"The board did not identify any non-compliances with its regulations that would pose an immediate hazard to public safety or the environment," the national energy watchdog said in a report released Monday.
The inspections last August and September were meant to assess improvements Enbridge had made since a high-profile oil spill in Marshall, Mich., nearly three years ago.
In July 2010, some three million litres of crude leaked from a ruptured pipeline into nearby wetlands and eventually the Kalamazoo River.
A scathing report by the U.S. National Transportation Safety Board last summer likened Enbridge's handling of the incident to the "Keystone Kops," the bumbling policemen of silent films.
Because many of the improvements since the spill hadn't yet been implemented, the NEB is demanding a third-party audit to "fully examine Enbridge's management system, any human factors associated with control room operation and the safety culture of the organization as a whole."
The third-party auditor will be directly accountable to the NEB and the energy regulator will set the parameters of the audit.
The board says issues related to management systems, human factors and team performance in the Enbridge control room in Edmonton directly contributed to the severity of the Michigan spill.
The NTSB report released last year honed in on those factors as well. The U.S. watchdog said it took 17 hours and 19 minutes for Enbridge staff to respond to alarms signalling a problem on the line in southern Michigan. And when they did respond, it was only after a worker with a local natural gas utility informed them of the spill.
Instead of stopping the flow, Enbridge staff misinterpreted the alarms and twice pumped more crude into the ruptured pipeline — representing about 81 per cent of the total spill.
The NTSB also took Enbridge to task for failing to fix a defect on the pipeline after it had been discovered five years earlier.