2025-04-14_HYDROLOGY - M2004044 - Laserfiche WebLink

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Holcim South Platte Combined SWSP April 14, 2025 Plan IDs 3614, 4773, 3624, 4772, 4616, 3437, 3376, 3650, 3668, 5475, 5829, Ft 6243 Page 34 of 37 continuously dewatered, the water returned to the stream system should be adequate to offset the depletions attributable to the dewatering operation. Once dewatering at a site ceases, the delayed depletions must be addressed. Accordingly, dewatering is required to continue at the Wattenberg Pit, W.W. Farms Pit, Tull Pit, DPG Pit, and Irwin-Thomas Pit during the term of this approval. At least three years prior to completion of dewatering, a plan must be submitted that specifies how the post pumping dewatering depletions (including refilling of the pit) will be replaced in time, place and amount. 23. Prior to claiming any credit for the water returned to the stream system from dewatering in excess of lagged dewatering depletions (a net accretion), the Applicant must install a totalizing flow meter that accurately measures the quantity of water being pumped and returned to the stream system via dewatering operations and account on a real time basis for the actual dewatering depletions and accretions. No net accretion credits are sought by the Applicant for this approval period. 24. If dewatering of any of these sites is discontinued, the pit would fill, creating additional depletions to the stream system due to increased evaporation. To ensure that additional depletions to the river do not occur, a bond has been obtained through the DRMS for lining or backfilling of the pits. Therefore, if the dewatering is discontinued, these bonds can finance the completion of the lining of these pits or the backfilling, thus preventing depletions to the stream system. 25.The approval of this substitute water supply plan does not relieve the Applicant and/or landowner of the requirement to obtain a Water Court decree approving a permanent plan for augmentation or mitigation to ensure the permanent replacement of all depletions, including long-term evaporation losses and lagged depletions after gravel mining operations have ceased. 26. If reclamation of the mine sites will produce a permanent water surface exposing groundwater to evaporation, an application for a plan for augmentation must be filed with the Division 1 Water Court at least three (3) years prior to the completion of mining to include, but not be limited to, long-term evaporation losses and lagged depletions. If a lined pond results after reclamation, replacement of lagged depletions shall continue until there is no longer an effect on stream flow. According to the SWSP request, mining of material has ceased at the Jeronimus Pit, Hazeltine Pit, Platte Valley Pit, F-Street Pit, Brighton Pit, Distel Pit, and Wattenberg Pit. Since material mining has ceased at these sites, either the lakes must be lined or backfilled, or an application for a plan of augmentation for the site must be filed with the water court. In addition all lagged depletions shall continue to be replaced under a SWSP until there is no longer an effect on stream flow or a court approved augmentation plan is approved by the water court. Granting of this plan does not