ANCHORAGE (AP) -- A new study says extensive sampling of the ocean floor of Cook Inlet is needed before a proposal to expand the Port of Anchorage can go forward.
The report, completed in August but not yet made public, says the underwater soils in Knik Arm may not be strong enough to support the planned expansion.
The city-funded report says the underwater soils in Knik Arm may not support a proposed open-cell sheet-pile dock design submitted by Anchorage-based Peratrovich, Nottingham & Drage. The report was conducted by David Chapman, geotechnical engineer for Colorado-based LACHEL & Associates. and Gabriel Fernandez, a geotechnical engineer at the University of Illinois, at a cost of $28,600.
Engineers drew their conclusions based on some 130 test holes near the port area and from information provided by Peratrovich, Nottingham & Drage. Some of the borings date to the 1950s, before the existing port was constructed.
Based on that data, PN&D's design ''does not appear feasible,'' the report said. No borings, however, have been taken 400 feet seaward of the port in Knik Arm, where PN&D's expansion would be built. The report recommends the offshore borings be taken ''to obtain the necessary geotechnical information for concept evaluation and design.''
A group of engineers, and city and port officials met in Anchorage Nov. 20 to review the study.
''The meeting was by invitation only and closed to the public,'' Roger Graves, government and environmental affairs manager at the Port of Anchorage, told the Alaska Journal of Commerce.
Anchorage Mayor George Wuerch said port expansion proposals will continue to be carefully studied. He's not yet ready to give up on PN&D's design.
''Anytime you get more than one engineer in a room, you're going to have more than one opinion,'' said Wuerch, himself an engineer.
Duane Anderson, chief structural engineer for R&M Consultants of Anchorage, said there was general consensus at the meeting that the Cook Inlet's soils are dense enough to support PN&D's proposal. That proposal uses technology the company developed in 1980, in which sheet pile membranes create a bulkhead for holding compacted gravel.
The plan for the Anchorage port calls for expansion 400 feet seaward of the existing dock, incorporating some 9 million tons of fill to create a nearly mile-long dock. Some 85 acres would be created and added to the port's existing 100-acre footprint.
The face of PN&D's design would be 80 feet high, which would take a strong and stable seabed to make it work, the report said.
''It requires pretty darn strong soil,'' Anderson said of PN&D's proposal. ''And personally, I don't think it is there.''
Anderson's firm was hired after the port's top engineer, Richard Burg, lost his job last spring over differences in the direction future expansion plans should take. Burg said he could not support PN&D's expansion plan being pushed by the port director, former Gov. Bill Sheffield.
Burg had been working with engineers at Tryck Nyman Hayes Inc. drawing up plans for a new deep-draft, dock expansion at the Port of Anchorage. The city already had spent for $1.5 million for that plan. But Sheffield has been interested in PN&D's plan since he believed it would save the city millions in construction costs and double the existing facility.
Sheffield has said Alaska's all-Republican Congressional delegation has been supportive toward funding the newest port expansion project designed by PN&D. Sheffield said the recent study only proves the Cook Inlet's seabed needs further study.
Additional borings would cost about $250,000, he said. It's unclear when those tests would be made.
''We'll try to prove it feasible. If not, we'll do something else,'' Sheffield said. ''We are going to do it right.''
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