The LaSalle Causeway, East Wharf is a critical element in the transportation link across the Cataraqui River between Barriefield and Kingston, Ontario.
Riggs was retained by PWGSC to analyze the existing structures that comprise the wharf and provide solutions. The most cost effective option with the least impact to the environment was to toe pin the existing steel sheet pile wall with steel H-piles some of which some required pinning to bedrock. A new wharf face was constructed of concrete panels threaded between the H-piles. The new H-piles were secured to a new steel pipe pile anchor system that maintained the existing anchorage functional during construction. The top of the H-pile was cast into a new concrete parapet formed over the top of the old steel sheet pile wall. A new paved surface with site landscaping completed the newly stabilized structure.
Riggs was engaged by Arcadis US Inc. for the marine and structural engineering components of an engineered containment facility (ECF) for the Randle Reef Sediment Remediation Project in Hamilton Harbour, on Lake Ontario, in Hamilton, Ontario. The ECF is designed to contain contaminated sediments to be dredged from the harbour and for future port development.
Riggs was responsible for developing and evaluating design alternatives for perimeter structures including relieving platforms, cellular steel sheet pile walls, double sheet pile walls and standard bulkhead walls with differing anchorages.
The ECF is comprised of double sheet pile walls to minimize the structural footprint, to maximize containment and to effectively seal in the sediments with a barrier anchor wall. Analyses included limit equilibrium and beam on elastic foundation analysis of sheet pile structures using various steel sheet pile and finite element analyses software. Methods were investigated to improve the wall loadings to economize the design selection of the sheet piling by replacing the weak clay where practical.
The lateral stiffness of the structure was assessed using a 2D plain strain finite element code. The stages of placing sediment inside the structure and of pre-loading the sediments for strength gain presented unique challenges. In the undrained condition, the stiffness of the double wall structure proved inadequate to resist the stresses imposed during the preloading. To address this, the preload is to be applied in stages with material strength gain assessed at the end of each stage.
Riggs was retained to provide a routine detailed inspection of the Owen Sound harbour structures and identified that ʺStructure 2ʺ had deteriorated due to damaged piles and lack of structural bearing of the superstructure. The bearing issues relate to a combination of deteriorated concrete and timber pile tops.
Riggs provided repair alternatives as follows:
On behalf of the Hamilton Port Authority, Riggs undertook the detailed design of Pier 22, a commercial berthing facility located in Hamilton, Ontario. Our tasks included marine structural design, dredging and containment, and supervision of the construction works.