Project Location:

The Project is located at the site of an existing causeway used for logging and barge landing as recently as 2012, on the east side of Ridley Island, south of the City of Prince Rupert. The Project is located entirely on federal crown land, wholly within the jurisdiction of PRPA. The Project is located on Ridley Island and bordered by the marine waters of Porpoise Harbour to the north, south, and east. Ridley Island near the Project location consists of heavily developed mixed-use industrial land as well as access roads and the PRPA settlement pond.

Project Description:

The primary structures consist of an extension of the existing causeway to increase the width to 30 m using tied sheet pile walls, and an approximately 30 m wide x 50 m long pile and deck structure extending seaward. The pile and deck extension structure type has been selected primarily to minimize the footprint of disturbed seabed in comparison with a seaward extension of the existing earth fill causeway.

The sheet pile wall extension consists of vertical tied sheet pile walls founded on shallow bedrock, with steel walers and thread bar cross ties at the base and top of the sheet piles. Shallow bedrock is anticipated based on visible bedrock to the north and south of the existing causeway although this will be confirmed by the geotechnical investigation.

The pile and deck structure consist a maximum of 44 steel pipe piles, likely 610 mm in diameter but up to 914 mm, socketed into bedrock. A concrete plug may be required depending on drilling method to suit the required bedrock socket. Pile quantities and sizes will be minimized to reduce the duration of in-water construction where possible during design finalization.

The pile support deck structure of a steel beam framework supporting a galvanized steel grating deck. The deck structure will be of a semi-modular construction to allow rapid construction.

Comparing the historic footprint to the proposed design, showed an approximate net increase of 279.57 m² below the high high-water large tide (HHWLT) due to the tied sheet pile wall and riprap infilling. Resolution of historical imagery limits the certainty with which the quantification can be made, therefore a conservative estimate of the historical infrastructure has been used. The pile installation itself adds an extra 28.89 m². Consequently, the proposed design results in a net footprint increase of around 308.46 m².

Project Components

• Tied sheet pile wall.
• Riprap infilling at the base of sheet pile wall for stability and reinforcement.
• Steel grate deck superstructure.
• Thirty-two piles to support deck structure.
• Four breasting dolphins, each consisting of 3 piles (max diameter of 914 mm).