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4.3 Analytical Results 4.3.1 Composition of the CKD D~C~[~~ Table 4.3 summarizes the results of the whole rock CKD analysis. The laboratory results data package is included in Appendix A. The results of the analysis indicate that the CKD is primarily composed of calcium carbonates and oxides, silicon dioxide, sodium and potassium sulfate, potassium chloride, potassium fluoride, and other trace metal oxides. The CKD also contains small quantities of natural radionuclides that are the source of the gross alpha and gross beta activities. The results of a CKD analysis conducted by the EPA in 1992 indicates that the predominant natural radionuclide in the CKD is potassium-40 (K-40). Lesser quantities of natural radionuclides also occur. These include bismuth-214 (Bi-214), lead-214 (Pb-214), radium-226 (Ra-226), radium-228 (Ra-228), thorium-230 (Th-230), uranium-234 (U-234), and uranium-238 (U-238). K-40, Ra- 228, and Bi-214 are the most likely sources of the gross beta activity. The other radionuclides are primarily alpha-emitters which is the source of the gross alpha activity. 4.3.2 Composition of the Leachate The concentration of leachable constituents determined for the CKD and other solid materials are summarized in Table 4.4. The laboratory results data package is included in Appendix A. Colorado primary and secondary drinking water standards and agricultural water standards are included in the table for comparison. The most stringent water quality standards were selected for comparison. The constituent concentration values shown in bold on Table 4.4 exceed the applicable water quality standard. The results of the CKD leachate analyses indicate that the primary leachable constituents are calcium, sodium, potassium, strontium, barium, sulfate, chloride, and fluoride. Trace quantities of chromium, lithium, molybdenum, silicon, zinc, arsenic, selenium, thallium, and phosphate were also detected. The CKD also contains leachable trace natural radionuclides (discussed above in Section 4.3.1) 1 that are the source of the gross alpha and beta activities of the leachate. I Most of the constituents detected in the leachate are less than the respective w uality standard. Of the constituents analyzed, only five constituents exceeded applicable water quality standard. Selenium (1.2), thallium (7.0), ~ and gross beta (1.2) exceeded the primary human health groundwater standards. ~ Selenium (3.1) also exceeded the agricultural water quality standard (0.02 milligrams per liter [mg/L]) which is more stringent than the hu an h alth standard (0.05 mg/L). Total dissolved solids (TDS; 5.1) and p (1.5~xceeded ' ~ the secondary human health groundwater quality standards. T source of the ~ high TDS concentration is primarily due to the high concentration of constituents that do not exceed any of the water quality standards, such as calcium, sodium, 6