1999-06-23_REVISION - M1977208 - Laserfiche WebLink

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' extremely low. There is a lack of faulting in the area of C-Pit. These factors create a favorable CKD storage environment. ' 7. The testing, modeling and interpretation used in this research was very conservtive (i.e. worst case scenarios). t - The model used the concentrated leachate from laboratory tests, not the much less concentrated water in the pit. - The model assumed the shale adjacent to C-Pit is saturated, which it is not - The model used conservative attenuation factors - The SPLP laboratory testis aggressive in that the CKD was ' ground up, mixed with a water solution having a lower pH than natural waters, and agitated for 24 hours. - The water flux rate (i.e. amount of water passing through the CKD in C-Pit) that was used in the model was conservative. ' 8. Southdown's management practice of periodically capping the disposed CKD with a layer of compacted shale or clay soils would further isolate the CKD from precipitation and infiltration of rain and t snowmelt. Southdown has committed to doing this in cells that are built to 7 acres in size and in approximately 20 ft. lifts. ' 2.0 Introduction and Regu{atory Background Southdown, Inc. and its predecessors have operated a cement plant and associated quarries in Boulder County near Lyons since about 1969. Cement kiln dust (CKD), baghouse dust, and plant clean-up dust have been managed in the quarries since the inception of the cement plant. There are no known ' adverse impacts to groundwater from this historic practice. The quarries south of the cement plant (referred to as the Lyons quarries) ~ , received a 112 permit for the Colorado Mined Land Reclamation Board in 1977. (Permit No. M-77-208). The permit is active and in good standing, the financial warranty is in place, and the facility is in compliance with the CMLRB permit. ' There are currently over 300 acres under active reclamation. Waste materials generated at a permitted mine site (the cement plant is within the permit area) may be disposed at the mine site without a Certificate of Designation pursuant to ' the requirements of the Colorado Department of Public Health and the Environment (CDPHE). Disposal of the CKD in the quarries is in compliance with the requirements of both the Division of Minerals and Geology (DMG) and the CDPHE . On January 20, 1999 Carl Mount and Christina Kamnikar of the DMG inspected the facility. The inspection report requested a characterization of the chemical constituents of the CKD, a characterization of the local geology and hydrology,