NPDES Permit

Types of Sewer Systems

The Village of La Grange maintains and operates three different types of sewer systems:

  • Combined sewer systems
  • Sanitary sewer
  • Storm sewer

Combined Sewer Overflow NPDES Permit

The combined sewer system is designed to convey both rainfall runoff and domestic and industrial wastewater in a single pipe to wastewater treatment plants operated by the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC).

The sewer systems are regulated by the U.S. Environmental Protection Agency (U.S. EPA) through the Illinois Environmental Protection Agency (IEPA) as well as the MWRDGC, which treats the sanitary sewage from the Village.

The Village is permitted to discharge wet weather sewer flows conveyed by its combined sewer system, which is not collected by the Deep Tunnel system. These sewer flows are discharged into regional surface waterways under a special National Pollutant Discharge Elimination System (NPDES) Permit issued by the IEPA.

The surface waterway receiving the Village’s combined sewer wet weather overflow is the Salt Creek tributary to the Des Plaines River.

Additional information regarding the Village’s Combined Sewer Overflow NPDES permit can be found in the following links:

Municipal Separate Storm Sewer System (MS4) NPDES Permit

The Village also operates a separate storm sewer system that transmits stormwater from the area generally bounded by Gilbert Avenue to Edgewood Avenue, and 47th Street to 51st Street to the McCook Ditch which drains to the Chicago Sanitary and Ship Canal.

The following information is being provided regarding the Illinois Environmental Protection Agency’s (IEPA) permit requirements for La Grange’s stormwater discharges to comply with the General NPDES Permit for Discharges from Small Municipal Separate Storm Sewer Systems (ILR40). ILR40 requires that a permittee reduce, to the maximum extent practicable, pollutants associated with stormwater runoff being discharged to any surface water of the state.

The Village of La Grange welcomes comments on its Stormwater Management Plan and the above documents.