Section 307.1102  Mercury

a)         Except as provided in this Section, no person may cause or allow the concentration of mercury in any discharge to a publicly owned or publicly regulated sewer system to exceed 0.0005 mg/L, subject to the averaging rule contained in 35 Ill. Adm. Code 304.104(a).

b)         Subsection (a) does not apply if the discharge is to a publicly owned or publicly regulated sewer system that is required to meet a limitation less stringent than the 0.0005 mg/L mercury concentration, in which case the discharge limitation must be the same as that applicable to the publicly owned or regulated sewer system to which it discharges.

c)         Subsection (a) does not apply if all the following conditions are met:

1)         The discharger does not use mercury, the discharger uses mercury and this use cannot be eliminated, or the discharger uses mercury only in chemical analysis or in laboratory or other equipment and takes reasonable care to avoid contamination of wastewater;

2)         The discharge's mercury concentration is less than 0.003 mg/L, as determined by applying the averaging rules of 35 Ill. Adm. Code 304.104(a);

3)         The discharger is providing the best degree of treatment consistent with technological feasibility, economic reasonableness, and sound engineering judgment.  This may include no treatment for mercury; and

4)         The discharger has an inspection and maintenance program likely to reduce or prevent an increase in the level of mercury discharges.

d)         The discharge of wastes from medicinal or therapeutic use of mercury, exclusive of laboratory use, will be exempt from the limitations of subsection (a) if all the following conditions are met:

1)         The total plant discharge is less than 227 g (one-half pound) as Hg in any year;

2)         This discharge is to a public sewer system; and

3)         The discharge does not, alone or in conjunction with other sources, cause the effluent from the sewer system or treatment plant to exceed 0.0005 mg/L of mercury.

e)         No person may cause or allow any discharge of mercury to a publicly owned or publicly regulated sewer system that, alone or in combination with other sources, causes the sewer treatment plant discharge to violate the water quality standard of 35 Ill. Adm. Code 302 for mercury applicable in the receiving stream.

f)         For purposes of permit issuance, the Agency may consider applying the exception under subsection (b) or (c) to determine compliance with this Section.  The Agency may impose permit conditions necessary or required to assure continued application of the exception.  When subsection (b) or (c) applies, the Agency may impose an effluent limitation in the permit that allows the discharge of a concentration of mercury greater than 0.0005 mg/L but not more than 0.003 mg/L.

g)         The mercury standards of Section 307.1102 will not apply to the Reilly Industries, Inc., Granite City, which discharges to any publicly-owned treatment works that receives such a manufacturing facility's wastewater. The amount of mercury discharged by any such manufacturing facility must not exceed a monthly average of 0.025 mg/L nor a maximum of 0.035 mg/L or 7.5 grams per day, subject to the Board's averaging rules during any one day.

(Source:  Amended at 47 Ill. Reg. 4662, effective March 23, 2023)