Sustainable choices in the optimisation of the Onlanden

How did you handle it?  

Daniëlle drafted the final report on sustainability. This was the culmination of the process she led, during which the possibilities for sustainable choices were explored step by step over the course of several sessions. 

"We started with a broad approach, looking at various topics such as material use and reducing CO2 emissions." 

Based on this broad perspective, we have identified which measures are most promising in the Onlanden region and where you can truly make a difference in terms of sustainability.  

Which themes were ultimately chosen to focus on?  

This broad exploration identified energy, materials, and ecology as the most promising themes. Marieke:

 “Energy is about keeping CO₂ emissions as low as possible during implementation.” 

It also became clear that there were many opportunities to deliberately choose more sustainable materials for the construction of the balancing lake. The choice of ecology as a theme was an obvious one, since the Onlanden is a nature reserve. Marieke explains: 

“We’re working on flood protection here, but we’re doing so right in the middle of a nature reserve. That means we have no choice but to treat nature with care and set high sustainability goals.”  

How do we take nature into account?  

An ecological study was conducted prior to the start of construction. When the locations of the weirs were determined, we considered together with Staatsbosbeheer (Dutch Forestry Commission) how the design could be as safe as possible for animals, such as otters crossing the area. The design also includes refuge mounds. Daniëlle explains: 

“When the Onlanden fills with water, animals can escape to higher ground.”  

In addition, some ditches have been made shallower so that water stays in the area longer. This is good for plants and makes the landscape more resilient to extreme weather, such as drought. Daniëlle:

 “That enhances biodiversity, which aligns perfectly with our sustainability goals. It’s great to see.”  

What sustainable materials are used?  

In this project, we are deliberately choosing materials that reduce our environmental impact. For example, we are using a used sheet pile wall. By reusing existing materials, we conserve raw materials and reduce CO₂ emissions.  

In addition, we use a materials passport. The contractor uses that to record which materials were used, such as the amount of steel and concrete. We keep this information on file so that we know exactly what can be reused at the end of the structure’s lifespan. This increases the opportunities for circular construction in future projects.  

How are we trying to reduce CO2 emissions?  

Driven by that same commitment to sustainability, we are also focusing on reducing emissions during the project’s implementation. 

“In this project, we are paying special attention to sustainable transport movements”

, says Daniëlle. 

“We use cleaner fuels in our lorries, such as HVO100, which significantly reduces CO₂ emissions.” 

We also limit the number of miles we drive. For example, the soil we need comes from the Cosun area. That saves a lot of trips and reduces emissions.  

We also looked into the use of an electric crane. However, such a crane currently costs about twice as much, while the additional sustainability benefits for the overall project are limited. That is why we are opting for measures that do have a significant impact, such as reducing the number of transport movements and using cleaner fuels. 

A formal evaluation is conducted at the end of the project. Marieke: 

“We figured out in advance what we wanted to achieve. We’ll see later whether the implementation actually contributes to that.”

 This way, the project team continues to learn, and future projects become even more sustainable.

Questions or concerns?
Eddi is here to help.
Email: optimalisatieonlanden@noorderzijlvest.nl
Phone: +31 (0)6-51403752