‘KIND OF A TEST PROJECT’

By Adam Spencer, The Triplicate October 22, 2012 05:48 pm

Del Norte Triplicate / Bryant Anderson Harbormaster Richard Young shows off new 38-foot sections of main dock to be installed in the Crescent City Harbor.
Del Norte Triplicate / Bryant Anderson Harbormaster Richard Young shows off new 38-foot sections of main dock to be installed in the Crescent City Harbor.
Upon completion sometime next year, the Crescent City Harbor will most likely be the only tsunami-resistant harbor on the West Coast.

The Port of Brookings-Harbor and the Santa Cruz Harbor were not rebuilt to be tsunami-
resistant after also being damaged from the March 2011 tsunami, said the harbor’s lead engineer, Ward Stover. In fact, the Crescent City Harbor is the only tsunami-resistant harbor that engineers working on the project are aware of, Stover said.

“It’s getting replaced right,” said Harbormaster/CEO Richard Young. “In the long run, it’s the cheapest way to do it.” Young said that short of building a giant wall around a harbor, you can’t make a marina “tsunami-proof,” but the Crescent City Harbor will be “tsunami-resistant” and, “It’s going to take a huge tsunami to damage this harbor.”

 

A tsunami of the same magnitude as last year’s would cause very little, if any, damage to the harbor’s new design, Young said. 

One of the engineering firms contracted by the Crescent City Harbor District, Ben C. Gerwick, Inc., is represented on a committee of the American Society of Civil Engineers, which is working on codifying standards for tsunami-resistant harbors. There’s a lot of interest in engineering circles in the tsunami-resistant design of the Crescent City Harbor.

“We’re looking forward to seeing how this works because it’s going to be kind of a test project for California and for this area,”  Stover said about the harbor’s design during a recent Harbor Commission meeting.

The dock closest to the entrance of the inner boat basin, H Dock, would be the first dock hammered by a tsunami surge, and it’s been designed to take a punch.

Called the “wave stopper” by one harbor commissioner, H Dock will be 16 feet wide and almost 7 feet tall, in order to absorb the energy and force of surges. The 400-foot dock will be constructed with 39-foot-long dock sections, which are currently being cast on harbor grounds because of their size. Each section of the monstrous wave-stopper will weigh almost 160,000 pounds.

At least nine of the other main dock sections, which were cast in Bellingham, Wash., have been delivered already.

The main dock sections are 8 feet wide, 38 feet long, almost 4 feet tall and 58,000 pounds each. And at $120 a square foot, each dock section costs almost $37,000.

The docks are built by first constructing a rebar cage to provide structural stability. Large styrofoam blocks are then placed inside the cage to provide buoyancy to the burly docks. PVC piping  designed for water and electricity hookups is snaked through the rebar cage. Then metal forms are placed around the rebar and styrofoam setup before concrete is poured over the entire apparatus.

Massive piling hoops, weighing at least 600 pounds and big enough to attach to 30-inch-wide pilings, are already attached to the main dock sections. A few of the sections can be seen awaiting installation next to the Harbor District office. Some of the docks have already been placed in the water and are waiting for pilings to be drilled to be fully installed.

And when will the pilings be drilled?

After weeks of delay, a specialized drill-bit is expected to be shipped today and arrive later this week, Stover said.

The fabricators of the drill bit hold the only patent for this specific design, said representatives of Dutra Construction, the contractor for the project.

The drill bit has retractable teeth that fold in to allow for the drill to be inserted into the hollow steel piling sleeve. The drill bit will be inserted through the entire length of the 30-foot piling sleeve and then the teeth will expand to drill a diameter just wide enough for the piling sleeve to drop into the freshly drilled hole in the bedrock, Stover said.

Debris from the drilling will be pumped up from the center of the drill bit and into a barge where the material will be separated for disposal.

Dutra has committed to installing at least 86 pilings before Nov. 15 — the last date the California Coastal Commission will allow in-water work. Dutra has said it will work 24/7 to meet this deadline.

With resident commercial fishing vessels returning to Crescent City after a summer spent salmon and tuna fishing, the harbor district is scrambling to find places to put all the boats.

“We’re having a heck of a time trying to park boats,” Young said at Tuesday’s Harbor Commission meeting. “We can double-up for a short period of time, because we’re not in the bad weather part of the year yet, but we need to get some pilings in and get some slips in this harbor.”

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