2019-01-30_HYDROLOGY - M1989120 - Laserfiche WebLink

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Aggregate Industries South Platte Combined SWSP January 30, 2019 Plan IDs 3614, 4773, 3624, 4772, 4616, 3437, 3376, 3650, 3668, and 5475 Page 19 of 21 in this SWSP. Information regarding depth to groundwater may be provided using existing irrigation wells, existing or new monitoring wells, or piezometers located on the dried-up fields. Applicant may utilize wells or piezometers located within ¼ mile of each field provided that the Applicant can demonstrate the depth to groundwater information available off-site is representative of the depth to groundwater on the dried-up land. The Applicant shall modify its accounting to reduce the amount of the calculated HCU that may be claimed in this SWSP according to the table below. Measurements taken at the start of each month will determine the necessary reduction in credit to be applied during the following month. The Applicant may use another methodology upon review and prior approval by the state engineer and division engineer. (Construction of monitoring holes/wells, or piezometers requires that permits or notices be obtained as described in Table 1 of the Water Well Construction Rules.) Depth to Groundwater (Feet) Percent Reduction in Calculated HCU1 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.