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• In summary, the law groundwater recharge rates at [he Trapper "line indicate that <br />transport (if any) of contaminants from the waste to the water table will be <br />extremely slow. <br />Moreover, infiltrating water which may reach the surface of [he disposal waste <br />will tend Go move laterally through the spoils, rather than through the waste, if <br />spoil permeabilities are signficantly higher than waste permeabilities. Availa- <br />ble data show that this in fact will be the case and after mining, permeabilities <br />for [he spoil will be higher khan undisturbed overburden permeablities. Several <br />sources of information exist concerning spoil permeabilities: <br />Stearns-Roger laboratory hydraulic conductivity measurements on <br />artificially weathered borehole core samples of the Trapper overburden <br />(Stearns-Roger, 1474), <br />Radian infil[rometer studies Cpart of the groundwater recharge studies), <br />~~ and <br />Literature refzrences on studies of spoil permeabilities of various U.S. <br />surface mines (Wilson and 1{amilton, 1978)(HOlland, 1979). <br />The Stearns-Roger permeabilities for two core samples range from about .OOL to <br />.88 gpd/ftz (2.8 x 10-7 to 4,1 x 10-5 cm/sec)• These are for weathered <br />samples and are probably much lower than the actual average spoil permeability, <br />because weathering would occur only very near the spoil surface. <br />Radian infiltrometer data ranged from 6.4B gpd/ftZ to 115.4 gpd/ftz (3 x <br />10 4 to 5 x 10-g em/sec). <br />Literature sources indicate [h a[ spoil permeabilities may be 6-10 times greater <br />than permeabilities for undisturbed consolidated overburden, Assuming a 1 gpd/f[ <br />average permeability far [he Upper Williams Fork, average spoil permeabilities <br />would range from 6-10 gpd/ftZ (3 x 10 4 to 5 x 10-4 cm/sec), <br />/~. <br />4-51 <br />