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derive from CKD in water will differ depending on the type of shale and its particular suite of <br />clay minerals. <br />LEACH TESTING <br />Some of the above characteristics of CKD have become evident in part through leach testing <br />conducted by the companies involved. Leach tests conducted on "fresh"CKD differ extremely <br />from "weathered" CKD. The results are characteristic not only of the "type" of CKD but also <br />the leach method. <br />"Weathered" CKD leach tests yielded small amounts of metals by most leach methods, but never <br />high pH. On the other hand, natural water samples collected below "weathered" CKD piles <br />tended not to show elevated metals or anomalous pH. <br />"Fresh"CKD leach tests produced elevated concentrations of several metals, regardless of the <br />leach test method. "Fresh" CKD also produced high paste pH and leachate solution pH. <br />CKD HANDLING <br />From these tests, it is evident that CKD chemistry is controlled by weathering. Most fresh CKD <br />bag-house dust is very reactive if placed directly in water. However, fresh CKD placed in thin <br />layers on the ground where precipitation can reach will typically harden and cure to become a <br />layer of pulverulent material similar to plaster or whitewash and consisting largely of calcium <br />carbonate (limestone). If a CKD disposal plan calls for spreading in thin layers within a disposal <br />cell, the CKD should be wetted to prevent fugitive dust emissions during spreading operations. <br />Disposal of CKD into water would not allow it to harden or cure. Disposal in water would result <br />in elevated pH and may facilitate leaching of metals. Disposal below the natural ground water <br />table should not be undertaken. Disposal into quarry pits filled with surface water should only <br />be done after adequate evaluation of the potential for ]eacha[e migration and installation of down <br />gradient ground water monitoring. The fact that a quarry pit fills with surface water is a good <br />indication that the quarry is cut into low permeability strata, and the leachate migration will be <br />minimal. CKD disposal should not occur in a floodplain unless it is demonstrated that the flood <br />would not wash CKD into the stream. <br />CKD DISPOSAL <br />Based on field examinations of the three CKD sites, leach test results, and surface and <br />groundwater analyses, the following general recommendations for CKD disposal are suggested. <br />These suggestions distinguish between "fresh" CKD and "weathered" CKD - "fresh" CKD <br />being that which is collected directly from abag-house, and "weathered" CKD being that which <br />has been in contact with the atmosphere, rain or snow for several weeks. <br />Fresh CKD should not be placed directly in ponded water. If conditions require such <br />disposal, or if such disposal occurs inadvertently, the Division should institute <br />groundwater monitoring. <br />