CLIENT: City of Kelowna
PROJECT DESCRIPTION
PRI provided engineering services to the City of Kelowna for the rehabilitation of Frazer Lake Dam, located in the Upper Mission neighbourhood of Kelowna, BC. The preliminary design phase included review of existing documentation, site reconnaissance with a geotechnical subsurface investigation, geotechnical and hydrotechnical analyses, development and evaluation of design alternatives, and a Class C cost estimate. Following preliminary design, the project advanced to detailed design and the completion of tender-ready, issued-for-construction (IFC) drawings and a schedule of quantities.
PRI’s team also completed environmental impact assessments, including several wildlife surveys, and prepared a construction environmental management plan as part of the BC Dam Safety Regulation Plan submission requirements. Key elements of the dam remediation design included:
- Removal of the existing earthen embankment, concrete headwall, and outlet works
- Temporary cofferdam design
- Steel sheet pile cut-off wall
- Rock ramp spillway channel
- Cast-in-place concrete level control structure
- Low-level outlet and gate works
CHALLENGE
Frazer Lake Dam required rehabilitation to meet BC Dam Safety Regulation requirements, but the site’s location within an established residential neighbourhood and its surrounding natural habitat added complexity to the design. The existing earthen embankment, headwall, and outlet works needed to be safely removed and replaced without compromising dam safety during construction, while subsurface conditions had to be well understood to support a durable, code-compliant structure. At the same time, the project needed to account for local wildlife and satisfy the environmental documentation required under provincial dam safety regulations, all while keeping the design on a path to a tender-ready package.
APPROACH
PRI began with a thorough preliminary design phase, reviewing existing records and conducting site reconnaissance, including a geotechnical subsurface investigation, to characterize site conditions. Geotechnical and hydrotechnical analyses informed a set of design alternatives, which were evaluated alongside a Class C cost estimate to guide the City’s decision-making before advancing to detailed design.
The resulting design package paired the removal of the deteriorated earthen embankment, concrete headwall, and outlet works with a temporary cofferdam to allow construction to proceed safely in the dry. A steel sheet pile cut-off wall was incorporated for seepage control, alongside a rock ramp spillway channel, a cast-in-place concrete level control structure, and new low-level outlet and gate works to manage water levels going forward. In parallel, PRI carried out environmental impact assessments and wildlife surveys and developed a construction environmental management plan to satisfy BC Dam Safety Regulation Plan submission requirements, ensuring the design was ready to move directly into tendering.
OUTCOME
PRI delivered a complete engineering solution for the City of Kelowna, from preliminary design through to tender-ready IFC drawings and a schedule of quantities. The rehabilitated dam design meets BC Dam Safety Regulation requirements while incorporating the environmental planning needed to protect the surrounding habitat, giving the City of Kelowna a safe, durable, and regulation-compliant dam for the Upper Mission community.
