CEDA DMC Visits the Anse du Portier Project in Monaco

CEDA Dredging Management Commission at a site visit in Monaco. (Credit: CEDA)
CEDA Dredging Management Commission at a site visit in Monaco. (Credit: CEDA)

In the past intermezzo, a lot of blog ideas past my mind. In due time, I will share some of them with you. Others already arrive by themselves naturally. e.g. Lately we’ve had another CEDA Dredging Management Commission meeting1. In preparation for the upcoming CEDA Dredging Days2, we discussed some publications that will be presented there3. Next to the meeting, we also did a site visit to a prestigious project. The Monaco extension project ‘Anse du Portier’ certainly demanded some serious management skills for the dredging works.

Overview of the Anse du Portier project
Overview of the Anse du Portier project

The extension project had already received a lot of attention in the press and in the dredging community. It certainly is a remarkable project, where a lot of disciplines are coming together. I would like to refer you from the excellent video on the Anse du Portier project itself4:

Extension en mer de Monaco – Techniques de construction (Credit: Anse du Portier Project)
Or, if you can hold your breath, to the presentation of Camille Kapella at the CEDA Dredging Days5, where she will elaborate on all the difficult challenges in the project. At the moment of our visit, the last caisson had just been placed in the construction6.

Last caisson in the constructed sea wall at Monaco
Last caisson in the constructed sea wall at Monaco

Caissons are a demanding construction in terms of dredging. Of course, there are examples, where location and placement were not so important, but usually the requirements are much stricter and the conditions much harsher. Caissons have to be placed next to each other in the first place. And joining them all together might end up in a big deviation as errors propagate through each misplacement. This has been recognised already for a long time. Even one of the first tunnels built of sunken caissons, the Maastunnel7, had specifications that are still in use today. So, how did they do this? There is a nice historic video available from the old Polygoon Journaal.

Building of the Maas Tunnel (Credit Polygoon Journaal)
In the case of the Maastunnel, they employed wires driving huge dials and sight line beacons. Under perfect conditions, enough time and an enormous amount of manpower, the objectives can be achieved. Nowadays, this approach would be too costly or can’t be used as the local circumstances prevent them. Waves, tides, difficult location or other factors are the edges of the envelope for modern caisson placement and all were present here in Monaco. Specifically, the challenges at the Anse du Portier site were the steep bedrock, the open coastline vulnerable to waves and environmental concerns. For each, of the challenges, appropriate solutions were chosen to manage the project.
The construction of the caissons to withstand the wave action during the lifetime is remarkable. The top of the caissons are equipped with so called patented Jarlan chambers8. This is a design concept known in the offshore construction to temper the wave action. Waves enter the construction through slots in the walls and enter a chamber with more columns for further dissipation of the wave energy. A similar approach is already discovered by nature itself: coastal mangrove forests.

Last caisson at the Anse du Portier with Jarlan chamber slots covered for transport
Last caisson at the Anse du Portier with Jarlan chamber slots covered for transport


  1. Dredging Management Commission discusses papers on contract-type selection and soil investigations, CEDA
  2. CEDA Dredging Days 2019, CEDA
  3. Effective contract selection: CEDA’s guide to optimised contracting methods, CEDA
  4. Anse Du Portier, Youtube
  5. Dredging in Monaco: challenges and solutions, CEDA
  6. Monaco Land Extension Project Reaches Milestone, Caissons Belt Completed, DredgingToday
  7. Maastunnel, Wikipedia
  8. Jarlan Chamber, Espacenet

See also

CEDA DMC Presentation On Dredging Innovations In Gdansk

Group photo of delegates attending the combined meeting of CEDA CEC & DMC and MIG on dredging in Baltic Ports. (Credit: CEDA)

Because of other activities these last weeks, my promised post about the DMC presentation had some delay. On October 10th, there was a symposium together with the Marine Institute Gdansk and the CEDA Environmental Commission and the CEDA Dredging Management Commission supported by Gdansk Science and Technology Park and the Baltic Ports Organisation1. The topic of the symposium was ‘Advances in Dredging Technology. My contribution was a presentation as DMC member2 on ‘Dredging technology developments versus requirements’.

Presenting the innovations in dredging technology. (Credit: CEDA)

Although dredging sounds like an old rusty trade, in fact, it is in constant movement and highly innovative when experienced from the inside. At the Dredging Management Commission, we have a separate focus group, that investigates the technological solutions that enable the stakeholders to efficiently manage a dredging project. A lot of ‘booby traps’ in the ‘Checklist For Successful Dredging Management’3 can be handled by applying the right technology. If there are issues with turbidity, e.g. one can apply a component as the ‘Plumigator®’4 attachment for the overflow in a trailing suction hopper dredge to comply with turbidity clauses in the contract. If the project has very narrow allowances for positioning, modern survey and control systems allow surgical precision dredging, to reduce overdredging and corresponding penalties.

All in all, we’ve identified more than 70 innovation over the last ten years, that have found a foothold in the dredging industry. These have been categorised to the field of technology: Components, Equipment, Industries, Initiatives, Methodology, Processes, Systems, Tools. Other descriptions that we’ve attributed to these innovations were their contribution in solving certain problems in dredging management, as they are found in the checklist. And how much effort they require and how much benefit they would yield. These last items are very subjective and still open for debate. More to follow later. But, at least the procedure can be laid out to recommend the best options for tackling certain problems in the ‘checklist.

Fields of technology and contributions to improvements in dredging management. (Credit: CEDA)

We had a good discussion at the symposium about this topic and from the other focus groups (contract management, checklist, etc.). There were also cross-over opportunities with the CEDA Environmental Commission. At least, there are enough leads, that can be used for the next CEDA Dredging Days in Rotterdam.

As an illustration of the long way we’ve came in the dredging industry, the conference room in the control centre of the Port of Gdansk5, was decorated with interesting pictures from the construction of the port.

Historic pictures of dredging works at the construction of the Port of Gdansk.


  1. CEDA-MIG Joint Symposium on Advances in Dredging Technology 2018 Supported by GSTP and BPO, MIG
  2. Dredging Management Commission, CEDA
  3. New CEDA paper encourages all parties to dredging contracts to start thinking and keep thinking, CEDA
  4. Plumigator, IHC
  5. Port of Gdansk

See also

A Visit to the Oresund Link with the CEDA Dredging Management Commission and 23 Years Ago with DOT

The CEDA Dredging Management Commission on site visit at the Oresund Link

Edit (11/08/2018): It appears, that my memory fails me on the details. It must have been late 1996 or early 1997.

This week, there was a meeting of the Dredging Management Commission of the CEDA. In this case, the venue was the offices of Femern A/S in Copenhagen1. The objective of the Dredging Management Commission is to provide expertise and guidelines to successfully manage dredging projects. A first publication was the ‘Checklist for Successful Dredging Management’ introduced at the CEDA Dredging Days last November. Currently I am involved in the Working Group on Innovative Dredging Technology2.
One of the items on the agenda was a visit to the artificial island of Peberholm. This island was reclaimed in 1995 during the Oresund Link Project, a tunnel and bridge connection that links Denmark and Sweden over the Oresund. A massive complex project, involving two countries, multiple contractors and numerous suppliers. Unlike most of the complex international government projects, the Oresund Link was delivered ahead of schedule and within budget3.

View from Peberholm on the Oresund Bridge and Sweden

At the time, I did my graduation thesis project with Skanska, one of the main contractors. There were also two other students working with Skanska. And as there were a lot of other Dutch contractors involved, the student club of Dredging and Offshore Technology organised a study tour to the project and have a first-hand experience with this landmark project. Returning to these sites with the CEDA was interesting to see the final product after it’s been working for several year in use.

Students of Dredging and Offshore Technology on study tour in 1995

On the Swedish side, a bridge was a good solution. On the Danish side, the link would be too close, to Copenhagen International Airport to build a bridge. It would interfere with the flight path of approaching planes. Therefore, a sunken section tunnel was chosen. Peberholm was created with fill material, dredged from this tunnel trench. Digging through hard limestone rock, the cutter suction dredge ‘Castor’4 consumed about 62,000 pick points. In the end, they had to exchange all the teeth every 15 minutes, sometimes too hot to handle.

Cutter head of the CSD ‘Castor’

Each pillar and the two pylons of the bridge have a foundation that reaches to the hard bedrock of the Oresund. For this dredging work, amongst others, the back-hoe dredge ‘Rocky’5 from Skanska was deployed. One of the contractual clauses was that turbidity had to be reduced to an absolute minimum, never seen before in any contract. Although protesting, the contractors complied and did a great job on reducing turbidity. The loose material from the bottom and the rubble from the bedrock created visual plumes anyway and Skanska had to modify their procedures and equipment to reach the stringent standards.

Left, Back hoe dredge ‘Rocky’. Middle, bucket of crushed limestone. Right, Spill plume.

It was fitting, that we visited the location of this impressive project as inspiration to advice how to successfully manage a dredging project. The next step to test the management skills of the Danish people will be the Fehmarn Belt Project6.

Panoramic view from Peberholm. Denmark left, Sweden right and Saltholm in the middle.


  1. Femern A/S
  2. CEDA Dredging Management Commission, CEDA
  3. Oresund on time and within budget, Øresundsbron
  4. Castor, Van Oord
  5. Rocky (after modification), Boskalis
  6. Fehmarn Belt Project, Wikipedia

See also