Delaware Canal Dredging: ALLU System Enables Reuse of Dredged Materials

14 October 2019

Dredging has resumed on the 96km long Delaware and Raritan Canal, with work expected to run through until the end of October.

The canal functions as a means of transporting water and acts as a reservoir, being part of the Raritan basin water supply system, providing water to millions of central New Jersey residents.

The canal itself is fed by the Delaware River and smaller streams, channels and other runoff sources. Sediment from road and land runoff is deposited in the canal, decreasing its water storage capacity, which periodically requires the sediment to be removed in order to restore the canal’s original capacity.

As part of this ongoing process, a soil improvement system from ALLU is being used to mix the dredged material with Portland cement, which enables the dredged material to be reused.

The main part of the system is the ALLU Processor itself; this is an attachment for a conventional excavator, powered by the excavator’s hydraulic system, thereby converting the excavator into a powerful and versatile mixing tool.

The mixing drums penetrate and mix a variety of material in place, or in-situ, meaning that materials can be mixed anywhere the excavator can go, thus capitalizing on the excavator’s mobility and articulation to reach difficult or soft areas.

In the case of the canal project, the Portland cement is delivered directly to the area of the highest mixing shear by an attached 80mm diameter pipe, injected via a nozzle located between the mixing drums.

The Processor penetrates through any hard crust layers and mixes the dredged material with the Portland cement effectively, with penetration and mixing effectiveness being enhanced by the angled position of the drums which minimizes the ‘dead’ area at the bottom frame.

The dredged material consists of varying mixtures of sands, gravels, silts and clays, which are ideal for reuse in a variety of applications. The added Portland cement helps dry out the material and gives the finer material more strength when used to reclaim a brownfield site.