TRAVERSE CITY, MICH. – Enbridge's plans for drilling an oil pipeline tunnel beneath a channel linking two of the Great Lakes do not meet industry standards and pose significant hazards to workers and the environment, experts who reviewed project documents on behalf of opposition groups said Monday.

Two geologists said they found numerous shortcomings with the Canadian company's proposals to the Michigan Department of Environment, Great Lakes and Energy, which is considering whether to allow construction of the tunnel under the Straits of Mackinac.

"What Enbridge has submitted to the state of Michigan doesn't come close to properly designing and preparing for a tunnel underwater," said Brian O'Mara, a geological engineer who has worked on dozens of tunnel projects.

The analysis was requested by Oil & Water Don't Mix, a coalition of environmental, business and tribal organizations. They are fighting to shut down Line 5, an Enbridge pipeline that crosses the bottom of the waterway connecting Lake Michigan and Lake Huron.

Enbridge spokesman Ryan Duffy said the tunnel plans were developed in consultation with experienced geologists and engineers.

The company contends the 67-year-old Line 5 that runs between Superior, Wis., and Sarnia, Ontario, is in good condition but wants to replace the 4-mile-long underwater segment with another to be housed in a nearby subterranean tunnel. Enbridge says it would pay the estimated $500 million cost.

Environmentalists urged state regulators to demand answers about issues raised by the outside review before green-lighting the project.

"Failure to do so could result in tragedy for the Great Lakes," said Beth Wallace of the National Wildlife Federation.

Spokesman Nick Assendelft said department staffers would consider the findings of the Oil & Water Don't Mix reviewers along with other public comments.