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Aggregate Industries, Morrison Quarry <br /> Amendment No.7 to Permit M-1973-021 FYZ <br /> Morrison,CO <br /> Surface Water <br /> Surface water is generally routed away from the Morrison Quarry site, with the exception of <br /> water stored in Reservoir Site II. The Town of Morrison owns Reservoir Site II, which is within <br /> the mine permit boundary. The reservoir has a maximum storage capacity of 1,641 acre-feet. <br /> The reservoir operating agreement between the Town of Morrison and Aggregate Industries, <br /> Inc. is included in Exhibit G.3. <br /> AM04 transmitted a Phase 1 Drainage Report(Chang Engineering, September 1994), which <br /> identified six drainage basins related to the Site: Strain Gulch Basin and five un-named basins. <br /> Strain Gulch is the major drainageway directly adjacent to the site. Where it meets the upstream <br /> extent of the property boundary, it is routed through a 72-inch culvert beneath the North Quarry <br /> and processing area. AM04 also identified the need to divert UD#1 around the South Quarry <br /> basin and provided a stipulation that the design for this diversion structure must be approved <br /> prior to making permanent changes. <br /> This permit amendment includes the draft final design for the drainage diversion in Appendix C <br /> of the Morrison Quarry Phase 11 Drainage Report. The report transmits the final design for the <br /> permanent diversion of UD#1 to UD#2. The drainage structure will contain a culvert and two <br /> retention basins with spillways, designed to manage 100- and 500-year floods, respectively. <br /> Water will discharge through a new outfall (Outfall 006) located near the southeastern corner of <br /> Phase III, which will be permitted before construction. <br /> Water Management <br /> Water from dewatering operations or from runoff from disturbed area and operating surfaces are <br /> managed according to a site-specific SWMP, which was certified by the CDPHE in June 2021 <br /> under certification number COG500320. The existing SWMP permit describes stormwater runoff <br /> and non-stormwater effluent that the mine is permitted to discharge to surface waters of the <br /> State. The SWMP complies with the provisions of the Colorado Water Quality Control Act and <br /> permits the discharge of process water and stormwater associated with mining and the <br /> processing of sand and gravel. The SWMP is covered under CDPHE general permit <br /> COG500000. <br /> Stormwater <br /> Stormwater drainage, retention, and discharge are major components of the drainage plan for <br /> the mine and can be found throughout the facility. Surface drainage at the facility is generally to <br /> the east of the mine site. All constructed retention basins and outfalls referenced in this <br /> discussion are shown in Exhibit C.2 and Exhibit C.3. <br /> September 2021 1 48 <br />