There are many rock-fill and earthen water control structures in western Canada, commonly called Riparian Dams that were built to provide reservoirs for irrigation and recreational purposes.
These structures, in addition to an overflow spillway, have a low- level intake conduit that runs through the base of the structure at lakebed elevation with a regulating gate system at the centreline of the dam. Many of these conduits were constructed with CSP or CMP (Corrugated steel or metal pipe).
As these dams age, settlement, corrosion and the weight of the structure can cause the low- level conduit to deform or become occluded.
One solution to prevent this condition from worsening is to introduce a liner of a smaller diameter, and of an inert material such as high density polyethylene, and cementing it in place by grouting the annular space.
Some of the challenges with a project like this might include dealing with sediment build-up in and around the intake or sloughing of the structure and intake channel. In this project, material had to be removed by dredging in an environmentally acceptable way in order to allow the liner to be introduced.
Another challenge that can arise, may be pulling a heavy liner into an out-of-round conduit while keeping it centred and maintaining the grout delivery system. This project required custom fitting of casing spacers and redundant systems for injecting the grout.
Due to the distance from a ready mix plant, an engineered, bagged, dry-mix grout was hydrated and mixed on site, during the pumping and injecting process. Especially important when grouting in-water is the containment of deleterious material. Dominion Divers accomplished this by providing a complete environmental plan with measures to contain and remove contaminants.
There are many and various applications where a conduit liner may be the best solution. Dominion Divers has completed liner installations as small as 100 mm diameter and as large as 1800 mm.