2001-12-11_PERMIT FILE - C1982056A ‎(5)‎

• Permit No: C1982056A
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: EXHIBIT 08 TAB 1 SEDIMENT CONTROL PLAN
• Media Type: D
• Archive: Yes

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EXHIBIT 8
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A
SEDIMENT CONTROL PLAN
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The sediment control plan for the Foidel Creek Mine includes structures designed to control surface runoff at the
Foidel Creek Mine Surface Facilities Area, facilities for treating mine discharge at the Fish Creek Borehole Area,
and a sump facility for emergency discharge of washdown water from the preparation plant thickener. The mine
portal area will drain through a series of diversion ditches to Sedimentation Pond D. Pond D discharges to Foidel
Creek, and has been designed so that the discharge meets the effluent limits of CDPS Permit CO-0027154.
Portions of the mine facilities area, coal stockpile area, and preparation plan area drain directly or through a
network of collecting ditches to Pond E. Pond E is designed to control effluent discharges to Foidel Creek under
applicable provisions of CDPS Permit CO-0027154. The tipple area drains to Pond B, which was approved
previously in Pern»t C-81-071 as a treatment facility. This pond discharges to Foidel Creek. The southeastern area
of the permit revision boundary drains to Sedimentation Pond G, which also dischazges to Foidel Creek. Ponds F
and G have been designed to meet the effluent limits of CPDS Permit CO-0027154. The FCB Treatment Facility
is designed to treat water pumped from boreholes and discharged at Site 115. This facility discharges to Fish Creek
and will meet all applicable effluent limit of the NPDES permit. Twentymile Coal Company discharges from this
facility per the requirements of CPDS permit CO-0042161.
The following description of sediment control facilities incorporates the certified design of certain sedimentation
ponds, diversion ditches and culverts previously approved under permit C-82-056. All applicable sediment control
structures in the mine portal area at the Foidel Creek Mine can be seen on Map 24, Surface Facilities. The Fish
Creek Borehole Area Facilities and Access Road Map (Map 26) delineates the FCB Treatment Facility and access
road into the facility. The design for sediment ponds acquired from Colorado Yampa coal Company (permit C-81-
071) is presented in Exhibit 8p.
• Design Criteria
All sediment control structures are designed according to minimum critena set forth under Rule 4.05. The
minimum flow capacity of the diversion ditches was determined for the peak runoff from the 10-year, 24-hour
precipitation event. The culvert sizes were determined from the peak mnoff resulting from the 10-year and 24-hour
precipitation or snowmelt event. The storage capacity of the sedimentation ponds was determined from the
required sediment storage plus the peak inflow from the 10-year, 24-hour precipitation event for embankments
under IO feet in height, or the 100-year, 24-hour event for embankments over l0 feet in height.
The Preparation Plant Emergency Discharge Sump is designed as anon-discharging pond to fully contain the
maximum capacity of the preparation plant thickener plus direct precipitation and runoff from the 10-year, 24-hour
event within the pond area. Any water or thickener, which accumulates in the sump, will be safely discharged
using current prudent engineering practices. Twentymile has a variety of submersible pumps (3.5 to IS hp), which
can be used to dewater the sump. The Fish Creek Borehole impoundment has been designed to facilitate handling
of mine discharge at that location.
The design specification for ditches, D-I, D-2, D-3A, D-3B, D-4, D-6(a), D-6(b), are presented in Tab 2.1;
specification for ditches E-1, E-2, and E-3 are presented in Tab 2.2; specification for ditches F-1, F-2, and F-3 aze
presented in Tab 2.3; specification for ditches G-1(a), G-1(b), G-a(c), G-2, G-3(a), G-3(b) and G~ are presented in
Tab 2.4; and specification for the Fish Creek Borehole ditches are found in Tab 2.5. Tab 2.6 provides specification
for ditches along Haulroad C and culvert HRC-l. Tab 2.7 provides for design of ditch TDFES-l, see pg. 2 of this
tab for figure showing location. Tab 2.8 provides SedCad runs for ditch D-3 rerouting Segment B. Tab 2.9
provides SedCad design for ditch D-3, Segment A. Tab 2.10 provides SedCad design for ditch D-3, Segment B.
Tab 2.11 provides SedCad design for Ditch D-1. Tab 2.12 provides a typical ditch schematic. Tab 3.1 provides
design information for the B, D, E, G, and the miscellaneous culverts at the mine. Tab 3.2 provides design for
culvert 2-2 located at the tipple. Tab 3.3 provides culvert and low water crossing design for the Fish Creek
.Borehole access road. Tab 3.4 provides design information for culvert D-1. Tab 3.5 provides SedCad design for
the culvert at the wastewater treatment facility. Tab 3.6 provides design information for the Pond F access
Permit Renewal No. 3 Tab 1 Page 1 1/15/00