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Drilling of caisson with Haine crane-mount drill rig. High mounting of drill rig allows for drilling to take place very close to the face of shoring.

Drilling of caisson with Haine crane-mount drill rig.
High mounting of drill rig allows for drilling to take place very close to the face of shoring.

The Anchor Group was awarded the contract for the shoring, caisson walls and structural caissons for the new Durham Regional Cancer Centre and Central Utilities Plant located in Oshawa, Ontario. The scope of work included over 15,000 ft2 of lagged shoring, 35,000 ft2 of caisson walls, and 170 structural caissons.

Shoring – Caisson Walls & Lagging

Site overview showing the multiple grade changes and complex shoring geometry required to accommodate existing buildings.

Site overview showing the multiple grade changes and complex shoring geometry required to accommodate existing buildings.

The excavation was up to 50 feet in depth. 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″ (915 mm) 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. 13,000 feet of regroutable tiebacks were installed at this site.

Caissons

High mounted Hain crane-mount drill rig removing soil from temporary casing.

High mounted Hain crane-mount drill rig removing soil from temporary casing.

Installation of temporary steel casing with vibratory hammer.

Installation of temporary steel casing with vibratory hammer.

Pouring of high slump concrete into drilled caisson.

Pouring of high slump concrete into drilled caisson.

Lakeridge Health Centre

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 2’-6″ to 7’-6″ in diameter. Over 3,500 cubic metres of concrete and 100 tonnes 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.

Other Health Care Projects by The Anchor Group

The Anchor Group have extensive experience in the health care sector and our recent contracts have included work at

  • St. Joseph’s Hospital – Hamilton,
  • Southlake Hospital – Newmarket,
  • Hospital for Sick Children,
  • Lakeridge Health Centre-Oshawa,
  • Durham Regional Cancer Centre,
  • Toronto General Hospital, and
  • Muskoka Regional Hospital.