A Nova Scotia environmentalist is criticizing federal Environment Minister Leona Aglukkaq's decision to approve an "almost inconceivable" offshore drilling plan from Shell that allows up to 21 days to contain a subsea blowout, despite the U.S. requiring the same company to cap blowouts within 24 hours.

On June 15, Aglukkaq signed off on the Canadian Environmental Assessment Agency's assessment of Shell Canada's Shelburne Basin Venture Exploration Drilling Project.

Shell Canada's spill containment plan, accepted by the agency, says it can have a primary capping stack in place within 12 to 21 days after a blowout off southern Nova Scotia.

The Canada-Nova Scotia Offshore Petroleum Board has not given Shell approval to do exploratory drilling yet.

John Davis environmentalist Nova Scotia

John Davis, a long-time environmentalist who spends a lot of time on Nova Scotia's South Shore, says any company getting 21 days to stop a subsea blowout is 'almost inconceivable.' (CBC)

John Davis, a long-time environmentalist who spends a lot of time on Nova Scotia's South Shore, said Shell's plan doesn't make sense.

"It seems to me almost inconceivable that [Shell] would give themselves up to 21 days to stop a blowout in an area that is so close to all of our major fishing ground here on the South Shore," he told CBC's Information Morning.

In the environmental assessment for the project, Shell Canada said the capping stack equipment would be brought in from Stavanger, Norway.

Shell said it would also deploy a backup capping stack from either Scotland, South Africa, Singapore or Brazil.

Stark contrast to U.S. regulation

Davis said the decision to allow Shell up to 21 days to cap a blowout in the Shelburne Basin is in stark contrast to what U.S. regulators are requiring from Shell for an exploratory drilling project in the Chukchi Sea in Alaska.

The U.S. Interior Department's Bureau of Safety and Environmental Enforcement has given Shell an exploration permit on the condition that it must have a capping stack on a vessel nearby on standby that must be deployed within 24 hours of a blowout.

"What Shell said to our regulator is, 'There isn't a capping stack available in Canada, nor in North America. Nor is there a vessel capable of moving and maintaining that capping stack, so we can't have one here because there isn't one,'" said Davis.

"The reality is, there is no capping stack and there is no vessel anywhere unless the oil companies are forced to have it near their drill site by the regulators.

"The vessel carrying the capping stack to the drill site [off Alaska] came from Norway. It simply doesn't make sense that you could accept that argument," Davis said.

CBC News has requested interviews with Environment Canada and the Canadian Environmental Assessment Agency to explain Aglukkaq's reasoning for approving Shell Canada's well containment plan for Shelburne Basin. They deferred questions to the Canada-Nova Scotia Offshore Petroleum Board.

The board wasn't available for comment Wednesday, but said it will speak to the issue later in the week.