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soCOLORADO <br /> Division of Water Resources <br /> Department of Natural Resources <br /> February 16, 2022 <br /> J Et T Consulting Inc. <br /> J.C. York, P.E. <br /> 305 Denver Avenue, Suite D <br /> Fort Lupton, Co 80621 <br /> Transmission via Email: icyork@i-tconsultinQ.com <br /> RE: SLURRY WALL LINER APPROVAL (PROVISIONAL) <br /> BENNETT PIT(SOUTH CELL) (WDID 0203977) <br /> BENNETT PIT, DRMS M-2016-085 (WDID 0210524) <br /> N1/2 OF SECTION 12, T2N, R67W <br /> WATER DIVISION 1, WATER DISTRICT 2, WELD COUNTY <br /> Dear Mr. York: <br /> The purpose of this letter is to provisionally approve the lining of the Bennett Pit (South Cell). The South Cell is <br /> primarily located in the N1/2 of Section 12, Township 2 North, Range 67 West of the 6t' P.M., and is part of the <br /> Bennett Gravel Pit (DRMS M-2016-85). The South Cell was lined with a soil bentonite slurry wall. The site is <br /> partially mined. The slurry wall liner leak test commenced on November 2, 2021 and concluded on February 1, <br /> 2022. A site inspection was performed by our office on October 26, 2021 to review site conditions and the leak <br /> test plan. <br /> Your report dated February 7, 2022 provides the liner summary and leak test results. The test data provided <br /> indicates that the liner meets the design standard referenced in the August 1999 State Engineer Guidelines for <br /> Lining Criteria for Gravel Pits(1999 SEO Guidelines). Meeting the design standard requires that during reservoir <br /> (pond)operations all water inflows and outflows for the liner perimeter enclosed area be accounted for on a <br /> monthly basis. <br /> This liner approval is applicable only during mining operations at the site and does not classify the structure as a <br /> reservoir capable of water storage. However, for the remainder of mining operations, water within the liner <br /> boundary is now classified as trapped native ground water. The trapped native ground water may be removed <br /> from within the lined area and returned to the stream system through surface flow or ground water recharge <br /> without the need for replacement so long as the operator does not put the water to beneficial use. All native <br /> trapped ground water remaining that is put to beneficial use (except for the water removed in product) must be <br /> replaced by the operator. All inflow of water into the liner boundary from any source, including precipitation and <br /> ground water inflows shall be removed by the pit operator so as not to cause out-of-priority storage. In order for <br /> the liner to be approved for water storage the operator must perform a final leak test once mining is complete <br /> and the site is at final grade. The final leak test will be allowed to have a modified duration of 45 to 60 days as <br /> long as the liner continues to satisfactorily operate during mining operations. <br /> Please contact me at 303-866-3581 x8246 if you have any questions. <br /> Sincerely, <br /> 4aka&'-6'� <br /> loana Comaniciu, P.E. <br /> Water Resource Engineer <br /> Ec: Jorge Vidal, District 2 Water Commissioner (Jorge.Vidal@state.co.us) <br /> Louis Flink, Diversion Records Coordinator (Louis.Flink@state.co.us) <br /> WDID File (0203977 Et 0210524) <br /> o coy <br /> 1313 Sherman Street, Room 821, Denver, CO 80203 P 303.866.3581 www.colorado.gov/water Fe <br /> Jared S. Polis, Governor I Dan Gibbs, Executive Director I Kevin G. Rein,State Engineer/Director <br /> ,�1876� <br />