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Lyons Quarry <br /> 112d Reclamation Permit Operations <br /> Technical Revision <br /> achieve 50-foot-high benches and sloped at 2HA V with 15-foot wide benches. In an effort to <br /> establish the final grading, the anticipated cut/fill quantities for the Technical Revision #2 grading <br /> plan would be approximately balanced at 364,700 CY. <br /> 1 .2 Background <br /> Aggregate Industries operated the Lyons Quarry mine located 3 miles southwest of the town of <br /> Lyons, Colorado, in the South St. Vrain canyon area. Quartz monzonite was extracted from the mine <br /> between 1977 and 2008. While the mining permit for the quarry is still under active status with <br /> DRMS, the quarry is currently inactive and in the process of closure and reclamation in accordance <br /> the rules and regulations of DRMS. A timeline of the approved Mining Plan and Reclamation Plan for <br /> the project, as described in the Lyons Quarry Colorado DMG File M-1977-141 (2004), is provided in <br /> Table 1 below. <br /> Table 1 - Mine Permit Activity for Lyons Quarry <br /> Description <br /> 1977 Original Permit Application <br /> 1984 Revised Permit Application <br /> 2003 AM01 —Permit Amendment Approved <br /> 2008 Cessation of Mining Activity <br /> 2011 Hall Ranch Open Space, including Lyons Quarry, is sold to Boulder <br /> County <br /> 2016 TR01 —Technical Revision Approved for Weed Control Plan <br /> 2017 TR02—Technical Revision Approved for Revised Reclamation Plan for <br /> Area 1 (Quarry) <br /> 2018 TR03—Technical Revision Approved for Importing Fill to Quarry 2 <br /> 2020 TR04—Technical Revision Under Review for Revised Reclamation Plan <br /> for Area 2 (Permitted Non-Mining Disturbance Area) <br /> Changes in the mining operations at Lyons Quarry resulted in much less mining (removal of quartz <br /> monzonite) than was originally planned. The reduction in mining activities resulted in less removal <br /> and stockpiling of overburden materials than were originally planned to support reclamation. Without <br /> the available stockpiled overburden materials for placement and re-grading at the site, extensive <br /> excavation will be required in the overburden sedimentary rocks to achieve a balance of the cut and <br /> fill quantities to re-grade the mined areas. <br /> In 2013, flooding of South St. Vrain Creek destroyed several structures on the site and displaced <br /> stockpiled materials within the floodplain area. Access to the site was restored via construction of a <br /> new bridge and road improvements in 2017. In 2018, the remains of the structures, equipment and <br /> March 2021 1 2 <br /> J <br />