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-4- <br />f <br />of water is allowed to percolate through it. Coal caste, hoca- <br />1 ever, is often a poor soil forming material and is cometimes <br />1 separated and placed at the base of an overburden pile where <br />( it becomes potentially involved in the ground water system. <br />r Water will percolate more readily through disturbed areas, sucks <br />(1 as overburden stockpiles or filled areas, increasing the ex~ostire <br />of the materials in the overburden to water that is generally <br />1 headed to the ground water system. Stored top soil is similarly <br />exposed to water percolating to the ground water system. Run- <br />t off from roads built of scoria or coal caaste may also contain <br />pollutants. Pit water collects pollutants from all of the <br />previous sources, as it is generally the lowest point in the <br />mined area. It is also the most mobile source, in that it is <br />often fed by or feeds directly into the ground water system. <br />(.~ Fi.nally, extreme fertilization of reclaimed areas may cause them <br />to become sources of nitrate pollution in the ground water. • <br />Another potential problem is a washing of possible pollutants <br />in fill, through the fill to the ground water during the first <br />phases of reclamation. <br />i_ <br />Coal in place, coal stockpiles, coal wastes, and overburden and <br />fill are several sources of the same pollutants. Trace element:> <br />ma.y be present in all of these, and soluable salts are also com- <br />monly found. Sulfur, the major percentage of which is in the <br />coals, may also be present in overburden and fill. Acid drainage <br />t is not a serious problem in the west, basically due to the low <br />su:Lfur content of western coal. but also in part because it is <br />f often rapidly neutralized by carbonate minerals in the soil and <br />overburden. Roads in the pit area, built of overburden and <br />scoria, may have a minor amount of water percolating through <br />them. It is more likely that limited amounts of waste oil and <br />grease will be washed off the roads. The base of the pit cuill <br />l._. collect water from direct ra~.nfall, rainfall on the rest of the • <br />pit. area, snowmelt from the pit, and any ground caater that seeps <br />from the overlying strata into the pit. Thus, the pit c~~ill be a <br />Lemmrd Rice Censulling Water Engineers.lnc. <br />