HYDRO22284

• 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 [
Page No. 12
Permit Nn.: CO-0043648
The permittee shall conduct each chronic WET test in general accordance with methods described Short Term Methods
for Estimating the Chronic Toxicity of Effluents and Receiving Waters [o Freshwater Organisms, EPA/600/4-89/001 or
the most current edition, except az modified by the most current Division guidance document entitled Guidelines for
Conductin¢ Whole Effluent Toxicitv Tests. The permittee shall conduct such tests using Ceriodaphnia dubia and fathead
minnows.
The pemtittee shall conduct each acute WET test in geoerel accordance with methods described in Methods for
Measurin¢ the Acute Toxicitv of Effluents and Receivin¢ Waters to Freshwater and Marine Organisms, EPA/600/4-
90/027 or the most current edition, except az modified by the most torten[ Division guidance document entitled
Guidelines for Conducting Whole EfFluent Toxicitv Tests. The permittce shall conduct an acute 48-hour WET test using
Ceriodaofmia sp., and an acute 96-hour WET test using fathead minnows. Acute tests wtll be replacement static tests of
a single efFluent grab sample.
(h) Failure of Test and Division Notification (Prior to Effective Dale of Limitation)
Prior to the effective date of the limitation, a chronic WET lest is failed whenever I) 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") and, 2) the IC,~, which represents an estimate of the effluent concentration at which 250 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 be 100 °k. The permiUee 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.(d)). Notification mast 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 LA.4(b),(c),(d) and (f)
means no later than the lazt day of the laboratory test.
An acute WET test is failed whenever the LCD, which represents an estimate o(the effluent concentration which is
lethal to 50`Yo of the test organisms in the time period prescribed by the test, is found to be less than or equal to
IOOR, 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')rI'oxicity identification Evaluatioo ("TIE')
investigation or accelerated testing is being performed (see next section). Notification mast be received by the
Division within 14 calendar days of the demonstration of acute WET in the routine required lest.
"Demonstration" for the purposes of Parts I.A.4(b),(c),(d) and (F) means no later than the last day of the laboretory
test.
(c) Failure of Test and Division Notification (Becinnitte on Effective 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 efluent concentration less than or equal to the instream
waste concentration ("IWC"). The IWC for this permit has been determined to be 100°h. 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 tasting is being
performed. 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 test.
For acute conditions, the same conditions listed in (b) above apply.
(d) Automatic Compliance Schedule Upon Failure of Test
If a routine chronic or acute WET lest 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~I'IE investigation as described in Part LA.4.e, or
(ii) conduct accelerated testing using the single species found to be more sensitive.
Corrected: 10/23/96