The O’Fallon Sewer Division serves the area of O’Fallon generally described as east of the FAI-64/Highway 50 interchange. This includes areas within the city limits and some unincorporated areas.
The Caseyville Township Sewer District serves the area of O’Fallon generally described as west of the FAI-64/Highway 50 interchange.
The O’Fallon Sewer Division serves a population base of nearly 18,000 through approximately 8,000 service delivery points.
The O’Fallon Sewer Division treats sewage at the Wastewater Treatment Facility (WWTF) located on Reider Road, about ½ mile north of Highway 50.
The Wastewater Treatment Facility (WWTF) was upgraded in 1997 at a cost of $8.0 million.
The WWTF has a capacity of 5.61 million gallons per day (mgd) Design Average Flow (DAF) and 13.14 mgd Design Maximum Flow (DMF).
The WWTF is presently operating at about 40% of design capacity and will provide adequate service for another 15 years at present growth levels.
Tests are conducted daily to evaluate the operation of the WWTF and confirm that it complies with the National Pollutant Discharge Elimination System (NPDES) permit for this facility.
The WWTF discharges treated effluent to Silver Creek which flows to the Kaskaskia River and then to the Mississippi River.
The O’Fallon Sewer Department collection system consists of approximately 80 miles of sewer main lines and 14 pumping stations.
The City sanitary sewer system is separate from the storm sewer system.
Storm water only enters the sanitary sewer through “Infiltration” (water leaking into cracked pipes and manholes) and by “Inflow” (illegal direct connections of roof drains, sump pumps, etc.) from private residences.
It is illegal to connect your roof drain, foundation drain or any other source of storm water to the City sanitary sewer system. If your roof drain or foundation drain is connected to the sanitary sewer, you must disconnect it immediately.
An Inflow/Infiltration (I/I) Study was conducted in 1999-2000 to evaluate areas where immediate repairs were needed to minimize the intrusion of storm water in the sanitary sewer.
The City is undertaking a program to make point repairs identified in the I/I Study and methodically replace portions of old sanitary sewer mains.
Approximately $2.0 million was spent over the past five years to replace old sanitary sewer mains.
Approximately $4.0 million in sewer main replacement projects are planned for the next ten years.
The City is also evaluating the locations of future new sewer lines to accommodate the City’s growth.
Sewer billing is administered by the Water and Sewer Billing Division.
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