Damaged dam needs expensive repairs

Tofino’s almost 40-year-old Sharp Creek Dam is falling apart faster than expected and district officials believe it’s high time for a face-lift.

Tofino’s manager of public works Bob Schantz said he first noticed signs of the dam’s cement decay in 2012, so he contacted a consulting firm. An assessment done in 2013 confirmed repairs are needed, he said.

“It isn’t imminent, the dam is not in immediate danger of causing any issues, but it’s something that we should plan for and put in motion,” he said.

He recommended, and Tofino’s municipal council agreed, that dam repairs be included in future budget discu ssions.

The dam is located at Meares Island. It helps dam the Sharp Creek reservoir, which holds about 45% of the Tofino water supply, according to CAO Bob MacPherson.

The consultant-Nanaimobased EBA Engineering Consultants Ltd.-recommended resurfacing the dam with shotcrete at an estimated cost of $405,000.

Coun. Cathy Thicke noted the consultant had not actually visited the site.

Schantz confirmed this, but said the consultant reviewed photos of the dam with contractors to come up with the cost estimate.

“It’s sort of like a ball-park price just so that we have an idea of what the costs will be; it could be substantially more it could be less,” Schantz said.

Coun. Duncan McMaster asked how the district has been maintaining the dam in the past.

“From what I can tell, there’s been no maintenance done on the dam,” Schantz responded.

He said maintaining the dam is difficult because it’s a boat ride away for district staff and added that “quite a heavy buildup of moss,” had to be removed before the assessment could be done.

“(EBA’s) assessment is that the moss actually helped cause the breakdown of the concrete,” he said adding the district will try to clear the moss more frequently moving

forward. While council agreed to consider adding dam repair to the district’s water capital plan, they were not convinced shotcrete was the best way to go.

Shotcrete is a construction method that projects concrete through a hose onto a surface at high speed.

“I know a lot of people, engineers, are wary of using it just because there’s a lot of problems installing it and if it’s not done correctly it’s going to cost you twice as much,” said Coun. Duncan McMaster.

McMaster said shotcrete would only add about 15 years of life to the dam, so the district would face another bill in short order, regardless of how much maintenance is done or how frequently moss is removed.

Schantz said the shotcrete recommendation was based on cost and time and that while the dam is being worked on, its water source will not be available.

He said he would look into alternatives but the alternatives would be more expensive and lead to a longer period without the dam’s water source.

Thicke asked if it’s “normal” that the dam has such wear and tear after just 40 years.

Schantz acknowledged the consultants were “quite surprised by the condition of the concrete,” and he suggested the dam’s origins may have been a factor.

In 1976, Tofino awarded the dam project to a contractor but heavy rains washed out the dam’s formwork, just as the concrete was about to be placed.

The formwork was rebuilt and concrete was trucked in from Port Alberni and then flown to the site by helicopter.

The helicopter ran into difficulties resulting in the concrete’s pour being halted and this halt caused an approximate 2-metre cold joint from the dam’s lowest point, according to Schantz’s report.

The helicopter’s issues were corrected and the dam was completed but Schantz said there was a “confrontation” between the district and the contractor regarding who should pay for the original formwork that washed away.

“The actual contractor actually had to do all the work himself so it was probably done fairly quickly,” he said, adding the cement’s long commute didn’t help matters.

“Maybe the conditions weren’t totally ideal for the actual concrete,” he said.

Thicke said provincial governments outside BC put their seal of approval on dams and asked if BC did any testing on the Sharp Creek Dam.

Schantz responded, “The district is responsible for their dams, including inspections of their dams.”

Thicke asked what safeguards are in place for the district in the absence of provincial government inspections.

“We don’t have that, so how are we going to be sure the money that we spend wouldn’t be wasted,” she asked.

Schantz said the district’s safeguards are hired registered professionals. McMaster noted the dam’s original life expectancy would have been about 50 years so it’s “within the ballpark” to need repairs now that it’s 37 years old.