HYDRO27562

• Permit No: C1982056
• IBM Index Class Name: Hydrology
• Doc Date: 3/31/1998
• Doc Name: AUTHORIZATION TO DISCHARGE UNDER COLO DISCHARGE PERMIT SYSTEM
• Permit Index Doc Type: NPDES
• Media Type: D
• Archive: No

PART I
Page In of 14
Permit No. CO-0027154
MONITORING REQUIREMENTS
4. Chronic WET Testing-Outfalls 001.. 005 and 007 (continued)
If accelerated testing is being performed, the permittee shall provide rritteth
notification of the results within 14 calendar days of completion of the "Pattei-~1
of Tozlcity"/"No To:ieity" demonstration. Testing will be at least once every two
weeks for up to five tests until; 1) two consecutive tests fail or three of five
tests fail, in which case a pattern of toxicity has been demonstrated or 2) two
consecutive tests pass or three of five tests pass, in which case no pattern of
toxicity has been found. If no pattern of toxicity is found the toxicity episode
is considered to be ended and routine testing is to resume. If a pattern of
toxicity is found, a PTI/TIE investigation is to be performed. If a pattern of
toxicity is not demonstrated but a significant level of erratic toxicity is found,
the Division may require an increased frequency of routine monitoring or some other
modified approach.
(e) PTI TIE
The results of the PTI/TIE investigation are to be received by the Division within
120 davs of the demonstration of chronic WET in the routine test. as defined above.
or if accelerated testing is verformed. the date the vattern of toxielty is
demonstrated. A status report is to be provided 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 yustification 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) Toxicitv Identification Evaluation: Characterization of
Chronically Toxic Effluents. Phase I, EPA/600/6-91/OOSF May 92, 2) Hethods for
Aquatic Toxicit~Identification Evaluations. Phase I 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 Aavatic Toxicitv 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.
Amendment No. 2 Issued ,~'/~'4 y Effective~~