The Anchor Group, headquartered in Toronto, was awarded the contract for the shoring, caisson walls and structural caissons for the Durham Regional Cancer Centre and Central Utilities Plant located in Oshawa, Ontario. The scope of work included more than 15,000 square feet of lagged shoring, 35,000 square feet of caisson walls, and 170 structural caissons.

The excavation was up to 50 feet in depth, and the water table was located at a depth of 10 feet above the base of the proposed excavation. As a result, it was necessary to extend the caisson wall piles and fillers 20 feet below the proposed excavation level to seal off the site from water recharge.

Liners were required for installation of the caisson walls below the water table. Casings were advanced using a vibratory hammer mounted on a service crane. The casings were drilled out using a crane mounted drill rig. There were 550 36-inch drill holes installed for the caisson and lagging walls. The walls were braced with regroutable soil anchors drilled by Crown Drilling Ltd., a member of the Anchor Group. Also, 13,000 feet of regroutable tiebacks were installed at this site.

The proposed structure was to be supported on 180 end-bearing caissons founded on rock. Drill lengths up to 80 feet were required with diameters ranging from 30 inches to 90 inches in diameter. Nearly 125,000 cubic feet of concrete, and 100 tons of rebar were placed in the caissons. The soil conditions at the site presented many challenges to the installation of the caissons. The sand was extremely dense, which made installation of liners through these layers with a vibratory hammer very difficult. The Anchor Group elected to high mount a Haine drill on a link belt crane to allow the drill to reach up over the liners. A vibratory hammer mounted on a service crane was used to place and remove the liners.

Founded in 1968, The Anchor Group offers more than 40 years of construction experience in the design and installation of soil retention and engineered foundation systems. In order to provide a full range of services, the original company of Anchor Shoring has evolved into several divisions and companies that form the Anchor Group – Anchor Shoring & Caissons Ltd., Banner Piling & Excavating Limited, and Crown Drilling Limited.