Port of Alaska discusses 7.1 earthquake and efforts to minimize damage in another quake
The Port of Alaska recently showed KTVA damage from the 7.1 earthquake. Several piles, which hold up docks at the port, split at the weld points.
"It's put together like a paper towel roll, like those Pillsbury rolls, dinner rolls," said Port Director Steve Ribuffo.
Ribuffo added, "You can't use that anymore because once it's untwisted you can't twist it back and weld it back."
The port has been working to repair piles, with all of them suffering corrosion damage over the years. The port says there are more than 1,400 in all.
"For years we have been doing this annual wharf pile repair program and putting sleeves on the piles to combat the corrosion in order to continue to keep the load bearing capacity on the docks going," Ribuffo said.
The port is concerned about earthquake damage to the piles, especially because they failed in clusters under docks. They worry a dock might collapse if a ship strikes it. They're also concerned about liquefaction above the port, which causes everything to flow downhill into the already weakened piles and sweep docks into the water.
The port discovered something interesting with the piles that were covered by metal sleeves.
"None of the failures that occurred during the earthquake were experienced on any of those piles that we repaired," Ribuffo said.
The port discovered something else as part of its modernization effort, which includes replacing docks and making them more resilient to big quakes. The main focus currently is the petroleum and cement terminal area.
The port says about half of the jet fuel for Ted Stevens Anchorage International Airport passes through the Port of Alaska each year, as does jet fuel for Joint Base Elmendorf-Richardson. Most of the gas people put in their cars in the Anchorage Bowl and the Matanuska and Susitna valleys also comes through the port.
Improvements are being made to make it easier and quicker to offload cement. Port of Alaska officials say about 80% of cement used for Alaska construction projects also comes through the port. That includes cement for a massive project in Fairbanks to support the U.S. Air Force's F-35 squadron.
In preparation for a new dock, crews worked to stabilize the area using cement in a process called deep soil mixing.
"The natural moisture content in the ground hardens the whole thing up and you create a grid of hardened cylinders that add a reinforcement to the shoreline to stabilize it," Ribuffo said.
The port says after last November's quake, officials discovered beginning signs of liquefaction on the outer sides of the cement dome. But there was no sign of liquefaction in front of the dome where deep soil mixing took place.
"That was hard as a rock and stable and untouched," Ribuffo said.
Port leaders continue to warn that some repairs are just quick fixes until there is money to modernize everything. They also say the project is not a port expansion.
The effort, they say, is to make operations more efficient and make docks much stronger to survive extreme seismic events for the next 75 years. They say it's hard to precisely say how big of an earthquake the modernized port could withstand.
Magnitude, depth, proximity to the port and duration of the shaking all factor in. But, in general terms, port officials expect it to be able to survive a quake a little bigger than the 1964 9.2 Good Friday earthquake.
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