A rockslide at Gallagher Lake recently damaged a section of irrigation flume, shown here.
As canal repair work continues, the Town of Oliver has set a tentative start-up date for the irrigation season.
On Monday, council set the date to April 11, hoping to avoid any delays in diverting water to the canal.
Meanwhile, crews are working on a temporary fix to a section of canal that was damaged by a rockslide at Gallagher Lake in January.
Last week rock scaling personnel blasted parts of the mountain to make it safe for crews to fix the canal siphon that sustained cracks during the slide.
Director of Operations Shawn Goodsell said they could potentially start diverting water from the canal on April 1, which will let crews test the fixes prior to turning the irrigation on.
The canal usually takes approximately four days to properly fill and undergo checks in different sections.
Goodsell said irrigation service turn-ons are proposed to start on Monday, April 11 if everything goes well with the repairs.
“If we find that additional work or fixes need to be conducted, we may ask council to set back the irrigation turn-on dates to accommodate.”
Goodsell noted there is also the possibility of charging the irrigation distribution lines with some domestic water from wells But this would be classified as a “cross connection” and a “boil water advisory” would have to be issued to all Town of Oliver domestic water users (except in system 2 and 2b for the duration of the cross connection).
“We would only go this route if we needed to buy more time for further repairs or fixes to the canal and not delay irrigation turn-ons.”
He stated this solution could help with early volume demands for a short period of time. Regardless of these potential problems, customers will already have early water for spraying crops, Goodsell said.
Irrigation users will need to be cognizant of the recent water problems with the damaged siphon, and that the proposed fixes will restrict the normal volumes of water the Town is capable of providing (until a more permanent fix is made).
“This could mean that irrigation users may have to restrict their water consumption this season,” Goodsell said. “And the Town of Oliver may have to enforce an odd/even day for watering or some other form of restriction.”
On Monday, March 7, Town of Oliver staff and engineers were able to enter the siphon through a coordinated effort with the rock scalers. They discovered that damage to the siphon was significant; the roof had collapsed in one section as much as two feet.
Based on the visual analysis the best temporary option for repair is to insert two sleeves (or culvert) inside the siphon. This is a temporary solution for the irrigation season and cannot guarantee a 100 per cent fix if there are more damages or settlement.
Rock scaling will shut down on March 18 to allow the engineers and Town staff to reassess and determine when and if scaling work continues.
The Town is also looking to a more permanent fix which will involve additional rock scaling in the irrigation off-season.
The mayor and council are lobbying the province for funding assistance for what has been deemed a “natural disaster.”
From March 19-25, the contractor will conduct work inside the siphon, and on April 1 the canal will open (upper section only).
On April 4-5, the work will be inspected. A week later the system will be filled with water for irrigation turn-on.
Background
This section of siphon was installed in 1997 to help minimize and eliminate damages to the existing canal system. It is a 1,950 mm (78-inch) diameter reinforced concrete pipe buried over with approximately three metres of fill. It was engineered to withstand a great force if more debris were to fall. But the fill was unable to withstand the rock slide on January 25 and damage occurred.
By Lyonel Doherty
