DuraHold2 - Hammersmith Parking Lot

Retaining Wall System : DuraHold2
Owner: Parking Authority of Toronto
Structural Engineer: Cole, Sherman Engineers, Architects, Planners Thornhill, ON
Geotechnical Engineer: VA Wood Associates Ltd. Scarborough, ON
Contractor: Gazzola Paving – Adrian Niekirk, Aldo Da Silva Toronto, ON
Geogrid Manufacturer: Conwed Strata Systems Minneapolis, MN

During the latter part of 1992, the Parking Authority of Toronto commissioned Cole, Sherman to design a retaining wall for a parking lot project. The wall was required to protect a parking area located at Hammersmith Ave. and Queen St. E. in Toronto, Canada. Cole, Sherman had orginally specified a conventional concrete reinforced retaining wall which was over budget. Gazzola Paving was then asked to recommend another cost-effective solution. The resulting proposal was a DuraHold2 wall with Stratagrid 500 and Risigrid reinforcement. The supply and install price was then to the Parking Authority’s approval.

The DuraHold2 system has a random block face pattern based on units 12” high, 12” deep, and 72” long. It is a high strength system with quick and easy installation - in this case, facilitated by a concrete pad with appropriate stepped-up footings. The concrete pad also ensured a good, solid base. The wall is eleven feet at the highest point, requiring layers of Stratagrid 500 on the top two courses, as well as five layers of Risigrid. The first three courses did not require the use of any grid. Aldo Da Silva of Gazzola Paving assessed the existing site material and used the superior quality free-draining sand and imported Granular A as needed. At present there is only five to six feet of the wall exposed, as the future plans for the neighbouring apartments and stores may require that the entire area be demolished and the new grade lowered by three to four feet.

The Hammersmith Avenue parking lot took five days to construct and is a total of 1300 square feet. All parties involved - the owner, contractor, and even the neighbours - are pleased with the results.