HYDRO31631

• Permit No: C1981044
• IBM Index Class Name: Hydrology
• Doc Date: 1/7/1994
• Doc Name: RATIONAL FOR PUBLIC NOTICE
• Permit Index Doc Type: SEDIMENT POND INSPECTIONS
• Media Type: D
• Archive: No

COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rnrionale -Page 19, Permit No. CO-01~34142
f. Whole ERluent Toxicirv fWETI Terrine
required to joBow the automatic compliance schedule identified in Part I. B of the permit, if the observed
toxicity is due to organism lethality. Once the chronic letlwlity Ivnitation becomes effective, only
exceedance ojthe limitation specked in Pan LA.2. will trigger the requirement for conducting the
automatic compliance schedule identijed in Pan I.B. of the permit. Prior to and after the limitation
becomes effect, if the toxicity is due to differences in the growth of the fathead minnows or the
reproduction of the Ceriodaphnia, no immediate action on the pan of the permittee will be required.
However, [hie incidem, along with other WET data, will be evaluated by the Division and may form the
basis for reopening the permit and including adduional WET limits or othe.~ requirements.
(5J General Information: The ptrnuttte should read the WET testing sections of Pan I.A. and /.B. of the
permit carefully. The permit outliers the test requirements and the required follow-up actions the
permittee must take to resolve o toxicity incident. The permittee shouki read, along with the
doeumenu listed in Pan /.B of the permit, the Colorado Water Oualirv Control Division BiomonitorinA
Guidance Document. dated June I5, 1993. This document outlines the criteria used by the Division in
such areas as granting relief from WET testing, modifying test methods and changing test species.
The permittee should be aware that some of the conditions outlined above may 6e subject to change if
the facility experiences a change in discharge, as outlined in Pan 1/. A.! of the permit. Such changes
shall be reported to the Division immediately.
(6J Outfall 023 is exempt because it is a small domestic wastewater treatment plant. However, the
Division reserves the right to reopen the permit to include WET testing, should facility conditions
change or if new information becomes available.
4. Starmxnfer
Active and inactive coo! mining operations where stormwater comes into contact with overburden, raw
material, intermediate products, byproducts, finished products or waste products located at the mining site are
included in category (iii! of the federal stormwater regulations. Such facilities are required to have npplied
for a permit to discharge stormwater associated with mining activity on or before October 1, /992. Cyprus
Empire Corp. submitted an application for a general permit for stormwater discharges for the Eagle Mine
Complex on October 6, 1992. This facility's cert~cation under the genera! permit became effective on
November 5, 1992. The Eagle Mine Complex cert~catian number is CDR-04Q083.
Since the requirements for stormwater permits have just recently become effective, the Division's policy is to
cover as many facilities as possible [hat are included in the regulations, with general permits. For facilities
that also have indivrdual CDPS permits for discharge of process water, any applicable stormwater provisions
would then be included in individual CDPS permits at the time ojindividual permit renewal. The current
renewal of the Eagle Mine Complex CDPS permit (No. CO-0034142J will contain stormwater provisions.
When this renewal becomes effective, cert~cation COR-040083 will be inactivated. Under the terms of the
combined individual permit (CO-0034142!, Cyprus Empire Corp. will be nuthori:ed to discharge stormwater
associated with industrial activity into waters of the State of Colorado.
4. Stormwnter (coot!
The terms and conditions ojthir permit, as related to stormwater discharges, include:
n. Seerezation of stormwater Drscharees: All discharges covered by the stormwater portion of this permit