PERMFILE100663 - Laserfiche WebLink

Home Browse Search

-31- 3. Chemical and Geological Considerations The chemical constituents in natural runoff origii ing process. In humid climates, precipitation is most soluble salts as rapidly as they are formed. However, in an arid to semi-arid climate as presently exists in watershed. In addition, much of the soil in this area gate from the weather- likely to leach out such 'IS not the case the Curtis Creek has been derived from sandstone and shales. These sedimentary rocks commonly contain substantial amounts of soluble salts (McWhorter et al., 1975). In dry climates, salts in soils. derived from tfiese sedimentary formations generally remain inadequate- ly leached, except in the top layers of the soil profile. Mining activities ' expose fresh surfaces of saline shales and sandstones for leaching by rainfall and snowmelt, thus influencing the quality of surface and subsurface runoff. Recent work has shown this to be the case in the Rocky Mountain Region (McWhorter et al., 1975). (- Such complex factors as geology, weathering, microbal activity, acid formation, cation exchange capacity and nonequilibrium chemical reactions-- to name a few, all influence the water pollution potential. Moreover, the I, salt pickup rate also depends heavily upon the local hydrology. Precise estimation of the total quantities of soluble salts that will be generated either from mine drainage or percolation of water through disturbed areas i.s beyond. the scope of this study, and for that matter, the state-of- the-art. However, recent work by McWhorter and Rowe (1976) suggests that total salt pickup can be estimated from saturated spoil analyses and a knowledge pf the local hydrology. 4lith further development, such a model would provide a method of evaluating the impacts of mining on water quality. For the present, however, we must rely on a pitifully small data base for predicting impacts.