2024-04-08_PERMIT FILE - M2024015

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Domestic Howard 12 23014 Well Breckon 538 Garfield Denver CO 80202 United Water WDID Koehn &Sanitation 3855 Lewiston 13 14028-R 0206862 Well#3 District Street#140 Aurora CO 80011 At the time of SWSP application/approval, a new gravel pit well permit will be applied for/obtained to include the evaporative and operational losses from the property. If the proposed use of groundwater at the Sweet Valley Pit mining site results in material injury to surrounding wells, CCWCD will ensure that all necessary measures are taken to address the issues. Water Quality An NPDES permit will be obtained from the Water Quality Control Division at the Colorado Department of Public Health & Environment for the Sweet Valley Pit mining site prior to discharging any groundwater that is dewatered from the site. This permit will be kept current and amended as necessary to ensure that any water discharged from the site will meet the permitted water quality standards. Impacts to Groundwater/Hydrologic Balance CCWCD will monitor the groundwater levels surrounding the site and provide groundwater mitigation via a groundwater drain or dewatering wells as described in the Groundwater Evaluation. The mitigation measures are provided with the Groundwater Evaluation. Design plans will be provided to the DRMS for the mitigation measures. CCWCD will discharge dewatering flows into existing adjacent irrigation laterals where possible to limit the disturbance to the surrounding land or discharge the dewatering flows via CCWCD's proposed pipeline that discharges directly to the South Platte River. A slurry wall liner is proposed around the Phase 1 and Phase 2 cells. To summarize the mitigation process, as the mining/dewatering occurs, CCWCD will monitor the groundwater levels adjacent to mine as the mining progresses. If groundwater levels drop to a level that prevents an adjacent well from performing acceptably, according to that well's owner, CCWCD will either implement a groundwater recharge ditch/pond near the well in order to raise the groundwater level in the vicinity of the well and hence return it's operation to acceptable standards, or will negotiate an agreement with that well owner to replace the well or provide replacement water via other means until the mining and reclamation activities are concluded but it is not anticipated that any groundwater levels will drop since the slurry wall will be installed prior to exposing groundwater and that mitigation measures to keep groundwater from mounding on the south side of the Phase 2 slurry wall will be in place such that baseline groundwater levels will be maintained to within plus or minus 2 feet. The north side of the Phase 1 slurry wall will be in a shadow area but all of the impacted wells are within the foot print of the approved permit boundaries of the Monarch Mine and the Section 20 Mine. Groundwater wells that are not owned by CCWCD are potentially located within 600 feet of the mining limits. The exact physical location of these wells will be determined during the SWSP and well permit application processes. If wells are found to be within 600 feet of the mining limits, CCWCD will either obtain a well waiver from the owner of the well, or provide an agreement with the well owner that CCWCD will mitigate and material damage to the well that is directly attributable to the mining and reclamation of the site. Central Colorado Water Conservancy District J&T Consulting,Inc. Sweet Valley Pit DRMS 112 Permit Application