1987-12-01_PERMIT FILE - C1981017 ‎(278)‎

• Permit No: C1981017
• IBM Index Class Name: PERMIT FILE
• Doc Date: 12/1/1987
• Doc Name: Wastewater Discharge Permits
• Section_Exhibit Name: Chapter IV Appendix IV-C-1
• Media Type: D
• Archive: No

COLORADO DEPARTMENT OF HEALTH
Water Quality Control Division
4210 East llth Avenue
• Denver, Colorado 80220
RATIONALE
AMENDMENT NO. 5
MID-CONTINENT RESOURCES, INC.
PERMIT NUMBER CO-0000396
PITKIN COUNTY
BACKGROUND:
By letter of November 19, 1986, the permittee has requested authorization to
use existing outfall 016 as an alternate discharge point for the mine water now
discharged through outfall 004 (primarily) or 026 (Mine No. 1). Eventually,
this outfall will be used as an alternate for outfall 019 (Mine No. 2).
Outfall 016 is now the discharge point for surface runoff from the Rock Tunnel
area. The new discharge would consist of this surface runoff commingled with
mine drainage.
Three sedimentation ponds in series currently serve the area. Two more will be
added in the summer of 1987. The total capacity will be 18.82 acre-feet
(including sediment storage) . The 10-year, 24-hour precipitation event
equivalent volume for the area served is 3.65 acre-feet. Three years sediment
storage volume equals 3.24 acre-feet. The maximum flow of mine water is
expected to be 3.35 cfs (6.64 acre-feet). The permittee estimates 0.88
acre-feet/year of sediment from the mine water. For three years' storage, this
would require an additional 2.64 acre-feet in the ponds. Thus, a total volume
of 16.17 acre-feet is required. With 18.84 acre-feet of capacity, the ponds
can handle the mine water while retaining 10-year, 24-hour event containment
capability.
It should be noted that Mines 3, 4 and 5 are not currently operating.
APPLICABLE RULES & REGULATIONS:
The potential. will exist for continuous discharge of mine water from this
outfall. Thus, water quality standards (WQS) must be met. An earlier division
assessment for outfalls 004 and 019 determined that the only parameter which
must be limited is total recoverable iron. This is carried over to outfall
• 016. The receiving water Q7-10 (7-day, 10-year low flow) is zero. The WQS
for total recoverable.iron is 1.0 mg/l. When the Q7-10 is zero, the effluent
limitation equals the WQS.