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i <br /> July 19,2019 18107649 <br /> 1.0 INTRODUCTION <br /> On behalf of Holcim (US) Inc., Golder Associates Inc. (Golder) is submitting this request for a technical revision <br /> (TR-10)to permit M-1977-348 to for the Boettcher Limestone Quarry located at 3060 West County Road 56, <br /> ' Laporte, Colorado 80535. This technical revision demonstrates that groundwater samples at the time of and prior <br /> to tritium dating conducted in August 2014 represent ambient concentrations in pre-January 31, 1994 <br /> groundwater. Therefore, per Regulation 41-Colorado Basic Standards for Groundwater(5 CCR 1002, BSGW), <br /> Section 41.5(C)(6): 1)the recent data can be used to assess ambient conditions as of January 30, 1994; and <br /> 2) in cases where ambient conditions are greater than the Regulation 41 Table Values Standards, a less <br /> restrictive standard based on the ambient conditions can be applied. <br /> A response to the Division of Reclamation, Mining, and Safety(DRMS)comments in Adequacy Review No. 1 is <br /> provided in Appendix A. Appendix A also provides and details on where the revised information for each comment <br /> can be found in the TR. <br /> 2.0 BACKGROUND INFORMATION <br /> 2.1 Site History and CKD Placement <br /> The Boettcher Limestone Quarry(the Site) is located in Larimer County near Laporte, Colorado(Figure 1). More <br /> specifically, the quarry comprises portions of Township 8 and 9 North, Range 69 West of the 6th Principal <br /> Meridian. The original permit for Ideal Basic Industries to operate the Boettcher Quarry(Permit No. M-1977-348) <br /> was approved on October 10, 1978 by the Colorado Mined Land Reclamation Board (MLRB)of the Department of <br /> Natural Resources. Although the Boettcher Quarry has had several owners during the active lifetime of the quarry, <br /> it is currently owned by Holcim (US) Inc., thus Holcim is referred to as the owner/operator in this document. <br /> Cement kiln dust(CKD)was generated on Site during operations, which occurred from the early 1900s to 2002. <br /> Disposal of CKD in mined out portions of the Boettcher Quarry began in 1980. Per the approval of Technical <br /> Revision No. 3(TR-003)to Permit No. M-1977-348 by the Division of Minerals and Geology(DMG)on October <br /> 15, 1999(DRMS 1999), CKD disposal would be limited to area A2. CKD disposal in area A2 began in the fall of <br /> 1999, and approximately 140,000 cubic yards were placed in the area by August 2002, when the plant closed. <br /> Limestone mining operations ceased in August 2002. Reclamation and monitoring activities have been occurring <br /> on Site since the plant closure in 2002(Holnam 2002; Holcim 2004, 2005, 2006, 2007, and 2009). Figure 1 shows <br /> the approximate location of CKD disposal area A2 in the A-band mining cut. <br /> 2.2 Groundwater Monitoring History <br /> Seven monitoring wells MW-1 through MW-7 are present at Site. The location of these wells is presented in <br /> Figure 1 and the construction details are summarized in Table 1. Appendix B provides monitoring well <br /> construction and lithological logs for monitoring wells MW-1, MW-2 and MW-3. No monitoring well construction <br /> details are available for monitoring well MW-4. Appendix C provides monitoring well construction and lithological <br /> logs for monitoring wells MW-5, MW-6 and MW-7. The locations and planned construction depths of MW-5 <br /> through MW-7 were provided to the DRMS for review and comment prior to installation (Golder 2012). The water <br /> quality data for these wells are summarized in Table 2 through Table 8. A timeline of the groundwater sampling <br /> history at Site is provided below: <br /> ■ June 1998: MW-1, MW-2, and MW-3 were installed <br /> & April 1999: MW-4 was installed <br /> 4 GOLDEP 1 <br />