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DARCY EQUATION CALCULATIONS <br />The Darcy equation can calculate ground water <br />1983). The equation follows: <br />v=velocity=distance/time=D/t, <br />K=hydraulic conductivity, <br />n=porosity, dimensionless, <br />dh/dl=potentiometric head gradient, dimensionless, <br />v=K/n*dh/dl (Equation 1, Heath 1983), <br />substitute D/t for v, <br />D/t=K/n*dh/dl, <br />multiply both sides by t, <br />system parameters (Heath <br />D=Kt/n*dh/dl (Equation 2) or rearrange to K=D/t*n*dl/dh (Equation 3). <br />Equation 2 can calculate the total distance of the horizontal flow path between <br />recharge and Monitor Well COV23, if the two points are directly connected, as <br />follows: <br />K=hydraulic conductivity=0.1 ft/day (Peabody 2009), <br />n=porosity=Assume 10% (Peabody 2009)=0.1 (Use of this value was suggested <br />by the Colorado Department of Mining, Reclamation and Safety), <br />t=time=1,150,000 years=419,750,000 days, <br />dh/dl=potentiometric gradient= 507 ft/7,547 ft (Peabody 2009)=0.0672, <br />D=(((0.1 ft/day)*(419,750,000 days))/0.1)*(0.0672)=28,207,200 ft or 5,342 miles. <br />This distance is much greater than the areal extent of the Williams Fork <br />Formation. So there is some type of hydraulic boundary between the Williams <br />Fork Formation outcrop and Monitor Well COV23. <br />Equation 3 can calculate the system hydraulic conductivity of the horizontal <br />flow path between the outcrop and Monitor Well COV23, if the two points are <br />directly connected, as follows: <br />D=distance=8900 feet, <br />dl/dh=inverse potentiometric gradient= 5,280 ft/355 ft (Peabody 2009), <br />K=(8,900 ft/419,750,000 days)*0.1 *(5,280 ft/355 ft)=0.000032 ft/day. <br />The measured hydraulic conductivity from a constant head test was 0.1 ft/day. <br />This was the highest bedrock hydraulic conductivity measured for the site. The <br />calculated hydraulic conductivity is four to five orders of magnitude less than <br />the measured hydraulic conductivity. So the outcrop and Monitor Well COV23 <br />are not directly connected. <br />8