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Humboldt Bay Harbor District hearings examine tsunami modeling, wet storage and heavy-lift wharf design for proposed terminal
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Summary
Consultants for the Heavy Lift Marine Terminal presented a site-specific tsunami model, wet-storage (in-water) options for assembled floating turbines and heavy-lift wharf design criteria; commissioners pressed on subsidence, mooring security and shore power while the board received the technical updates.
Consultants for the proposed Heavy Lift Marine Terminal gave the Humboldt Bay Harbor District board a technical update on coastal hazards, in-water storage needs and wharf design at the meeting.
Eunice Murray, a coastal engineer with Moffatt & Nichol, presented a site-specific tsunami model built to inform site design and compliance with building-code–level hazard requirements. "This model ... is showing the approach of the wave as it approaches the open coast and then the project site," Murray said, describing a Cascadia, magnitude-9 scenario with a return period of roughly 2,500 years. She said the model shows an initial drawdown followed by multiple inundating waves that can travel through the jetties into the channel; Murray told the board her runs used both existing and proposed site elevations to compare designs and that subsidence during a seismic event was included in the analysis.
Board members asked for clarifications about the modeling inputs and expected effects. Murray said the runs reflected the proposed elevations and that inundation along the open coast in scenarios she showed varied "between 15 to close to 30 feet depending on where you are" from the jetty. She confirmed the team included anticipated subsidence from a Cascadia rupture in the scenarios.
Shuying Xin, a coastal/port engineer, described "wet storage" locations to temporarily hold fully assembled floating foundations and turbines before they are towed to the site. Xin said preliminary work identified two candidate areas — a south-side site near the navigation channel and an inner-basin site adjacent to the turning basin — and estimated the project would need roughly "5 to 10 spots to park" fully assembled units. She described alternatives to secure parked units, including fixed piers or "dolphins," catenary-buoy systems and anchor-chain arrangements, and said the team is evaluating environmental, cultural and navigational impacts.
Structural engineer Maryam Abu Sauber outlined wharf design drivers for heavy-lift operations: berthing and mooring of delivery vessels, transfer and storage of large components and on-wharf assembly with high service loads. The team described conceptual wharf geometry (two berths roughly in the order of thousands of feet, with wide decks and a deep berth pocket) and high live-load design values (presented to the board as approximately 6,000 pounds per square foot) that drive deep foundations such as open-ended steel pipe piles. She said further geotechnical investigations are planned to refine pile capacity and deck design.
Commissioners raised operational questions — including whether large delivery ships could plug into shore power while berthed to reduce emissions — and were told ship-to-shore power is being considered for the larger vessels expected to call at the terminal.
The presentations were framed as technical updates to inform ongoing permitting, environmental study and design work; no regulatory approvals were taken at this meeting and consultants said further studies, permitting and community engagement would follow.
