Case Study Details

At the Lawrence Avenue interchange along I-90 in Chicago, the Illinois Department of Transportation (IDOT) completed repairs and drainage improvements to existing concrete retaining walls supporting the interstate entrance and exit ramp infrastructure.

Water accumulation behind the retaining wall had created significant drainage concerns and contributed to pressure against the existing structure. As part of the repair project, approximately 100 JET Filter maintainable weep hole assemblies were installed through the concrete retaining wall, generally at a rate of one unit per wall panel.

The retrofit provided a permanent, accessible drainage solution designed to relieve hydrostatic pressure, reduce the potential for future wall movement, and extend the service life of this heavily traveled transportation infrastructure..

Products Used

• 100 units of JET Filter – JF4SS: 4″ Diameter Open-End Maintainable Weep Hole Filters featuring a corrosion-resistant stainless steel housing and Mirafi® Filter-Weave FW 300 Geotextile Filter Media. The units were installed through cored openings in the existing concrete retaining wall, providing drainage near the base of the structure while allowing future access to the filter cartridge from the exposed face of the wall.

I-90 Retaining Wall Drainage Solutions

The Lawrence Avenue / I-90 retaining wall drainage project demonstrates the importance of maintaining adequate drainage behind large transportation retaining structures.

Water that becomes trapped within retained soil can increase hydrostatic pressure against a wall. In Chicago’s freeze-thaw environment, saturated soil can create additional concerns when freezing conditions cause water within the retained material to expand. Over time, inadequate drainage can contribute to wall movement, cracking, displacement, and costly structural repairs.

JET Filter maintainable weep holes were installed to provide trapped water with a controlled exit path through the existing concrete wall. The system allows water to drain while the geotextile filter media helps retain surrounding soil.

Unlike conventional weep holes with inaccessible filter fabric installed behind the wall, the JET Filter System incorporates a removable inner filter cartridge. Maintenance personnel can access, inspect, clean, or replace the filter media directly from the front face of the retaining wall without excavating the retained soil behind the structure.

For IDOT, this provided both immediate pressure relief and a long-term method for maintaining drainage performance throughout the service life of the retaining wall.

Technical Details