Skip to main content

Understanding Dredging

Become a member

Addressing knowledge gaps to reduce environmental impact

2023-05-12 Tamara Parkin

120523 // arjen_wijdeveld_news.png (355 K)

Photo Credit: Arjan Wijdeveld

To minimise the environmental consequences of dredging, the industry needs to make continual efforts to stay abreast of scientific understanding. With that goal in mind, CEDA has been a non-governmental observer at the OSPAR Commission, which governs the Oslo and Paris Conventions on marine protection of the North Atlantic, since 1992. According to CEDAs new representative to OSPAR’s Environmental Impact of Human Activities Working Group, Arjan Wijdeveld, there is more than ever to talk about in this crucial policy area.

“There are a variety of topics we discuss within the Human Activities work group, including issues that are of specific interest for the dredging industry,” says Wijdeveld. “Disposal of sediments at sea, contaminated sediments, underwater noise, and climate change adaptation are just a few of those.”

Wijdeveld is well qualified to take up those conversations. He is a geochemical expert on sediment/water interaction at the research institute Deltares, as well as the chair of the SedNet working group on circular economy use of sediment. Before taking up the role as an OSPAR representative he was previously a member of CEDA’s working group on beneficial use of sediment. 

Influencing decisions

CEDA’s role at OSPAR meetings is to provide information and recommendations rather than decide measures, says Wijdeveld.

“We are not a member state, so we don’t have the power to vote at the meetings. Instead, we prepare the work that is discussed during the meetings. There are opportunities for us to take the floor to speak to commission members and inform them about the impact of issues and decisions on the dredging industry and on member states, but we ourselves do not make the decisions.”

Despite the absence of voting power, CEDA’s input can have a big influence on OSPAR. Some CEDA members work at the governmental level and so are actively involved in discussions, while others are involved as dredging industry representatives in OSPAR’s various working group committees preparing the information leading to decisions. This places an important responsibility on CEDA as a knowledge-sharing organisation for the governments that form the commission.  

Wijdeveld notes the importance of representing not only the CEDA members but also the interests of the wider dredging community. The aim is to have, as much as possible, a common strategy.

“Currently we are having discussions on the implications of legislation from the Water Framework Directive on the sediment environmental quality standard (EQS)  for tributyltin (TBT), a very old anti-fouling treatment that is still having an effect on the environment. During these discussions, we are looking at the impact of this legislation on dredging not only within CEDA but also with the Permanent International Association of Navigation Congresses (PIANC), the European Sediment Network (SedNet) and different ports.” 

Wijdeveld explains that having a common strategy among dredging organisations is key when delivering information to the OSPAR Committee.

“During the formal meetings, each state representative has a mandate from their respective ministers that they use to guide their agenda and position in meetings. Because that is the opinion of the member state and representatives must stay within their mandate, it can mean discussions at the table are limited. By knowing and understanding what the main points of conflict or agreement are, we can provide information and recommendations to tackle specific problems.” 

Expanding knowledge

As the agenda of the OSPAR Commission is set by member states, the topics of importance are dependent on the long-term industry understanding of committee and working group personnel. This is critical as government representation lasts only for the time span of a typical ministry job cycle, which can be between four and six years. 

“That means that the knowledge level also fluctuates quite a lot,” says Wijdeveld. “Topics change a bit over time depending on the strength of other legislation (like the EU Water Framework Directive), but also the gaps or possibilities to work together with different groups. As an example, the cooperation with HELCOM (Baltic Sea) is historically strong, while the link with the new (2023) High Seas Treaty is still to be explored”

This ministerial cycle places more emphasis on the importance of assistant organisations such as CEDA to supply the knowledge and continually build on that research. Knowledge sharing is an integral part of CEDA’s involvement with the OSPAR Commission, so identifying gaps and opportunities for expanding existing knowledge is a core responsibility. 

Wijdeveld identifies microplastic pollution as a prime example of where further research is required to help with decision and policy making. 

“We currently don’t have a good grasp on how to detect marine litter, particularly microplastics. There is an awareness that we don’t know how to define microplastics or how to trace them back to their sources. Although there are techniques to screen out litter in sediments, we have found that approximately 20% of the total marine litter is coming from sediment disposed at sea. So it’s important that we build on knowledge but also create a standard for litter screening and removal. This, of course, might impact the relocation strategy and the dredging strategy for areas with a lot of marine litter.” 

Decarbonisation journey 

CEDA members can expect a large output of information related to emission reductions and the environmental impacts of human activity over the coming year. 

“One of the driving factors for the next ten years is being emission-free or at least having an emission-free dredging cycle on site,” says Wijdeveld. “As a result, there will be either an information or position paper from CEDA on greenhouse gas emissions. We recently announced the CEDA greenhouse gas emissions from sediments working group to help tackle all aspects of the dredging process that contribute to greenhouse emissions. We are looking at land use, water use and how we can influence emissions by doing things differently. One way is through pilot studies on land restoration for carbon sequestration, which we can see in Asia with mangrove restoration for coastal protection, for example.”

There is plenty more to come from the human impact working group in 2023, potentially including a monitoring strategy on marine litter released this year. Wijdeveld also notes discussions with the CEDA environmental commission about setting up a working group for emerging compounds of great concern, such as per- and polyfluroalkyl substances (PFAS).

He says: “Though this issue mainly concerns Flanders and the Netherlands, we are starting to see it affect more of Europe, such as Germany and France, so having a discussion now will help prepare us for the future.”

CEDA is looking for a member to become its representative on the OSPAR Commission intersessional correspondence group on the marine strategy framework directive. For further information or to apply, please contact Frederik Roose, Chairman of CEC ( or Mieke van Loenen, General Manager of CEDA (

While the advice given in this editorial content has been developed using the best information available, it is intended purely as guidance to be used at the user’s own risk. No responsibility is accepted by CEDA or by the Intent Communications Ltd or by any person, firm, corporation or organisation who or which has been in any way concerned with the furnishing of information or data, the compilation, publication or any translation, supply or sale of this Guidance for the accuracy of any information or advice given herein or for any omission herefrom or from any consequences whatsoever resulting directly or indirectly from compliance with or adoption of guidance contained therein even if caused by a failure to exercise reasonable care.