2019-08-27_HYDROLOGY - M1989120 - Laserfiche WebLink

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Amended Aggregate Industries South Platte Combined SWSP August 27, 2019 Plan I Ds 3614, 47731 3624, 47721 4616, 3437, 3376, 3650, 3668, and 5475 Page 19 of 21 Depth to Groundwater Percent Reduction in Calculated HCU' (Feet) Native Grass Alfalfa 1 85% 100% 2 50% 90% 3 30% 75% 4 20% 50% 5 15% 35% 6 10% 20% 7 5% 15% 8 0% 10% 1. Adapted from EVAPOTRANSPIRATION AND AGRONOMIC RESPONSES IN FORMERLY IRRIGATED MOUNTAIN MEADOWS, South Park, Colorado, March 1, 1990; Revised September 1, 1991 18. If reclamation of any mine site included in this SWSP 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 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. Granting of this plan does not imply approval by this office of any such court application(s). 19. Dewatering at the Wattenberg Pit, W.W. Farms Pit, Tull Pit, and Tucson South Pit will produce delayed depletions to the stream system. As long as the pits are 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 the W.W. Farms Pit, Wattenberg Pit, Tull Pit, and Tucson South 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. 20. 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. 21. 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 assure that additional depletions to the river do not occur, a bond has been obtained through the DRMS for lining or backfilling of the lakes. 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. 22. 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.