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When it comes to design concepts for structures to handle tsunami-type emergencies, Cannon Beach city officials have pretty much seen the gamut.

This past fall, city councilors were considering as many as eight different alternatives. The front-runner was a new, $4.5 million city hall that would double as a tsunami evacuation building.

The 10,000-square-foot, two-story reinforced concrete structure would be elevated on pretensioned concrete pilings. During a tsunami, as many as 1,500 people would be able to wait out high waves inside the building.

The idea petered out.

鈥淭hat (idea) is a very difficult one for people to accept,鈥� Cannon Beach Councilman Sam Steidel said. 鈥淔or the most part, they just don’t trust it.鈥�

Steidel said that any city project to mitigate tsunami danger would need to be financed by a locally supported bond measure, so public buy-in is essential. With support for the city hall idea waning, Steidel said the city is now targeting construction of a new evacuation bridge across Ecola Creek.

The existing bridge represents the only viable escape route for downtown residents to reach safer, higher ground in the event of a tsunami. However, a one-two punch of an earthquake and a tsunami would likely cause the bridge to collapse.

Kevin Boyle, project coordinator for , the company hired to conduct a feasibility study, said that in addition to being founded on shallow wood pilings, the existing bridge is held together by weak, steel pins that connect the concrete slab to its foundation.

鈥淭he concern is if they have a big earthquake 鈥� those could potentially rip the pile cap apart and cause the bridge to collapse into the creek,鈥� Boyle said. 鈥淭here is just a very high probability of liquefaction of the soils in that area too.鈥�

It has happened before. The 1964 Alaska earthquake sent a tsunami rippling up Ecola Creek, destroying the bridge and causing $250,000 in damage, according to OBEC’s report.

Part of the solution to ensure that doesn’t happen again, Boyle said, is to conduct a full geo-analysis of the soils and drive concrete pilings to necessary depths. But the city first needs to choose from among seven options, which range in scope from a $796,000 floating pedestrian bridge to a $4.76 million replacement bridge.

The first option, which Boyle said was requested by the city, is a floating timber pontoon bridge with a 6-foot-wide deck. That bridge would withstand a large earthquake, but it would not resist a tsunami wave. Boyle said it had another key drawback too.

鈥淔or a 6-foot wide bridge, if there’s a panic situation you really create a lot of chaos trying to get people across that in one way,鈥� he said. 鈥淵ou just can’t pass that many people.鈥�

The second option, a 6-foot-wide fixed timber bridge, faces the same issues.

Other options include constructing a 12-foot-wide, fixed, pre-stressed concrete pedestrian bridge; replacing half of the existing bridge with a concrete section; and building a fixed timber suspension bridge.

While some of those options have more merit than others, all share the same hurdle.

鈥淎ll of those have fairly significant costs associated with them for a small community,鈥� Boyle said. 鈥淐annon Beach is not a community that necessarily has a lot of money.鈥�

The feasibility study alone cost approximately $10,000.

One potentially affordable concept is for a pyramid-shaped berm near the city center. Yumei Wang, a geotechnical engineer at the , said it would cost between $1 million and $1.5 million.

Wang said the berm represents the second draft of a conceptual platform evacuation structure (like a multistory carport for people). It would essentially be a large, sloped dirt mound that people could run up to escape rising waters.

Steidel said City Council had not reviewed that idea yet.

One thing the city is pushing forward though, Steidel said, is creation of stores of food and water around town that people can access in the event of an emergency.

鈥淚f all the roads are down and the Willamette Valley is hit hard, we’re not going to see people for quite a while and so we’ll be dependent upon ourselves,鈥� he said.

But Cannon Beach residents also have in their hands the opportunity to choose an evacuation measure.

鈥淥ne of the things that is difficult about this is there are many ways to skin a cat and to have the community decide on one is difficult,鈥� Wang said.