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ARCADIS Environment (CDPHE), Water Quality Control Commission (WQCC) Regulation No. 41 "Basic Standards for Ground Water" (CDPHE 2008). 1.3.1 Baseline Groundwater Monitoring Program On August 16, 1999, Holcim submitted a request to the Colorado DRMS for a Technical Revision (TR -06) to its permit for the disposal of CKD in previously mined areas at the quarry (K -S & Company 1999). TR -06 included a description of CKD disposal procedures and facilities, closure plan for the disposal areas, description of erosion control measures used at the site, discussion of CKD sampling and analysis, and description of hydrogeologic conditions at the site. The DRMS, formerly the Division of Minerals and Geology (DMG), reviewed TR -06 and responded with an initial adequacy review letter on January 18, 2000 (DMG 2000). On behalf of Holcim, K -S & Company submitted responses to DMG's adequacy review letter in May 2001 (Holnam 2001). The DMG responded with a second adequacy review letter on October 22, 2002 (DMG 2002). ARCADIS was retained by Holcim to provide technical support for Mine Permit Technical Revision TR -06 (TR -06) to State of Colorado Mining Permit No. M -77 -344 for the Holcim Portland plant and quarry. In partial fulfillment of the Colorado DRMS requirements for TR -06, a Groundwater Monitoring Plan (GMP) was developed for the approximately 1,330 acres included within the boundaries of the mining permit (Figure 2) (BBL 2002). The main purpose of the GMP was to meet the requirements of the Colorado MLRB's Construction Materials Rules and Regulations Rule 3.1.7 for the protection of existing and reasonably potential future uses of the unclassified groundwater located beneath the quarry (MLRB 2001). These requirements were triggered by the disposal of CKD into previously mined sections of the site, and the potential for leachate from CKD to adversely impact ambient groundwater quality for existing and reasonably potential future uses. In 2004, all requirements from the DRMS's adequacy reviews were fulfilled with the submittal of the final quarter of data for monitoring well MW -10 (BBL 2004). The DRMS was to use the data from the groundwater monitoring program to establish ambient groundwater concentrations and a parameter list for future monitoring. Holcim was to initiate annual groundwater monitoring per the GMP once the ambient groundwater concentrations and parameter list had been established by the DRMS. The DRMS responded to the BBL 2004 report as part of a December 2007 site inspection. As a result of that site inspection, Holcim performed a site -wide monitoring 2013 Groundwater Monitoring Report Florence, Colorado 3