The Greater Vancouver Water District (GVWD) supplies water to approximately 2.4 million people, about half the population of British Columbia.
The water distribution network includes 25 service reservoirs, critical for providing storage in the system and providing additional capacity during peak day demand.
The GVWD initiated a program to carry out a seismic evaluation and upgrade those reservoirs that present a significant safety hazard or were critical to their ability to distribute water throughout the region.
Ausenco carried out both the initial seismic evaluation and the detailed design for the seismic upgrade of the cast-in-place concrete structure originally constructed in 1928 and expanded in 1968.
The evaluation confirmed the deficiency of the structure to meet specific seismic performance at the service level earthquake, the operating basis earthquake (comparable to the NBCC 1995 design earthquake) and the Maximum Credible earthquake.
The proximity of residents “downstream” of two vulnerable sides of the reservoir made the upgrade imperative. New internal shear walls for the roof structure and innovative use of tension-compression mini-piles for the exterior walls allowed essentially all construction to be completed within the reservoir minimising disturbance to the nearby residents.