John Hart G.S.R.
Tunnelling project - John Hart Generating Station Replacement
BC Hydro, Vancouver, Canada
Main Contractor: InPower BC (SNC-Lavalin)
Tunnelling Contractor: Frontier-Kemper Constructors, Inc. / ASL JV
Consultant for SEM/NATM: BeMo Tunnelling Canada Inc. as consultant for execution of NATM tunnelling works in an unexpected soft ground zone. Technical support, SEM/NATM onsite support by experienced BeMo specialists (Senior NATM Engineer and 2 Superintendents on site)
Campbell River, British Columbia
Start of construction
End of construction
Project total value
1 million €
Sand, cobbles, boulders, wood, hard rock (basalt).
Total length: 1,250 m
Measures: 8.3 m high; 8.1 m wide
Total length: 400 m
Measures: 10.7 m high; 6.5 m wide
Main Access Tunnel:
Total excavation: 300,000 m³
Measures: 7.5 m high; 9.5 m wide
BeM;o’s work zone:
60 m long soft ground zone consisting of weak rock and sand
After surprisingly entering a soft ground zone (sand, gravel, cobbles) excavation applying SEM / NATM using pipe arch canopies, spiling, face bolts, grouted face bolts, elephants feet in combination with shotcrete (dry/wet) as tunnel pre support.
Further project related information
Extreme mixed face conditions with loose sand required intense application of pipe roofing in double layers including ground improvement by using grouting via endcaps and via double packers with microfine cement.
Dewatering measures by applying gravitational methods and vacuum dewatering.