What began as a check on a large, leaking pipe at the Bay d’Espoir hydroelectric power plant has turned into a series of required inspections and pricey refurbishments for Newfoundland and Labrador Hydro, reaching into the tens of millions of dollars, with the latest piece of work expected this year.
The pipe was specifically a penstock — the first of three carrying water from the main Bay d’Espoir system reservoir to the power plant.
As reported by The Telegram in late 2016, Hydro found a leak in the pipe in May of that year. The leak was thought to be an anomaly, and was fixed. But when a second leak appeared that September, the utility had another inspection done of the entire penstock. It found problems, including hairline cracks with the potential for more leaks if they were not addressed.
Welding work followed and was completed before that winter.
RELATED STORY:
Urgent repairs needed at Bay d’Espoir
Meanwhile the last inspection, findings and repair process were all given further consideration by Hydro.
“We started contemplating: OK, something might be happening in penstock two as well,” Jennifer Williams, Hydro’s vice-president responsible for production, said this week in an interview with The Telegram.
In 2017, the next penstock was checked, refurbished and put back into service. But before that winter, another leak was found in the first penstock.
The utility sought a collection of tests by Hatch consultants — from pressure-related testing to particle-level checks on the pipe — to get to the root of the problem.
“It was a real eye opener,” Williams said of the results.
It found that the coating on the inside of the more than 50-year-old penstocks had worn away over time, she said, exposing an increasing amount of the pipes to greater natural damage. It also identified differences in how the pipes were originally constructed compared to current standards, and found some adjustments that could be made in how the plant is being operated, to reduce stress on the penstocks. Any “microscopic cracking” was addressed.
The utility is looking at both the first and second penstocks to see how the repair and refurbishment work is holding up, while looking to complete detailed review and repair on the third penstock.
In terms of cost, Hydro had a capital cost of $7.2 million for the work in 2016 on the first penstock, $4.6 million for further work there in 2017 and $3.6 million for work in 2017 on the second penstock.
The utility expects to work on penstock three in 2018, with an estimated capital budget of about $6 million. If required in full, it would bring the total capital cost for the penstock work at Bay d’Espoir over the $21 million mark.
“We need to assure the penstocks are going to be reliable,” Williams said, adding that it’s ultimately a reasonable investment if it can help assure another 50 years or more of reliable service.
