HYDRO29975

• Permit No: C1981022
• IBM Index Class Name: Hydrology
• Doc Date: 11/12/1991
• Doc Name: RATIONALE FOR PUBLIC NOTICE
• Permit Index Doc Type: NPDES
• Media Type: D
• Archive: No

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COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale - Page 8. Permit No. CO-0000132.
VI. TERMS AND CONDITIONS OF PERMIT
It is only upon acceptance by the Division of said proof that
the settleable solids limitation will apply in place of the TSS
and total iron limitations for precipitation events that are
less than or equal to the 10-year, 24-hour storm event. Failure
to submit the required information will result in the denial of
the exemption by the Division.
Similarly, for precipitation events greater than the 10-year,
24-hour event (or equivalent snowmelt volume), proof of the size
of the storm will consist, again, of (1)-(iii), above. Upo^
acceptance of proof that discharge xas caused by precipitation,
compliance xith TSS, total iron and settleable solids
limitations will be exempted. This means such a discharge would
be subject to pH and oil and grease limitations only for the
exempted timeframe. The Division allows these exemptions for a
period of to 48 hours after measurable rainfall has stopped.
For snowmelt, the Division allows these exemptions for a period
up to 48 hours after inflox to the sedimentation pond has ceased.
b) Post-Mining Areas - discharge points 003, 004, 005, 006, 007,
009 and 010: Commencing at the time active mining has ceased
and surface areas have been returned to the required contour,
and the permit has .been modified, all applicable discharges
skull be subject to limitations other than those specified in
Part I.A.1. These post-mining limitations skull remain in
effect until bond release. The permittee shall notify the
Division upon cessation of active mining so that appropriate
permit modifications can be made.
3. Regulations for Effluent Limitations: The Regulations for Effluent
Limitations 10.1.0 apply to the conventional pollutants. For
this facility the limitation for 031 and Grease is based on this
regulation.
4. Discussion of Limitations:
a) Salinity (Total Dissolved Solids): The Regulation for
Implementation of the Colorado Salinity Standards Through the
Colorado Discharge Permit Program (3.10.0), addresses the
discharge of total dissolved solids (TDS) to the Colorado River
Basin. It is a requirement of this regulation that all
discharges into the Colorado River basin be monitored for TDS on
a continual basis. Therefore, in compliance with this
regulation the permittee must monitor for TDS on a quarterly
basis at discharge points 003, 004, 005, 006, 007, 009 and 010.