The City of Penticton has completed a significant upgrade to the Greyback Dam infrastructure.
Greyback Dam is the main source of water feeding Penticton Creek and is controlled by the City of Penticton for domestic supply and north-end irrigation purposes. The reservoir has a storage capacity of approximately 12.33 million cubic metres of water. The dam was original constructed in 1967 and is considered a very high-consequence dam, according to the Canadian Dam Association.
Over the last five years, the city has conducted work on Greyback Dam to bring it up to current federal safety standards by raising the dam crest and widening the spillway.
A formal inspection of the operating gates of the dam was completed in 2011 and found that the gates were in need of full replacement as they were reaching the end of their lifespan. Two existing gates (one eight inches in diameter, and the other 24 inches in diameter) that function like valves were to be replaced, and a third isolation gate (24 inches in diameter) was also installed to assist with future maintenance requirements.
A team of city staff worked alongside contractors and consultants with dam gate expertise. Working approximately 150 feet from the shore, divers swam to the bottom of the reservoir installing a bulkhead to plug off the inlet structure and stop the water flow. Two cranes were used to remove and install new gate structures — accessed from the crest of dam through a tower chamber approximately 70 feet deep. Once the bulkhead was in place, pumps were required to divert water back into Penticton Creek.
Crews worked 12 consecutive 12-hour days on the removal and replacement of gates weighing in excess of 3,000 pounds. Once all the structures were in place, divers went back down to remove the bulkhead and return the dam to normal operations.
“This was an incredibly intensive project, and our foremen Brent Deleeuw and Ron Johnson were instrumental in directing and guiding this project from start to finish with no major setbacks,” said Len Robson, public works manager.
The three operating gates have brought Greyback Dam fully up to current standards. Regular maintenance is required, which is ongoing by city staff.