VANCOUVER – Nine dams in B.C. were rated to be of “high risk” of failing in recent government audits, including a large dam near the southern city of Greenwood, The Vancouver Sun has learned.
Ministry of Environment audits of the 2,000 dams in B.C. found that of the nine “high risk” dams, five of them are additionally classified as “high consequence,” meaning they could cause significant damage if they failed.
The information was released last week in response to a freedom of information request filed by The Sun, following the collapse in June of the Testalinden Lake dam, which caused extensive damage to 14 private properties.
In an interview Wednesday, a senior ministry official said action has been taken, and most maintenance and inspection concerns have been addressed with the nine dams. He insisted no one living near them should be afraid.
“They were classified once based on the inspection or audit, and at that time classified as high risk, and those risks have been dealt with,” said Glen Davidson, the controller of water rights for B.C.
He said the provincial government is on the verge of releasing a new report based on the “rapid assessments” undertaken on every B.C. dam since the Testalinden accident. That report will contain more up-to-date information about the safety of local dams.
Despite the damage caused by the Testalinden dam, it was not classified as a high consequence structure.
Davidson said the government prioritizes its inspections towards high consequence dams, as they can cause the most damage in the event of a failure. Five of the nine so-called high-risk dams fit into this category.
“If the water stored behind any of these [high consequence] dams is released suddenly as the result of a dam failure, there would likely be loss of life, significant social and economic loss or severe environmental damage to the area downstream,” says the B.C. government’s May 2010 Dam Safety Review Guidelines.
The largest of the dams considered to be of both high-risk and of high-consequence in the FOI is the Providence Lake Dam, which ministry documents say is more than 10 metres tall.
The dam was built a century ago to create the lake, also known as Marshall Lake, for a mine near the now-razed town of Phoenix, in the mountains east of Greenwood.
The dam, which is now owned by the Fish and Wildlife Branch of the environment ministry, is experiencing water seepage “that may get progressively worse,” says a letter dated May 12.
The letter – written by dam safety officer Bert Brazier to a fish and wildlife official – says “inspection and maintenance to date has not been acceptable.” He warns that money is needed to properly maintain the dam or new owners will have to be located.
“If the dam isn’t taken care of properly it becomes a potential liability to everyone living and working downstream of the dam,” Brazier writes.
The FOI documents said the dam was in the process of being decommissioned, but Davidson said that decision hasn’t been made yet.
Davidson added the ministry would like safety upgrades to be made to the aging dam. But he added Providence is a rock-filled dam, which is more stable than earth-filled dams like Testalinden, and insisted people living in the area have nothing to fear.
“Because it is a rock-filled structure it causes me less concerns,” he said, adding the ministry has “to be better than everybody else” when it comes to keeping their own dams safe.
Marge MacLean, a local history buff who works at the Greenwood Museum, said the now-closed mine’s tailings pond, which is located beside Marshall Lake, gave way about 40 years ago and flooded the town. She worries about the same thing happening again to the city of 700 people.
“We were always very concerned about that because [the tailings pond] went before and we often wondered how safe that thing was,” she said. “It would be probably the same size as the lake and they would be within a mile of each other.”
The other “high consequence dams” on the ministry’s internal list included three near Prince Rupert: Kloiya, Rainbow Lake and Diana Lake. The city of Prince Rupert is conducting weekly checks of the facilities – which are also the responsibility of a local forestry company – to ensure no new problems arise, Davidson said.
The fifth high-consequence dam was Charlie Lake near Fort St. John. Davidson said all concerns have been addressed with it and three other lower-consequence dams: One Island Lake and Swan Lake near Dawson Creek, and East Twin Creek near McBride.
The Bertchi Creek dam, north of Prince George, was deemed high risk but has now been removed. Due to extensive erosion, a May 2008 audit said “the dam has a large failure probability and immediate attention is required.”
Mark Angelo, with BCIT’s Rivers Institute, has long called for the decommissioning of some aging B.C. dams.
He said identifying high-risk dams and conducting this summer’s rapid assessment inspections “is the appropriate course of action” to avoid another disaster like Testalinden.
He said more extensive audits of all 2,000 B.C. dams might identify more than nine that are of high risk of failing, but gave the government credit for trying to play “catch-up” with dam safety checks.
“My hope is we’ll look at what has unfolded this summer [at Testalinden] and we’ll learn from that,” Angelo said.
lculbert@vancouversun.com
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