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and stabilization plan with the Division in the form of a revision to the permit. 8. "...However, after reviewing pertinent supplemental data submitted with the easement information, the Reclamation Plan, the Mining Plan, and the various maps, it appears that the 1:2 slopes between the buffer area and the excavated area could stand untreated for somewhere between 2 and 9 %z years before the clay liner is completed..." (Colorado Department of Transportation; March 26, 2005) Division of Minerals and Geology (DMG) Response- The operator will mine the site in 20 to 25-acre sections, as depicted on the Mining Plan Map. Reclamation will begin at the end of each mining sequence. In order to constmct the reservoir in the most efficient manner, the applicant proposes to limit the number of mobilizations and inter-clay liner joints (traverse slopes within the liner). According to the applicant, it will likely take the contractor two months to construct 1,000 feet of slope liner. No more than 50 acres will be exposed at any given time before a clay liner is constructed. To further insure that reclamation is performed concurrently (to be consistent with the hydrology model and phased bonding option), the following stipulation will be included; Stipulation No. 4 In order to maintain phased bonding for the clay liner, the following permit conditions must be followed; • The applicant shall not mine Pond 2 below the groundwater table until Pond 1 is reclaimed to two feet above the groundwater level. • The applicant must begin construction of the slope liner no later than ajer two phases have been completely mined to bedrock. • The maximum linear feet ofslope that may be disturbed and not reclaimed at any given time shall be no greater than 6,000 lineal feet. • Prior to construction of the compacted clay liner, the applicant shall submit a revision to the permit with detailed information on construction of the compacted clay liner and submit a quality control and assurance plan for the Division's review and approval. A copy of the revision shall be forwarded to the Colorado Department of Transportation (CDOT) when submitted to the Division ofMinera[s and Geology. • The applicant shall submit and obtain approval from the Division ofconsfruction reports on clay-lined slopes that have been completed in order to initiate the next 6,000 lineal feet of mining. • Final release of the clay liner must be obtained from the OJ~ce of the State Engineer in order for the Division to release any remaining reclamation bond. 9. "Is there a provision for some type of keying operation to help bond the clay liner to the claystone bedrock, and prevent the intrusion of water between the liner and the bedrock?" (Colorado Department of Transportation; March 26, 2005) Division of Minerals and Geology (DMG) Response- According to the application, the project plan is to excavate all the soils on the interior of the site and into bedrock to create the reservoir basin. The reservoir bottom will consist of a graded level bedrock surface, positively graded with a slight slope to the outlet. The slope liner is a homogeneous embankment with the below grade portion constructed of clays primarily derived from claystone bedrock. The crest width will be 12 feet with a 4h:ly upstream slope from the crest that terminates at the top of bedrock. The upstream slope will terminate at the top of existing bedrock and a 25-foot wide horizontal bedrock bench. The bedrock bench will be graded to a 6:1 slope to the reservoir bottom. As noted in Stipulation No. 4, prior to construction of the compacted clay liner, the applicant shall submit a revision to the pemrit with detailed information on construction of the compacted clay liner and submit a quality control and assurance plan for the Division's review and approval. A copy of the revision shall be forwarded to the Colorado Department of Transportation (CDOT) when submitted to the Division of Minerals and Geology. 4