With the cost to dismantle a historical water source too dam high, the City of Trail is embarking on a contingency plan should the Cambridge Creek system ever spring a leak.
It’s been about 20 years since Trail has drawn water for municipal use from an open water source known as the Cambridge reservoir in the area of Violin Lake.
The city is responsible for maintaining the Cambridge Dam, a barrier to water drawn from Violin Lake, and earlier this year under the direction of Trail council, staff members investigated measures with the Ministry of Environment (MOE) to decommission the water system and restore the land according to the ministry’s guidelines.
“This is a huge job we’ll never do because it’s in the millions of dollars,” Larry Abenante, Trail’s public works manager told the Trail Times Thursday.
“So now we are going to have to follow regulations through the dam inspectors and come up with an emergency management plan if Cambridge breaches.”
Dam safety emergencies and immediate response actions include ongoing removal of debris blocking spillway channels, sandbagging along the crest in case of over topping by floodwater, placing additional rip-rap and sandbags in damaged areas to prevent further embankment erosion, and an emergency evacuation plan in the worst case scenario, cracking of concrete and excessive seepage.
The dam is up to code according to MOE’s dam safety guidelines, said Abenante, but in light of increased costs and tightened government regulations to maintain privately-owned dams, the city was hoping to one day eliminate the responsibility.
Since the breach of the privately-owned Testalinden Creek Dam eight kilometres south of Oliver in 2010, which caused enormous debris and mud torrent that impacted homes and agriculture in the area, the ministry stepped up efforts to monitor B.C. dams to mitigate loss of life and damage to property and the environment in cases of a dam break.
The Cambridge Dam is classified as high consequence under B.C.’s dam safety commission, meaning if it ever breached, downstream impacts would be catastrophic.
“The dam is in good shape and kept up to specifications,” Warren Proulx, Trail’s working foreman and engineering technician said last fall following an annual inspection. “But we want to eliminate this responsibility because it no longer has value to the city.”
The reservoir is still active as a man-made lake (on private property) and for the last few years, the biggest problem in the area is human-caused because the property is often accessed illegally.
“There’s lots of people up there who shouldn’t be,” said Abenante. “We’ve put up gates and barriers but they still find a way to get in and cause trouble.”
Dams nine metres or higher are monitored by the Ministry’s Victoria-based staff with the dam safety program established to reduce the risks to people, property, infrastructure, cultural values and the environment that are associated with the design, construction, operation, maintenance and/or decommissioning of a dam.
There are over 1650 regulated dams in the province that are regulated under the Water Act, and over 450 unregulated dams that the Ministry maintains have outlived their purpose or sit abandoned, posing a threat to public safety.
Since the 1920’s the area around Cambridge Creek and Violin Lake was the primary source of water to half of the city’s annual water demand.
At that time, the city purchased the lands, and over the decades, built infrastructure to draw water from creeks, lakes and reservoirs in that area. Included was an intake on Cambridge Creek, with a pipeline to reservoirs and a chlorination plant, with the city maintaining water licences for diversion use and storage of the water in the area.
In 1994 Trail established the Columbia River as the city’s main water supply source and built modernized water treatment facilities, in part due to the 1990 community outbreak of giardiasis (beaver fever) a parasitic gastrointestinal infection traced to inadequately treated drinking water pulled from the reservoir.
After the treatment plant using the Columbia River was completed, the city decided to maintain the infrastructure of the Cambridge Creek/Violin Lake water system as a back up water supply.
However, four years later, Trail’s conditional water license was cancelled by the ministry (MOE) under the Water Act, because the water system was deemed no longer actively used for domestic water supply purposes.