Structural Strengthening
BACKGROUND TO REHABILITATION PROJECT
A large in-ground reservoir including two holding tanks located in a high seismic zone, required rehabilitation to ensure it was resilient enough to handle any future earthquakes. The dual-purpose structure also acts as playing courts for recreational activities.
SOLUTION
FyfeFRP has worked with the owner several times in the past, again retrofitting water reservoirs. FRP was chosen over other technologies due to the structure being unable to support additional dead loading as it would significantly require additional strengthening if traditional repair methods were chosen. FRP was able to add the needed performance at a lower price compared to traditional retrofit methods.
Fyfe Certified Applicator, Polycrete Restoration had a team of six working on the project, alongside two water district engineers, two representatives from General Contractor, Bennett Construction Group, and two engineers from a hired peer review group. The project lasted 18-months.
CHALLENGES
The project faced several challenges, the main being scheduling of the operation of the reservoir. Half of the scope was on the inside of the structure, and half was on the exterior and exposed to weather. The climate of the project location is subjected to consistent rain through the year and freezing temperatures in the winter months. The reservoir top is a flat slab which was prone to water ponding.
SUMMARY
- Application: Drinking water Reservior
- Location: Pebble Hill Reservoir, Metro Vancouver BC, Canada
- Installation: Polycrete Restoration
The project team’s solution was to construct movable hording tents over the area they were working on to ensure the application wasn’t exposed to the rain. When one area was complete, the tent would be moving to the next location.
Another challenge included dealing with drainage channels that were cut into the slab to accommodate the rain runoff. Fyfe engineers worked with the owner’s engineers to address any concerns and recommended to the engineer of record what steps were required to resolve the drains cut into the slab as they intersected with the FRP layout.
The entire top deck and soffit of the slab were retrofitted with NSF approved (certified to be in contact with water) Tyfo SCH-41 and SCH 41-2X Unidirectional Carbon saturated with Tyfo S epoxy in both directions resulting in a crisscrossing pattern.
The Fyfe Certified Applicator had to phase the FRP installation in the interior of the tanks as they were filled with water during the summer months and empty during the winter months. The FRP application was able to be conveniently started and stopped based on the seasonal demands of the reservoir with minimal mobilization to swap between exterior and interior work proving FRP’s ability to save time and money.
The installed FRP system effectively added no additional weight to the structure helping reduce the seismic design loads that would have otherwise been increased with traditional retrofit methods.
Once completed the top of the tank was restored for the use of recreational activities. This project adds to t he inventory of the water district’s reservoir assets in providing seismic resiliency for future seismic events in the region.
