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STORMWATER MANAGEMENT PLAN MORRISON QUARRY <br /> REVISION NO.8 1 August 2022 CERTIFICATION NO.COG500320 <br /> Mining occurs on benches located on the western side of the quarry. Haul trucks are <br /> loaded and bring material to the plant.The material is crushed and screened to size and <br /> stockpiled. Some material goes through the wash plant where the material is washed <br /> before being loaded into silos. Customer trucks travel up the haul road and wait to be <br /> loaded by either the loader or under the silos before returning to the scales. <br /> 2.2 SITE DRAINAGE <br /> Surface drainage at the facility is generally to the east. The majority of stormwater from <br /> the plant and mining areas will remain onsite and percolate into the ground. The list <br /> provided below describes the drainage paths for stormwater that discharges offsite. See <br /> Figure 2 for a map of the drainage paths listed below: <br /> • Drainage Path A-Stormwater flows via sheet flow to onsite roadside ditches and two <br /> stormwater retention structures (for additional settling) then into the storm water <br /> retention pond by the scales where stormwater either evaporates or is allowed to <br /> settle before being discharged at Outfall 005 to an unnamed gulch to Turkey Creek. <br /> • Drainage Path B - In high intensity or long duration precipitation events stormwater <br /> flows via sheet flow to onsite roadside ditches and then into the sediment basin where <br /> it either evaporates or is allowed to settle before being discharged at Outfall 003 to <br /> an unnamed gulch to Turkey Creek. <br /> • Drainage Path C-Stormwater flows via sheet flow to onsite roadside ditches and then <br /> into the storm water retention pond by the facility entrance gate where it either <br /> evaporates or is allowed to settle before being discharged at Outfall 001 to the <br /> roadside ditch north of the site access road to No Name Gulch, which discharges to <br /> Bear Creek. <br /> • Drainage Path D -Stormwater flows via sheet flow past the retention pond at Outfall <br /> 001 to Outfall 004, which discharges directly to the roadside ditch north of the site <br /> access to No Name Gulch, which discharges to Bear Creek. <br /> • Drainage Path E - Stormwater flows via natural drainage channel into the sediment <br /> basin where it either evaporates or is allowed to settle before being discharged at <br /> Outfall 006 to an unnamed drainage to Turkey Creek. Stormwater that collects in the <br /> basin within the South Quarry is pumped to Outfall 006 as necessary. <br /> Figure 2 depicts facility drainage and the location of all control structures. The drainage <br /> from facility operation areas is described in more detail in Section 3. <br /> 12 <br />