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August 1994 -9- 933-2713.003 <br /> Q = K * i * A [Equation 1] <br /> where: <br /> Q = Volume of groundwater flow per time; <br /> K = Hydraulic conductivity; <br /> i = Hydraulic gradient; and, <br /> A = Cross-sectional area through which the groundwater is passing. <br /> By adding the volume of groundwater to the volume of surface water passing a given point <br /> during a specified period of time, it is possible to determine the total volume of water flow (i.e., <br /> conjunctive flow). <br /> Sandy Gravel Zone <br /> The cross-sectional area of flow in the sandy gravel was determined by averaging the area below <br /> the water level and above the base of the sandy gravel lense. Based on cross-sections AW and <br /> B-B', the area contributing groundwater flow is determined to be about 2,400 ft2. <br /> A representative, conservative, hydraulic conductivity for the gravel unit (creek sediments) is <br /> considered to be 2.8 x 10' cm/s = 5.5 x 10' ft/min on the basis of the slug test analyses (see <br /> Section 4.2). <br /> The hydraulic gradient was calculated between the two cross sections using the lowest <br /> groundwater level in each section. Based on March, 1994 data, the hydraulic gradient is 0.0676 <br /> ft/ft. <br /> Assuming that the permeability of the sandy gravel is representative of the entire cross-sectional <br /> area of flow, Equation 1 can be used to determine the volume of groundwater flow: <br /> Q = (5.5 x 10' ft/min) * (0.0676 ft/ft) * (2,400 ft.2) * = 0.09 W/min = 0.67 gpm = 965 <br /> gpd [gallons per day] = 9.7 x 10-4 Mgd [million gallons per day] <br /> Golder Associates <br />