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PART B <br />STOP,M R'JVOFF FRECICTIOPIS <br />In general, water does not fail to infiltrate the undisturbed <br />forest floor, but there are exceptions. Regardless, there are two <br />factors associated ~•rith storm flow production that can be altered by <br />mining activities: (a) alteration of the infiltration characteristics <br />of thz surface, and (6) alteration by disturbance of the storage <br />capacity in tflz soil. Leaf (1977) has discussed in detail the effect <br />of tree removal on the distribution and melt rate of ~vinter snolrpack, <br />potentially a third factor. Because of changes in both the amount and <br />;welt rate of the pack, either the infiltration rate or storages capacity <br />could be exceeded causing higher peak flow rates; but we are not treating <br />• this as storm runoff as it has already been dealt with in Tables 1 and <br />2 of this report. <br />P'.ost mining activities, excluding site preparation, do not signifi- <br />cantly disturb the soil surface except for the access and related syste~^s. <br />These access systems havz the potential for changing the hill slope <br />hydrology. Subsurface soil 1•rater is intercepted 6y road cuts and benchzs, <br />for example, and routed over the surface as is the rain falling directly <br />nn them. There is a potential for altering the timing and delivery <br />route to thz channel of perhaps 10 - 15 percent of the precipitation. <br />The impact of this potential on the storm hydregraph can be expected <br />to be variable--the storm flo~+r peak and volume may or ~cay not ba increased <br />by :rater from the access system and the effect depends on hpo-r the re- <br />• routed water enters the s}~stem. The net effect can be to reduce the <br />~; ,:J r. ;if aC ~': ant It !~^_j)c C'~11:~ On nU rll}3j b'Sln reippn5?. <br />