HYDRO26625

• Permit No: C1981010
• IBM Index Class Name: Hydrology
• Doc Date: 6/3/1991
• Doc Name: RATIONALE FOR PUBLIC NOTICE
• Permit Index Doc Type: NPDES
• Media Type: D
• Archive: No

COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale - Page 15. Permit No. CO-0032115.
VI. TERMS AND CONDITIONS OF PERMIT
2. Change in Discharge: During mining, the dragline can be moved
along several local watersheds. Because of this, the series of
sediment ponds to be used for the mine dewatering can change in a
relatively short period of time. The permittee wishes to maintain
flexibility in which discharge points are used for mine dewatering
water. Specifically, discharge points 001, 008 and 010, which are
currently used for stormwater runoff only, may be used in the
future for mine dewatering as well.
The monitoring requirements and permit limits for outfalls with
mine water are more rigorous than for those outfalls with only
surface runoff (e.g., WET tenting is required, and
precipitation-induced discharges cannot be exempt from the TSS and
T. Iron limits). During times when the ponds are not used for mine
dewatering, this puts unnecessary monitoring requirements on the
permittee. Therefore, this permit will list the notification
requirements whereby the permittee may change the status of a
discharge point from having only surface runoff as the source to
adding mine water. To make this change, the permittee is
technically required to notify the Division 180 days prior to the
change taking place. However, the Division will try to streamline
the amendment process to the eztent possible, so that the changes
can go into effect as quickly as possible. (Public notice of the
amendment will still be required.)
Notification shall include:
- the discharge point in question;
- the source(s) of wastewater;
- the estimated volume, in MGD; and
- the estimated length of time such dewatering will occur with
relation to this discharge point.
Once this notification has been reviewed and approved by the
Division, the Division will institute an amendment to the permit to
change the effluent limits for that discharge point from those in
Table VI.1 or Table VI.2, to those in Table VI.3, which are
appllca le to mine water discharges. WET testing will now be
required at these points.
If the permi[tee desires to reverse the process, and eliminate the
mine water as a source at a discharge point, the same procedure for
amending a permit must be followed. Also, the permittee must be
able to document thaC ao sigaificaat amount of mine water remains
in the sediment pond(s) in question.
D. Specific Compliance Requirements
1. Submissions to the Division: The following are specific compliance
items w ch require permittee action. Please check the referenced
parts of the permit for details on what is required.