A specialized mix and a strict pour schedule for the TTC

Working alongside Buttcon, Dufferin Concrete completed a job for the Toronto Transit Commission (TTC) on the Patten Building, providing not only innovative products, but ensuring quality service and technical support.

Having worked with the TTC on numerous occasions, our team is familiar with their requirements on schedule dates, health and safety, security controls and of course quality products and services. During construction, the building remained completely functional with the exception of the ground parking level, where the new concrete reinforcement was added. Due to the reduced working area and limited space to delimit a construction zone, all concrete pours were scheduled for Saturdays, leaving no room for error.

Our team worked to design a completely new Self Consolidated Concrete (SCC) mix that would meet the TTC’s strict specifications. The concrete was pumped from an offsite location across from the job site and had to flow through the forms between two layers of rebar and stir-ups. The complex formwork needed to remain completely water tight and valves and ports were installed to release air and eliminate air pockets. As an extra measure of care, camera ports were added to confirm that all voids were filled. There were three scheduled days to complete the six phases of the pour in a designed sequence in order to reduce the stress of the structure and possibility of voids. The largest of these phases was 50+/-m3. Two testing companies, comprising of 35 testers and monitors, were on site to perform several tests on each load of SCC going into the pour. The compressive strength was achieved on average three to five days after pouring. TTC and Buttcon were pleased with the technical support as well as the excellent quality of the concrete, workability, uniformity and performance of the SCC mix supplied by Dufferin Concrete and have indicated that this would be a preferred mix for future similar TTC projects.

Mid-Halton Wastewater Treatment Plant

To meet increased demand and continue to protect the water of Lake Ontario, the Regional Municipality of Halton had to address the need to increase capacity at the Mid-Halton Wastewater Treatment Plant in Oakville Ontario from 75 million litres per day to 125 million litres per day. The project will not only provide environmental benefits to Lake Ontario, but will also improve the safe handling and management of wastewater as our communities continue to grow.

The project, valued at $79 million began in 2014 when Strabag Inc., the construction contractor was awarded the job and began production. For this project, a 3.6m diameter Tunnel Boring Machine (TBM) was required to excavate through layers of shale and limestone starting from the QEW under Third Line in Oakville into the lake. The project includes a 6.3Km underground pipe in two stretches; The onshore stretch spanning 4.2 km from the wastewater treatment plant on North Service Road to Lake Ontario, 60m below the roads surface, and an additional 2.1km offshore stretch ranging from 15 m to 50 m beneath the bedrock of Lake Ontario for a total length of 6.3km.

Dufferin Concrete designed a specialty concrete mix to endure a four hour lifespan and be delivered by rail inside the tunnel. Our team also used wet Shotcrete to secure and shape the tunnel’s rounded profile. Dufferin Concrete provided approximately 25,000m3 meters of concrete used in the project.