HYDRO25963

• Permit No: M1980244
• IBM Index Class Name: Hydrology
• Doc Date: 3/12/1992
• Doc Name: AUTHORIZATION TO DISCHARGE UNDER THE COLO DISCHARGE PERMIT SYSTEM
• Media Type: D
• Archive: No

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Part I
Page li of 19
Permit No. CO-0042562
B. MONITORING REQUIREMENTS
11. Frequency and Sample Type - Chronic WET Testing
The monitoring frequency for chronic toxicity tests shall be once every
six months on a January - June, July - December sequence, and cannot
coincide with acute testing. Chronic tests will be static replacement
tests using three composite effluent samples, each of which is to be
composited for a minimum of eight hours. Chronic testing will be
conducted with both Ceriodaphnia ap. and fathead minnows during the
first year. During years two and three, if requested in writing by the
permittee, the Divsion may grant relief from continued two species
testing. Such relief shall be for continued testing with only that
species which has demonstrated the greatest sensitivity during the first
year of testing. The results shall be submitted on the Chronic Toxicity
Test report form, available from the Division. Copies of these reports
are to be submitted to both the Division and EPA.
The permittee shall conduct each chronic toxicity test in general
accordance with methods described in the Division guidance document
entitled Guidelines for Conducting Whole Effluent Toxicity Tests.
As general information, chronic toxicity occurs when there is a
statistically significant difference in survival, growth or reproduction
for either species.
12. Toxicity Reopener
This permit may be reopened and modified (following proper
administrative procedures) to include new compliance dates, additional
or modified numerical permit limitation, a new or different compliance
schedule, a change in the whole effluent toxicity testing
protocol, or any other conditions related to the control of toxicants if
one or more of the following events occur:
a. Toxicity has been demonstrated in the effluent and the permit does
not contain an toxicity limitation.
b. The THE results indicate that the toxicant (s) represent pollutant(s)
that may be controlled with specific numerical limits, and the permit
issuing authority agrees that the numerical controls are the most
appropriate course of action.
c. The THE reveals other unique conditions or characteristics which, in
the opinion of the permit issuing authority, justify the
incorporation of unanticipated special conditions in the permit.