Crews working on the John Hart Generating Station replacement project are preparing to start tunnelling which will set the stage for the new underground generating station.
To accommodate the single tunnel that will be replacing the three penstocks, two entrances – one to the south and one to the north – upstream of the surge towers are being created.
At the southern portal, project contractor Aecon SNC-Lavalin Joint Venture has dug a 25 metre (82 feet) deep hole in the ground. Stephen Watson, spokesperson for BC Hydro, said the portal is about 18 metres wide at the top and narrows to eight metres at the bottom.
“The tunnel will begin to be excavated and blasted out at the far end and bottom of the portal,” Watson said in a project update report. Tunnelling on both the southern and northern portals is expected to get underway in mid-December.
At the northern portal, overburden removal and excavation is still continuing and a laydown area has been levelled off to the left of the surge towers.
Watson said removal of the overburden from both portals “has generated the highest intensity truck traffic anticipated, as up to 15 trucks have steadily circled through the site.”
Trucks have been hauling up and down both Highway 19A and Highway 28 to sites at Middle Point and Farwell Road.
Meanwhile, Brewster Lake Road is still scheduled to be closed in the new year.
“Intermittent road closures, i.e. 15 minutes, to Brewster Lake Road are expected to begin in January and last through March 2015,” Watson said. “This is to allow for the tree clearing and bridge construction. In April, the planned three-year road closure is expected to begin in full.
“The existing bridge will remain in place and (be) used for regular construction vehicle traffic during the construction period.”
The Brewster Lake Bridge, which crosses over the three penstocks on the road to Elk Falls, will eventually be re-built.
“When project construction is complete, (the bridge) will be removed and an earth berm will be installed to allow for public vehicle traffic,” Watson said.
Environmental considerations
- Crews completed tree planting at the entrance to the new Elk Falls parking lot as compensation for trees approved for removal because they were deemed dangerous to workers on site.
- Roughly 100 red-legged frogs have been relocated to adjacent wetlands.
- Water run-off is being monitored and mitigated. Mitigation plan is being developed for run-off from Surge Tower Road.
- Acid rock drainage tests for both portals completed and indications are that those locations are not acid-creating.
