Md. Code Regs. 26.08.04.02-4

Current through Register Vol. 51, No. 22, November 1, 2024

Section 26.08.04.02-4 - Discharge Permit Limits Based on Chemical Translator

A. General.

(1) The chemical translator is a mechanism for establishing the relationship between the dissolved concentration used in determining compliance with the instream aquatic life water quality criteria for metals and the measurement required for permit limits and waste load allocation.

(2) The chemical translator may not be used to establish discharge permit limits if the discharger has completed studies, under Regulation .02-3 of this chapter, which support the use of the biological translator.

B. Discharge Requirements for Use of the Chemical Translator.

(1) Before the use of a chemical 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 of 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 throughout the period of the 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 chemical translator to derive permit limits, a discharger shall repeat the process of data collection and calculation each time the permit is renewed or changed to assure that all factors influencing the chemical translator 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 chemical translator to the satisfaction of the Department.

C. Procedure.

(1) Notification. A discharger who wants permit limits developed using the chemical translator shall notify the Department in writing in accordance with Regulation .01-2B(4) of this chapter. This notification shall include:

(a) The metal or metals for which chemical translator limits are to be developed;

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

(c) The proposed methodology for deriving the chemical translator, including sampling times and locations, analytical methods, and all 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 necessary studies supporting the use of the chemical translator and apply to the Department for approval of the chemical translator within 12 months of this notification.

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

(a) Substance or substances for which the chemical translator limits are to be developed;

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

(c) Data supporting the chemical translator developed permit limits.

(4) Development of Chemical Translator. The chemical translator is a ratio designed to estimate concentrations of total recoverable metal from a water quality criterion applied as dissolved metal. This ratio shall be developed using one of the following methods:

(a) The discharger demonstrates, to the satisfaction of the Department, the ratio between dissolved and total recoverable metal concentrations through the collection and evaluation of appropriate field data; or

(b) For fresh receiving waters only, the discharger uses the following ratio of total recoverable (C_T) to dissolved (C) metal concentrations:

C_T divided by C = 1 + K_p[ss] x 10^-6th), where

(i) K_p is the linear partition coefficient in the units Kg^-1);

(ii) [ss] is the concentration of suspended solids in the units mg/L; and

(iii) K_p = K_po[ss]^a, where the values for Kpo and a are given in the following table:

LINEAR PARTITION COEFFICIENTS FOR PRIORITY METALS IN STREAMS AND LAKES
Streams		Lakes
Metal	K_po	a	K_po	a
Arsenic	0.48x10⁶	-0.73	(Assumed to be equal to streams)
Cadmium	4.00x10⁶	-1.13	3.52x10⁶	-0.92
Chromium	3.36x10⁶	-0.93	2.17x10⁶	-0.27
Copper	1.04x10⁶	-0.74	2.85x10⁶	-0.90
Lead	0.31x10⁶	-0.19	2.04x10⁶	-0.53
Mercury	2.9x10⁶	-1.14	1.97x10⁶	-1.17
Nickel	0.49x10⁶	-0.57	2.21x10⁶	-0.76
Zinc	1.25x10⁶	-0.70	3.34x10⁶	-0.68

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

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

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

Md. Code Regs. 26.08.04.02-4

Regulations .02-4 adopted effective June 7, 1993 (20:11 Md. R. 917)