2021-11-01_HYDROLOGY - M2016030 - Laserfiche WebLink

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Valley's Edge Resource Substitute Water Supply Pla,, November 1, 2021 Page 2 of 7 Depletions The projected depletions for the period of this SWSP impact the South Platte River below Brighton, CO and consist of net evaporation from exposed groundwater surface area and dust suppression. No mining will occur during this SWSP period. The total consumptive use for this SWSP approval period is anticipated at 56.57 acre-feet. Evaporation The Applicant proposes to replace evaporation from exposed groundwater at the site based upon evaporation atlases in NOAA Technical Report NWS 33 and the precipitation at the Brighton station, as shown in attached Table 1. Gross annual evaporation at the gravel pit location is estimated to be 45.00 inches per year. Net evaporation is defined as gross evaporation less the consumptive use of water by vegetation that naturally occurred at the site prior to construction of the pit. The effective precipitation (14.04 inches) was estimated based on the data from the Brighton NOAA weather station. The net evaporation from the 17.0 acres of exposed water surface is 49.85 acre-feet (2.93 acre-feet per acre) for this SWSP approval period. Dust Suppression The Applicant anticipates that 6.72 acre-feet (0.56 acre-feet per month) will be used during this SWSP approval period for dust control which will be fully consumed. The total consumptive use of water during this SWSP period is 56.57 acre-feet. Lagged Depletions The IDS AWAS stream depletion model was used to determine the lagged depletions to the South Platte River. The aquifer characteristics used in the model for the evaporative depletions are: transmissivity (T) = 70,000 gallons per day per foot, specific yield (SY) = 0.2, the distance from the well to the stream (X) = 5,700 feet, and the location of the parallel impermeable boundary from the stream (W) = 7,900 feet. The total replacement obligations for November 2021 through October 2022 are 61.74 acre-feet. Depletions from this operation will accrue to the South Platte River in the SE '/a of the NW '/a of Section 19, Township 1 North, Range 66 West, 6th P.M. For purposes of this SWSP, the depletions will be owed at the location where the South Platte River crosses the north line of the SE'/a of the NW'/a of Section 19. Replacements Out -of -priority depletions from the Valley's Edge Resource Gravel Mine will be replaced using fully consumable municipal return flows leased from the City of Aurora. The replacement is provided through a lease dated March 7, 2017. If actual depletions are greater than projected depletions in any month, the amount of replacement water required from the City of Aurora may exceed the agreed upon volume. The Applicant is responsible for assuring that adequate replacement volume is provided. Under the lease, water will be delivered to the outfall of the Robert W. Hite Treatment Facility (aka Metro Sewer, WDID 0200700) located in Denver, CO on the South Platte River. According to the lease, Aurora may alternatively deliver water at other points along a reach of the South Platte River beginning at or below the Hite Treatment Facility extending downstream to the confluence of the St. Vrain River and the South Platte River. The Applicant must notify the Water Commissioner at