HYDRO22809

• Permit No: C1981010
• IBM Index Class Name: Hydrology
• Doc Name: RATINALE FOR PUBLIC NOTICE
• Permit Index Doc Type: CORRESPONDENCE
• Media Type: D
• Archive: No

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PART I
Page ldi of 19
Permit No. CD-0032115
A. TERMS AND CObIDTTI0N5
2. Burden of Proof Requirements
Tne permittee has the burden of proof when seeking relief from total suspended solids (TSS}, total
iron and/or settleable solids (SS) limitations. All discharges are eligible for this relief
providing the exceedence of effluent limitations is the result of precipitation. For outfalls 001,
003, 006, 006, 010, 012 and 014, the total discharges IRl.t consist of surface runoff; thus as long
as this is true, this relief is available. For outfalls 002, 009, 013, 015, 016 and 017, either
surface nmoff or mine water (or both) may be discharged, for outfalls 001 and 005, either surface
nmoff or spoils spring water (or both) may be discharged, for outfall 011, either surface nmoff or
mine water or spoils spring wafer (or all three) may be discharged. For this relief to be a~•ailable
for these six outfalls, the majority of the discharge must be surface runoff.
Relief may be granted for each discharge occurrence only when necessary and shall not be granted
when the permittee has control over the discharge. The permittee should endeavor to meet the
primary limitations whenever possible. The permittee will need to show that exceedence of the
applicable limitations was caused by precipitation and no other source and that the discharge was
beyond their control.
a) For rainfall, to waive TSS and total iron limitations, it is necessary to prove that discharge
occurred within 48 hours after measurable precipitation has stopped. In addition, to waive
settleable solids limitations, it is necessary to prove that discharge occurred within 48 hours
after precipitation greater than the 10-year, 24-hour event has stopped.
b) For snownielt. to waive TSS and total iron limitations, it is necessary to prove that discharge
occurred within 48 hours after pond inflow has stopped. In addition, to waive settleable solids
limitations, it is necessary to prove that discharge occurred within 48 hours after pond inflow
volwne greater than the 10-year, 24-hour event has stopped.
Should a precipitation event or snowmelt occur, the permittee shall submit adequate proof in order
for an exemption to be claimed. Said proof shall be submitted as an attachment to the Discharge
Monitoring Report (DMR) for the appropriate period. The Division shall determine the adequacy of
proof. As part of this determination, the Division shall evaluate whether the permittee could have
controlled the discharge in such a mariner that primary linti[ations could have been met. All mzmt~al
dewatering of the ponds shall meet TSS and total iron limitations.
3. Post-Minim Areas
Commencing at the time active mining has ceased and surface areas have been returned to die required
contour and revegetation has begun, all applicable discharges may be eligible for limitations other
than those specified in Parts I.A.1. These post-mining limitations shall remain in effect until
bond release. The permittee shall notify the Division ton cessation of active mining so that
consideration of appropriate permit modifications can be made.

Amendment 4 Issued Effective
See Part I.C. for Definitions.