PERMFILE103125

• Permit No: C1982056
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: Tipple EXHIBIT 10 NPDES PERMIT
• Media Type: D
• Archive: No

COLORADO DEPARTMENT OF PUb...~ HEALTH AND ENVIRONMENT, Water Qr....rq~ Corrlrol Division
Rationale -Page 5, Permit No. CO-0036684
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b) Applicable Federal Effluent Guidelines and Standards: The federal guidelines which apply to this type of facilirv
are found under 40 CFR 434, titled Coal Mininr Point Source Effluent Guidelines. The limitations which apply
are:
Table VI-2 -Federal Standards (40 CFR 434)
Parameter . Limitations
30 Day Av¢ Daily rtfas
pH, s.u. (minimum -maximum) --6.0 - 9.0---
Total Suspended Solids, mg/P* 35
Total Iron, mg/P* 3.5
70
7.0
Settleable Solids, mP/P* N/A 0.5
These parameters rubjed 7o Burden of Proof Requiremenn, see nest section

Alternate Limitation Burden o(Proaf Requirements: In conformance with 40 CFR 434.63, the permirtee has the
burden ojprooj when requesting relief from total suspended solids (ISS), total iron and/or settleable solids
limitations, as appropriate. The intent of this regulation is ro afford relief only when needed due to a volume of
water generated by a specific storm event, it is not intended to be automatically applied to all discharges caused
6y precipitation, nor to be used to discharge volumes in excess of that generated by the storm event. On this
basis, relief shall be granted only when necessary and shall not be granted when the permirtee has control over
the discharge, enabling them to meet the primary limitations. The permirtee should endeavor to meet the
primary limitations whenever possible. Because manual dewarering can usually be accomplished as «me and
conditions permit, manual dewatering shall be required to meet the primary limitations -unless the .system has
no automatic dewatering device. Applicable systems shall be evaluated individually. Pit dervaterirrg is not
eligible for alternate limitations. The Division shall determine the adequacy of proof. As part of this
determination, the Division shall evaluate whether the permirtee could have controlled the discharge in such a
manner that primary [imitations could have been met.
For rainfall, to waive TSS and total iron limitations, it is necessary ro prove that discharge directly resrtlred
from a specific event and occurred through automatic dewatering devices within 48 hours nfrr• nrr: currhle
precipitation has stopped. /n addition, to waive settleable solids limitations, it is necessary to prove drat an
event greater than the magnitude of the 10-year, 24-hour event attuned.
For snowmelt, to waive TSS and total iron limitations, it is necessary to prove that discharge directly resulted
from snowmelt and occurred through automatic dewatering devices within 98 Irours after pond inflow has
stopped. In addition, to waive settleable solids limitations, it is necessary ro prove that an event greater than
the magnitude of the applicable 10-year, 24-hour event occurred.
c) Pollutants Limited by Water Oualirv Standards: For the parameters shown in Table VI-2, the mass balance
equation shown in VI.A.1. was used to calculate the allowable effluent limitations that would nor cause the
waver quality standards to be violated. These limitations are shown as the values far M= in Table VI-2. The
values for Qr, Q2 and Q~ for chronic and acute limitations, taken from section l/1.B.2. of this rationale, and
used in the calcu[atlons for water quality limited parameters are:
Flow Acute (l E3) .: Chronic (30E3)
i Qr
Q,
0.7 cfs 0.7 cfs
o.l tfs o.2s ~s
Q, 0.8 cfs 0.95 cfs