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2012-07-03_REVISION - M1984014
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2012-07-03_REVISION - M1984014
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Last modified
6/15/2021 2:25:42 PM
Creation date
7/11/2012 3:05:11 PM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
M1984014
IBM Index Class Name
REVISION
Doc Date
7/3/2012
Doc Name
RESPONSE TO ADEQUACY REVIEW #2
From
COTTER
To
DRMS
Type & Sequence
AM1
Email Name
GRM
Media Type
D
Archive
No
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JD -8 Mine — Drainage Design Plan 1 <br />1. INTRODUCTION <br />1.1 Purpose <br />This report presents the design analysis for the storm water drainage facilities at the JD - 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 - Mine is currently not actively mined. However, the JD -8 Mine is expected to be operational in <br />the future, and the existing waste rock pile will be expanded as the underground workings are further <br />developed. This drainage design plan is intended to address both the current and expected final drainage <br />conditions. The design criteria and methodology are described in Section 2. <br />1.2 Background - Lower Runoff Areas and Routing <br />Storm water runoff at the JD -8 Mine occurs from both disturbed and undisturbed areas. Runoff from <br />undisturbed areas is considered "non- contact" storm water because it has not had exposure to potential <br />industrial pollutants (roof runoff, access roads, employee parking areas, waste rock piles, etc.). The fuel <br />storage area is bermed and lined, and does not contribute storm water to any catchment onsite. As shown <br />in Figure 1 and Table 1, drainage areas have been divided into four contributing sub - basins and two <br />receiving sub - basins. <br />Table 1. Sub -Basin Areas at the JD -8 Mine under Current Conditions <br />Sub- Area Area <br />Basin (ft2) (acres) Type <br />1 50,280 1.15 Contributing non - contact area (undisturbed) <br />2 49760 1.14 Contributing disturbed area <br />3 24,660 0.57 Receiving area (near soil stockpile) <br />4 73,550 1.69 Contributing non - contact area (undisturbed) <br />5 137,600 3.16 Contributing disturbed area <br />6 8,050 0.18 Receiving area (Constructed Catchment) <br />Drainage at the site is controlled by ditches, berms, culverts, and topography. Sub - basins located above the <br />Lower Mine Permit Area that would contribute run -on to the site during extreme storm events under <br />current site conditions are shown in Figure 1 and Table 1. <br />Surface flow from undisturbed contributing Sub -Basin 1 and disturbed contributing Sub -Basin 2 is routed <br />to retention Pond 1 in Sub -Basin 3, near the topsoil stockpile. In addition, a portion of the western waste <br />rock pile area (on which the mine facilities have been constructed) slopes westward toward receiving Sub - <br />Basin 3 (Figure 1). <br />Similarly, runoff from undisturbed areas above the mine (Sub -Basin 4) and disturbed areas associated with <br />the access road, ore storage area, and a portion of the eastern waste rock pile (Sub -Basin 5) are routed to <br />the constructed retention Pond 2 in Sub -Basin 6. The eastern portion of the waste rock pile is sloped <br />gradually westward while the berm along the crest of the waste rock pile diverts flow westward and <br />prevents runoff from eroding the face of the pile (Photo 2). Runoff from the waste rock is intercepted by a <br />constructed notch in the berm, where water is routed down the face of the waste rock pile to the constructed <br />catchment (Pond 2). Photo 3 shows a former rivulet that developed into a small gully on the face of the <br />pile, and was then mitigated by repairing the berm along the crest of the waste rock pile. <br />4122A.120702 Whetstone Associates • <br />
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