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<br />' 1.t) Conclusions <br />' As requested by the Colorado Division of Minerals and Geology, Southdown <br /> conducted an evaluation of their CKD management practices at the Lyons <br />' cement plant. This evaluation included a review of historical and current mining <br />permits, characterization of cement kiln dust, assessment of local geology and <br /> hydrology, and an analysis of potential ground water impacts. <br />' Conclusions from the above studies are summarized as follows: <br />1. Disposal of the CKD in C-Pit is allowed under CMLRB Permit No. M- <br />~~-2oa <br />t 2. Disposal of CKD in C-Pit presents little or no impact to ground water <br />resources in the area. <br />3. Although the laboratory CKD samples showed several parameters <br />which exceeded ground water standards, the two background samples <br />(pasture soil and North 59~' St.) also had parameters above the ground <br />water standard. <br />4. There were five parameters from the laboratory CKD sample that <br />' exceeded applicable ground water standards by small levels. The <br />parameters are: <br />- selenium <br />- thallium <br />- total dissolved solids <br />- pH <br />- gross beta <br /> Geochemical com_ puter modeling of the transport and fate of these five <br /> parameters over distance and time indicates compliance with all <br /> ground water standards before they could potentially migrate off of <br /> Southdown's property to the locally utilized aquifers. <br /> 5. The only useable ground water sources in this area are in the alluvial <br />' deposits of St. Vrain Creek and in the Dakota Sandstone. There is no <br /> hydraulic pathway from the C-Pit limestone and shale units to either of <br /> these ground water sources <br /> 6. The rock formations adjacent to and beneath C-Pit have relatively low <br /> permeability. The bedding planes in these sedimentary rocks do not <br />' provide a hydraulic connection with the alluvial or Dakota Sandstone <br /> aquifers. Permeability perpendicular to or across bedding planes is <br />1 <br />