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JD-8 Mine - Drainage Design Plan 1 <br />• 1. INTRODUCTION <br />This report presents the design analysis for the storm water drainage facilities at the JD-8 Mine, located in <br />Montrose County, Colorado. The report addresses aspects of storm water collection, conveyance, and <br />retention design necessary to comply with the Colorado Division of Reclamation Mining and Safety <br />(DRMS) drainage criteria. <br />The JD-8 Mine is currently in "intermittent status" and is not being actively mined. However, the JD-8 <br />Mine is expected to be operational at some future date, and the existing waste rock pile will be expanded as <br />the underground workings are further developed. This drainage design plan is intended to address both the <br />current and expected final drainage conditions. <br />2. EXISTING DRAINAGE CONDITIONS <br />2.1 Runoff Areas <br />The JD-8 Mine lower mine permit area occupies approximately 11.9 acres on the north-facing escarpment <br />of Monogram Mesa. Runoff from most of the upland areas above the site is intercepted and controlled by <br />borrow' ditches, cutoff ditches, culverts, and topography associated with existing county roads and access <br />roads. These areas below the crest of Monogram Mesa and above the mine that do not runoff onto the <br />property are shown as "non-contributing areas" in Figure 1 and their acreages are listed in Table 1. <br />Table 1. Upland Non-Contributing Drainage Areas <br />(Including Upslope Drainage Areas Intercepted by Existing Roadways and Borrow Ditches) <br />ZONE <br />• AREA <br />(ft) AREA <br />(acres) <br />N-A 293,870 6.7 <br />N-B 586,350 13.5 <br />N-C 202,920 4.7 <br />N-D 137,200 3.1 <br />N-E 135,480 3.1 <br />Photo 1 shows an existing berm and cutoff ditch on the access road to the mine. The photograph was taken <br />on the access road southeast of the mine permit boundary, near the intersection of the haul road, lower <br />access road and road leading to the water tank above the JD-8 Mine. Stormwater and snowmelt from <br />upland areas are routed toward a natural channel, away from the mine site. <br />• For the purpose of this document, a borrow ditch (or "bar ditch") is a ditch constructed parallel to a road from which material was <br />excavated (borrowed) to build up the road, and in which runoff water from the road or surrounding area may collect and be <br />conveyed. <br />4122A.110601 Whetstone Associates