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 11. Permit No. CO-0032115.
VI. TERMS AND CONDITIONS OF PERMIT
The following discussion is applicable for discharge points 001,
008, 010, 012, 013 and 014.
Limitations for pR sad oil and grease apply to all discharges,
regardless of precipitation conditions. Additionally, TSS and
total iron samples should always be taken. If the results of
the analyses exceed the permit limit, the permittee may submit
documentation proving that the discharge was precipitation
induced. The proof of the size of the precipitation event
consists of:
(i) rain gauge data or the volume of water contained in the
snow, based upon calculations from actual snow samples;
(ii) the sample results for TSS, iron, pH, settleable solids and
oil sad grease; and
<iii) influent/effluent metered flow.
It is only upon acceptance by the Division of said proof that
the settleable solids limitation will apply in place o£ the TSS
sad 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 (i)-(iii), above. Upon
acceptance of proof that discharge was caused by precipitation,
compliance with TSS, total iron sad 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 inflow to the sedimentation pond has ceased.
b) Post-Mining Areas - 001, 006, 010, 012, 013 and 014: 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 shall be subject to
limitations other than those specified in Part I.A.1. These
post-mining limitations shall 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 011 and Grease is based on this
regulation.