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Marine Structures

Hultgren – Tillis Engineers provides geotechnical engineering services to owners, designers and builders of marine structures, including wharves, mooring dolphins, and tidal gate structures. We have designed cantilevered and tied back bulkheads and Open Cell Walls®.

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Marine Structures

Cemex Marine Terminal (Redwood City, CA) - The project included a new cement marine off-loading terminal and an electrical distribution station. The project also included dredging the berth area to Elevation –37 feet (MLLW), cutting back the existing shoreline slopes to accommodate the planned dredge depths, providing shore protection against wave action, providing breasting dolphins consisting of 60-inch diameter monopiles, and concrete-pile-supported mooring dolphins. Hultgren – Tillis Engineers reviewed existing data and explored subsurface conditions using barge-mounted drilling equipment and cone penetration testing. Hultgren – Tillis Engineers provided geotechnical design criteria for each of the project elements, including assessing safe cut slope inclinations along the shoreline and axial and lateral capacities of concrete and steel piles for foundations and mooring systems.

George Lowy Marina (Pittsburg, CA) - Hultgren – Tillis Engineers provided geotechnical engineering services for reconfiguration and marina dock replacement of the George Lowy Marina in Pittsburg. Prestressed concrete guide piles were used for the new floating docks. Shore side improvements include constructing an anchored sheetpile bulkhead wall in front of a new Promenade. In all, Hultgren – Tillis Engineers’ staff has worked on over a dozen small boat marinas and launch ramps in California and the Pacific Basin.

Marine Oil Terminal (Benicia, CA) - Hultgren – Tillis Engineers provided geotechnical criteria for a seismic stability evaluation of an existing marine oil terminal. The terminal consists of a main pier with nearby dolphins and connecting walkways. Geotechnical exploration included drilling borings, pushing CPTs, and performing P-wave and S-wave suspension logging from a drill ship.

Benicia Wharf (Benicia, CA) - A 760 feet long by 81 feet wide section of wharf was destroyed by fire. Hultgren – Tillis Engineers provided geotechnical engineering for the replacement section of the wharf. The wharf has a concrete deck supported on 24-inch octagonal prestressed concrete piles. An additional row of piles were placed along the alignment of a possible future crane rail line. The fender system utilizes 18-inch square prestressed concrete piles. Hultgren – Tillis Engineers reviewed existing geotechnical data, performed site exploration using barge-mounted drilling equipment, developed geotechnical design parameters and foundation recommendations, monitored installation of indicator and production piles, and reviewed dynamic measurements from a pile driving analyzer.

Wharves 1 and 2 Replacement (Port of Redwood City, CA) - Hultgren – Tillis Engineers were the geotechnical engineers for the new wharf. This design-build contract consisted of demolishing an existing wharf and related backland features, and constructing a new wharf, seawall, Longshoreman Building, parking lot, roads and utilities. The new wharf is 430 feet long and 60 feet wide, with an access ramp at each end of the wharf. To control settlement, Hultgren – Tillis Engineers replaced earth fill with Cellcrete® under the Longshoreman Building and wharf access ramps. We designed an alternate seawall concept to greatly simplify seawall installation. Hultgren – Tillis Engineers estimated pile tip elevations, developed soil springs for pile design, provided criteria for settlement control, and assessed slope stability and lateral ground movements associated with earthquake shaking.

Two Gates Project (Sacramento-San Joaquin River Delta) - The Two Gates Project is intended to tidally close both Old River and Connection Slough on a flood tide to aid in limiting fish takes at the export pumps during extreme low outflow years. The gates would be open on ebb tides. The gates would be constructed on steel barges and sunk in place in the middle of the slough and river on prepared excavations, such that the deck of the barge would be near the flow line of the waterway. The gates would be “butterfly” gates that would pivot around vertical steel columns. The gates would be able to pass all marine traffic that currently uses the waterways. Steel sheet piles would be used to block the river or slough between the temporarily sunken gate barge and the adjacent levees. The sheet piles would be laterally supported in part by king piles consisting of 36-inch diameter, 1-inch wall thickness pipe piles. The gate barge would be refloated at the end of low outflow summer-fall season to allow unrestricted winter runoff flows. The sheet piles and king piles would also be extracted. Hultgren – Tillis Engineers designed the foundation pads for bedding the two barges in the river and slough channels, designed the lateral restraint of the gate barge to resist the unbalanced water head, estimated minimum sheet pile lengths and maximum bending moment for the sheetpile barriers, and evaluated seepage impacts from excavating river sediments beneath the barge.

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