Our Interview About New Pump Designs In The Latest Damen Nieuws

Headline of our interview in ‘Damen Nieuws’
Headline of our interview in ‘Damen Nieuws’

Another magazine dropped on my doormat, albeit a digital edition of ‘Damen Nieuws’1. The internal magazine for Damen colleagues. It featured an article with Suman Sapkota and me. Suman is our pump design specialist2 and at a Damen wide R&D convention he presented a poster on his pump design workflow within Damen Dredging Equipment. This caught the attention of the editorial board and we were interviewed on what we actually do for a living. Although we can’t share the exact details of the article or the poster, it is still an interesting message that we can highlight here.

Pump design workflow (inspired by Suman Sapkota)
Pump design workflow (inspired by Suman Sapkota)

The design of a dredge pump is based on the required specifications(1). The most important properties of the pump are: efficiency, NPSH, wear and ball passage. The first important property we try to fix is the ball passage3. We do use our own geometry generator(2) that assist us in creating a pump with a big ball passage. Unlike normal pumps, dredge pumps have to cope with debris and boulders that have to pass the impeller. The bigger chunks that can pass, the more uptime the dredge will have. Once we are satisfied with the geometry, we feed this through a file format converter(3). The resulting 3D file can be used on several platforms. This will enable us to create the digital solid for the engineering4, but it also gives us the negative volume, also known as fluid. Then to do mathematical operations on the digital fluid, we have to divide the volume into tiny cells. This process is called meshing.(4) When the mesh is available, the fluid flow through the mesh can be simulated with computational fluid dynamics.(5) All the fluid properties of every cell are calculated and the results are shared with the adjoining cells. This can be repeated until all properties of the cells don’t change very much anymore, a stable solution. Integrating all the properties of the cells give the resulting performance of the pump.

Balancing the four dredge pump performance properties
Balancing the four dredge pump performance properties

The estimated performance can be evaluated against the four properties.(6) The head times the capacity divided by the power required will give the efficiency. That is one of the items we wanted to know, as it relates to how much fuel will be consumed. The other parameter obtained from the CFD is the NPSH, or roughly: the suction performance. Wear cannot be estimated yet, but we are working on that2. Although the calculated turbulence might give a clue what wear to expect. If the properties are not satisfying our requirements we make an iteration in the geometry for improving the performance. However, changing the geometry will usually result in a smaller ball passage. If the parameters are OK to our requirements we have a pump design.(7) Manufacturing it is a completely different game.5

The design process of the dredge pump takes quite some effort and we are continually looking to improve the workflow6. Eventually we would like to be able to cater for all special requirements each individual customer might have.

Working for a dredge manufacturer, I am happy we design and produce our own pumps. It gives us the confidence, that when we supply dredges, they are as we like them to be. Another benefit is in discussions with the customer. It is easier when we can sit at the table as experts on their equipment assit them in finding a solution for their dredge.

Pump experts immersing themselves in checking the design of their pumps
Pump experts immersing themselves in checking the design of their pumps


  1. Damen Nieuws, Juni 2020, Damen
  2. Graduation Suman Sapkota: Where wear parts were worn down, Discover Dredging
  3. On The Relation Of Maximum Ball Passage And Recirculation Losses In Dredge Pumps, WODA
  4. Graduation Of Carsten Markus: Designing And Casting Of Impellers
  5. Don’t Play Games With Your Wear Part Planning
  6. Innovation, Damen

See also

HYDRO 2018 Gdansk: Selecting A Dredge For Your Reservoir Maintenance

Barrage du Ksob, M’Sila, Algeria with a DOP dredge 350

This week, I am here in Gdansk for a presentation on the HYDRO 2018 Conference1 and assist at the Damen booth at the corresponding exhibition. The paper and the presentation are already prepared and I am very excited to do the presentation, but I can’t wait till tomorrow and I like to share the story now, already. So, you, as my favourite audience, will have my personal spoiler after so many teasers have been floating around2,3,4.

General modes of siltation at the usual location in a reservoir

The thing is, dam maintenance and reservoir restoration is something already long on my attention list. Back already in 2008, I wrote a paper on this subject for the CEDA Dredging Days5. Over and over we’ve conveyed the message on various platforms, that dredging might be a viable solution for sedimentation problems in reservoirs. Usually, the solution by dam owners and operators is to flush, sluice or store the sediment. This looks horrible from a dredging perspective, but it is also to the environment. You either smother or starve the downstream river with sediment. As a right minded dredge enthusiast, you see many possibilities to dredge such a project. Immediately we can identify what dredge to use on which location for which purpose.

Selection of applicable dredges for reservoir dredging

If you are very close to the dam and the length of the discharge line allows it, you might even not need a dredge pump. (No wear parts!) It is a so called siphon dredge. But as soon as there is some further transport involved, either distance or uphill, you need a dredge like a cutter suction dredge or a DOP dredge. For even further discharge, you might employ a booster for increased discharge pressure. If the distance becomes very far, you might have to resort to grabs and barges.

Water injection dredging principle and example (this example would be too big for a common reservoir)

As an intermediate solution you might even consider using a water injection dredge. Usually the reservoir is in the mountains and a bottom gradient will be present, enabling the required gravity flow. The actual dredge should have created a silt trap where it can collect the inflowing material from the water injection dredge. Than it can handle the material as usual.

Alternative uses for the dredged sediment a) silt farming as fertile additive b) gravel extraction for concrete

Off course, the dredged sediment belongs to the river and the best thing would be to gradually release the sediment after the dam. But there might be conditions, where it is beneficial to extract the valuable fraction of the sediment and use it for agriculture or as aggregate in the construction industry.

Dredge selection diagram for reservoirs

We noticed, that it is often difficult to convey to dam owners and operators which dredge to select for which job. Sediment is seen as a liability and not as an asset and they rather neglect issues associated with the sediment. So, I made an attempt to have a plain and simple selection diagram. That is the core of my manuscript. But my objective is, that we will see many beautiful dredges contributing to a sustainable and viable operation of hydropower dams and reservoirs.

New DOP dredge family


  1. HYDRO 2018: Progress through partnerships, Hydropower and Dams
  2. LinkedIn Teaser, Saskia den Herder
  3. Damen: Spotlight on Hydro Power Dam Maintenance
  4. LinkedIn Teaser, Olivier Marcus
  5. Multi Functional Small Dredging Solution For Maintenance Of Deep Irrigation Reservoirs And Hydro Power Dams, CEDA

See also

¡VAMOS! mining concept for submerged inland mining on any continent

¡VAMOS! equipment on trial at Lee Moor, Devon, UK

Today, the WEDA Dredging Summit and Expo 2018 starts1. Tomorrow, Olivier Marcus is going to present a paper on the ¡VAMOS! project2, I assisted co-authoring. The message we wanted to convey is the applicability of the ¡VAMOS! system we’ve developed in a European Research and Development consortium3. By now we were well acquainted with the European Situation, but as this was going to be presented in the United States I had to do some research all over, for the American market situation. It turned out that ¡VAMOS! concept could be used their as anywhere else.

Schematic of typical vertical ore body in an opencast or submerged setting (Credit: ¡VAMOS!)

First of all, some explanation what the ¡VAMOS! project is about. We’ve noticed that here in Europe mineral resources are heavily depleted or located at locations that are not accessible due to their economic or environmental value. One solution would be to dig deeper, but in open cast mining, you’ll run into an enormous overburden removal and drainage problems. The other is to tunnel mining, but that is very expensive and dangerous. The ¡VAMOS! concept opens up a new approach: submerged mining.

Diagram of the original ¡VAMOS! concept (Credit:¡VAMOS!)

Instead of pumping the water out, we use it to transport the mineral to the plant. And this is very familiar for us in the dredging industry. So, we’ve found another location where we can discover dredging! Usually dredging involves transporting huge volumes of sediment, but the fraction of the ore, that is really paying for the operation tends to be very small. In mining terms it is the ore grade. Depending on the ore grade, the operation can be economically feasible or not. As this is a very fine line, mining economics have already done a lot of research on this and they call it the ‘Exergy Cost’. In short: an operation for low grade ore may be more expensive when the mineral is expensive. In fact, when one is mining sand, the ore grade is 100% and the price will be low, so the profit has to come from its volume.

Exergy cost (kWh) needed for producing a given mineral from bare rock to market. (Credit: Valero)

This model is basically applicable in both the European and the American market. Although the local business mentality will result in different underlying economic calculations. In Europe we were working with a report on the critical resources that are on the agenda of the European Commission4. It turns out, that now the United States has their own list of critical minerals5, just signed into executive order6. The list differs somewhat, but is certainly recognisable. This is a good indication, that the ¡VAMOS! mining concept can be evaluated equally to the other options for the American market.

Medium-Term (2015–2025) Criticality Matrix (Credit: US DOE)

So, who knows, maybe there is an innovative entrepreneur in Olivier’s audience at the WEDA and the first real production model might be put to work in an American mine. At least, when delivering a product like this, we would not have to worry about the Jones Act.

MV handling on LARV at Lee Moor test site in Devon, UK


  1. Dredging Summit and Expo 2018, WEDA
  2. WEDA Dredging Summit & Expo, Damen
  3. ¡VAMOS!
  4. EIP on Raw Materials, European Commission
  5. Interior Seeks Public Comment on Draft List of 35 Minerals Deemed Critical to U.S. National Security and the Economy, US Department of the Interior
  6. A Federal Strategy To Ensure Secure and Reliable Supplies of Critical Minerals, Executive Order 13817 of December 20, 2017

See also