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Ms. Jennifer S. Lindahl Page 2 of 9 <br />June 28, 2018 <br />SWSP Operations <br />In the current SWSP approval, RMCC had planned to dewater Stage 6B through the end of 2018. <br />However, RMCC incrementally filled Stage 6B with free river water in March 2018, according to <br />information received on April 20, 2018. RMCC estimates that approximately 1.0 acre of <br />groundwater was previously exposed in Stage 6B. Stage 6B was filled to a depth of 12 feet above <br />the bottom elevation of Stage 6B, which increased the exposed surface area to 5 acres. <br /> <br />Mining at Stages 6A and 6B has been completed and it is expected that Stage 6A will expose up <br />to 3.0 acres of ground water beginning in March 2018 through the end of the mining plan. As <br />mentioned above the exposed surface are in Stage 6B will increase from 1.0 acre to 5.0 acres in <br />March 2018. The current SWSP approval allows for the ongoing mining through the end of 2018 <br />at Stage 3 and Stage 4. Mining at Stage 3 began in June 2017 and is anticipated to be completed <br />in the next couple of months. Stage 3 currently exposes approximately 1.0 acre of ground water <br />and is expected to be partially backfilled in the spring of 2018, thus the exposed surface area <br />will be reduced from 1 acre to 0.5 acre in May 2018. Ultimately Stage 3 will be backfilled with <br />overburden from other stages which will fully eliminate the evaporation depletions. A slurry wall <br />was constructed around the Stage 4 and Stage 4 is currently going through a 90-day leak test. <br />Stage 4 currently exposes 1.0 acre of ground water. <br /> <br />Mining of the Morton-Holton Lakes site is presently expected to last up to fifteen years. The <br />current mining plan for the site is shown in attached Figure 1. The replacement of depletions for <br />Morton-Holton site is fully consumable water leased from the City of Aurora. <br /> <br />The Morton-Holton Lakes Mine is located in the SE ¼ of Section 1 and the NE1/4 of Section 12, <br />all in Township 1 North, Range 67 West of the 6th P.M., and the SW ¼ of Section 6, and the <br />NW1/4 of Section 7, all in Township 1 North, Range 66 West of the 6th P.M. The depletions that <br />result from the mining operation over the period of this SWSP amendment include evaporation <br />from exposed ground water, dust suppression, dewatering, and water lost with the mined <br />product. <br />In accordance with the letter dated April 30, 2010 (copy attached) from the Colorado Division of <br />Reclamation, Mining, and Safety (“DRMS”), all sand and gravel mining operators must comply <br />with the requirements of the Colorado Reclamation Act and the Mineral Rules and Regulations <br />for the protection of water resources. The April 30, 2010 letter from DRMS requires that you <br />provide information to DRMS to demonstrate you can replace long term injurious stream <br />depletions that result from mining related exposure of ground water. The DRMS letter identified <br />four approaches to satisfy this requirement. <br />In accordance with approach nos. 1 and 3, you have indicated that a bond has been obtained for <br />the new Morton-Holton Lakes site that can cover the cost of lining, to prevent the exposure of <br />ground water. The current bond amount for the new Morton-Holton Lakes site is $4,150,000.00. <br /> <br /> <br />Depletions <br /> <br />The projected depletions for Stages 1, 2, 6A, 6B, 3 and 4 are resulting from evaporation, water <br />lost in product, dust control, and first fill. The Applicant proposed to replace evaporation from <br />exposed ground water at the Morton-Holton site based upon evaporation atlases in NOAA <br />Technical Report NWS 33 and the SEO monthly distribution factors for sites below 6,500 feet, as