Sediment containment footprint reduced by stacking Geotube® containers
DATE POSTED: June 25, 2018
Sediment containment solution provides permanent home for dredged, dewatered sediment in Geotube® containers
An innovative sediment containment solution removed and dewatered a large volume of contaminated sediments from an urban lake in Syracuse, New York. The material is now permanently contained in a compact naturalized area. The footprint used was considerably smaller than would be estimated based on the amount of sediment removed. This was achieved by stacking Geotube® containers to create a structure that can be expanded as needed. As a result, the sediment containment storage capacity drastically increased.
About 2.1 million cubic yards (1.6 million cubic metres) of sediment, which had been heavily contaminated from a century of industrial activity, was dredged from Onondaga Lake and dewatered in a 50-acre (20-hectare) cell where six layers of Geotube® containers are held permanently. The Geotube® containers were then covered and capped with a barrier system to provide public health protection from the contaminants in the sediment, as well as to allow a natural habitat to re-establish on site.
Geotube® containers have been successfully dewatering and containing sediment in a variety of applications for over 50 years. A single layer of Geotube® containers typically provides the capacity needed to achieve the required treatment performance in most applications. Since the 1990’s however, many sites have been struggling to contain and dewater a high volume of solids in a limited amount of space. To overcome this challenge, an approach that stacks Geotube® containers as much as 10 layers high was developed to maximize the capabilities of the system in a small land footprint.
The Geotube® container advantage
Compared to alternatives, Geotube® containers can be stacked higher since they are constructed using circumferential seams. Since the seam is the area of highest stress, this method of seaming allows one longitudinal seam to run along the bottom of the container. With the seam facing downward, the stress and, ultimately, the safety factor are reduced. Conversely, conventional geotextile tubes are sewn in the longitudinal direction. This creates more points of stress and an increased risk of rupture.
Understanding site parameters to meet performance requirements
Stacking Geotube® containers to effectively meet performance requirements requires a good understanding of the site where they will be installed. Therefore Bishop Water uses a suite of analytical tools to ensure the stability and durability of the structures. One such tool, for example, can calculate the force that the structure will have on the surface where it will be built. Furthermore, to maximize the capabilities of the system, Bishop’s highly experienced team assists with all aspects of a project. This includes design, obtaining the appropriate permits, site preparation, and installation.
Watch this video to learn more about the Onondaga Lake dewatering project in Syracuse, New York.
Learn more about the differences between Geotube® containers and other geotextile containers.
Contact us to discuss your dewatering needs.
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From Contaminated Sediment to Cargo Terminal
DATE POSTED: February 22, 2018
Contaminated sediment becomes foundation for massive container terminal in Brazil
An innovative solids management solution was used to dewater over 600,000 m3 of contaminated sediment in Sao Paulo, Brazil. The material was then reused onsite for the construction of a large container and bulk cargo terminal. This approach, which combines dewatering and containment in a single process, enabled the team to dramatically reduce the amount of fill trucked to the site. They needed fill material to create an elevated foundation under the new container building.
About 40% of the required 1.5 million m3 of fill was dredged from the Empresa Brasileira de Terminal Portuarios S.A. (Embraport) facility’s new entrance channel and pumped directly into Geotube® containers permanently arranged where the foundation would be formed. Not only did this reduce transportation costs associated with moving the contaminated sediment offsite, it also eliminated the need for the site operator to purchase additional land for a disposal facility to store the contaminated sediment.
The Dewatering Process
Three 65,000m2 dewatering cells were constructed to support 280 Geotube® containers, each of which is 213-feet-(65-metre-) long, to simplify the handling the contaminated sediment. Each Geotube® container was filled to a height of 7 feet (2 metres), allowed to drawdown in height then filled again. This process was repeated until they reached their final height of 5 feet (2 metres) and dewatered to a solids concentration between 62% and 67%.
As the dewatering occurred, the filtrate from the Geotube® containers was drained into a collection basin and then pumped into a water treatment basin where the pH of the water was raised to precipitate heavy metals. It was then transferred to a second basin where the pH of the water was neutralized and passed through an activated carbon filter to ensure that it met the discharge standards required by the environmental permit for the site.
Watch this video to learn more about the project.
Learn more about using Geotube® containers for dredging and dewatering contaminated sediments.
Contact us to discuss your dredging and dewatering needs.