Dredging sediment is safely disposed using a binding agent
The cleanup of the Ashtabula Harbor is being managed by the U.S. Army Corps of Engineers and includes plans to dredge 120,000 cubic yards of sediment from the harbor. Dredged sediment will be treated and then placed into an existing wastewater settling pond near the harbor and will double as fill material to create and support a crowned cap during closure of the pond.
Engineers, planners, and contractors turned to ALLU-brand equipment to perform in situ mass stabilization for safe disposal of dredged harbor sediment and the need for additional fill material for closure and capping of the Ohio EPA-approved closure plan for the 9-acre pond.
This project will involve mixing a binding agent into approximately 200,000 cubic yards of pond sediment using in situ mass stabilization. The in situ mixing devices being used are two ALLU Power Mixers (PM or PM-X), which attach to an excavator and resemble a rototiller on a stem. Powered by the excavator’s hydraulic system, each PM has two rotating mixing drums that quickly and thoroughly mix binding agents into the pond in depths up to 20 feet. Binding agents are injected pneumatically directly to the area being mixed through an internal nozzle located at the base of the PM mixing drums.
The high mixing shear of PMs makes the most efficient use of binding agents, increases production rates, and reduces man and machine hours required. The cost of binding agents can be a significant part of the mass stabilization process. In order to use the binding agent effectively, ALLU developed the ALLU Pressure Feeder (PF), to define, control, and measure the binding agent, although it’s not being used on this project.
In some areas of the pond, previously excavated material is being mixed with a binding agent by using an ALLU Screener Crusher processing bucket which resembles an excavator bucket with rolling mixing drums in the bottom. Rows of drums within the attachment size-reduce and screen material scooped into the attachment as the material passes through. It is perfect for mixing binding agent into piled soil material.
“The mixing efficiencies of the PMs and Screener Crushers make the best use of blinding agents and improve production rates for contractors,” comments Chuck Wilk, ALLU’s manager of mass stabilization and remediation applications. “ALLU equipment is directly involved in geotechnical and environmental projects and contributes to lowering the closure costs of the Ashtabula Harbor cleanup.”
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Modern Contractor Solutions, June 2014
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