PRINCE GEORGE, B.C. -- The company proposing to build the Northern Gateway pipeline to British Columbia's pristine coast was hammered with its own record Thursday by a lawyer for environmentalists who wanted to know how the company can be trusted even to conduct the building phase without environmental damage.

Frustrations were palpable on both sides at environmental hearings into the project as critics demanded definitive answers from Calgary-based Enbridge (TSX:ENB) about what are yet only preliminary plans.

Tim Leadem, the lawyer for EcoJustice, which represents a coalition of conservation groups at the final hearings, cited violations during the construction of an Enbridge pipeline in Wisconsin in 2007. The company paid $1.1 million to settle a lawsuit by the state for those incidents.

"You're obviously proposing something to the people of Canada that's going to be built... that may carry with it the potential during the construction phase to actually significantly affect ecosystems and habitat of wild species that Canadians tend to value," Leadem noted on the third day of testimony under oath.

"On the record, when we look around, we see incidents such as what happened in construction in Wisconsin. Can you really assure the people of Canada that you're to be trusted, that your company can be trusted to do this job?"

Ray Doering, manager of engineering for the Northern Gateway project, said Enbridge has spent 10 years already on the project and has filed volumes of field work, assessments, and preliminary plans in volumes "unlike any that I've ever seen."

Tom Fiddler, the company's senior manager of safety and construction, said there are thousands of kilometres of company pipelines operating safely throughout Canada that speak to their record.

"The evidence is clear," Fiddler told the panel.

"I appreciate your answer, Mr. Fiddler and Mr. Doering, but I suppose the good people of Wisconsin were told more or less the same thing before construction debris was placed in their wetlands," Leadem countered.

"I don't imagine they were told in advance we're going to build you a pipeline and we're going to foul your wetlands in the process."

Enbridge has pointed out repeatedly that despite several high-profile incidents, it safely delivers more than 99.99 per cent of volume in the largest pipeline network in North America.

But the track record does not instill a great degree of trust, Leadem said.

"With all respect, how can you assure the people of British Columbia, the people of Alberta, the people of Canada, that this pipeline is going to be built, that you're not going to foul wetlands, that you're going to treat everything carefully, that you've got endangered species that will be encountered. I've yet to hear that you can actually do something about ensuring those kinds of things will not occur, will not happen."

Leadem said he and his clients are also concerned that the design of the pipeline is continually changing.

"At some point I'm trying to understand what exactly will be built," Leadem said.

B.C. Environment Minister Terry Lake had a similar complaint after the province's initial two days of questioning, saying he was "extremely concerned" about the incomplete responses from Enbridge experts.

John Carruthers, president of Enbridge Northern Gateway Pipelines, said outside the hearings that the company has gone well beyond what is required and what is normally provided at this point in the approval process. The company has filed more than 20,000 pages of documents with the joint review panel, more information than has been filed on any pipeline in the past, he said.

"We will have spent $300 million getting through this part of the process, to getting to a decision: Is the pipeline in the Canadian interest and what will be the environmental impact of that project," Carruthers told reporters.

"After those larger questions are answered at this stage, the NEB has a very thorough process as the specifics of construction are decided."

Testing, assessment and planning continues, resulting in the updates and revisions to the plan filed with the panel.

"People want to know the specifics, but there's another phase if the project is approved, then we have to go into the more detailed design and the NEB approves that as well," he said.