PERMFILE139112

• Permit No: C1982056A
• IBM Index Class Name: Permit File
• Doc Date: 9/14/2005
• Section_Exhibit Name: 2.05 Operation and Reclamation Plans
• Media Type: D
• Archive: Yes

These activities are briefly described in the following sections.
Site-specific investigations required for design and permitting of the new ventilation shaft included a
cultural resource survey of potential disturbance azeas, soil and foundation characterization as the basis for
shaft pad and access road design, and completion of a wetland/AVF survey for the shaft pad and access
.,_
road. The cultural resource survey was conducted by Metcalf Archaeological Consultants, the engineering
soils characterization by Northwest Colorado Consultants, and the soils/wetland/AVF survey by Habitat
Management, as described in Section 2.04.
The perimeter of all areas affected by surface facilities will be clearly marked before the beginning of
surface disturbances. The proposed shaft pad surface azea is approximately 280' squaze (1.8 acres), with a
total pad disturbance area (includes cut and fill slopes) of 2.5 acres. The associated access road corridor is
approximately 7,100' long, with a finished top width of 24 feet (road corridor 35 feet wide, 5.7 acres). See
Exhibit 25T, 18 Right Ventilation Shaft Geotechnical Pavement Design, for details on the road, and Map
24-CDI, a new road profile and cross-section. Approximately 4,400 feet of the access road crosses upland
azeas, with the remaining 2,700 feet crossing lowland areas where road construction will involve removal
of any large vegetation and stripping and stockpiling of other vegetation, topsoil, and organic materials.
Given an average topsoil depth of approximately 6 inches in the upland area and a total road distwbance
area of approximately 5.7 acres, approximately 4,600 CY of topsoil will be salvaged from the road
corridor, and 2,000 CY from the 2.5 acre pad azea. Prior to initiating topsoil removal activities,
stream wetland buffer zones will be marked with identifying signs to prevent surface disturbance within
buffer zone azeas. The topsoil from the road corridor was initially windrowed downslope beyond the edge
of the 35-foot road disturbance area, and topsoil from the pad area was placed in a stockpile adjacent to the
shaft pad and within the 100-foot road corridor, for future reclamation use. As a result of concerns related
to protection of windrowed topsoil from erosion and contamination, a decision was made to recover topsoil
from the windrows and place it in stockpile. The topsoil salvage volumes are indicated on Table 49A.
~~•" Natural vegetative materials (mulch) incorporated into the topsoil, and seeding with the topsoil stockpile
stabilization seed mixtwe identified on page 2.05-121 will stabilize the windrowed and stockpiled topsoil.
Following topsoil removal, required drainage and sediment control structures will be constructed or
installed. These structures include the upslope road drainage ditch, road crossings of smaller ephemeral
drainage channels; discharge control structure (rock check dam) at the down-gradient limit of the shaft pad,
and a temporary diversion ditch azound the up-gradient perimeter of the shaft pad. The drainage from the
shaft pad is addressed under a Small Area Exemption (SAE), as both the associated drainage area (4.3
acres) and the pad disturbance (2.5 acres, includes 0.2 acre ditch disturbance) are relatively small, the pad
will be grave]-surfaced, and the remainder of the drainage area is undisturbed and vegetated. The access
road follows variable topography, generally consisting of rolling terrain, and will be gravel-surfaced, so
access road drainage control requirements aze minimal. Atypical road drainage ditch design is provided in
Figure 2 of Exhibit 8T, prepared by Water & Earth Technologies, Inc, April 2004. Six (6) culverts are
required to remove the 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 will assure that the ditches remain stable with no chammel scour or
degradation during peak flow events. Breaks in the topsoil windrow will allow runoff to drain. All
drainage calculations and documentation are provided in Exhibit 8T, the SAE demonstration is provided
later in this section, and the drainage structures are shown on Map 24. The SAE demonstration includes
ditch sizing for the upland diversion ditch and road ditch.
Construction of the ventilation shaft access road will involve topsoil recovery and windrowing, installation
i of required drainage structures, scarification and re-compaction of surface materials, and placement and
TROS-48 2.05 - 45.4 08/22/05