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REP34614
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REP34614
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Entry Properties
Last modified
8/25/2016 12:11:36 AM
Creation date
11/27/2007 6:54:18 AM
Metadata
Fields
Template:
DRMS Permit Index
Permit No
C1981041
IBM Index Class Name
Report
Doc Date
8/5/1997
Doc Name
MINE SITE EVALUATION INSPECTION REPORT
Permit Index Doc Type
Waste Pile/Fill Report
Media Type
D
Archive
No
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RRDA. Exhibits 6A and 66 show its location and figure 2.05.3D illustrates a cross <br />section of the pipeline's installation. That installation includes an underdrain in the <br />pipeline trench to convey potential leaks through the pile without major erosion. The <br />underdrain is to daylight at the toe of the pile. I didn't specifically notice an underdrain <br />outlet during the field review, though vegetation growing at the south end of the pond <br />area was very dense and easily could have concealed it. The pipeline's installation <br />was approved 1993. <br />Approved drainage controls in the RRDA area include a South (uphill) Diversion, a <br />drop structure, and two lower catch ditches. As noted above, the South Diversion will <br />be reconstructed at a new location when the pile is permanently reclaimed. Cross <br />section T-T on Exhibit 20 shows its design. Presently, it's designed with a V-shaped <br />cross section, a top width of 8.8', a depth of 2.5' including freeboard, 2h:1v inside <br />slopes, a capacity of 15.1 cfs, and a gradient s 0.5%. Two 18" diameter CMP culverts <br />are called for under access roads in north-south and east-west trending sections of the <br />diversion at its southern end. A drop structure to convey drainage downslope from the <br />storage area is shown on Exhibit 20 as a 12 inch diameter CMP. One ditch line is <br />constructed along the western toe of the pile: the northern part of it is Lower Catch <br />Ditch 1, and the southern part is Lower Catch Ditch 2. Cross section S-S on Exhibit 20 <br />shows the design for Lower Catch Ditch 1, which includes: V-shaped profile; top width, <br />2'; total depth 1.3', including freeboard; 1h:1v inside slopes; 2.4 cfs capacity; and a 2% <br />grade. The design for Lower Catch Ditch 2 is shown as cross section U-U on Exhibit <br />20, and includes: a V-shaped profile; top width, 3.5', excluding additional width at the <br />top of freeboard; total depth just over 2', including freeboard; 1 h:1 v inside slopes; a <br />capacity of 9.2 cfs; and a gradient of 2%. Lower Catch Ditch 2 and the 12-inch CMP <br />drop structure discharge into pond 9, which is sized fora 10-year, 24 hour event. <br />Lower Catch ditch 1 flows north into pond 8. Pond 8 also receives runoff from the <br />facilities area and appeared to be filled to the clean-0ut level. The ditches and drop <br />structures are designed for 100-year, 24 hour events. <br />A few drainage controls that aren't specifically approved by DMG have been in place <br />for some time at the RRDA. Three grated drop drains along the western edge of the <br />storage area convey water from the top of the pile into an 8-inch CMP that joins the 12- <br />inch CMP. These drains have been in place since around 1983. A 24-inch inlet pipe at <br />the south end of the storage area conveys drainage to a reducer and then into the 12- <br />inch CMP. According to Mr. Reschke, these measures are designed to handle runoff <br />from a 100-year, 24-hour precipitation event. DMG presently is reviewing a permit <br />revision that, if approved, will eliminate the current system of unapproved controls and <br />will provide for the permanent reconstruction of the South Diversion and possibly <br />benches on the pile's outslope. Last, a 100' segment of ditch was constructed at the <br />southern-most end of the refuse area from the vertical rock face toward, and around, <br />the concrete drop structure at the southern inlet to pond 9. It isn't included in the <br />approved permit or the pending permit revision. No water was flowing in any of the <br />14 <br />
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