Alterra Power Corp. announced that a large naturally-occurring rockslide near its 88 MW Montrose hydroelectric facility caused significant damage December 2013, to a 200-300 metre section of the five kilometer penstock which supplies water from the water intake to the power generating plant. The intake and power plant were not affected. The nearby 146 MW Toba hydroelectric plant was not affected and remains in operation. Each facility is comprised of an intake structure, penstock, powerhouse as well as a tailrace channel. A 156-km, 230 kV transmission line connects the powerhouses to a substation at Saltery Bay. Since the project’s completion, it has generated energy at an estimated average of 745 GW hours per year. At peak production there is enough hydroelectricity to power 75,000 homes.
The project scope includes removing the slide material deposited over the penstock, and constructing and rehabilitating the damaged section of penstock to return the area to a safe, operational state. EDS delivers the Independent Environmental Monitoring (IEM) service (ongoing) to Alterra Power Corp. and has been doing so since March, 2013.