HYDRO24170

• Permit No: M1980244
• IBM Index Class Name: Hydrology
• Doc Date: 11/11/1996
• Doc Name: AUTHORIZATION TO DISCHARGE UNDER THE COLO DISCHARGE PERMIT SYSTEM
• Media Type: D
• Archive: No

Part i
Page No. 12
Permit No.: CO-0043648
The permittee shall conduct each cfironic WET test in general accordance with methods described Short Term Methals
for Estimative the Chronic Toxicitv of EfFluents and Receivin¢ Waters [o Freshwater Oreanisms, EPA/600/4-89/OOI or
the most current edition, except as modified by the most current Division guidance document entitled Guidelines for
Conductine Whole EfFluent Toxicity Tests. The permittee shall conduct Stich tests using Ceriodaphnia dubia and fathead
minnows.
The permittee shall conduct each acute WET test in general accordance with methods described in Meth«Is for
Measurine the Acute Toxicitv of EfFluents and Receivine Waters to Freshwater and Marine Oreanisms, EPA/600/4-
90/027 or the most current edition, except as modified by the most current Division guidance document entitled
Guidelines for Conductine Whole EfFluent Toxicitv Tests. The pernittee shall conduct an acute 48-hour WET test using
Ceriodamhnia sp., and an acute 96-hour WET test using fathead minnows. Acute tests will be replacement static tests of
a single effluent grab sample.
(h) Failure of Test and Division Notification (Prior to Effective Date of Limitation)
Prior to the effective date of the limitation, a chronic WET test is failed whenever I) there is a statistically significant
difference in lethality hetwrzn the control and any effluent concentration lass than or eyual to the instream waste
concentration ("IWC') and, 2) the IC3, which represents an estimate of the effluent concentration at which 2S`Po of
the test organisms demonstrate inhibition as reFlected by lethality, is at any efFluent concentration less than or equal
to the IWC. The IWC for this permit has been determined to he 100 °.b. The pumittee must provide written
notification of the failure of a WET test to the Division, along with a statement as to whether a Preliminary Toxicity
Investigation ("PTI')/Toxicity Identification Evaluation ("TIE') ..r accelerated testing is being performed (see Part
LA.4.(dp. Notification mutt he received by the Division within 21 calendar days of the demonstration of
chronic WET in the routine required test. "Demonstration" for the purposes of Parts I.A.4(h),(c),(d) and (f)
means no later than the last day of the laboratory tesC.
An acute WET test is Failed whenever the LCD, which represents an estimate of the effluent concentration which is
lethal to SONY of the test organisms in the time period prescribed by the test, is found to be less than or equal to
IOOSb effluent. The permittee must provide written notification of the failure of a WET test to the Division, along
with a statement as to whether the Preliminary Toxicity Incident ('PTI')/Toxicity Identification Evaluation ("TIE")
investigation or accelerated testing is being performed (see next section). Notification mutt Fee received by the
Division within l4 calendar days of the demonstration of acute WET in the routine required lest.
'Demonstration" for the purposes of Para I.A.4(b),(c),(d) and (fJ means no later than the last day of the laboratory
test.
(c) Failure of Test and Division Notification (BeQinnitt¢ on EtFeclive Date of Limitation)
Beginning on the effective date of the limitation, a chronic WET test is failed whenever there is a statistically
significant difference in lethality between the control and any efFluent concentration less than or equal to the instream
waste concentration ("IWC"). •The IWC for this permit has been determined to be 100°k. The permittee must
provide written notification of the failure of a WET test to the Division, along with a statement as to whether a
Preliminary Toxicity Investigation ('PTI')/Toxicity Identification Evaluation ('TIE") or accelerated testing is being
perforned. Notification must be received by the Division within 21 calendar days of the demonstration of
chronic WET in the routine required test. 'Demonstration" for the purposes of Parts I. A.4(h),(c),(d), (e) and (g)
means no later than the last day of the laboratory [est.
For acute conditions, the same conditions listed in (b) above apply.
(d) Automatic Compliance Schedule Unon Failure of Test
If a routine chronic or 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) proceul to conduct the PTI~I'IE investigation as descrihetl in Part I.A.4.e, or
(ii) conduct accelerated testing using the single species found to be more sensitive.
Corrected: 10/23/96