW RATE CALCULATIONS <br /> Groundwater elevations in the monitoring wells are obtained quarterly. These measurements are <br /> used to define the direction and gradient of groundwater flow in the vicinity of the Harney Lane <br /> Sanitary Landfill. The average groundwater velocity in this area was calculated using the following <br /> 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= 9.8 x 10-3 centimeters per second(cm/s) <br /> = 10,100 feet per year(ft/yr) <br /> I = 0.0009 foot per foot (ft/ft) <br /> n = 0.30 <br /> ! The groundwater flow velocity was calculated as follows: <br /> V= 10,100 ft/yr(0.0009 ft/ft) <br /> 0.30 <br /> = 30.6 ft/yr <br /> The permeability coefficient was determined with a slug test in well G-1 at the North County <br /> Recycling Center and Sanitary Landfill to be 9.8 x 10-3 cm/s. Well G-1 at North County monitors <br /> similar soil types at the equivalent horizon as the water-bearing zone beneath the Harney Lane <br /> ! Sanitary Landfill. The hydraulic gradient was calculated by dividing the difference in groundwater <br /> elevations -30.50 feet and-31.00 feet by the distance between lines measured in the direction of <br /> flow. An average porosity value of 0.3 was used, based on published porosity values for similar <br /> geologic materials. <br /> ! Harney Lane Sanitary Landfill Department of Public Works/Solid Waste <br /> 2"'Quarter 2007 Groundwater Monitoring Report County of San Joaquin—July 15,2007 <br /> G-1 <br />