The URL can be used to link to this page

Home My WebLink AboutDWQ-2024-008095Comment No. Commenter Comment Response 1 Kennecott Utah Copper I.C.2, South Tailings Impoundment- “Consider using natural liner instead of barrier.” DWQ maintains that a liner is an engineeredstructure which has been designed and installed and is distinctly different in definition from a natural clay barrier in place prior to construction. No changes were made as a result of this comment. 2 Kennecott Utah Copper I.C.2, North Tailings Impoundment- “Consider using natural liner instead of barrier.” See response to comment 1. No changes were made as a result of this comment. 3 Kennecott Utah Copper I.C.2, East Tailings Expansion- “Consider using natural liner instead of barrier.” See response to comment 1. DWQ added “natural” to barrier to maintain consistency with the north and south tailings impoundment descriptions. 4 Kennecott Utah Copper I.D.3- “it looks like missing "of", please complete it as "disposing of any waste" DWQ inserted “of “ in the sentence to correct the error. 5 Kennecott Utah Copper I.J.2.a, iv.- “Consider removing this section. DWQ still has the authority to request any additional investigation without stating it. By stating it specifically in the permit, it sounds like the director already intends to conduct an additional investigation.” DWQ believes this provision provides clarity to both the Permittee and to the public. The inclusion of a provision for additional investigation pending data analysis is in no way a pre-made decision to pursue an investigation and reflects an intention to leave open all pathways for information gathering in pursuit of fair regulation while being protective of groundwater resources. No changes were made as a result of this comment. 6 Kennecott Utah Copper I.J.2.d - “Consider modifying the whole section as follows: Hydrogeologic study - Within two (2) years of the issuance of this Permit, the Permittee shall provide DWQ with a report analyzing the hydrogeology and groundwater flow underlying the North Impoundment based on data from existing groundwater compliance wells. We believe the hydrogeology and groundwater flow study can address the mixing zone between saline waters below the Great Salt Lake and the freshwater system underlying the facility. It also repeated the calculation of the equilibrium depth of hydraulic head pressure versus natural upward flow, which was already requested in Part I, J. 2a, iii.” DWQ maintains the need to specifically locate the geographic location and depth curve of the potential brine from the Great Salt Lake. DWQ has removed the repeated language requesting the equilibrium depth of head pressure between tailings water and natural upwards flow. 7 Kennecott Utah Copper I.J.2.d – Misspelling of “Salt” DWQ corrected the spelling error. 8 Kennecott Utah Copper Appendix C: “Add Plan to “Assessment of Acidification Potential.” DWQ added Plan. 9, 10, 11 Kennecott Utah Copper Appendix C: 2.2, 3.0: “It's Appendix D not Appendix B” DWQ corrected appendix reference. 12, 13 Kennecott Utah Copper Appendix C 4.0: “The latest version of this SOP will be provided to DWQ” DWQ incorporated the latest SOP version. 14 Kennecott Utah Copper Appendix D: “Its Appendix C not Appendix A.” DWQ updated the appendix reference. 15 Kennecott Utah Copper Appendix D: “Consider adding decommissioned and making it "near the decommissioned 001 UPDES Outfall" DWQ maintains that UPDES outfall 001 is geographically descriptive and the reference to decommissioned is unnecessary. No changes were made as a result of this comment. 16 Kennecott Utah Copper Appendix D 3.0: “Its Appendix C not Appendix A.” DWQ updated the appendix reference. 17 Kennecott Utah Copper Appendix D Table 1: “Consider adding NET1384B well, it looks like missing this well in the table. The depth, screen top, and screen bottom for NET1384B well are 60 ft, 49 ft, and 59 ft bgl, respectively. The elevation of the ground is 4216.18 ft amsl and elevation mark is 4218.06 ft amsl for NET1384B well. The rest of the information in the table is same as NET1384A well.” DWQ Updated Table 1. 18 Kennecott Utah Copper Appendix E 1.0: “Its Appendix E not Appendix C.” DWQ updated the appendix reference. 19 Kennecott Utah Copper Statement of Basis Date: “Should this be updated?” DWQ Updated the SOB date from June 2024 to July 2024. 20 Kennecott Utah Copper Statement of Basis 1.a. Compliance Schedule: “Consider removing this section. DWQ still has the authority to request any additional investigation without stating it. By stating it specifically in the permit, it sounds like the director already intends to conduct an additional investigation.” See response to comment 5. No changes were made as a result of this comment. 21 Kennecott Utah Copper Statement of Basis 1.d. Compliance Schedule:” Consider modifying the whole section as follows: Hydrogeologic study - Within two (2) years of the issuance of this Permit, the Permittee shall provide DWQ with a report analyzing the hydrogeology and groundwater flow underlying the North Impoundment based on data from existing groundwater compliance wells. We believe the hydrogeology and groundwater flow study can address the mixing zone between saline waters below the Great Salt Lake and the freshwater system underlying the facility. It also repeated the calculation of the equilibrium depth of hydraulic head pressure versus natural upward flow, which was already requested in Part I, J. 2a, iii.” See response to comment 6. No changes were made as a result of this comment. 22 Kennecott Utah Copper Statement of Basis, Potential Impacts to Water Quality: “Consider replacing barrier by natural liner.” See response to comment 1. No changes were made as a result of this comment. 23 Kennecott Utah Copper Statement of Basis Permit Reference Documents: “Please correct the typo in year” DWQ has corrected the year typo from 20122 to 2022. 23 Kennecott Utah Copper Statement of Basis Table 1: “The average values in this table should be verified. Specifically, the average sulfate concentration of tailings pore waters of 3,813 mg/L needs to be corrected based on the raw data on the water quality of operational wells. The spreadsheets with estimated average values are submitted separately.” DWQ compared table 1 to the submitted data and corrected to table 1 to reflect the data submitted in the Tailings permit renewal package in April 2022. The table may be further updated during future renewal and modifications of the permit. 24 Ivan Weber 32 pagedocument regarding the impact of mining on communities and their water sources and air quality. The commenter raised questions regarding the south zone cleanup, the transport, final disposition and possible discharge or release of cleanup materials and mine waste at the north end. The south zone cleanup is managed and administered by the Division of Environmental Response and Remediation (DERR) and the United States Environmental Protection Agency (EPA). The South Zone Technical Review Committee holds an annual public meeting to discuss the state of the south zone plume. The use of the active tailings disposal line as a treatment reactor for the impacted water removed from the south zone plume is managed though a memorandum of agreement between Kennecott Utah Copper (KUC), DWQ, DERR, and EPA. This agreement is intended to ensure the waste placed in the tailings line is neutralized and placed in the tailings impoundment in a solid form, to the satisfaction of State of Utah Ground Water Quality Protection rules, as well as EPA and DERR requirements to ensure waste materials cleaned up at one site do not impact another site. Any water discharges to the Great Salt Lake from KUC systems or tailings are managed under the UPDES surface water discharge permit UT0000051. Regarding 1) the ability of the tailings impoundments to contain waste and limit impacts to the environment; and 2) the permit’s effectiveness in ensuring the facility meets the antidegradation standard in state groundwater rules, the permit has been updated to include a wide range of investigation and data-based approaches to verify the integrity and protectiveness of the tailing’s facility. These additions are appropriate for the age of the facility and to ensure protection of state groundwater resources in critical areas, such as the margin of the Great Salt Lake.