Project Name: 17th Street Canal
Project Location: New Orleans, LA
New Orleans’ three outfall canals—the 17th Street Canal, the London Avenue Canal, and the Orleans Canal—are critical for providing discharge of surface water collected from the city’s stormwater runoff systems to prevent flooding. The 17th Street Canal is the largest of the three canals and is the most important drainage canal in the city of New Orleans. The canal consists of 18 hydraulic pumps, 11 direct drive pumps, and 14 bridge pumps, and it has a pumping capacity of 9,200 cubic feet per second. Operating with Pump Station 6, the 17th Street Canal functions to move water into Lake Pontchartrain.
Erosion of the 17th Street Canal’s flood protection system was a major concern for the Southwest Louisiana Flood Protection Authority-East. The Authority required a solution to protect the canal’s slope against erosive forces and prevent a floodwall breach in the event of a tropical storm event.
The Solution to Slope Erosion Challenges
To mitigate channel slope erosion, engineers at Eaves-Graves Engineers Inc. chose the GEOWEB® 3D Confinement System to stabilize the slopes along the Metairie side of the drainage channel. By confining the infill material, the GEOWEB system prevents flow from causing scour and erosion on slope surfaces.
Cycle Construction Company installed approximately 380,000 square feet of GW40V6 (six-inch deep panels) over a woven geotextile along the canal’s slope and infilled the cells with crushed aggregate sized based on research and testing at Colorado State University hydraulics lab. As part of the complete GEOWEB system, the GEOWEB panels were secured with ATRA Key Connective Devices and ATRA Tendon Clips.
Benefits of GEOWEB-Confined Aggregate Channel Slopes
The GEOWEB system’s 3D cellular structure significantly improves the stability and erosion resistance of granular materials compared to when left unconfined. The system can accommodate a wide range of slope angles by selecting the appropriate cell size and cell depth for the considered aggregate.
The GEOWEB System:
- allows the use of smaller, less expensive rock—even waste rock which decreases installation and transportation costs.
- creates a permeable, cover when drainage is desired but vegetation cannot be established.
- resists high velocities and tractive forces.