2023-03-24_HYDROLOGY - M2016030 - Laserfiche WebLink

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Valley's Edge Resource Substitute Water Supply Plan Page 2 of 5 March 24, 2023 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. No mining will occur during this SWSP period. 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. 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 centroid of the site to the stream (X) = 5,700 feet, and the location of the parallel impermeable boundary from the stream (W) _ 7,900 feet. Lagged depletions are 57.91 acre-feet for this SWSP approval period. 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 63.07 acre-feet of fully consumable municipal return flows leased from the City of Aurora. The replacement is provided through the attached renewable lease dated October 19, 2021 renewed on November 7, 2022. 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 least 48 hours prior to making replacement deliveries at a location other than the Hite Treatment Facility. In the instance of an intervening call, the Applicant will not be allowed to make replacements downstream of the calling right. The Hite Treatment Facility is located approximately 22 miles upstream of the Pit. The delivery schedule includes a transit loss of 0.5% per mile (11% for 22 miles) during the months of April through October and 0.25% per mile (5.5% for 22 miles) during the months of November through March. Conveyance loss for delivery of augmentation water to the South Platte River is subject to assessment and modification as determined by the Division Engineer.