Tour the Westside Sanitary Sewer

Westside Sanitary Sewer

Location: West of Ridge Road.
History: Started at Kenilworth Gardens in 1920s, expanded in 1930s and ’50s.

The “separate” sanitary sewer on Wilmette’s westside has two basins:

  • Harms Basin:
    Located west of Romona Road.
    Connects to MWRD at Harms Road.
  • Princeton Basin:
    The area between Romona and Ridge Roads.
    Connects to MWRD at Princeton Place.

System For:

Household-Toilet-Pan-icon from iconarchive dot comDomestic sewage

icon copyright Johavel/ShutterstockIndustrial/commercial wastewater

Sanitary Sewer Specs:

  • 55.6 miles of sewer lines.
  • Mostly made of vitrified clay pipes, 2 to 3 feet long, joined with mortar.
  • Each basin flows into the MWRD system.
  • MWRD treats the sewage at the Northside Water Reclamation Plant.
  • The treated water flows into the Chicago River.

Sanitary Sewer Issues:

  1. Infiltration/inflow from:
    • Leaky manholes, and aging sewer lines with cracks or leaky joints.
    • Leaky homeowner service pipes (sometimes called laterals).
    • Sump/downspout connections
      (no longer legal, many were disconnected in the ’80s).
    • Tree roots that enlarge cracks and holes.
  2. Some pipes are backpitched, inclining away from the outflow, causing clogging.
  3. MWRD sewage backs up into Wilmette’s system at the Harms Road interceptor, and possibly at Princeton Place.
 Our antique sanitary sewers

Here’s what our antique sanitary sewers look like: many manholes made of bricks or blocks, with I/I, and some major root invasions!

Source: Village of Wilmette, Separate Sanitary Sewer Hydraulic Modeling, by RJN Group, Inc (August 2012), p 3-3.

Recent Projects for the Entire Sanitary Sewer:

  • To comply with an MWRD maintenance agreement, the village inspects 20 percent of the pipes annually.
  • Also, the village has conducted smoke tests to find sources of inflow and infiltration (I/I), especially in the Kenilworth Gardens area.
  • Repair crews have used Closed Circuit Televising (CCTV) to inspect pipes for structural damage.
  • Crews have repaired severe damage and relined pipes to seal up cracks.
  • Manholes have been rehabilitated to reduce stormwater infiltration.

West Park Storage and Pumping Station for Harms Basin:

  • Serves only the area of Wilmette west of Romona Road.
  • West Park Sanitary Storage tank provides storage capacity for infiltrating stormwater during intense rainfall to prevent basement backups.
  • Specs for the West Park Storage and Pumping Station include 5.5 million gallon reservoir with 8 pumps.
  • A check valve at the Harms Road interceptor prevents MWRD sewage from backing up into basements from downstream MWRD flows.

Past & Future Projects for Princeton Basin:

  • Hunter Road (2013):
    Pipes replaced to increase sewer capacity.
  • Wilmette Avenue (2014):
    Relief sewer added to increase capacity.
  • MWRD Interceptor Study (TBD Spring 2016):
    The MWRD will lead and help fund a study, with Wilmette, Glencoe, Northfield, and Winnetka (each contributing $14,000). Flow meters installed at Princeton Place and other MWRD interceptors will collect data for three months. The goal is to check the capacity and efficiency of MWRD interceptors when it’s rainy (and see if sewage from MWRD is backing up into the Princeton Basin).


Sanitary Sewer Map
Source: Village of Wilmette, Separate Sanitary Sewer Hydraulic Modeling, by RJN Group (August 2012), Exh 2-1.

Fact check:

  • For more information on the sanitary sewer and maintenance requirements, see Village of Wilmette Public Works Dept., 2014 Annual Report (2014), pp 71-72.
  • For a detailed study of the sanitary sewer and stormwater issues, see the Village of Wilmette, Separate Sanitary Sewer Hydraulic Modeling, by RJN Group (Aug 2012).

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