Back to top

a)  Malfunctions. All treatment works and associated facilities must be constructed and operated to minimize violations of applicable standards during contingencies including flooding, adverse weather, power failure, equipment failure, or maintenance, through measures including multiple units, holding tanks, duplicate power sources, or other appropriate measures.

b)  Spills. All reasonable measures, including where appropriate catchment areas, relief vessels, or entrapment dikes, must be taken to prevent any spillage of contaminants from causing water pollution.

(Source: Amended at 47 Ill. Reg. 4641, effective March 23, 2023)

Section 306.103  Combined Sewers and Treatment Plant Bypasses (renumbered)

a)  The combined sewer service area has adequate treatment or retention capacity to ensure that the effluent limitations of 35 Ill. Adm. Code 304 and the provisions of the Act are not violated;

b)  Any anticipated increased flow will not overload connecting segments of the combined sewer system;

c)  Increased flow will not aggravate combined sewer overflow problems, including combined sewer surcharges, basement backups, and street flow; and

d)  The new combined sewer service area will be tributary to an existing combined sewer system.

(Source: Amended at 47 Ill. Reg. 4641, effective March 23, 2023)

(Source: Amended at 47 Ill. Reg. 4641, effective March 23, 2023)
 

a)  All dry weather flows, and the first flush of storm flows as determined by the Agency, must meet the applicable effluent standards; and
 
b)  Additional flows, as determined by the Agency but not less than ten times the average dry weather flow for the design year, must receive a minimum of primary treatment and disinfection with adequate retention time; and
 
c)  Flows exceeding those described in subsection (b) must be treated, in whole or in part, to the extent necessary to prevent any accumulation of sludge deposits, floating debris, and solids in compliance with 35 Ill. Adm. Code 302.203 and to prevent depression of oxygen levels; or
 
d)  Compliance with a treatment program authorized by the Board in an exception proceeding.

(Source: Amended at 47 Ill. Reg. 4641, effective March 23, 2023)

a)  All treatment plant bypasses, by the applicable date for improvement of treatment works under 35 Ill. Adm. Code 304.

b)  All combined sewer overflows within the Metropolitan Sanitary District of Greater Chicago, by December 31, 1977;

d)  The compliance dates set by subsections (b) and (c) must be met unless:

1)  The discharger's combined sewer overflow is eligible for a construction grant under Section 201(g) of the CWA; and,

2)  The discharger applied for a construction grant on or before March 1, 1977; and,

3)  The discharger has timely taken all appropriate pre-grant and post-grant actions necessary to the specific grant step for which the discharger is then eligible, or

4)  The discharger has been granted an exception by the Board.

e)  Nothing in subsection (d) limits the power of the Board to enter an abatement order under Section 46 of the Act necessary to abate pollution of waters of the State, when the Board has found, as the result of an enforcement or variance case initiated under Titles VIII or IX of the Act, that the discharger is causing a violation of the Act or regulations.

f)  The exemption provided by subsection (d) must terminate upon completion of construction under the grant provided.

a)  The Agency must publish and make available to the public at intervals of not more than three months a comprehensive and up-to-date list of sanitary districts and other wastewater treatment or transportation authorities then subject to restricted status on further sewer connections, and a list of those which are then under critical review by the Agency.
 
b)  Such lists must include the name of the affected facility, the responsible authority, and an estimate of the affected facility's capacity. The Critical Review List must also include estimates of treatment plant and sewer capacity, and the amount of population equivalent added according to the Agency permit records since publication of the previous list.
 
c)  All such lists must be made available without charge to any person upon request and must be published in the Pollution Control Board's Environmental Register.
 

a)  Restricted status means the Agency's determination that a sewer has reached hydraulic capacity or a sewage treatment plant has reached design capacity and, as a result, additional sewer connection permits may no longer be issued without causing a violation of the Act or regulations.
 
b)  The Agency may place a sewage treatment plant on Restricted Status when any of the following conditions exist, as shown by Agency field inspections, operational reports, records of permits issued, or other information:
 
1)  Hydraulic overloading of the treatment plant as determined by a comparison of the permitted design capacity of the plant with the actual average monthly flows measured at the plant during the three low-flow months in the preceding 12-month period, adjusted to include all outstanding (permitted but not connected) permits issued by the Agency, or other information on hydraulic loading of the plant available to the Agency (i.e., water pumpage, recent development, demographic and meteorological data, etc.);
 
2)  Organic overloading of the treatment plant as determined by the comparison of the permitted design capacity of the plant with the actual average monthly loadings in the preceding 12-month period, adjusted to include all outstanding (permitted but not connected) permits issued by the Agency, or other information on organic loading of the treatment plant available to the Agency (i.e., water pumpage, recent development, demographic and meteorological data, etc.);
 
3)  Continuing violation of effluent limitations established by the treatment plant's National Pollutant Discharge Elimination System (NPDES) permit. Determining a violation of effluent limitations must be made according to the sampling, testing, and averaging procedures specified in the NPDES permit;
 
4)  Operational neglect resulting in frequent bypassing of any treatment unit or units; or
 
5)  An Illinois Pollution Control Board decision finding a violation of Section 12(a) of the Environmental Protection Act [415 ILCS 5/12(a)].

c)  The Agency may place sanitary sewers and lift stations on Restricted Status to prevent overflows as prohibited under Subpart C. Restricted Status may be imposed upon confirming overflows in the form of basement backups, overflows of sanitary sewer manholes, or sanitary sewer overflow devices.
 
d)  All combined and sanitary sewers and lift stations are subject to Restricted Status when they become hydraulically overloaded, meaning unable to accommodate the following flows:
 
1)  Combined sewers and lift stations serving combined sewers must be able to handle 350 percent of the average daily flow (based on best available information) before overflowing.
 
2)  Interceptors serving both combined sewers and sanitary sewers must be able to accommodate 250 percent of the average daily dry weather flow (based on best available information) from the sanitary sewers tributary to them and 350 percent of the average daily dry weather flow from the combined sewers tributary to them before overflowing.

a)  Critical review means the Agency's determination that a sewer is approaching hydraulic capacity or a sewage treatment plant is approaching design capacity and, as a result, additional sewer connection permit applications will require close scrutiny to determine whether issuance would result in a violation of the Act or regulations.
 
b)  Notification of Critical Review is a warning that Restricted Status is imminent unless corrective action is taken. A facility may be placed on Critical Review whenever, based upon information available to it, the Agency determines that the organic or hydraulic loading of any facility is greater than 80% of the permitted or designed capacity of that facility, as defined in Section 306.402.
 

(Source: Amended at 47 Ill. Reg. 4641, effective March 23, 2023)
 

a)  When the Agency determines that conditions warrant placing a facility on Restricted Status or Critical Review, the Agency must send a letter stating the action proposed, the reasons for the action, and a summary of supporting documentation to the sanitary district or other wastewater treatment or transportation authority responsible for the facility.

b)  The sanitary district or other wastewater treatment or transportation authority must be allowed to submit additional relevant information and to meet with the responsible permit engineers or to respond in writing.

c)  If, after review of information or response offered by the sanitary district or other wastewater treatment or transportation authority, the Agency's determination does not change, the Agency must send a final notification of Restricted Status or Critical Review, stating the meaning and reasons for the action, to the sanitary district or other wastewater treatment or transportation authority.
 
d)  The facility thus classified will remain under that status until the Agency receives information of a change in condition sufficient to warrant a revision of the status, or until a revision in status is ordered by the Pollution Control Board. The Agency must send notice of any revised status to the sanitary district or other wastewater treatment or transportation authority.

(Source: Amended at 47 Ill. Reg. 4641, effective March 23, 2023)

(Source: Amended at 47 Ill. Reg. 4641, effective March 23, 2023)

a)  The discharge from the sewer system of the City of East St. Louis, as described below, is not subject to the treatment requirements and timetables of Sections 306.305(b) and 306.306. The discharge is located in one of or both Lots 305 and 306 of Sixth Subdivision of Cahokia Commons and also in the Northwest Quarter Section 23, Township Two North, Range Ten West, of the Third Principal Meridian, and is at Mississippi River Mile Number 178.7 and at North 38º, 36”40’ latitude and West 90º, 10”40’.

b)  The first flush of storm flows must meet the applicable effluent standards of 35 Ill. Adm. Code Part 304, except when attempting to treat such flows would cause the treatment plant to operate beyond design capacity.

c)  In compliance with 35 Ill. Adm. Code 302.203, overflows exceeding plant treatment capacity must be passed through a 1/2 inch bar screen before discharge.

d)  Overflows must not cause any accumulation of unnatural sludge deposits in the receiving stream.

a)  The discharge from the Piasa-State Street Sewer at Mississippi River mile 202.64 is not subject to 35 Ill. Adm. Code 304.106, 304.120, 304.121 and 304.124 during the following conditions:

1)  Before replacement of the existing Locks and Dam 26, when the tailwater elevation exceeds 415.3 Mean Sea Level (MSL); or

2)  After replacement of Locks and Dam 26, when the pool level exceeds elevation 420 MSL at Mississippi River miles 203.12 and 203.22 (Piasa and State Street Outlets relocated).

b)  Discharges from the City of Alton at Mississippi River miles 201.66 (Shields Valley), 202.24 (Central Avenue), 203.12 (Piasa Outlet), 203.22 (State Street Outlet), 203.61 (Summit Street), 203.87 (Bluff Street) and 204.30 (Turner Tract), are subject to the following conditions:

1)  The overflow structures and the associated interceptor sewer must be protected against intrusion by flood waters and be maintained operational at flood stages from Mississippi River backflow for a 25-year Mississippi River flood stage, except as follows:

2)  The City of Alton must maintain the south side interceptor sewer system in working condition to ensure that the system will flow at a maximum capacity.

3)  No later than the date of completion of Lock and Dam 26, the south side interceptor pump station must be upgraded to a design capacity of a minimum of 13.7 million gallons per day.

c)  Discharges from the combined sewer overflows designated in subsection (b) are not subject to the treatment requirements of Section 306.305(a) and (b) provided that:

1)  The City of Alton maintains the south side interceptor sewer system in working condition to ensure that the system will flow at a maximum capacity.

2)  The South Side interceptor pump station must be upgraded to a design capacity of a minimum of 13.7 million gallons per day.

Back to top