Laserfiche WebLink
APPENDIX G <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. 00 18 foot per foot (ft/ft) <br />n= 0.30 <br />The groundwater flow velocity was 61.21 ft/yr for the third quarter and was calculated as <br />follows: <br />V =10,100 ft/yr 0.0018 ft/ft) <br />0.30 <br />= 61.21 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 <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 third quarter 2012 was calculated by <br />dividing the difference in groundwater elevations between contour lines 46.00 and 44.00 by the <br />lateral distance between the two elevations in the direction of groundwater flow (1100 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 74.81 ft/yr for the fourth quarter and was calculated as <br />follows: <br />V = 10,100 ft/,g0.0022 ft/ft) <br />0.30 <br />= 74.81 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 2012 was calculated by dividing the <br />Foothill Sanitary Landfill Department of Public Works/Solid Waste <br />2nd Semester and Annual 2012 Groundwater Monitoring County of San Joaquin — January 15, 2013 <br />