Boreholes to show the way for sewage-treatment leftovers
The first of 65 boreholes up to five metres deep are being drilled in Greater Victoria municipalities as part of the groundwork for a pipeline that will transport leftovers from a sewage treatment plant at McLoughlin Point.
The pipeline will run from McLoughlin in Esquimalt to Hartland Landfill in Saanich.
Boreholes, mostly along roads, are required to collect soil samples to determine what is under the pavement before trench digging begins.
A drilling rig mounted on a truck got the work underway last week, starting at the intersection of Interurban and Grange roads.
Eight locations will be drilled in Esquimalt, three in Victoria, two along the Esquimalt-Victoria boundary and 52 in Saanich.
“Residual solids” will be carried by water in a pipeline 18.5 kilometres from McLoughlin to Hartland. After the solids are delivered to Hartland, the water will flow 11.5 kilometres to a pump station in the Marigold neighbourhood, where it will enter an existing system back to McLoughlin.
Daily flow from McLoughlin is estimated at 108 million litres.
At Hartland, the solids are to be processed at an as-yet unbuilt treatment facility to turn them into “Class A” biosolids that are safe for further use; a soil supplement has been given as an example.
“The number of boreholes may change as the investigation requires,” said Capital Regional District spokesman Andy Orr.
“The anticipated plan is to continue to work north through Saanich for the rest of this week and resume at other locations in subsequent weeks. The geophysical crew also started on Aug. 21 in the northern part of the route.”
Drilling is expected to take two to three hours per hole, but “the actual duration could extend longer depending on the soil conditions encountered during the drilling operation,” Elizabeth Scott, deputy director of the CRD wastewater treatment project, said in a statement.
The work is to be completed within six weeks and the borehole openings covered so as not to affect traffic.
Once a route based on the drilling is finalized, community engagement will get underway to develop plans to address construction impacts on nearby neighbourhoods, the Saanich municipal website says. Construction of the system, which involves pump stations, is expected to begin in spring 2018.