Misunderstandings about dredged material abound: “It’s dirty.” “It’s a waste.” “Dump it, but not in my backyard!” In an effort to create clarity about the characteristics of dredged material and how it can be used to improve our environment, the IADC has created this brief question-and-answer narrative.
Can dredged material really be a resource?
Many people all over the world think of dredged material as dirty, unwanted soil – something that is unclean. This is by and large erroneous. Dredged material is predominantly a clean, usable product; in many cases akin to the soil in one’s garden, in which vegetables are grown.
Only in limited, generally industrialised, places in the world are there appreciable quantities of dredged material that have been affected by industrial contaminants. By and large most dredged material is clean or only lightly contaminated and can be used as a resource by project developers in effective and economic ways.
What are the benefits of using dredged material as a resource?
Using dredged material as a resource is important, one could almost say urgent, because use – rather than disposal – has broad societal, environmental and financial benefits. It contributes to global sustainability. Worldwide, millions of cubic metres of material are dredged annually from ports, harbours and waterways in order to optimise navigation, remediation and flood management. Disposal and placement of this dredged material is often one of the greatest challenges facing a dredging project.
When these materials are treated as a waste, as though they had no value, their destination on land or at sea often becomes controversial. Over the last 15 years, however, research and experience have demonstrated that dredged material is not inevitably a waste, but can in many cases have added value. The focus has now shifted to finding uses for dredged material and for coordinating the supply of dredged material with a concurrent demand.
Is using dredged material as a resource cost-effective?
Although cost is not the only obstacle that prevents the use of dredged material, it is certainly an important hindrance. Realistically, at first glance, traditional disposal may be less expensive than transporting and/or treating dredged material for another use.
The need for new legislation and enforcement may also add costs. Moreover, finding appropriate destinations or markets for the materials requires planning, and quite regularly negative public perceptions can be difficult to overcome. In the long run, however, studies have identified a wide range of uses and these more often than not provide a cost-efficient, sustainable, win-win scenario for the client, contractor and community.
