Sediment leaks into Fall River water supply during bridge repair

Sediment leaked into a lake used as a water supplyoutside Halifax during construction to repair a bridge Friday afternoon.

Crews with Dexter Construction are repairingMcQuarrie Bridge in Fall River, N.S., at anestimated cost of $1.3 million to the municipality.

That work has been halted until the cause of the leak in Lake Thomas can be determined, provincial environment departmentspokeswoman KristaHigdon said in an email late Friday.

Higdon declined an interview.It's unclear how the concentrated sedimentmight affect the lake's ecosystem.

Water not contaminated

The water that leaked is not contaminated, as it came directly from the bottom of the lake,butwater that makes it to household taps may containmore silt than usual, municipal spokesman Brendan Elliot said.

"This is more of an issue for the environmental impact on the water way than it is for the human side of things," he said in an interview.

Water from lake's bottom

Crews have to drain the water around the current bridge footings in order to fix them.

That water drawn from the lake's bottom will be put into a shallow part of Lake Thomas, like a containment tank,surrounded by two booms likebarriers to prevent leakage.

When the bridge repairs are done, that water will befiltered and returned.

But somehow that silty water leaked through the booms, Elliot said. A photo he provided to CBC shows brown water spread out past the containment pond's barriers.

Check filters

That means a higher concentration of silt mixed into regular lake water.

Homes and businesses draw water from Lake Thomas and nearby Lake Fletcher, so owners should check their filtration systems are working properly, Elliot said.

"The bottomline is that water, no matter what, should not be ingested without being filtered first," Elliot said.

Still on time

Work will resume only whenthe cause is determined, as is spelled out in Dexter's contract, Elliot said. That means, no compliance order needed to be issued, he said.

The projectis expected to still be done on time by August 26, as a bit of "wiggle room" was built into the schedule, he said.