2023-10-30_HYDROLOGY - M2001085 (2)

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COLORADO Division of Water Resources Department of Natural Resources October 30, 2023 Craig M. Lis, P.E., Senior Water Rights Engineer Martin and Wood Water Consultants, Inc. 538 Commons Drive Golden, CO 80401 Re: GSL Sand and Gravel Substitute Water Supply Plan (WDID 0202584) (a.k.a. 120th Estates Partners Sand and Gravel Mine and 124th Estates Pit) GSL Sand and Gravel Mine, DRMS Permit No. M-2001-085 (WDID 0203018) S 'h of the SW'/a of Sec. 35, Twp. 1 South, Rng. 67 West, 6th P.M. Water Division 1, Water District 2, Adams County SWSP ID: 4558 Approval Period: November 1, 2023 through October 31, 2024 Contact information for Craig Lis: 303-526-2600 and clis@martinandwood.com Dear Craig M. Lis: We have reviewed your renewal request dated September 15, 2023 regarding the above-referenced substitute water supply plan ("SWSP") to cover depletions caused by the GSL Sand and Gravel mine in accordance with section 37-90-137(11), C.R.S. The original plan was approved on May 20, 2002 and its renewal was most recently approved in a letter dated December 19, 2022. That plan was valid through October 31, 2023. The required fee of $257 for this renewal of the SWSP has been submitted (receipt number 10031716). Plan Operation The GSL Sand and Gravel Mine is generally located in the S 'h of the SW'/a of Section 35, Township 1 South, Range 67 West of the Sixth P.M. This SWSP covers depletions at the GSL Sand and Gravel Mine ("Applicant"). Mining operations were completed in November 2011 and a slurry wall was installed around the pond. However, the liner is not functional,therefore the Applicant requested an amendment to the mining permit to the Division of Reclamation Mining and Safety("DRMS") to allow for backfilling of the pit. Since February 2012 when the exposed surface area was 26.7 acres, the Applicant has been working on backfilling the pond and the exposed groundwater surface area as of May 2023 was 0.91 acres. Depletions during this SWSP period consist of evaporative depletions from the exposed groundwater surface. Replacement water is fully consumable water leased from the City of Aurora ("Aurora") which will be released upstream of the pit. Depletions The depletions at the site during the period of this SWSP consist of evaporation from exposed groundwater since the lagged depletions from prior mining operations no longer have an effect on the stream. Other than evaporation from the exposed groundwater surface, no new operating depletions will occur during this SWSP approval period. The current total exposed groundwater surface area at this site is 0.91 acres. For the purposes of this SWSP, it is assumed that the exposed groundwater at the site will remain at 0.91 acres. Net evaporation is defined as gross evaporation less the consumptive use of water by vegetation that naturally occurred at the site prior to mining activity. The historical consumptive use was assumed to be equal to the effective precipitation, which was estimated based on the data from the Denver Stapleton Station. Net evaporative F CO Q 1313 Sherman Street, Room 821, Denver, CO80203 P 303.866.3581 www.colorado.gov/water Jared S. Polis, Governor I Dan Gibbs, Executive Director I Kevin G. Rein, State Engineer/Director I yei 0 f 1876{`