Sec. 26.08.04.02-3. Discharge Permit Limits Based on Biological Translator

A. General. Biologically available equivalence addresses the potential for an effluent constituent, present primarily in the particulate or relatively non-bioavailable form, to become transformed by mixing with the receiving water to a bioavailable form. The biological translator utilizes the relationship between effluent-receiving water toxicity testing results and the laboratory standard dilution water toxicity data to relate an instream aquatic life criterion to the impact of a specific effluent. This ratio provides discharge-specific information concerning the assimilative capacity of the surface water for a specific pollutant when contained in a particular discharge.

B. Discharge Requirements for Use of the Biological Translator.

(1) Before the use of a biological translator in a waste load allocation to determine specific discharge permit limits, a discharger shall demonstrate:

(a) For acute aquatic life criteria, a history of repeated whole effluent toxicity testing at four consecutive quarterly intervals where the effluent, upon allowance for confirmation tests on failures, consistently exhibits an LC₅₀ greater than 100 percent;

(b) For chronic aquatic life criteria, a history of repeated whole effluent toxicity testing at four consecutive quarterly intervals where the effluent, upon allowance for confirmation tests on failures, consistently exhibits an IC₂₅ greater than the instream waste concentration at the edge of the chronic mixing zone; and

(c) Achievement of best available technology with satisfactory operation and maintenance.

(2) The discharger shall continue to demonstrate, as appropriate, through whole effluent toxicity testing at quarterly intervals, as required by the discharge permit:

(a) An LC₅₀ which, upon allowance for confirmation tests for failures, consistently exceeds 100 percent; or

(b) An IC₂₅ which, upon allowance for confirmation tests for failures, consistently exceeds the instream waste concentration at the edge of the chronic mixing zone.

(3) To have the Department continue using a biological translator to derive permit limits, a discharger shall repeat the process of data collection and effects ratio calculation each time the permit is renewed or changed to assure that all factors influencing the effluent-receiving water effects ratio remain the same.

(4) The discharger shall demonstrate that no new BAT is available at each permit renewal.

(5) The discharger shall provide all the necessary data to support the biological translator to the satisfaction of the Department.

C. Procedure.

(1) Notification. A discharger who wants permit limits developed using the biological translator shall notify the Department in writing in accordance with Regulation .01-2B of this chapter. This notification shall include:

(a) The substance or substances for which biologically available equivalence limits are to be developed;

(b) The data demonstrating that the preconditions specified in §B of this regulation have been met; and

(c) The proposed methodology for deriving the biological translator, including sampling times and locations, effluent dilutions, species to be tested, and laboratory quality assurance/quality control procedures.

(2) Time for Completion of Studies. A discharger, having notified the Department as required by §C(1) of this regulation, shall complete all studies supporting use of the biological translator and apply to the Department for approval of the biological translator within 12 months after this notification.

(3) Application. An application for the biological translator shall include the:

(a) Substance or substances for which biologically available equivalence limits are to be developed;

(b) Most recent data collected to satisfy the preconditions in §B of this regulation; and

(c) Data supporting the biological translator.

(4) Development of the Biological Translator. The biological translator shall be developed in accordance with "Guidelines for the Use of a Biological Translator in Wasteload Allocations", (MDE-WMA-003, March 16, 1992), which is incorporated by reference, and current EPA sampling and testing procedures listed in the 1994 Interim Guidance on Determination and Use of Water-Effect Ratios for Metals (EPA-823-B-94-001) or the 2001 Streamlined Water-Effect Ratio Procedure for Discharges of Copper (EPA-822-R-01-005), which are incorporated by reference.

(5) Time for Department Action on Application. The Department shall complete its review and either approve or deny use of the biological translator within 6 months after receipt of the application.

(6) Use of the Biological Translator. When the Department has completed its review and determined that the supporting data are satisfactory, the Department shall use the resulting ratio with the appropriate water quality criterion to obtain a revised value for use in the derivation of a permit limit.

(7) Unsatisfactory Biological Translator. If the Department determines that the data supporting the biological translator are unsatisfactory, the Department may not use the resulting ratio. The discharger shall be required by the Department to revise the application or select an alternative approach for establishing permit limits.

(8) Public Participation. Those permit limits developed using the biological translator shall be included in the draft NPDES permit and in the public participation process for permit review.