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have submitted [ethnical rzvisions to incorporate ChD disposal standards into their reclamation permits. The [ethnical revisions detail [hz geochemistry of [he CKD, ;round water protection measures and monitorrng, dust convol, and closure and reclamation. The procedure being Followed by the DMG is to incorporate the CKD disposal standards into the permit through the technical revision process, then to includz all areas of [he operation where CKD is generatzd. temporarily stored, or transported into [he permit through an amendment. From a regulatory standpont, approval of the amendment makes thz CKD an onsite rather than an imported waste. From a technical standpoint, [he cement plant must be included in the reclamation permit area in order [o provide regulatory controls over [he genzration of the CKD, z. g., the types of fuel or chemicals used in thz kilning process, which may effect the geochemistry of [he CKD. In particular, if a cement plant were [o begin using alternative fuels such as wood, tires, or wastz oil. the potential changes [o the nature of the CICD should be zvaluated. This mzmo 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 Hotnam-Boettcher operation and the Southdown-Lyons operation have completed waste characterization studies and have established groundwater monitoring programs. The Holnam- Portland operation has completed waste characterization and ;ome groundwater monitoring, and the Division is processing a TR for continued CKD disposal at the Portland plan[. Based on (a) leach test results, (b) chemical analysis of pit water adjacent [o one of the quarries, and (c) CKD wastz handling commitments, groundwater monitoring may be perfunctory in some cases because the potential for off-site damage is limited. The latter point - "CKD waste handling commitments" -was most important m reaching that determination and is discussed in the following sections. PRODUCTIOY, CHENIISTRY, AND PROPERTIES OF CEivIENT Cement is produced by burning limestone and clay at around ?700°F in a horizontal, 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 four stages of transformation. Initially, fret water is driven off. Next, calcination occurs as bound water and cazbon dioxide are libzrated. After calcination, the limestone has been converted to lime (CaO). In thz third or clinkering stage, Lime and decrepitated clay combine ro form calcium silicates and calcium alurninates (see equations following). The fourth stage involves cooling of the clinker. In some cemzn[ plants, the first three steps all occur in the same kiln; in other plants, the process occurs in szpazate calciners and cement kilns. CaCO; + (SiO~ + AhO; + Fe,O~ + H~O(bound)] + n (limestone) (clayj (haaq --~ 3Ca0 SiO; + 2CaO SiO, + 3CaO AhO; + 4CaO A1,O;~Fe,O; (iricalnum siVic~[e) + (dicalcium sillnte) + (tricnlcium ~luntinme) + (ee~ncalnum aluminofarnte) Compounds on the product side of thz above equation comprise about 90 percent of portland cement. The two calcium silicates form approximately 7~ percent of cement by weight. When water reacts with the two calcium silicates, tobermonte gel and calcium hydroxide are produced. 3