Highway 403 Culvert Repair

Highway 403 Culvert Repair – Brantford, Ontario 2005-2006

Background
In September of 2005, Avertex Utility Solutions Inc. was working on a contract for MTO to clean out the existing 1.67 m concrete pipe culvert that ran under both Highway 403 and Paris Road at their intersection. At approximately the midpoint of the cleaning operation and directly under the bridge abutment, the cleaning bucket hit a solid obstacle. On inspection, it became apparent that at least 3 steel piles had been driven completely through the concrete culvert during the construction of the abutment 28 years earlier. The culvert had plugged with debris at the pile obstruction and subsequently silted in almost blocking the flow completely.

The blockage had to be removed from the culvert to ensure the upstream properties were not flooded and the concrete pipe had to be repaired to ensure it would not collapse completely. The piles also had to stay in place to support the abutment above the culvert. MTO expanded Avertex’s contract to include the repairs to the culvert at the pile location. Gary was retained by Avertex to design the culvert repairs and oversee the construction. Culvert Cleaning and Repair Work Prior to undertaking the repairs inside the culvert, probe holes were drilled from the surface to determine if a void existed above the culvert near the abutment. Voids were found and subsequently filled with 5 m³ of low strength concrete. UCI determined that corrugated steel liner plate would be the most reliable method of reinforcing the culvert. Liner plate for the repair was ordered from Armtec Inc. of Guelph.

The nature of the repair work required the expertise of a tunnel contractor and Avertex subcontracted the repair work to James Elliott Underground. A trench box was installed to stabilize the ground at the culvert entrance. In order to access to the pile location (which was 150 m from the downstream end), a tunnel railwa was built in the culvert and an electric locomotive used to haul the muck out and deliver and tools and materials to the work area. As the culvert was cleaned under Highway 403 and temporary lighting installed, it became apparent that the concrete pipes under this point of greatest fill cover were under considerable duress. Measurements indicated a 50 mm deflection of the vertical dimension which was essentially a structural failure of the rigid concrete pipe. Longitudinal cracking of the pipes was also evident.

On review by MTO, it was decided to line the entire culvert under Highway 403 including the area of the piles. The liner plate installation proceeded at the start of 2006 with final grouting of the liner plate being carried out on February 15, 2006. A total of 87 metres of 1500 mm liner plate was installed. The annular space between the concrete pipe and the steel liner was filled with approximately 32 m³ of 2:1 sand/cement grout.

The work around the piles was very labour intensive. Initially, the intruding reinforcing steel had to be cut away to allow removal of the debris, stones and silt. It was determined that one of the piles had pushed another pile right through the culvert pipe wall and bent it over on itself. This pile was serving no purpose and was removed. The liner plates had to be cut to make a custom fit around the intruding piles. The gaps were then filled with wedges, blocks and expandable foam. The efforts of the miners in doing this allowed the liner to retain the pressurized grout with only minor leakage.

During the entire period of the repairs, the creek water had to be by-passed around the work area with tanker trucks. In the end, a routine culvert cleaning project had turned into a major repair project, but the process had uncovered a serious deficiency in the culvert under Highway 403 and the repair may have saved the highway from a future collapse.