Canadian Consulting Engineer

Mudslide prompts tighter control of B.C.’s 2,000 dams

The B.C. Environment Minister has determined that 140 dams across the province require remedial action. The re...

July 19, 2010   Canadian Consulting Engineer

The B.C. Environment Minister has determined that 140 dams across the province require remedial action. The recommendation comes after the Ministry completed a “rapid assessment” that it conducted following a mudslide last month near Oliver, in the Okanagan Valley.
The Ministry has also indicated it will follow the recommendations in a report by the Deputy Solicitor General. The report recommends taking action on priority areas, and oulines several steps for tightening up the provincial oversight of dam structures.
The province has approximately 2,000 dams, and while most are owned by private licence-holders, the B.C. Environment Ministry is required to audit them every 5 or 10 years depending on their status. Some experts believe the ministry does not have the manpower currently to monitor and oversee this audit program. Contacted in June by CCE magazine as the Ministry launched its dam assessment process, the Ministry said “At this time we believe there is no need to hire outside consulting engineers to do this work.”
The Deputy Solicitor General was asked to investigate and report after a rancher’s dam gave way on June 13. The water from the man-made reservoir on Testalinden Creek had risen during heavy rainfall, and even though a hiker had reported that the dam was overflowing, word did not reach the proper authorities in time to stop the disaster. News media at the time said it was a “miracle” that no-one was killed by the mudslide, which occurred on a Sunday at around 2 p.m., A mother and her daughter narrowly escaped with their lives, and three homes and several farms and orchards, were engulfed.
Two days afterwards, the B.C. Solicitor General ordered an independent review of the circumstances of the dam failure, and the Ministry of Environment ordered its staff to conduct rapid assessments of all dams in the province that were classified as high priority risks. As it happened, the Taliensen Dam, was classified as low risk.
The deputy solicitor general’s report on the Testalinden dam failure explained that they had uncovered records of problems with the dam going back to the 1960s, but that “there is no indication that actions had been taken to remedy the situation that has persisted for decades.” For example, the report says, “An inspection was carried out on July 13, 1988, and concluded that ‘this structure is in a very poor state of repair. the dam has reached the end of its lifespan and should be replaced by a new one. Most of the repairs … have been requested previously … No attempt has been made to carry out our instructions.”
The dam, which was constructed on Mount Kobau with the South Okanaan Grasslands Protected Area, was built in the 1930s for water storage and irrigation. It has been owned by its present owner, since 1981.

 


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