Laserfiche WebLink
Fj <br />0 <br />APPENDIX <br />GROUNDWATER DIRECTION, FLOW RATE CALCULATIONS, AND <br />HYDROGRAPYS <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 = 0.00062 foot per foot (ft/ft) <br />n = 0.30 <br />The groundwater flow velocity was 20.87 ft/yr for the second quarter and was calculated as <br />follows: <br />V = 10,100 ft/yr (0.00062 ft/ft) <br />0.30 <br />= 20.87 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 -40 and -41 by the lateral distance between the two elevations <br />in the direction of groundwater flow (1,600 ft). An average porosity value of 0.3 was used, <br />based on published porosity values for similar geologic materials. <br />North County RCSL Public Works/Solid Waste <br />2nd Semester and Annual 2005 Groundwater Monitoring G-1 County of San Joaquin — January 24, 2006 <br />