When culverts, storm drains, and manholes age or settle, joints that once were tight begin to open up. When that happens, water and soil can migrate through these cracks, termed inflow and infiltration (I&I). It may seem like a minor nuisance to have soil on the bottom of your culvert, but that’s not the real issue. The migration leaves a void behind that can grow with time, and eventually cause settlement above the structure or migrate all the way to the surface. Now imagine you were spending money widening a roadway going over one of these such culverts. Your options are to replace the structure or to find some way to repair the structure.
This was the case in the City of Richmond in British Columbia where a 10 ft by 5 ft box culvert measuring over a mile long had an average of 12 to 18 inches of silt on the culvert floor. SlabJack Geotechnical was hired to perform geotechnical polyurethane grouting to stabilize the base of the culvert, fill voids, and seal up joints. With a 3 person crew, they averaged about 8,000 lbs of TerraThane 24-042 geotechnical polyurethane grout injected per day and treated a 150 ft length of the culvert treated. They accessed the culvert through manholes spaced every 300 feet along the culvert. They finished the project over a 9 week period. By filling voids, restoring the contact of the box with the soil, and sealing joints, they solved immediate issues and prevented future issues with the box or the new roadway above it, helping to extend the culvert life and protect the City’s investments.
More info on the Richmond Culvert Stabilization Project page on TerraThane’s website.
[Editor] NCFI Polyurethanes, maker of TerraThane, is a sponsor of GeoPrac.net. [/Editor]