Northern Ontario Construction News special feature
Tulloch Engineering provides consulting engineering services in eastern and throughout northern Ontario, with a range of specialties including land development. The company provided site grading design and contract administration services for the Elliot Lake Mall project.
Project manager Chris Kirby says the first challenge involved deciding how to handle the site. Comprised of 80 per cent rock and with a 25 meter elevation change from one side to the other, creating a flat area for the mall’s sprawling design took more than one design iteration to solve satisfactorily. “Our initial design resulted in too much excavated material and didn’t adequately meet the needs of the one-storey design,” Kirby said.
In the end the team decided to maintain an elevation above Ontario Ave., rather than trying to meet it, and a large retaining wall (2,400 sq. m.), which Kirby calls technically challenging, has been designed.
The retaining wall required concrete footings, pinned to the bedrock and, constructed largely during the winter months, also required heating to cure the concrete and additional testing to ensure the cure’s success.
He says 80,000 cu. m. of rock excavation and 20,000 cu. m. of earth excavation work were needed to level the site with the retaining wall (10m at its highest) and provide access from the site’s north and south ends. “The volume of rock grading completed here is fairly typical for Northern Ontario but not within a city setting,” Kirby said.
Though much of the excavated rock was repurposed on the site, some had to be removed along Ontario Ave. and Hillside Dr. South, both main thoroughfares through Elliot Lake, to a clean dump identified for the purpose by the city.
The engineer also needed to take into account the site’s location within a residential community. “The blasting could be felt 500 to 600 metres away from the site and there had been a request from the community to be notified in advance of each blast, so that took a fair bit of co-ordination by the contractor.”
Kirby says it is evident this project has great community interest. The site is bordered on all sides by public areas, and many people visited to observe the work, especially at the start of construction. Some visitors had questions, which workers tried to answer.