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' 2019 GROUNDWATER MONITORING REPORT <br /> Bypass dust is currently produced at a lower rate than CKD when the wet kiln system was in operation. <br /> Between 2005 and 2018, an average of approximately 10,000 tons of bypass dust was placed in the CKD <br /> disposal area each year. <br /> In 2001, with the construction of the dry kiln, a pug mill was installed to add water to the bypass dust prior <br /> ' to transporting the bypass dust to the CKD disposal area in the quarry, in order to reduce dust emissions. <br /> With the addition of the pug mill, Holcim discontinued the use of sludge from the Fremont Sanitation <br /> District WWTP for dust control. <br /> Bypass dust is currently disposed of in a previously mined section (cut) of the limestone quarry to the <br /> south of former monitoring well MW-10. The locations of cuts previously used for CKD disposal are <br /> indicated on Figure 2 The bottoms of these cuts coincide with the top of the underlying Codell <br /> Sandstone, which is the primary water-bearing unit in the quarry area. To prevent contact of CKD and <br /> bypass dust with this groundwater, approximately 10 feet of shale was backfilled and compacted in the <br /> bottom of these cuts prior to placement of CKD and bypass dust. The site geology and hydrogeology are <br /> described in the Groundwater Monitoring Plan (GMP; Blasland, Bouck& Lee, Inc. [BBL]2002) <br /> 1.3 Site Regulatory History <br /> In Colorado, the DRMS is responsible for regulating CKD and bypass dust disposal. Therefore, the <br /> requirements for CKD and bypass dust management are incorporated into each facility's Mined Land <br /> 1 Reclamation Permit. The plant is permitted to dispose of CKD and bypass dust(although CKD is no <br /> longer generated by the plant) in the quarry under State of Colorado Mining Permit No. M-77-344 <br /> (permit). Specific requirements for protection of groundwater are described in Rule 3.1.7(7)(i)through (viii) <br /> of the Construction Material Rules and Regulations (Mined Land Reclamation Board [MLRB] 2001)and <br /> the Colorado Department of Public Health and Environment(CDPHE), Water Quality Control Commission <br /> (WQCC) Regulation No. 41, Basic Standards for Ground Water(CDPHE 2008). <br /> 1.3.1 Baseline Groundwater Monitoring Program <br /> On August 16, 1999, Holcim submitted a request to the DRMS for a Mine Permit Technical Revision TR- <br /> ' 06 (TR-06)to its permit for the disposal of CKD in previously mined areas at the quarry(K-S &Company <br /> 1999) TR-06 describes the CKD disposal procedures and facilities, a closure plan for the disposal areas, <br /> erosion control measures used at the site, CKD sampling and analysis, and hydrogeologic conditions at <br /> ' the site. The DRMS, formerly the Division of Minerals and Geology(DMG), reviewed TR-06 and <br /> responded with an initial adequacy review letter on January 18, 2000 (DMG 2000). On behalf of Holcim, <br /> K-S &Company submitted responses to DMG's adequacy review letter in May 2001 (Holnam 2001). The <br /> DMG responded with a second adequacy review letter on October 22, 2002 (DMG 2002). <br /> Holcim retained Arcadis to provide technical support for TR-06. In partial fulfilment of the DRMS <br /> requirements for TR-06, a GMP (BBL 2002)was developed for the approximately 1,330 acres included <br /> within the boundaries of the mining permit(Figure 2). The main purpose of the GMP was to meet the <br /> requirements of the MLRB's Construction Materials Rules and Regulations Rule 3.1.7 for the protection of <br /> existing and reasonably potential future uses of the unclassified groundwater located beneath the quarry <br /> ' (MLRB 2001). These requirements were triggered by the disposal of CKD into previously mined sections <br /> r <br /> arcades com <br />