Client: City of Ottawa
Location: Ottawa, Ontario
Size: N/A
The 3.6 m x 3.4 m concrete box culvert that conveys Barrhaven Creek under Prince of Wales Drive, in the south end of the City of Ottawa, was identified for replacement due to insufficient hydraulic capacity and structural deterioration. The new culvert had to be designed to meet current hydraulic design requirements, and was to be lengthened substantially to accommodate a future widening of Prince of Wales Drive.
During the preliminary investigations, JLR identified a significant design constraint: the West Rideau Collector (WRC), one the City’s most important trunk sanitary sewers, crosses under Barrhaven Creek, just upstream of the existing culvert inlet. The trunk sewer transitions from a circular pipe to a lower height, rectangular section in order to pass just under the creek bed. The new, longer culvert, therefore, could only be built over this rectangular section.
The width of the new culvert was maximized by crossing perpendicularly over the rectangular section of the WRC enabling the required hydraulic capacity to be achieved. The upstream portion of the new culvert had to be designed as a custom, cast-in-place section with a horizontal bend to meet the skew of the existing culvert, and a vertical drop to meet the minimum cover requirements under the roadway.
The alignment and elevation of the WRC also complicated constructability, as the new culvert could only be built at the same location as the existing one. During construction, the creek had to be dammed to an elevation where water could flow by gravity through temporary by-pass culverts installed over the circular section of the WRC and around the existing culvert.
Prince of Wales Drive is a major north-south collector roadway, with significant commuter traffic volumes in the morning and afternoon peak periods. A weekend closure, however, was permitted to facilitate the installation of the 6.0 m x 2.6 m precast sections across the roadway. The contract was structured with an incentive clause for the Contractor to complete the entire culvert crossing, including final restoration of the asphalt, over a single long weekend period. While a turkey dinner was barbequing near the site trailer, the last precast section was hoisted into place by the mobile crane on Thanksgiving Sunday afternoon, marking a successful end to a project completed on time and well under budget.
