Tappan Zee Bridge Sediment Removal

Location: Tarrytown, NY
Owner: NY State Thruway Authority
Completion Date: January 1, 2015
Categories: Construction, Environmental Dredging

Work consisted of dredging, transporting, amending and offloading 800,000 CY of contaminated material for the Tappan Zee Bridge project on the Hudson River in NY. Using RTK GPS and Hypack software for positioning and dredge depth management, sediment was removed using an environmental bucket. After allowing the material to settle, the free water in the barges was pumped off into a decant barge for disposal in accordance with the permit. Once decanted, a portion of the sediment barges were towed to the Weeks Marine Greenville Yard in Jersey City, NJ for processing of the dredged material.

Sediment processing was performed using Weeks Marine’s in-barge stabilization and solidification method. The method uses a grout pump in conjunction with an engineered mixing head to create a cement slurry and homogeneously mix it throughout the dredged sediment. The cement slurry is directly injected at the mixing head for controlled and uniform processing, while minimizing the potential for air particulates. Once the stabilized dredge material (SDM) was ready for offload, the barges were transported to a site in Linden, NJ where the SDM was offloaded and spread out as beneficial reuse.

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