Section 309.157  Permit Limits for Total Metals

a)         The NPDES permit limits for metals must be expressed in total metals form even though the water quality standards for metals specified in 35 Ill. Adm. Code 302.208(e), 302.504(a), and 304.105 are in their dissolved form.  The total metals permit limit is determined by multiplying the dissolved metals concentration and the appropriate metals translator.

b)         Site-specific metals translators must be determined according to "The Metals Translator: Guidance for Calculating a Total Recoverable Permit Limit from a Dissolved Criterion," incorporated by reference at 35 Ill. Adm. Code 301.106.

c)         Except as otherwise specified in subsection (d), the reciprocal of the conversion factor multiplier used for obtaining the dissolved metals standards at 35 Ill. Adm. Code 302.208(e) and 302.504(a) becomes the metals translator and the resulting total metals value becomes the NPDES permit limit.

d)         A permittee may request the Agency to calculate a total metals permit limit based on a site-specific metals translator.  Upon review and approval of the information submitted by the permittee, the Agency must calculate a total metals permit limit that is protective of the dissolved metals water quality standard.

(Source:  Amended at 47 Ill. Reg. 5017, effective March 23, 2023)