HYDRO26429

• Permit No: C1981041
• IBM Index Class Name: Hydrology
• Doc Date: 7/27/1992
• Doc Name: AUTHORIZATION TO DISCHARGE UNDER THE COLORADO DISCHARGE PERMIT SYSTEM
• Permit Index Doc Type: NPDES
• Media Type: D
• Archive: No

PART I
Page lg of 19
Permit No, CO-0027146
B, MONITORING REQUIREMENTS
4. Acute WET Testing - Outfalls 001. 002. 004 and 015 (continued)
Notification must be received by the Division within 14 calendar days of the
demonstration of acute i7ET in the routine required test. "Demonstration" for the
purposes of Parts I.B.4(b),(c),(d) and (f) means no later than the last day of
the laboratory test.
(c) Automatic Compliance Schedule Upon Failure of Test
If a routine acute WET test is failed, regardless of whether the limit is in
effect, the following automatic compliance schedule shall apply, As part of this
the permittee shall either:
(i) proceed to conduct the PTI/TIE investigation as described in Part
I.B.4.(d), or
(ii) conduct accelerated testing using the single species found to be mare
sensitive.
If accelerated testing is being performed, the permittee shall provide written
notification of the results within 14 calendar days of completion of the "Pattern
of Toxicity"/"No Toxicity" 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.
(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 testi ¢ is performed, the date the pattern of
toxicity is demonstrated. A status report Ss to be provided to the Division at
the 30. 60 and 90 day points of the P I/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.
Amendment No. 1 Issued 0 7 P' 4 Effective Dy D/ 4