REP42616

• Permit No: C1981008
• IBM Index Class Name: Report
• Doc Date: 12/11/2001
• Doc Name: NUCLA NPDES PERMINT CO-0000213
• Permit Index Doc Type: HYDROLOGY REPORT
• Media Type: D
• Archive: No

COLORADO DEPART;SENT OF HEALTH, Water Quality Control Division
Rationale - Page 9. Permit No. CO-0000213
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DISCUSSION OF PERMIT LIMITATIONS AND CONDITIONS:
J. Whole Effluent Toaicity (WET) Testing (Continued)
The Colorado Permit Regulations on biomonitoring call For several
approaches on llmits which are objectionable to EPA. In an effort to
maintain continuity of the permit issuance process, EPA and Colorado have
agreed to a temporary accommodation which calls for the imposition of
monitoring and a series of triggered responses for control of WET if
detected rather than immediate WET limits for selected Colorado permits.
These selected permits are limited to those facilities that have no loaowa
tonicity problem or potential for tonicity. A mandatory reopener clause
will be placed in this permit which calls for the imposition of limits in
three years in those cases where a real or potential WET problem has been
established. Occurence of tonicity during the fourth and fifth years
calls for the immediate introduction of limits. This approach is in
conformance with the objective of the Region VIII NPDES WET Control
Program is that, under both approaches, limits will be in effect in three
years where there is a tonicity problem. The reference in the reopener
clause to federal regulations directs that such limits must conform to
applicable federal regulations in effect at that time.
The determination as to whether or not an individual facility must conduct
• chronic WET testing is dependent upon the ratio of the chronic stream low
flow (30E3) to the design flow of the wastewater treatment plant, as well
as the receiving waters classifications. Since the Tuttle Draw is
classified as Aquatic Life Class 2 but does not have numeric inorganic and
metals standards, chronic biomonitoring is not required at this time.
Industrial facilities having simple effluents of consistent quality, which
can be totally characterized chemically, may request a full or partial
waiver of WET testing for the remainder of the life of the permit, subject
to Division approval, if the first four quarters of testing show no
pattern of toxicity.
The permittee should read the WET testing sections of Part I.A, and I.B.
of the permit carefully, and should note that the teat methods for the
toxicity testa are described in detail is the Division guidance document,
Guidelines for Conducting Whole Effluent Toaicity Tests. This document
should be read thoroughly prior to commencing the required WET testing, to
ensure that the permittee is aware of the various test conditions that
could affect the test results (e.g., sample holding time).
The permit tee should be aware that some 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.
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