DuraHold - To the Rescue

Retaining Wall System: DuraHold with Stratagrid 500 geogrid reinforcement
Owner : Oakville Fire Department
Contractor : Tarrascape Innovations Inc., Hamilton, ON
Wall Design : RisiStone Systems, Thornhill, ON
Retaining Wall Manufacturer : Unilock Ltd., ON

In the summer of 2000, the City of Oakville, Ontario completed construction of a new, state-of-the-art training center for its emergency services. In order to be fully equipped for fire and rescue simulations, it was necessary to install a retention pond immediately adjacent to the new training facilities. The design had to take into account the issue of vehicle accessibility. So that emergency vehicles (fire pumping trucks) could park immediately adjacent to the deepest water, the architect’s design called for the application of vertical retaining walls running along two sides of the pond.

Through the efforts of Unilock Territory Manager Dave Laurie, the DuraHold geogrid reinforced segmental retaining wall system was approved and a sealed RisiStone Systems design was completed.

The substantial loading and potential hydrostatic effects posed a number of unique design challenges. In order to account for the effects of a significant drop in the water level due to pumping, the wall analysis incorporated the AASHTO recommendations for rapid draw-down conditions. With a maximum design height of 4.0m (13.0ft), vertical orientation, and significant potential loading, the DuraHold wall design required a heavy-duty geogrid reinforcement to do the job. The Stratagrid 500 geosynthetic was utilized for its high tensile strength and durability. As well, in order to facilitate the dissipation of hydrostatic forces immediately behind the wall face, a ¾” clear stone drainage layer wrapped in filter cloth was incorporated into the design.

The Contractor, Tarrascape Innovations Inc., employed time-saving techniques to maintain an efficient rate of installation. On top of the standard 300mm (12”) granular base, reinforced 2x2 patio slabs were used to provide an even leveling pad for the base course to be placed. As the site consisted mainly of a clay material, a pond liner was not required to contain the water. This proved to be an asset during construction.

Once the walls were completed and grading of the pond finalized, the “pit” was flooded to the design elevations. With the addition of creative landscaping, the result is an aesthetically pleasing water feature, designed and constructed with the structural stability to provide years of use as an effective training tool. This project emphasizes the applicability of the DuraHold retaining wall system when a variety of challenging design conditions are presented.