- Home
- Companies
- Sevenson Environmental Services, Inc.
- Services
- Sediment Capping Services
Sediment Capping Services
Sevenson uses several different capping approaches depending on project specifications, project location, water depths and environmental factors and cap material type. Sevenson has developed a custom-built slurry system for hydraulic placement of granular cap materials. The system consists of a feed hopper, oversized screening and slurry system that pumps the material through a pipeline for placement through a diffuser system on a barge. The pump used to convey the sand slurry is a booster type pump commonly found on dredging projects. The hopper, screening and slurry system is typically place on the shoreline. The system is capable of placing thin lifts of backfill consistently. The positioning system for the barge uses a RTK GPS system.
Capping sand and armor materials can be placed using an excavator or crane. Sevenson often uses best management practices for mechanical placement to achieve proper thickness and low energy placement. Typically, the operator makes short sweeps with the bucket while it is open distributing the materials at the water surface or below the surface. The operator can mark the Dredgepack screen where each bucket of material is released. This will give an indication of the horizontal limits where materials have been placed.
Sevenson places cap materials using a Telebelt system. The Telebelt system works well when capping subtidal and intertidal areas. The reach of the belt system allows work to continue as the tides fluctuate. The Telebelt placement method is an alternative method of mechanical placement.