Gravity-based sediment dewatering reduces disposal volume and hauling for waterway remediation project

For several months of 2023, thousands of tonnes of sediment lay alongside a busy highway in Hamilton, Ontario as a major environmental remediation project occurred in the Chedoke Creek. But most passers-by never saw huge mounds of sediment nor were they inconvenienced by a daily convoy of trucks removing mucky material from the site.

Instead, the City of Hamilton selected the team of Bishop Water, Milestone Environmental Contracting and Eco Technologies to hydraulically dredge sediment from the creek, then pump it through a pipe that stretched almost 400 metres to the Bishop Solids Management Solution (BSMS). This simple, low-energy system uses Geotube containers, polymers and passive, gravity-based dewatering to produce dry solids that can be easily loaded into trucks for relocation or disposal.

Dewatering enables significant reduction in slurry volume

Although an enormous volume of slurried sediments was dredged from the creek—nearly 140,000 m³—the dewatering process significantly reduced the volume, which meant far fewer trucks were needed to remove the material from the site. During pumping the average solids concentration of the slurry was in the range of three to five percent, but after a few days of dewatering, the solids increased dramatically to more than 70%.

The BSMS also enabled sediment removal to proceed quickly since the dredge could pump material at rates as high as 4,000 L/min through an 8-inch line. A manifold system then split the flow and directed it to multiple Geotubes.

Effective water containment and management