HYDRO25740

• Permit No: C1981010
• IBM Index Class Name: Hydrology
• Doc Date: 2/7/1994
• Doc Name: RATIONALE FOR PUBLIC NOTICE
• Permit Index Doc Type: NPDES
• Media Type: D
• Archive: No

PART I
Page li of 19
Permit No. CO-0032115
B. MONITORING REQUIREMENTS
4. Acute WET Testin¢-Outfalls 002. 005. 009. 011. 013 and 015 (continued)
(d) PTI TIE
The results of the PTI/TIE investigation are to be received by the Division
within 120 days of the demonstration of acute WET in the routine test. as
defined above. or if accelerated testing is performed. the date the oattern of
toxicity is demonstrated. A status reoort is to be urovided to the Division
at the 30. 60 and 90 day points of the PTI/TIE investigation. The Division
may extend the time frame for investigation where reasonable justification
exists. A request for an extension must be made in writing and received prior
to the 120 day deadline. Such request must include a justification and
supporting data for such an extension.
The permittee may use the time for investigation to conduct a PTI or move
directly into the TIE. A PTI consists of a brief search for possible sources
of WET, which might reveal causes of such toxicity and appropriate corrective
actions more simply and cost effectively than a formal TIE. If the PTI allows
resolution of the WET incident, the TIE need not necessarily be conducted.
If, however, WET is not identified or resolved during the PTI, the TIE must be
conducted within the allowed 120 day time frame.
Any permittee that is required to conduct a PTI/TIE investigation shall do so
in conformance with procedures identified in the following documents, or as
subsequently updated: 1) Methods for Aquatic Toxicity Identification
Evaluations, Phase I Toxicity Characterization Procedures, EPA/600/6-91/003
Feb. 91 and 2) Methods for Aquatic Toxicity Identification Evaluations. Phase
II Toxicity Identification Procedures, EPA/600/3-88/035 Feb. 1989.
A third document in this series is Methods for Aquatic Toxicit~Identification
Evaluations. Phase III Toxicity Confirmation Procedures, EPA/600/3-88/036 Feb.
1989. As indicated by the title, this procedure is intended to confirm that
the suspected toxicant is truly the toxicant. This investigation is optional.
Within 90 days of the determination of the toxicant or no later than 210 days
after demonstration of toxicity, whichever is sooner, a control program is to
be developed and received by the Division. The program shall set down a
me[hod and procedure for elimination of the toxicity to acceptable levels.
(e) Request For Relief
The permittee may request relief from further investigation and testing where
the toxicant has not been determined and the Division has determined suitable
treatment does not appear possible. In requesting such relief, the permittee
shall submit material sufficient to establish the following:
(i) It has complied with terms and conditions of the permit compliance
schedule for the PTI/TIE investigation and other appropriate conditions
as may have been required by the Division;
(ii) During the period of the toxicity incident
with all other permit conditions, including
pretreatment requirements;
it has been in compliance
in the case of a POTW,
Amendment 2 Issued Effective