Mich. Admin. Code R. 323.1209 - Development of wasteload allocations for toxic substances

Rule 1209.

(1) In the absence of a total maximum daily load (TMDL) established under R 323.1207, or where consistent with a TMDL, the following procedure shall be used to calculate individual point source wasteload allocations (WLAs) for aquatic life, human health, and wildlife values consistent with the requirements of R 323.1211(2):

(a) Chronic WLAs for discharges to lotic waters shall be developed for the toxic substance as follows:

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Where:

Zt = water quality value developed for the toxic substance expressed as total or total recoverable.

Zd = water quality value for aquatic life expressed as dissolved metal. Values expressed as dissolved, but for which a translator (T) is not available, shall be expressed as total or total recoverable for purposes of this subdivision.

T = dissolved to total metal translator for aquatic life wasteload allocations. For the metals in table 2, T equals the given value or one derived from site- specific data. For metals not listed in table 2, T is equal to a translator derived by the department when sufficient information is available or from site-specific data.

Qe = effluent design flow, which is the annual average design flow for municipalities and maximum authorized flow for other facilities, unless it can be demonstrated to the department that an alternate design flow is appropriate.

Qr = flow of the receiving water allocated for mixing under R 323.1082. If a discharger has an intake upstream of the point of discharge, then Qr shall reflect the reduction in the design flow volume attributable to the intake.

Cr = receiving water background concentration of the toxic substance developed under R 323.1207(1)(g).

The lowest of the WLAs developed under this subdivision for the chronic aquatic life, human health, or wildlife values for each toxic substance shall be the basis for the water quality-based effluent limit (WQBEL) as specified in R 323.1211(4)(a).

Table 2.

Dissolved to total metal translators for aquatic life wasteload allocations.

Toxic Substance	Translator (T)
Cadmium ...................................................	2.1
Chromium ..................................................	1.5
Copper ........................................................	1.5
Lead ...........................................................	4.5
Nickel .........................................................	1.1
Zinc ............................................................	2.1

(b) Chronic WLAs for discharges to the Great Lakes and inland lakes shall be developed for a toxic substance as follows:

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Where:

Zt = the lowest water quality value developed for the toxic substance expressed as total or total recoverable.

Zd = water quality value for aquatic life expressed as dissolved metal. Values expressed as dissolved, but for which a translator (T) is not available, shall be expressed as total or total recoverable for purposes of this subdivision.

T = dissolved to total translator for aquatic life wasteload allocations. For the metals in table 2, T equals the given value or one derived from site- specific data. For the metals not listed in table 2, T is equal to a translator derived by the department when sufficient information is available or from site-specific data.

Q = number of parts receiving water allocated for mixing under R 323.1082(5).

Cr = receiving water background concentration of the toxic substance developed under R 323.1207(1)(g).

The lowest of the WLAs developed under this subdivision for the chronic aquatic life, human health, or wildlife values for each toxic substance shall be the basis for the WQBEL as specified in R 323.1211(4)(a).

(2) If the receiving water background concentration (Cr) of a toxic substance exceeds the most stringent applicable water quality value for that substance, then the WLA shall be established equal to the most stringent water quality values, unless the provisions of R 323.1211(7)(d) allow for a different approach.

(3) WLAs based upon acute aquatic life protection shall not exceed the following acute WLA, unless it can be demonstrated to the department that a higher level is acceptable under R 323.1082(1). :

WLA = (At)

or

WLA = (Ad)(T)

Where:

At = the final acute value developed for the toxic substance under R 323.1057 expressed as total or total recoverable.

Ad = final acute value for aquatic life expressed as dissolved metal under R 323.1057. Values expressed as dissolved, but for which a translator (T) is not available, shall be expressed as total or total recoverable for purposes of this subdivision.

T= dissolved to total translator for aquatic life wasteload allocations. For the metals in table 2, T equals the given value or one derived from site- specific data. For the metals not listed in table 2, T is equal to a translator derived by the department when sufficient information is available or from site-specific data.

(4) When establishing WLAs based on human health values for individual point source discharges, the potential interaction between multiple toxic substances in the effluent shall be addressed by the following provisions:

(a) If an effluent contains carcinogens for which available scientific information supports a reasonable assumption that the toxic substances produce the same type of cancer through the same mechanism of action and for which WQBELs are required pursuant to R 323.1211 on an individual basis, then the total incremental risk created by the effluent in the surface waters of the state after mixing with the allowable receiving water body volume specified in R 323.1082 shall not exceed 1 X 10^-5for individual carcinogens and 1 X 10^-4for the total effluent. This additivity provision shall be implemented on a case-by-case basis and shall be evaluated at each facility independent of other carcinogens that may be present in the receiving water.

(b) If an effluent contains 2 or more noncarcinogens for which available scientific information supports a reasonable assumption that the toxic substances produce the same adverse effects through the same mechanisms of action and for which WQBELs are required under R 323.1211 on an individual basis, then the noncarcinogenic effects of the chemicals may be assumed additive and considered by the department when calculating WLAs protective of human health. This subdivision shall be implemented on a case-by-case basis and shall be evaluated at each facility independent of other noncarcinogens that may be present in the receiving stream.

(c) Notwithstanding the requirements in subdivisions (a) and (b) of this subrule, human health-based WLAs for the chlorinated dibenzo-p-dioxins (CDDs) and chlorinated dibenzofurans (CDFs) listed in table 2 shall be calculated using the following procedures:

(i) The human cancer value and human noncancer value for 2,3,7,8-TCDD shall be used consistent with the procedures in subrules (1) and (2) of this rule to calculate total 2,3,7,8-TCDD toxicity equivalence WLAs for effluents.

(ii) The toxicity equivalency factors (TEFs) and bioaccumulation equivalency factors (BEFs) in table 2 3 shall be used to calculate a 2,3,7,8- TCDD toxicity equivalence concentration for an effluent when implementing the WLAs derived in paragraph (i) of this subdivision. The equation for calculating the 2,3,7,8-TCDD toxicity equivalence concentration in an effluent is as follows:

(TEC)TCDD = [SUM](C)_x (TEF)_x (BEF)_x

Where:

(TEC)TCDD = 2,3,7,8-TCDD toxicity equivalence concentration in the discharge.

(C)_x = the concentration of congener x in the discharge.

(TEF)_x = toxicity equivalency factor for congener x.

(BEF)_x = bioaccumulation equivalency factor for congener x.

Table 3. Toxicity equivalency factors and BEFs for CDDs and CDFs.

Congener	TEF	BEF
2,3,7,8-TCDD	1.0	1.0
1,2,3,7,8-PeCDD	0.5	0.9
1,2,3,4,7,8-HxCDD	0.1	0.3
1,2,3,6,7,8-HxCDD	0.1	0.1
1,2,3,7,8,9-HxCDD	0.1	0.1
1,2,3,4,6,7,8-HpCDD	0.01	0.05
OCDD	0.001	0.01
2,3,7,8-TCDF	0.1	0.8
1,2,3,7,8-PeCDF	0.05	0.2
2,3,4,7,8-PeCDF	0.5	1.6
1,2,3,4,7,8-HxCDF	0.1	0.08
1,2,3,6,7,8-HxCDF	0.1	0.2
2,3,4,6,7,8-HxCDF	0.1	0.7
1,2,3,7,8,9-HxCDF	0.1	0.6
1,2,3,4,6,7,8-HpCDF	0.01	0.01
1,2,3,4,7,8,9-HpCDF	0.01	0.4
OCDF	0.001	0.02

Notes

Mich. Admin. Code R. 323.1209

1997 AACS; 2006 AACS