Cofferdam to control dirty water

By Tanya Collier Macdonald
Cape Breton Post
Wed., Nov. 24, 2005

A new cofferdam will soon control contaminated water leaving the tar ponds and travelling into the harbour, says a project leader.

For more than a year and a half, engineers have perfected a design aimed at stopping toxic water from reaching the ocean. The extensive analysis was needed to overcome the project's greatest challenge - the history of flooding along Brookland and Townsend streets, said Richard Morykot, project manager with the Sydney Tar Ponds Agency "We founded the design on that flooding issue," he said. "We can not exasperate the flooding problem."

The engineers considered possible impacts on about 2,430 acres, reaching as far as Gilhomes Lake in the Wash-brook Watershed. The result is a cofferdam that stretches from the tip of Battery Point to the Sysco Piers - the most northern point of the north tar pond. "It's as far out as possible," said Morykot.

The cofferdam will consist of a mattress of rock topped with clean slag from Sysco's high dump, and capped with another layer of rock. Armour-stone, with each stone weighing up to three tonnes, will be placed on top to protect the structure from ice and waves. The cofferdam will have an opening of about 50 metres to ease waterflow and prevent flooding into Wash Brook and Coke Ovens Brook.

When the $400 million tar ponds cleanup gets underway, a channel will be constructed at the opening to isolate the tar ponds from the harbour while allowing clean water from nearby brooks to run through.

It's expected tenders will be called in January and the work will begin in April. The cofferdam project is expected to cost about $2.7 million.