Sewer System Studies
2010 Separate Sewer System Study
The Village of Wilmette has experienced surcharged and backed up sanitary sewers in their separate sewer system west of Ridge Road. This is due to multiple factors, including aging infrastructure and inadequate sewer capacity. The Village hired MWH to execute a screening level assessment of options available to the Village for reducing sanitary basement backups and flooding in the separate sewer system area.
Click here to view the full study
1990's Separate Sewer System Study
Since then, the Village has invested millions of capital and maintenance dollars to improve the storm and sanitary collection systems. As a result of the August 23, 2007 and September 13, 2008 storms and many residential sewer system basement backups, it was recommended that a study be conducted to evaluate the current operation of the systems to determine where the Village should focus future resources.
This study will develop an implementation plans and corresponding funding schedule for inclusion in the capital sewer improvement program. This study is one of several multi-faceted strategies to improving the sewer system including development of programs that encourage home owners to protect their properties from chronic sewer backups.
Relief Sewer Project
Existing Sewer System
The Village, with a population of approximately 27,500, is served in the area east of Ridge Road by a combined sewer system and in the area west of Ridge Road by a separated sanitary and storm sewer system. The entire system collects wastewater from approximately 9,000 residential, commercial and institutional buildings and also storm water from approximately 2,500 acres of intensely urbanized area. The combined sewer area is bounded by the Village of Kenilworth on the north, Lake Michigan on the east, the Village of Evanston to the south and Ridge Road on the west.
The combined sewers convey sanitary sewage and storm water runoff from residential neighborhoods through Village-owned east-west trunk sewers to the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) interceptors. Flows travel to the interceptors located along Green Bay Road and Sheridan Road for later treatment at the MWRDGC Northside Water Reclamation Plant on Howard Street in Skokie, Illinois. Storm water runoff exceeding the capacity of the MWRDGC interceptors is conveyed by Village-owned combined sewers to a dropshaft to the MWRDGC deep tunnel under Sheridan Road and the North Shore Channel. Runoff which exceeds the capacity of the deep tunnel overflows into the North Shore Channel.
Previous Studies
Prior to 1990, the Village experienced persistent street flooding and basement backups in the combined sewer area of the Village during rains that were rated a 3-month storm event or larger. In the early 1990’s the Village implemented an aggressive Storm Water Runoff Control Program in an effort to reduce the frequency and severity of basement flooding due to sewer surcharging. The program involves the implementation of a multi-phase improvement project including the construction of over 250 inlet control berms (i.e., roadway storage areas) as well as new interceptor and relief sewers in the combined sewer area.
The first several phases of the Storm Water Runoff Control Program are complete and have reduced the frequency and magnitude of street flooding and basement backups in the Village. The tentative schedule for the remaining Phases of the Program is as follows:
- 2012 6th Street (Elmwood to Greenleaf Avenue, 24-inch, 36-inch, 48-inch)
- 2013 Laurel Avenue (8th Street to 5th Street, 24-inch)
9th Street (Gregory Avenue to Oakwood Avenue, 24-inches)
- 2014 Isabella Street (Lawndale Avenue to 15th Street, 24-inc, 36-inch)
- 2015 Chestnut Avenue (Sheridan Road to 8th Street, 24-inch)
8th Street (Chestnut to Ashland, 24-inch)
Ashland Avenue (8th to 9th, 24-inch)
Greenwood Avenue (8th to 9th, 24-inch)
- 2016 6th Street (Isabella Street to Maple Avenue, 24-inch)
North Shore Channel (Linden Avenue to Maple Avenue, 24-inch)
Laurel Avenue (Sheridan Road to the North Shore Channel, 24-inch)
- 2017 11th Street (Lake to Forest, 24-inch)
Elmwood Avenue (Michigan to Sheridan Road, 24-inches)
Forest Avenue (Michigan Avenue to 6th Street, 24-inches)
- 2018 Ashland Avenue (12th Street to 13th Street, 24-inches)
Greenwood Avenue (11th Street to 13th Street, 24-inches)
Elmwood Avenue (12th Street to 13th Street, 24-inches)