HYDRO29812

• Permit No: C1981041
• IBM Index Class Name: Hydrology
• Doc Date: 6/8/1992
• Doc Name: RATIONAL FOR PUBLIC NOTICE POWDERHORN COAL CO
• Permit Index Doc Type: NPDES
• Media Type: D
• Archive: No

COLORADO DEPARTMENT OF HEALTH, Water Quality Control Division
Rationale - Page 16. Permit No. CO-0027146
VI. TERMS AND CONDITIONS OF PERMIT
A. Effluent Limitations (continued)
5. Whole Effluent Toxicicv (WETS Testing (continued)
Chroi:ic Biomonicotine: (continued) For outfalls 001 and 002,
discharge is co the Colorado River, which is classified aquatic
life 1 (warm). On this basis, chronic LIET testing is required
for these outfalls regardless of the dilution ratio. For
outfall 004, discharge is to Coal Creek. Coal Creek is not
classified aquatic life 1; however the ratio of receiving water
to design flow is 0:1; therefore chronic WET testing is
required, also, for outfall 004. Such testing shall be
"semi-annually, with two species for the first year, and with
only the most sensitive species during years two and three.
After the third year of monitoring, the chronic testing
{ requirement ends unless applicable regulations are adopted.
~_
General Information: The permittee should read the WET testing
sections of Part I.A. and I.B. of the permit carefully, and
should note chat the test methods for the toxicity tests are
described in detail in the Division guidance document,
Guidelines for Conducting Whole Effluent Toxicicv Tests. This
document should be read thorough l}' prior to commencing the
required WET testing, to ensure chat the permittee is aware of
tkie various test conditions chat could affect the test results
(e.g., sample holding time).
Tha permittee should be aware that same of the conditions
outlined above may be subject to change if the facility
experiences a change in discharge, as outlined in Part II.A.1 of
the permit. Such changes shall be reported to the Division
immediately.
WET Tescine Waiver For Outfalls 005 - 014: Based upon the
exemption for coal mining surface runoff, as allowed in the
Regulations for the State Discharge Permit System (6.1.0), WET
testing is not a requirement for outfalls 005 - 014. However,
the Division reserves Che right co reopen the permit to include
WET testing, should facility conditions change or if new
information becomes available.
6. Economic Reasonableness Evaluation: Section 25-B-503(8) of the
revised (June 1985) Colorado Water Quality Control Acc required
the Division co "determine whether or not any or all of the
water quality standard based effluent limitations are reasonably
related to the economic, environmental, public health and energy
impacts co the public and affected persons, and are in
furtherance of the policies sec forth in sections 25-8-192 and
25-8-104."