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have submitted technical revisions to incorporate CKD disposal standards into their reclamation permits. The technical revisions detail [he geochemistry of the CKD, ground water protection measures and monitoring, dust control, and closure and reclamation. The ptocedw-e being followed by the DMG is to incorporate the CKD disposal standards into the permit through the technical revision process, then to include all azeas of the operation where CKD is generated, temporarily stored, or transported into the permit through an amendment. From a regulatory . standpoint, approval of the amendment makes the CICD an onsite rather than an ircported waste. From a technical standpoint, [he cement plant must be included in the reclamation permit area in order io provide regulatory controls over the generation of the CKD, e.g., the types of fuel or chemicals used in the kilning process, which may effect the geochemistry of the CKD. In particular, if a cement plant were to begin using alternative fuels such as wood, tirt:s, or waste oil, the potential changes to the nature of the CKD should be evaluated. This memo discusses some of the details of CKD generation and disposal at the three Colorado cement plants. A discussion of the geochemistry of cement and CKD are provided for background. The Holnam-Boettcher operation and the Southdown-Lyons operation have completed waste characterization studies and have established groundwater monitoring programs. 'i'he Holnam- Pottland operation has completed waste characterization and some groundwater monitoring, and the Division is processing a TR for continued CKD disposal at the Portland plant. Based on (a) leach test results, (b) chemical analysis of pit water adjacent to one of the quarries, and (c) CKD waste handling commitments, groundwater monitoring may be perfunctory in some cases because the potential for off-site damage is limited. The latter point - "GIGO warn: handling commitments" -was most important in reaching that determination and is discussed in the following sections. PRODUCTION, CHEMISTRY, AND PROPERTIES OF CEMENT Cement is produced by burning limestone and clay at around 2700°F in a hori::ontal, inclined rotary kiln. It can take up to 2 hours for the raw materials to pass through the kiln depending on its length. Moving down the cylinder, the mixture progresses through fotir stages of transformation. Initially, free water is driven off. Next, calcination occurs as bound water and carbon dioxide are liberated. After calcination, the limestone has been converted to lime (CaO). In the third or ctinkering stage, lime and decrepitated clay combine to form calcium silicates and calcium aluminates (see equations following). The fourth stage involves cooling of the clinker. In some cement plants, the first three steps all occur in the same kiln; in other plants, the process occurs in separate calciners and cement kilns. CaCO3 + (SiO, + A1,O3 + Fe,O3 + H,O(bound)] + e Uimestone) (clay) (heau ~ 3CaO•SiO, + 2CaO•SiO, + 3CaO•AhOa + 4CaO•AhO3•Fe,O3 (tncalcium silicate)+ (dicalnum silicate) +Uricatcium aluminate) + (tetracalcium alumi noferrite) Compounds on the product side of the above equation comprise about 90 perct:nt of portland cement. The two calcium silicates form approximately 75 percent of cement by weight. When water reacts with the two calcium silicates, tobermorite gel and calcium hydroxide are produced.