The City of Delta has issued a request for proposals for an engineering consultant to come up with a preliminary design, detailed design and construction service to improve the efficiency of the city’s irrigation water conveyance system.
Partially funded by the BC Ministry of Agriculture through the Investment Agriculture Foundation’s Agriculture Water Infrastructure program, the project has a tight construction deadline as set by the grant funders.
According to the request for proposals, the project includes conveyance system upgrades at two locations, one being a culvert upgrade at Ladner Trunk Road and 72 Street, while the other is an irrigation channel upgrade along Highway 17, west of the 72 Street overpass.
It is anticipated that a new culvert, or siphon, is required under Ladner Trunk Road to convey more irrigation water along 72 Street. The proposed culvert crossing should be able to convey approximately three cubic meters per second with minimal head loss.
As far as the second site along the east side of Highway 17, the existing drainage/irrigation channel is constricted at spots for approximately 400 metres, adversely affecting both the irrigation and drainage flow capacity of the ditch.
The city notes that the choking of flow leads to reduced irrigation water flow through the area during peak summer demand season. The problem needs to be removed to provide a more efficient irrigation water conveyance.
However, the ground underneath the channel adjoining Highway 17 primarily consists of peat, which makes the ground conditions challenging. A detailed geotechnical investigation is required to determine the ideal solution to remove the constriction.
All feasible options must be considered including, but not limited to, enclosing the channel with large diameter pipes or culverts, or an open concrete channel, an open channel with sheet piles walls, as well as a pump station.
The preliminary design for the Ladner Trunk Road crossing should be completed no later than May 31, 2024, while external agency approvals need to be completed before Dec. 31, 2024. Construction is anticipated in early 2025 before the irrigation season.
As far as the Highway 17 irrigation channel upgrade, the initial investigation should be completed no later than the end of this May. The initial report outlining the constriction causes with conceptual solutions is expected to be submitted in July 2024.
The detailed design, external agency permitting applications, tender and construction services will be awarded in August 2024, after the recommended option is selected.
Dry conditions last summer prompted the city to deploy additional irrigation efforts to keep water flowing to local farmers. The engineering department said significant costs were incurred for the temporary measures, including installing pumps and deployment of staff, which were borne by the city.
