PERMFILE134290

• Permit No: C1981038
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: VOLUME 4-SURFACE WATER APPENDIX- EAST ROATCAP CREEK
• Media Type: D
• Archive: No

2.10 Fill Slope Sediment Control
2.10.1 General Description
The haul road crossing of East Roatcap Creek at an elevation
sufficient to match that of the portal bench requires a road fill
of about 100 feet at the creek. These fill slopes are proposed
to be constructed of excavated material from the portal bench.
The slopes result in a slope area of about one acre on the
downstream side and about three acres on the upstream side,
depending on the final design. These fill slopes will drain
directly to the creek, and water and sediment flows from them
cannot be intercepted by the sediment pond described above.
Sediment control structures and measures designed for small area
disturbances are appropriate. Criteria for selection of these
various structures and methods are described below.
2.10.2 Design Criteria
The State of Colorado Mined Land Reclamation Division
Regulations require that temporary erosion control methods be
used during embankment construction. After construction,
vegetation or other cover is to be used. Due to the proposed
accelerated earthwork schedule, and it's occurence during the low
rainfall time of year, no temporary erosion control methods will
• be necessary. After construction, vegetation and stabilization
methods meeting the following criteria is recommended:
a) Surface protection measures consisting of
vegetation, mulches or one of various types
of proprietary erosion control cover products
are to be evaluated. These methods control
erosion at the start of the process and are
most effective;
b) Detention and filtering structures such as
small rock-overflow detention basins and
filter fences will be used, if required,
while vegetation is being established.
2.11 Probable Hydrologic Consequences
The proposed new portal for the Orchard Valley mine is
located in the central portion of East Roatcap Creek. The bench
from which the entries will be driven will be composed of cut and
fill. The fill would be placed across East Roatcap Creek. To
limit the probable hydrologic consequences of the proposed
construction, Colorado Westmoreland, Inc. performed a surface
water hydrology investigation. This investigation consisted of
the installation of an additional stream gaging station, flow
• monitoring, hydrologic analysis for the construction site and
conceptual design of hydraulic and sediment control structures.
These structures will consist of a corrugated steel pipe (CSP)
culvert on East Roatcap Creek underneath the fill, a
sedimentation pond, a perimeter ditch, and bench and haul road
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