The Brief

With extensive collaboration between our team, the City of Hamilton, and project stakeholders (and a little RVA ingenuity), we successfully completed the major rehabilitation of a large sewer outfall located below a busy industrial intersection in Hamilton in under three weeks.

Project Overview

Building livable communities for the long-term

The City of Hamilton maintains numerous sewer outfalls to Lake Ontario. Among these is the Wellington Street Sewer Outfall, is a 2.5 m-wide by 2.13 m-tall twin box storm sewer within the Hamilton-Oshawa Port Authority (HOPA) Pier 10. Originally constructed in 1921, the structure had been modified over the years to accommodate a railway crossing above the sewer and an extension of the outlet as part of a new dock wall construction project in the 1930s. RVA was approached by the City in 2021 to complete a visual inspection of a 70 m section of the outfall.

Our team identified extensive deterioration along the outfall that required immediate repair to mitigate the potential for major damage to the structure which, if unaddressed, could lead to risks to the City, HOPA and its clients, the environment, and the local community. The City and RVA took immediate proactive measures to prioritize it as an emergency project, and RVA’s structural and conveyance teams quickly mobilized to expedite the design, procurement, and construction of a staged rehabilitation of the outfall within a strict 2-month timeframe, all while minimizing impacts to stakeholders.

The extent of deterioration in the outfall was particularly pronounced at the railway crossing, which was used by CN Rail and its clients for transport to and from Hamilton Harbour. Our team discovered that a section of the sewer had been modified in 1928, when concrete columns and a thickened roof slab complete with steel I-beams had been installed to support the rail track. Increased railway traffic, vibration, and harsh environments within the sewer in the subsequent years had resulted in structural deterioration to the concrete roof along the entire length of the structure. Together with the City, our team assessed the project constraints and determined that the most appropriate solution was to remove and replace the damaged sewer roof at the railway crossing, and construct a new concrete roof topping outside of the limits of the railway crossing.

Setting the stage for success

In addition to prioritizing the needs of various stakeholders, the location of the outfall entailed several unique considerations. But with these challenges came the possibility for innovation and collaboration. Due to the size of the sewer and varying water levels from Lake Ontario, the flow could not be bypassed, and rehabilitation work had to be carried out in live conditions. To accommodate this, our team designed the roof to be removed and replaced in alternating sections to maintain support to the sewer walls, without the need for internal bracing.

In addition, the sewer was located under a busy intersection and access driveway that saw frequent truck traffic and had to be maintained throughout construction, which necessitated a thorough traffic management study by RVA’s Transportation group to allow workers and delivery trucks to enter and exit the surrounding properties unobstructed. To prevent the re-entry of fish when work commenced, RVA’s Ecology team also had to coordinate with the contractor prior to construction to herd out aquatic life from the twin box sewers towards Lake Ontario using fish nets at the outlet to the lake. 

With these considerations in mind, our team developed a program that not only provided significant enhancements to the design, but also fast-tracked the construction schedule and balanced the priorities of multiple stakeholders, such as HOPA (which operated the rail on a daily basis), the Hamilton Conservation Authority, public utilities, and local tenants. After close consultation with key stakeholders, RVA was able to identify a critical three-week period between January and February that permitted construction to take place during a railway shutdown, and a ten-day window to complete the sewer rehabilitation work at the access driveway.

With our preparations complete, the stage was set for fast-tracked and seamless construction. In the Spring of 2022, RVA’s project team managed the successful completion of all repair work on the Wellington Outfall rail crossing, within the span of a three-week period, including:

  1. Temporarily removing the rail section that crosses the sewer structure;
  2. Removal and replacement of the concrete roof of the structure, including interior concrete wall repairs to mitigate further deterioration, and;
  3. Reinstatement of the roadway and CN rail crossing above the sewer structure.

From planning to execution, every step in our Wellington Street Sewer Outfall Repair project required meticulous coordination, extraordinary collaboration, and a shared sense of collective ownership between the RVA project team and its key players, including the City of Hamilton, HOPA and its tenants, CN Rail, Sun-Canadian Pipeline, and the Hamilton Conservation Authority. Our Wellington Outfall project is not just an incredible feat of engineering and collaboration; it’s a shining example of how diverse stakeholders united under a common goal can lead to outcomes that transcend the challenges they solve, and shape the communities we serve for the better.

Gallery

Related