HYDRO26010

• Permit No: C1981010
• IBM Index Class Name: Hydrology
• Doc Date: 4/7/1993
• Doc Name: RATIONALE FOR PUBLIC NOTICE
• Permit Index Doc Type: NPDES
• Media Type: D
• Archive: No

PART I
Page Ih of 19
Permit No. CO-0032115
B. MONITORING REQUIREMENTS
6. Frequency and Sample Tvce, Acute WET Testine - Outfalls 002, 003, 005, 006, 009, and 01 I
The monitoring frequency for acute WET tests shall be yuarerly, commencing with the first full calendar
quarter following the permit effective date.* Quarterly test resulu shall be reported along with the
Discharge Monitoring Repoli (DMR) submitted for the end of the reporting calendar quarter (i.e., WET
testing results for the calendar quarter ending March 31 shall be reported with the DMR due April 28, with
the remaining WET testing reports submitted with DMRs due each July 28, October 28 and January 28).
The results shall be submitted on the Acute Toxicity Test report form, available from [he Division. Copies
of these reports are to be submitted to both the Division and EPA.
* For outfalls 002 and 006, [he monitoring frequency for acute WET tests shall be once x year.
The permit[ee shall conduct each acute WET test in general accordance with methods described in [he
Division guidance document entitled Guidelines for Conducting Whole Effluent Toxicity Tests. The
permittee shall conduct an acute 48-hour WET test using Ceriodanhnia sp., and an acute 96-hour WET test
using fathead minnows. Acute tests will be replacement static tests of a single zfFluzm crab sample.
7. Accelerated Testing - Outfalls 002, 003, 005, 006, 009, and OI I
If an individual toxicity test shows toxicity at any concentration less Ihan or equal to the Instream Waste
Concentration (IWC) of 100%, or if 50% species mortality in any dilution is detected in any acute WET
test conducted in accordance with this permit, the permittee shall notify the Division verbally within 24
hours and in writing within 5 days of becoming aware of the toxicity. Within 7 days of becoming aware of
the toxicity, the permittee shall then begin accelerated testing of [he discharge with whichever spuies has
proven (through the first instance of toxicity) to be the most sensitive. The permittee will continue such
testing with one species, once every week until directed by the Division to do otherwise, but in no case for
more thin five represemative tests.
8. Preliminary Toxicity Investi~•ation
If directed by the Division, thz permittu shell perform a preliminary toxicity investigation. The permillee
will have IS working days from the date of Division notification to complete a preliminary toxicity
investigation end submit the results to the Division, in writing. The preliminary toxicity investigation may
include, but is not limited to: additional chemical and biolocical monitoring, zxamination of pretreatment
program records, examination of discharge monitoring reports, evaluation of treatment processes and
chemical use, inspection of material srorage and transfer areas to determine if a spill may have occurred,
and similar procedures.
If the preliminary toxicity investigation identifies a probahle toxicant and/or a probable source of roxicity,
the permittu shall submit, as part of its final report results, written notification to that effect to the
Division. Within 30 days of completing the preliminary toxicity investigation, the permittee shall submit
for the Division's approval a control program to control effluent toxicity, and shall proceed to implement
such plan within 7 days following approval from the Division.
Amended Effective