Under pressure

The AMORAS scheme, a sediment separation and treatment installation in the port of Antwerp demonstrates different thinking The AMORAS scheme, a sediment separation and treatment installation in the port of Antwerp demonstrates different thinking
Industry Database

Environmental regulations and increasing costs continue to pose challenges to maintenance dredging programmes. Felicity Landon reports

From scheduling dredge operations so that disturbance to wildlife is minimised, to gaining approval for the disposal of dredged sediments, environmental pressures continue to loom large in ports’ maintenance dredging programmes.

According to Belgian dredging giant Jan De Nul, regulations on the disposal of dredged sediments have become ever more stringent in recent years – and the required environmental compensation schemes make the task even more challenging for port authorities.

The pressures are similar in the US, where Joe Miller, senior director for facilities development at Jacksonville Port Authority in Florida says: “We have limitations on the time of year we can dredge and restrictions we must implement on the dredging firms to ensure the protection of marine mammals – for example, to make sure dolphins, manatee and turtles are not impacted during the nesting or mating seasons. We work around these to make sure our harbour and berths are maintained.”

However, Jaxport, already battling to secure a better return from Congress out of the controversial Harbour Maintenance Tax, is expecting a different type of ‘green’ pressure to add significant costs to its dredging requirements in the near future. “We see in California some of the regulatory initiatives with regard to clean air – and we expect some of that will be working its way east with regard to the use of low-sulphur fuels,” says Mr Miller. “The dredging firm working for us also works in California, and had to retrofit all of its dredgers there to use low-sulphur fuel. It is only a matter of time before that spreads east, with the associated costs.”

In the UK, a new challenge is the creation, under the Marine and Coastal Access Act, of England’s new Marine Conservation Zones (MCZs); these will co-exist with European designated sites but will protect wildlife, habitats, geology and geomorphology of national importance that are not already protected as of European importance.

The implications for dredging are interesting; port and harbour authorities have been closely involved as stakeholders in the discussions leading up to the first proposals, with the government due to designate the MCZs at the end of 2012 after assessments and consultation. Their keenness to be involved is understandable.

In theory, if an area is designated specifically to protect a particular type of species or habitat, then dredging could be restricted or disallowed. At least one port is looking at a potential situation of this kind: “We are fully supportive of the MCZ project and we have been environmentally responsible for many years,” said one of the team. “But we have to be practical about the commercial activities of the commercial port. We are working with them [the MCZ projects] to resolve this.”

The environment could benefit from a different way of thinking, Mark van Koningsveld, head of Dutch contractor Van Oord’s environmental engineering group, believes.

Van Oord is one of the initiators of the Building with Nature (ecodynamic development and design) initiative, which focuses on building while ‘drawing on the dynamics of the natural system’ – in other words, making use of nature rather than working against it.

“Hydraulic engineering or dredging projects can be more than just for their economic function – they also give the opportunity to add some benefits for the natural environment,” he says. “And that is the challenge. If you are going to do something, then try to make it a win-win situation by incorporating preferably environmental benefits or adding recreational uses.”

Although none of the four cases within BwN are maintenance dredging, ‘you can imagine’ what can be done, says Mr van Koningsveld.

“For example, maintenance contracts tend to run for several years. If we were taking one on now, we would definitely try to start with a database of historic data and build up new data to better understand the siltation process and its main causes.

“Rather than just dredging, can you manipulate things a little bit, so that the sediment might occur but not in the undesired place? Current deflection, for example; if the harbour is next to a flowing river, you might be able to guide the water into the harbour basin, to take out some silt. It will not solve all the problems, but at least it is in the right direction.

“Depending on the situation, there are interventions you can think of – natural processes such as river discharge to help with silt management. It is working with nature instead of trying to defeat it.”

Previously people built ‘in’ nature without considering what was there; next they moved to building ‘for’ nature, so compensating for negative effects, sometimes at another site, says Mr van Koningsveld. “Now we are taking the next step to see if we can have positive effects at the project site. We have several cases where at least we shall look at the problem with a different pair of glasses.”

Money can be saved with certain solutions, he says. "For example, within Building with Nature we are looking at a project to mitigate/prevent the effects of high water influx, which was to involve a new dyke to protect a village. It was decided to build a willow forest in front to break any waves. This allowed the dyke in front of the village to be lower. It is just like using the mangroves to dampen waves. Using vegetation like this has been done for hundreds of years – but something we forgot a little bit about, because perhaps we focus too much on what we now consider ‘traditional’ solutions.”

And stringent regulation doesn’t always lead to the best solution, says Mr van Koningsveld.

Mr van Koningsveld is the case manager of new ‘ecodynamic design guidelines’ being drawn up by BwN; these will be used to show politicians another way of thinking.

Jan De Nul says it always assists clients in finding the right solution to the main question: how to dispose of dredged (polluted or non-polluted) sediment. In one example, the company has been involved in the development of the AMORAS scheme, a sediment separation and treatment installation at the Port of Antwerp.


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