Victoria, British Columbia
Construction: 2014 – 2016
Owner: Transport Canada
Client: Quantum Murray LP
Shoring Contractor: Vancouver Pile Driving Ltd.
Rock Bay is the site of a former coal gasification plant that operated from 1862 to 1949 by Victoria Gas and BC Electric. The coal gasification process resulted in significant environmental impact to soil, groundwater, and harbour sediments. The clean-up of Rock Bay included almost 4 hectares of uplands and harbour floor and has been one of the most significant remediation projects in Canadian history. Adding to the complexity were fish and wildlife habitats, as well as heritage and archaeological claims in the area.
Isherwood was hired to facilitate the removal and replacement of contaminated soils from Rock Bay prior to land transfer to the Songees and Esquimalt First Nations. A number of specifications had to be respected, including complete removal of impacted materials and a strict zero-encroachment rule for shoring. The saturated soft clays in Rock Bay contributed to challenging working conditions on site.
The shoring design consisted of multiple components. A raker-supported sheet pile system and internally braced cofferdams were installed around the perimeter of Rock Bay to protect adjacent buildings. In order to cut off the bay from tidal inflow, allow for dewatering, and facilitate subsequent soil removal, a cellular bin wall was built connecting the north and south shores. A storm water bypass pipe was supported by temporary steel braces and acted independently from the shoring and cofferdam elements.
Through continuous coordination with contractors on site, Isherwood was able to efficiently re-design shoring elements when actual site conditions varied from assumptions used in the original design. A comprehensive monitoring program also allowed Isherwood to react in real-time to any unexpected movements and make adjustments as needed.