Gaspereau River is dry...
Dusan Soudek
Andrew Steeves
Dusan:
Well, not quite unexpectedly. Local media was reporting on this planned maintenance (the removal and rebuild of the turbine at Methals) and its inevitable results on the river and canal flow about a month ago. I guess it didn’t trickle out beyond local readership and it didn’t occur to me to warn you.
Best regards,
Andrew
Methals turbine is being replaced by Nova Scotia Power
“This is the first major refurbishment of the turbine since it first went in to service in 1948 which tells you how solid and reliable this unit is,” said Tim Curry, who is superintendent of the Nova Scotia Power’s Black River hydro system.
He said the work, which includes replacing the turbine, will improve the efficiency and reliability of the generating unit.
The Methals generating station is the first powerhouse along the 29,600 horsepower system. There are four other powerhouses along the waterway: Hollow Bridge, Lumsden, Hell’s Gate and White Rock.
Water flows into Methals head gate building from Methals Pond, which is 188 metres above sea level, then drops 14 metres and enters the generator in the powerhouse below.
“It creates 3.4 megawatts of electricity before it passes in to Black River Lake and continues on its journey through four more generating plants along the way,” Curry said.
He said the unit is valuable to the system because it provides a dependable, renewable source of energy and supports stability of the western grid.
Aileen Woodman is the lead civil engineer on the project. She said other work includes refurbishing the wicket gates, which regulate how much water flows through the turbine, and general refurbishment of bushings and bearings.
Employees with a contract company called Enerserv will work alongside NSP employees, taking apart the turbine and generator a piece at a time. Once it’s open and the top sections have been removed, the 20-ton crane inside the powerhouse will lift the 4,500 kilogram turbine up and out of the unit and place it on a trailer for transport.
It has propeller blades at the bottom that, over nearly seven decades of water rushing against them, have become pitted and rusty.
The brand new stainless steel turbine will be mounted on the existing turbine shaft at a facility in Ontario before being shipped back to site for reassembly.
Technological advancements since the original unit was installed mean the pitch of the blades will be slightly different on the new turbine, which is expected to increase the generating capacity of the new unit to 3.6 MW.
Sorry tubers! Responding to questions from readers:
NSP spokesperson Bev Ware says the amount of water we can flow down the Black River system, which feeds Gaspereau River, is regulated by our environmental permits. Those rules are in place to protect fish and fish habitats.
"Under our environmental permits, we have to run the system 24 hours a day from April 15 to June 15 to enable fish migration. We want to keep these populations of smelt, gaspereau, salmon and bass healthy but running strong river flows 24/7 drains a lot of water from the system."
At the same time, Ware adds, our permits also require us to maintain a certain water level on Black River Lake between Victoria Day in May and Labour Day in September. That’s to maintain high enough water levels for cottages along the lake, as well as for the end of the bass nesting season.
"We are at that point in the year where those two environmental requirements intersect – we’ve drained a lot of water by maintaining flows for fish migration, and now we’ve got to reduce the flows for a few weeks to keep the water levels up in Black River Lake for the cottages and bass."
This means the river won’t be high enough for tubing, Ware noted, but that’s due to environment requirements, not the work that is going on at Methals.
"It used to be that we could flow water year-round. But in 1998, our environmental permits were revised and modernized, because there just wasn’t enough water entering the system to maintain good fish habit, and also for cottagers on Black River Lake. That’s when the flow reductions that happen each summer began."
As for why this work was required after work was done in 2013, Ware continued, the work carried out that year was to the intake structure and the penstock at the powerhouse. The work being carried out this year is installation of the new turbine. These two projects were too big to complete in one season.
The work is scheduled at this time because we have to reduce water flow, she explained. "We don’t reduce generation so that we can carry out the work."
Did you know?
The Black River System is one of the workhorses of Nova Scotia Power’s 17 hydro systems across the province. It’s been generating renewable electricity for 68 years. In all, the system generates 23 MW of electricity.
Generation from hydro facilities is an important part of NSP’s compliance plan for 25 per cent renewable generation sources. Hydrosystems across the province with their more than 155 dams and 33 hydro units generated 9.8 per cent of the electricity that powered homes and businesses across Nova Scotia in 2015.