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-32- <br />F1cWhorter et al. (1975) estimated that the normalized annual salt <br />pickup rate from mine spoils varies from 0.23 metric tons per acre per inch <br />in a surface and subsurface runoff regime of less than 1 inch. These are <br />order-of-magnitude estimates that serve only as indicators of potential <br />impact. <br />Assuming the upper limit (0.79 metric tons/acre/inch} of salt pickup <br />from all sources, 2 inches of annual runoff, of which 0.5 inch is surface <br />and 1.5 inches result from subsurface floi•+ and deep seepage to ground water, <br />salt pickup during the first few years would 6e: <br />0.8 T/acre/inch x 1.5 inches/year (subsurface runoff} <br />= 1.2 T/acre/yr.. <br />During dry years, salt pickup should he negligihle, whereas during wet <br />years, salt pickup might be twice that estimated above. Some persistent <br />albeit minor degradation in water quality can thus be expected downstream <br />from the mine over the design life of the project and for some time to come <br />after the mine is abandoned. <br />The recklessly rough calculations above are by no means complete, but <br />they do serve to put the problem in perspective, considering that the averaoe <br />annual salt loading from irrigation return flow is perhaps 6 T/acre <br />(Mc4shorter et al., 1475). <br />' 4. ;dine Drainage <br />Groundwater is often encountered in many mine areas. Currently, the Meeker <br />Mine is wet; however, seepage is not yet sufficient to cause problems. Mo <br />mine waters are being discharged at this time. The quality of the seepage <br />water is summarazed in Appendix V. It is extremely hard (Bicarbonate Alkalinity <br />= 870; pH = 8.3); however, the water meets the OSM effluent limitations of <br />717.17. The summary below compares mine water quality with the effluent standards. <br />