We know that the Coast Guard, the state Department of Environmental Protection and the Casco BayKeeper have all signed off on the Portland Pipe Line’s recent dredging and pier-improvement project. We hope that the improvements will result in an oil-handling operation that’s safer and more environmentally sound than ever. But something isn’t being said here: the deeper berths at the Pipe Line’s Pier 2 will allow bigger, deeper-draft, more fully-loaded tankers to come into Portland Harbor. Keel clearance under these vessels will be “comfortable,” according to the experts interviewed for our story on this project last month, but “comfortable” is still measured in the single digits – less than 10 feet – at low tide. New basins at Pier 2 will be 57 feet deep, but vessels with drafts of 49 feet are increasingly common in Portland. That’s not a lot of clearance, particularly in a harbor with a relatively narrow entrance channel, and where silting is historically a problem.

It’s well to remember that Portland is the second largest oil port on the east coast, after Philadelphia. Before improvements, we reported last month, vessels typically offloaded an average of 700,000 barrels. When the upgrade is complete, that capacity will be 900,000 to 950,000 barrels per ship. The port experienced a serious spill a decade ago. As the volume of oil continues to grow, despite dredging, pier improvements and careful operations, the risk of more spills will grow as well.