Case Study Details

Along Archer Avenue and Joliet Road in the Village of McCook, Illinois, the Illinois Department of Transportation completed drainage and restoration improvements to existing concrete retaining wall infrastructure.

The project included coring new retaining wall weep holes through the existing retaining wall to provide improved drainage and hydrostatic pressure relief. Approximately 123 JET Filter maintainable weep hole systems were installed along the base of the wall, generally spaced approximately 6 to 8 feet apart.

By retrofitting the existing concrete structure with accessible, maintainable, retaining wall weep holes, the project provided accumulated groundwater with a controlled path through the retaining wall while helping reduce the long-term effects of hydrostatic pressure, saturated backfill, erosion, and freeze-thaw conditions.

IDOT project documents for Contract 62K26 specifically identify weep-hole coring, drainage-structure cleaning and reconstruction, gutter work, debris removal, and selective clearing as components of the improvement.

Products Used

• 123 units of JET Filter – JF4SS: 4″ Diameter Open-End Maintainable Weep Hole Filters featuring a corrosion-resistant stainless steel housing and Mirafi® FW 300 Series geotextile filter media.

The units were installed through cored openings in the existing concrete, and the retaining wall weep holes were positioned primarily along the lower portion of the structure to provide drainage relief where water pressure can accumulate behind the wall.

A key feature of the JET Filter System is its removable inner filter cartridge. The cartridge can be accessed, inspected, cleaned, or replaced directly from the exposed face of the retaining wall without excavating material from behind the structure.

JET Filter’s current product line uses 316L stainless steel housings and serviceable filter cartridges designed for long-term drainage applications in retaining walls and other critical infrastructure.

Retaining Wall Weep Holes Drainage Solution

Retaining walls are a major component of transportation infrastructure, and effective drainage is critical to their long-term performance.

When groundwater or stormwater enters the retained soil behind a wall, the water can become trapped if sufficient drainage pathways are unavailable. As soil becomes saturated, hydrostatic pressure increases against the structure. Over time, this pressure can contribute to cracking, leaning, displacement, deterioration, and premature rehabilitation of the retaining wall.

The Archer Avenue / Joliet Road project addressed this condition by coring new drainage openings through the existing concrete wall and installing maintainable JET Filter weep hole systems approximately 6 to 8 feet apart.

The retaining wall weep holes systems create controlled retaining wall drainage outlets that allow accumulated water to exit while the geotextile filter media helps retain surrounding soil and aggregate.

This configuration provides two important benefits: immediate pressure relief and long-term serviceability.

Unlike conventional drainage systems where filter fabric may be inaccessible behind the structure, the JET Filter incorporates a removable filter cartridge accessible from the exposed face of the wall. Maintenance crews can inspect, clean, or replace the filtration component without excavating retained soil or disturbing the roadway infrastructure behind the wall.

JET Filter systems are designed specifically for applications such as retaining walls, bridge abutments, wing walls, culverts, seawalls, and other earth-retaining structures where hydrostatic pressure and soil retention must be managed together.

Technical Details