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CONCLUSIONS <br />The objectives of this geochemical investigation were to <br />establish present day groundwater quality, to identify the trace <br />elements that are readily leached from typical coal-waste, and <br />to assess the capacity of local soils and clay alluvium to mitigate <br />trace element migration. Groundwaters in the vicinity of the pro- <br />posed coal-waste disposal and impoundment site are enriched in <br />calcium, magnesium, and sulfate content and depleted in trace <br />metals. The chemical composition of the coal-waste Ieachate solu- <br />tions closely fingerprint the chemical composition of present day <br />groundwater in the area. The coal-waste that is discharged to <br />the disposal pile is not likely to introduce significant quanti- <br />ties of contaminants other than the type ions that are already <br />present in local groundwaters, and furthermore, is unlikely to <br />significantly alter the overall groundwater quality. <br />The clay alluvium extending at shallow depth beneath the <br />coal-waste disposal site has the capacity to scavenge limited <br />quantities of environmentally sensitive ions. The sorbtive <br />property of the clay alluvium that underlies the disposal Bite <br />may be evident when the chemical profile of the groundwater <br />samples listed in table 2 are compared. Groundwaters at the toe <br />of the dam are somewhat lower in heavy metal content than ground- <br />waters at the head of the hollow. Heavy metals such as copper, <br />uranium, and zinc are strongly sorbed by natural clays from <br />slightly alkaline solutions. <br />13 <br />