HYDRO21916

• Permit No: C1980007
• IBM Index Class Name: Hydrology
• Doc Date: 3/6/1995
• Doc Name: CDPS permit
• Permit Index Doc Type: NPDES
• Media Type: D
• Archive: No

PART 1
Page 13
Permit No. CO-0038776
B. MONITORING REQUIREMENTS
4. Chronic WET Testing - Outfall 012 (continued)
If no pattern of toxicity is found the toxicity episode is considered to be ended and routine testing is to resume. 1f a
pattem of toxicity is found, sPTI/TIE investigation is to be performed. If a pattem of toxicity is not demonstrated
but a significant level of erratic tonicity is found, the Division rosy require an increased frequency of routine
monitoring or some other modified approach.
(d) PTIl1'lE
The results of the PTI/1'IE investigation ere to be received by the Division within 120 days of the
demonstration of chronic WET in the routine test to defined above or if accelerated testing is performed. the
date the pattern of toxicity is demonstrated A status report is to be provided to the Division at the 30 60
and 90 day points of the PTi/I'IE 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 Jay
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
e 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
TlE 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 aPTI/TIE investigation shall do so in conformance with procedures
identified in the following documents, or as subsequently updated: 1) Toxicity Identification Evaluation:
Characterization of Chronically Toxic Efnuents. Phase I, EPA/600/6-91/OOSF May 92, 2) Methods for Aquatic
Toxicitv Identification Evaluations. Phase 1 Toxicitv Characterization Procedures, EPA/600/6-91/003 Feb. 91 and 3)
Methods for Aquatic Toxicitv Identification Evaluations. Phase II Toxicitv Identification Procedures, EPA/600/3-
88/035 Feb. 1989.
A fourth document in this series is Methods for Aauetic Toxicitv Identification Evaluations, Phase llI Toxicitv
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 method and procedure for elimination of the toxicity to acceptable levels.
(e) Reouest 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 apptar possible. In requestinc such relief, the permitter
shall submit material sufficient to establish the following:
(i) It has complied with terms and conditions of the permit compliance schedule for the PTI/T[E investigation
and other appropriate conditions as may have been required by the Division;
(ii) During the period of the toxicity incident it has been in compliance with all other permit conditions,
including, in the case of a POTW, pre-treatment requirements;
(iii) During the period of the toxicity incident it has properly maintained and operated all facilities and systems
of trutment and control; and
INnIIP 9/9/97