PERMFILE129847

• Permit No: C1982056A
• IBM Index Class Name: Permit File
• Doc Date: 1/2/2007
• Section_Exhibit Name: 2.05 Operation and Reclamation Plans
• Media Type: D
• Archive: Yes

The perimeter of all areas affected by surface facilities was clearly marked before initiating surface
disturbance activities. The shaft pad surface area is approximately 11.1 acres in size with minimal cut and
fills. The associated access road comdor is approximately 2,930 feet long, with a finished top width of 24
• feet (road corridor 35 feet wide, 2.4 acres). See Exhibit 25U, 6-North Mains Ventilation Shaft -
Geotechnical Pavement Design, for details on the road, and Map EX49A-Ml, a new road profile and
cross-section.
Given an average topsoil depth of approximately 6 inches and a total road disturbance area of
approximately 2.4 acres, approximately 1,940 cubic yazds of topsoil were salvaged from the road
corridor, and 8,954 cubic yards from the 11.1 acre pad area. Prior to initiating topsoil removal activities,
stream and wetland buffer zones were marked with identifying signs to limit surface disturbance within
these areas to the planned and approved activities. Topsoil from the road corridor was recovered and
placed in a stockpile at the north end of the road corridor beyond the edge of the 35-foot road disturbance
azea. Topsoil from the pad azea was placed in a stockpile within the shaft pad on the southwest edge of
the pad and along the west edge of the access road, just south of the pad, for future reclamation use.
Topsoil salvage volumes aze indicated on Table 49A. Natural vegetative materials (mulch) incorporated
into the topsoil, and seeding with the topsoil stockpile stabilization seed mixture identified on page 2.05-
121 will stabilize the stockpiled topsoil.
Following topsoil removal from ditch and pond areas, required drainage and sediment control structures
were constructed or installed. Surface drainage for the shaft pad disturbance is controlled by two
downgradient ditches on the north side of the pad, compacted road-base surfacing of the shaft pad,
revegetation of cut and fill slopes and the topsoil stockpile, and a small, non-dischazging sediment pond
that will completely contain three years of sediment plus the runoff from the 100-yeaz, 24-hour
precipitation event. During shaft excavation, excess groundwater accumulations in the shaft aze also
pumped to the main collection ditch and pond. The sediment pond was constructed by excavating the
• pond basin to depth. The interior pond embankment slopes (incised) are constructed at 2.SH:1 V or flatter.
Design calculations have been completed to determine the elevation corresponding to the 25-year, 24-
hour storm runoff volume. A marker has been placed in the pond at this elevation and any accumulations
of runoff or pumped goundwater above this level aze pumped from the pond within 24-hours to maintain
adequate stormwater storage capacity. TCC utilizes a portable floating pump to transfer excess water
accumulations from the pond to a water tanker or apumper-truck, which hauls the water to the existing
Pond D for final treatment and discharge; to dischazge the water from the pond to one of the utility
boreholes, with routing of flows to the abandoned underground mine workings; or to dischazge through a
riprapped ditch segment to the adjacent ephemeral drainage channel under temporary CDPHE-WQCD
Construction Dewatering Dischazge Permit Permit No. COG-0072272. The limited road drainage is
controlled by two road drainage ditches, compacted road-base surfacing of the access road, revegetation
of cut and fill slopes and the topsoil stockpile, and two road crossing culverts. Active use areas are
graveled to control dust and drainage, other disturbed areas (including topsoil stockpiles) are stabilized
with temporary vegetation, and any structures are painted in neutral earth-tone colors to blend with the
natural surroundings.
The access road follows the natural topography, generally consisting of rolling terrain, and will be gravel-
surfaced, so access road drainage control requirements are minimal. Structures along the access road
include two road drainage ditches, compacted road-base surfacing of the access road, revegetation of cut
and fill slopes and the topsoil stockpile, and two road crossing culverts.
A typical road drainage ditch design is provided in Figure 2 of Exhibit 8X, prepazed by Water & Earth
. Technologies, Inc, August 2004. Two culverts are required to intercept and transfer flow from the runoff
ditches to limit runoff velocities in the ditches to less than or equal to 3.75 feet per second (fps). This
systems approach assures that the ditches remain stable with no channel scour or degradation during peak
flow events. Al] drainage calculations and documentation for the shaft pad, sedimentation pond, and
access road are provided in Exhibit 8X, and drainage structures are shown on Map 24 (Sheet 3 of 3).
MR06-208 2.05-45.6b 07/25/06