Jimmy Jimmy (Judd) Slough – Dike Upgrade

The District of Squamish completed an Integrated Flood Hazard Management Plan (IFHMP) in 2017 which laid out a prioritized list of dike upgrades to raise the standard of flood protection for the community. The highest priority project was to upgrade the Squamish River dike at Upper Jimmy Jimmy (Judd) Slough to meet provincial requirements so that the dike can withstand a 1 in 200-year return period flood with 0.6 metres of freeboard.

• This project was established as the highest priority due to the IFHMP concluding that failure of the dike could result in direct damage totalling $190M (2016$) and displace up to 7,000 residents in the neighbourhoods of Brackendale, Garibaldi Estates and several Squamish Nation reserves.
• This section of dike also protects significant community and regional infrastructure including Highway 99, CN Rail mainline, wastewater treatment plant and several major drainage pump stations. A dike breach would cause significant social and environmental impacts due to the flooding of homes and businesses.

This upgrade was completed in 2019.

The IFHMP also recommended a longer-term priority to raise the local standard of protection for the Squamish River dike beyond provincial standards, to meet a 1 in 500-year return period flood (see Figure 1 below for details). This increase of standard was recommended in recognition of the substantial community development that relies on the protection of the Squamish River dike. In anticipation of this future upgrade, the 2019 upgrade widened the footprint of the dike so that future upgrades would only need to raise the dike without requiring any additional space.

The proposed scope of work will:

• Raise approximately 900 metres of the Squamish River dike on private land in between Wai’wakum Reserve and Aik’wuck’s
• Reserve as shown in Figure 2 below.
• Widen the dike crest from 4 metres to 6 metres.
• Provide rip-rap erosion protection for the raised portion of the dike.
• Add new vehicle turnout.
• Upgrade one access ramp.

The total cost of the project is $5.4 million, 73.3% of which is covered by grants. The District received $2,169,600 in federal funding through the Green Infrastructure Stream of the Investing in Canada Infrastructure Program for the Squamish River Dike Raising. The District received an additional investment $1,807,819 in provincial funding for the project. The remaining cost of the project is proposed to be funded through borrowing to spread the cost of the project out over time, ensuring that future taxpayers also support the upgrade. $1,446,581 of this project is proposed to be financed by debt.

Please contact Reid Plasterer, Project Manager, Capital Projects, at [email protected] with any questions.