Canals

Portadam cofferdams create a dry work area so canal repairs or replacement projects can be completed. Damaged canals don’t need to be abandoned or removed. Narrow and hard-to-see drainage and field channels need to be drained and filled to avoid serious injury to humans and animals. If you’re interested in continuing to use a leaking canal or restore the use of an abandoned channel, you’ll need to use at least one of the four following methods. Each method for repairing a cracked or collapsed canal has its own benefits and drawbacks, and some of them may need to be combined for a successful and long-lasting repair.

Installing a Geomembrane Over the Surface

Cracked concrete canal liners work particularly well with an application of geomembrane over the surface. Draining the canal temporarily and spreading a layer across the damaged surface, will provide a new impermeable layer to put an end to leaks. For best results, cover the entire length of the canal since the damage may spread if you only cover small parts at a time. If one part of the canal surface has already failed, there’s a good chance another part may also develop damage soon, without a protective cover. Investing in a geomembrane layer over the entire canal limits future damage to reduce repair costs for years to come.

Replacing Existing Materials

For more extensive damage, like collapses, major erosion, or missing slabs of concrete liner, you may need to also replace at least some of the existing materials to restore the stability of the structure. These replacements tend to cost more than just covering the damage with a new surface, but it may be required for a stable and safe canal. Collapsed and eroded canal walls may need re-engineering and significant reinforcement before water can flow again. In order to keep the replaced concrete, brick, or stonework from being damaged in the future, cover it with geomembrane as soon as the repaired sections are cured.

Sealing Techniques

Some canal owners attempt to seal the cracks in their concrete, clay-lined, or mortared brick/stone canal with various adhesive products. Small and thin cracks can be patched this way if you can find a product that doesn’t release any contaminants into the water. Filling larger cracks, or more extensive damage, will take a lot of time and costly material and is likely to fail. Mortar and patching compounds can fill larger voids, but they also become brittle and eventually crumble, especially in areas with a lot of freeze and thaw cycles in the winter.

Reshaping the Canal Bed

If the original shape or angle of the canal contributed to its damage, you may want to re-excavate part or all of the earthwork to reshape it. Preventing future wall collapses and silt accumulation may require cutting substantially less angled walls or cutting a deeper channel bed to increase velocity. Reshaping from the soil up, also gives you a chance to increase the capacity of the canal before finishing the surface with a higher quality liner, such as geomembrane.