Construction on the John Hart Power Generating replacement project continues to expand, advancing on four fronts this month, BC Hydro has announced.
One of those projects may impact visitors using the trail system entering Elk Falls Provincial Park in the coming week.
In addition to ongoing blasting at the main power generating cavern and its associated tunnels, work on the new intake system at John Hart Dam, and the beginning of construction on the water discharge outlet below the power station, workers this week will be preparing the site for the new surge tower near the current trail system leading into the park and to the popular Elk Falls suspension bridge.
Beginning this week, tree removal will take place along the access road that parallels the existing woodstave penstocks, near the pedestrian bridge that crosses the three penstocks.
“People should expect sporadic delays of about 10 minutes (each) to safely allow the contractor to fall the trees,” BC Hydro spokesperson Stephen Watson wrote in the project update released at the end of August.
Delays are expected to continue for about a week. After the trees are removed, the access road will then be widened to allow for two-way construction traffic to the new surge tank area.
The single surge tank will eventually replace the three existing, 90-metre surge towers, which provide pressure control for each of the three penstocks.
The new tank will serve the same purpose in the new, underground inflow tunnel when the project is completed, tentatively set for fall of 2018.
“Popeye” on the job
Construction crews’ answer to a problematic area of “unconsolidated ground” — or loose rock — in the main access tunnel has been to adopt the New Austrian Tunneling Method (NATM), which has been growing in use throughout Europe in recent years.
At the John Hart project site, this takes the form of installing pipes along the roof of the tunnel and grouting between the pipes before excavating the loose rock below.
Instead of blasting, excavation is done by a CAT 328 excavator with a specialized arm nicknamed the “Popeye Arm” due to its bulky claw and outer extension.
Going to bat for bats
Underground workers were credited with capturing and releasing a bat that had become caught in the mine area recently, but the death of other bats that were caught in the underground ventilation system led to a more proactive solution.
“The contractors have been working with environmental professionals to grate off different areas to prevent bats from entering,” Watson said.
“These adjustments have been successful to date.”