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APPENDIX F <br /> GROUNDWATER DIRECTION AND FLOW RATE CALCULATIONS <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 Foothill 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=0.00235 foot per foot (ft/ft) <br /> n=0.30 <br /> The groundwater flow velocity was 79.21 ft/yr for the third quarter and was calculated as <br /> follows: <br /> V= 10,100 ft/yr(0.00235 ft/ft) <br /> 0.30 <br /> =79.21 ft/yr <br /> The permeability coefficient was determined with a slugtest in well G-1 at the North County <br /> Y <br /> Recycling Center and Sanitary Landfill to be 9.8 x 10-3 cm/s. Well G-1 at North County <br /> monitors similar soil types at the equivalent horizon as the water-bearing zone beneath the <br /> Foothill Sanitary Landfill. The hydraulic gradient for the first quarter 2013 was calculated by <br /> dividing the difference in groundwater elevations between contour lines 54.00 and 52.00 by the <br /> lateral distance between the two elevations in the direction of groundwater flow(850 ft). An <br /> average porosity value of 0.3 was used, based on published porosity values for similar geologic <br /> materials. <br /> The groundwater flow velocity was 76.952 ft/yr for the fourth quarter and was calculated as <br /> follows: <br /> V=10,100 ft/ <br /> �r(0.00228 ft/ft) <br /> 0.30 <br /> = 76.952 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 for the fourth quarter 2013 was calculated by dividing the <br /> Foothill Sanitary Landfill Department of Public Works/Solid Waste <br /> 2nd Semester and Annual 2013 Groundwater Monitoring County of San Joaquin—January 31,2014 <br />