EDMONTON -- A team of six Calgary-based inspectors wrapped up a two-day look at Enbridge's recently refurbished Edmonton control room Thursday.

The site came under fire from America's National Transportation Safety Board (NTSB) for reported neglect in the United States' worst-ever land oil spill. The Marshall, MI, spill sent 20,000 barrels of oil into the Kalamazoo River.

The inspection is the agency's first of the completely new control centre installed a year ago, said Iain Colquhoun, chief engineer for the federal National Energy Board.

"Generally, we know of improvements to the monitoring system and improvements to the operating procedures they use," he said.

"What we're particularly interested in is the human aspect -- how these operating procedures are used to promote safety and environmental protection."

On July 25, the NTSB released a summary report of the 2010 spill.

"In general terms, it was human error. It was activities that took place in the control room that gave them the greatest concern. It would seem that some of the procedures were not followed correctly, procedures in relation to changes in operating pressure," Colquhoun said.

NTSB chairman Deborah A.P. Hersman had scathing remarks for Enbridge as she announced the report in July.

"When the pipe had ruptured, multiple alarms were generated, which the Enbridge control centre staff failed to understand. Over three shifts, the control center misinterpreted repeated leak alarms as a condition known as 'column separation' and re-started the pipeline twice," Hersman said, adding that Enbridge took advantage of weak US regulations for assessing and repairing crack indications.

The initial failure and misinterpretation made the spill five times as bad as it would have been otherwise, Hersman said.

The American regulatory body, Pipeline and Hazardous Materials Safety Administration, was assigned some of the blame, Hersman said.

Colquhoun said the two-day inspection could inform the NEB if a more frequent inspection cycle is required.

"The NEB holds all operators accountable for safety and environmental protection -- that's a basic tenet of our operation and it continues to be so," he said.

Enbridge is currently seeking meeting resistance from BC Premier Christy Clark and a number of Aboriginal groups in its quest to build the proposed $5.5 billion Northern Gateway pipeline. The 1,177 km line would carry Alberta bitumen from near Bruderheim, AB, to Kitimat, BC, and Asian markets beyond.

The NEB report is expected at the end of August or beginning of September, Colquhoun said.

"The NEB is committed to a policy of transparency. Unless some confidential information is uncovered, I would expect that report, in some form, will be publicly available," he said.