The $3 million, one-year-long construction of a 250-metre long erosion protection wall/headland along the most protruding portion of Toronto’s Bluffer’s Park was scheduled to wrap up at the end of July.
Designed by Riggs Engineering for the Toronto and Region Conservation Authority (TRCA), the Bluffer’s Park South Headland is comprised of a double layer of 14,000 tonnes of seven- and five-tonne armourstone supplied by C.D.R Young Aggregates Inc. from its limestone quarry in Bobcaygeon, Ont., as well as a layer of geotextile and rip rap.
For the five-member installation crew the project has been a mix of trials and triumphs. The scenery is spectacular and the worksite includes views of Lake Ontario and an erosion/geological feature known as the Scarborough Bluffs, which is where the park gets its name from.
Working conditions, however, have been somewhat less ideal and could even be harsh, since there were times the workers had to contend with the impact of waves and wind whipping the site, blowing sand into their faces.
“There are good days and bad days,” says conservation authority site supervisor Ryan Doody.
There is big difference between working on the site on a nice sunny June day compared to a freezing one in January, says Doody, whose crew is comprised of two other TRCA employees and two TMI Contracting Ltd. heavy equipment operators.
Although the stones are randomly placed, the installation process was not a haphazard one. The seven-tonne armourstone was placed along the toe of the headland and, once that was completed, the five-tonne pieces positioned on top, he says.
Every stone was weighed onsite and carefully selected to ensure it would interlock when placed adjacent to already installed ones. If there are any voids between the stones the headland will be weakened, he explains.
The evaluation process, which took into account the stones’ configuration, was conducted by Doody and fellow TRCA employees Michael Ball and Mavrick Purchase. Under their direction, TMI heavy equipment operator Jim Curtis used a 40-tonne excavator to lift and lower the stones in place. There is a certain amount of “trial and error” and sometimes stones had to be adjusted or lifted out and replaced with another, says Doody.
When asked if the operation is somewhat like the work performed by stonemasons, he says, “Yes, but without the mortar.”
With a limited perspective on all angles, Curtis relied on TRCA staff to help navigate the right stone into the right place, while considering the machine’s load restrictions and limitations.
“You have to stay calm and cool or try to anyways,” says Curtis.
The fifth crew member is Mauro Zanconato who used a 40-tonne loader to move the stone from a stockpile area to the installation site.
To ensure public safety, the headland area was closed during the project and other park areas were also closed on weekdays to ensure access to the construction area, says TRCA senior project manager Jet Taylor.
A 2018 windstorm which seriously damaged the old headland was the catalyst for the project. In that storm the mid-portion of the shoreline completely collapsed. Five-tonne armourstone was completely displaced and large pieces of rip rap were thrown 10 metres inland.
A heavily used trail in this area was also eroded away in many areas and covered in aggregate debris which was a safety hazard. The shoreline was also destabilized making it susceptible to ongoing erosion, he says.
Shortly after the storm occurred, planning and design for the new headland got underway. It included interim designs for the replacement of the most seriously damaged mid-portion. The work was carried out in 2018, says Taylor.
Now that the headland project is reaching its conclusion, the conservation authority will be embarking on the restoration of an adjacent beach later this summer, says Taylor.