PERMFILE139367

• Permit No: C1981013
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: Exhibit 22 NPDES Permit Part 2
• Media Type: D
• Archive: No

COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale - Page 2. Permit No. CO-0033367

PURPOSE OF AMENDMENT:
By letter of September 16, 1988, the permittee has requested an amendment to
their permit to add a new discharge point (005), and to combine two existing
points, 001 and 004.
In January of 1988, the permittee informed the Division that, due to an
unexpected increase of mine water at the facility, they were not able to treat
the entire flow volume at Pond 002. They then requested that they be allowed
to discharge some of the mine water through Pond 003, on a temporary basis,
with the expectation that the source would dry up within the nett few weeks.
The Division agreed, with the stipulations that the mine water permit limits
for 002 would apply at 003, and that the monitoring frequencies would be
increased. The Colorado Mined Land Reclamation Division also approved the
arrangement. (Their approval was needed since Pond 003 is designed for runoff
control, and its capacity for this function was decreased as long as mine
water was present.) In mid-February, the permittee requested an extension to
this permission, due to the source of water continuing.
Also at this time, the permittee was having difficulty in meeting the Total
Suspended Solids (TSS) limits in the permit for the mine water, and so began
to use a flocculant as part of the treatment process. The Division has
alleged that this flocculant caused a fish kill in the Purgatoire River, and
• is currently pursuing an enforcement action. However, this incident will not
have an impact on the permit amendment, except as outlined under Paragraph H,
Discussion, which deals with flocculant use.
In the meantime, since the increased mine water flow has continued unabated,
the permittee is planning to construct a new pond (005) for treatment of the
additional water. The design of the pond will be similar to the design of
Pond 003, since it has been shown to provide adequate treatment of the mine
water. Ponds 002 and 005 will both be used for mine water, with Pond 005 as
the primary system. Pond 002 will be used for additional surge capacity and
when Pond 005 requires maintenance. The estimated maximum flow from 005 is
500 gpm (0.72 MGD). Discharge point 005 shall be the outfall from Pond 005,
as shown in Figure 1, Part III of the permit.
The permittee submitted monitoring data for June through August, 1988, at 002
and 003. One minor pH violation was reported for 003; 002 had several TSS
violations, due to the pond being overloaded. Additionally, the permittee
submitted data for the mine water in January, 1988, to demonstrate the quality
of the mine water to be discharged at 003 (see Appendix B). All of the metals
were below the WQS for the Purgatoire River. The TSS level was high, but this
was prior to treatment by settling. (Previous monitoring data is not relevant
since the site conditions have changed.)
The permittee has also indicated that the permit does not accurately reflect
site conditions concerning discharge from the domestic wastewater treatment
facility (WWTF). The permit shows that the WWTF effluent discharges directly
• to Ciruela Canyon via 001. This has been changed; WWTF effluent 'is now routed
to Pond 004 to provide additional treatment. The pond is sized large enough
to be able to handle runoff from a 10-year, 24-hour storm event as well as the