Bovaird Drive is a key east-west arterial in the Region of Peel, with traffic volumes of approximately 5500 AADT. Just west of Heritage Road, a tributary to the Credit River crosses Bovaird Drive through a 14m deep culvert with three distinct segments, including a 20m long 75 year +/- old masonry structure, and two newer sections – a 20m long cast-in-place concrete box culvert, and a larger 60m long cast-in-place concrete box culvert. Both the first and second segments were structurally deficient and required removal and replacement. A 2m vertical internal drop between the first and second culvert sections impeded fish passage.
Extensive consultation was undertaken with the Department of Fisheries and Oceans Canada (DFO), Ministry of Natural Resources and Forestry (MNRF), and Credit Valley Conservation (CVC) to develop a design that would meet the requirements for hydraulic passage and environmental permitting. The approved designed, tendered and constructed culvert involved 20,000 m3 of earth excavation to expose the deficient portion of the culvert, removal of 40m of the existing deficient culvert and replacement with a 20m long x 1.2m wide by 2.8m high precast concrete box structure, installation of wooden fish baffles within the culvert to improve passage for large-bodied fish, reconstruction of the upstream portion of the tributary for approximately 65m using a pool-step configuration, temporary realignment of Bovaird Drive (reduced to one lane in each direction and with lanes shifted to the south), roadside protection, construction of temporary access roads into the valley to facilitate construction equipment movement, and reforestation of the disturbed area with 400+ trees and 450+ shrubs.
The culvert was over 14m deep which required movement of a large volume of earth by heavy excavation equipment. Careful consideration was required for protection of the natural environment. As required by agencies, the final construction must improve the ability for fish to travel upstream. The new 20m long precast culvert created a 4m difference between the existing tributary and the new culvert invert. Fish passage was achieved through an innovative approach which utilized a fish baffle system within the existing culvert, followed by a pool-step channel, connecting the existing channel to the new culvert in the shortest distance possible, while allowing the fish to jump from pool to pool. Finally, and most importantly, the structurally deficient sections of the existing culvert were removed and replaced. This not only ensures continued operation of a key arterial roadway, but also has improved the ability of the Credit River Tributary to function as a healthy and vibrant natural system.
