Muskrat flooding still on schedule, government order will remove trees only: Nalcor

A new order from the provincial government will direct Nalcor to clear more of the Muskrat Falls reservoir, but even a Nalcor biology consultant says the directive falls short of an optimal plan.

Clearing trees not effective as removing soil, Nalcor environmental consultant says

A new order from the provincial government will direct Nalcor to clear more of the Muskrat Falls reservoir, but even a Nalcor biology consultant says the directive falls short of an optimal plan. 0:37

A new order from the provincial government will direct Nalcor to clear more of the Muskrat Falls reservoir, but even a Nalcor biology consultant says the directive falls short of an optimal plan.

Jim McCarthy, a senior biologist for Amec Foster Wheeler and an environmental consultant for the project, says cutting trees from the planned flooding zone is not as effective as clearing soil to reduce methylmercury threats.

"Typically, the trees aren't the biggest source of carbon for methylation," he told reporters at a technical briefing on Wednesday. "It wouldn't have as big an effect as removing the topsoil. Taking out that wood is not the biggest kind of energy source."

In an interview CBC Here and Now's Debbie Cooper, Environment Minister Perry Trimper said he understood McCarthy's comments.

"The majority of the source of methylmercury does come from the organic [matter] in the soil," he said. "Nevertheless, it's been estimated that some 10 per cent could come from forest cover… If there's more we can do, we're saying today, we're going to do that."

Timelines still in place

On Wednesday afternoon, Nalcor executive vice-president Gilbert Bennett told reporters the company's timeline was still in place, despite a directive to do more clearing of the Muskrat Falls reservoir site coming from the province just hours earlier.

Nalcor has been asked to clear more vegetation from the Muskrat Falls reservoir, but the plan does not call for soil clearing.

"We're going to work on schedule and we've been asked to look at what additional clearing can be completed while still maintaining our project schedule," Bennett said.

For now, clearing of trees will take place inside the initial 25-metre flooding zone before the flooding begins. They will continue to look at clearing options for the second watermark at 39 metres.

Image of the Muskrat Falls hydroelectric generating facility. (Courtesy Nalcor Energy)

McCarthy said project models do not show methylmercury levels in fish on Lake Melville rising above a dangerous level. From their assessments, levels in fish will rise between 2.3 and 4.8 times the current level.

However, a peer-reviewed study conducted by scientists from Memorial University, University of Manitoba and Harvard University, indicated some people around Lake Melville can expect to see an increase of methylmercury of about 1,500 per cent.

Methylmercury is found in greater concentration the further it travels up the food chain.

Methylmercury a main concern among protesters

Protesters have been at the Muskrat Falls site since the weekend, with tensions coming to a head Sunday night. Nine people were arrested after some blocked access to the work site.

The protest against flooding the reservoir at Muskrat Falls started Saturday and continued into Tuesday. (Katie Breen/CBC)

Methylmercury has been at the forefront of protesters' concerns. If trees and soil are left in the reservoir, the breaking down of that organic material will create methylmercury in increasing amounts for the next five to 15 years.

While the government directive pertains to trees right now, Nalcor is being told to assess the feasibility of removing topsoil — something Bennett called "unprecedented" in hydroelectric projects.

"We've been asked to assess all aspects of the reservoir," Bennett said. "We're going to do that …That directive came out today. We're working on it."

About the Author

Ryan Cooke

Ryan Cooke works for CBC out of its bureau in St. John's.