OnlineSentinel.com has a story and video by Tom Bell that provides an insider’s perspective on how Portland Harbor is being dredged. The project, which started on February 6 and ends March 25, will dredge the Maine harbor to its charted depth of 35’ MLW.
Here’s an excerpt:
Sitting in a massive crane propped on the edge of a barge, Tim Kollman pulls a lever that lifts a clamshell bucket off the bottom of Portland Harbor. As the bucket rises, the entire crane swivels until the boom hangs over a hollowed-out barge called a dump scow. He releases the bucket’s contents, swings the crane back to position and lets the bucket drop to the water.
Kollman makes this same maneuver every 70 seconds. In one shift, he lifts up the bucket 300 times and digs up enough mud to fill more than five Olympic-sized swimming pools.