Sustainability and Performance at Hampton Roads Bridge Tunnel (HRBT)-Paper

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The Hampton Roads Bridge-Tunnel expansion used triple-fluid jet grouting to construct hundreds of soil-cement columns for the South Island tunnel approach. The process generated large volumes of slurry. Earth pits initially used to manage the spoils proved inefficient: clay-rich material cured slowly, taking up valuable space and delaying column production. Other options, such as vacuum trucks and temporary tanks, were considered costly, labor-intensive, or prone to equipment clogging.<br /><br />Stage 3 Separation (S3S) implemented an on-site treatment system that processed slurry directly from up to two drilling rigs. Shakers removed coarse material; centrifuges, assisted by flocculants, separated finer solids. The system adjusted the treated water’s pH before sending it to the island’s water treatment plant, while dry, stackable solids were hauled to landfill.<br /><br />From May to December 2022, the operation processed 601 columns and approximately 31 million gallons of slurry. It recovered and sent about 18.8 million gallons of water to the treatment plant, while producing roughly 45,000–60,000 cubic yards of solids. Average production increased from about 20 columns per month before the system’s deployment to 86 per month afterward. Solids loads also rose from roughly 3 cubic yards per truck to more than 10.<br /><br />Real-time processing reduced delays associated with waiting for pits to cure, supported around-the-clock, two-rig operations, and cut anticipated waste volumes by approximately 40%. The approach also avoided substantial wet-waste hauling, reducing truck traffic and associated emissions. The project demonstrates how on-site separation and water recovery can improve productivity and waste management where space, schedule, or environmental constraints make conventional spoil handling impractical.

Keywords

Hampton Roads Bridge-Tunnel

triple-fluid jet grouting

soil-cement columns

slurry treatment

on-site separation

centrifuge dewatering

flocculant

water recovery

waste management

soil stabilization