Herbronnen

Aquafin Goes for RENEWAL

During periods of drought, measures are introduced that restrict farmers, managers of public green spaces and private individuals from using ground, surface or rainwater. Indignation is very high when, at the same time, groundwater during drainage works on construction sites simply disappears into the sewers. 

The Flemish Environment Agency clearly formulates that return drainage and limiting drainage is mandatory, but in practice this is often not the case. Technical and financial reasons are an obstacle, but also insufficient expertise at the licensing authorities or lack of manpower to follow up on enforcement. For reuse, other bottlenecks emerge, such as water quality, use for essential versus non-essential applications, legal agreements ... 

Through the Herbronnen project, Aquafin is investigating these bottlenecks. With the help of experts from the drainage sector, we want to offer as many solutions as possible and analyse technical alternatives. We are trying to evaluate the technical limitations and want to share the specialised knowledge with all stakeholders. In addition, we investigate which water quality is desirable for reuse. Based on the available laboratory results, we look at the most common contaminants in the drainage water and how the water can be purified and reused.

Key results

Key lessons learned
  1. We made a realistic estimate of how many m³ of groundwater is being pumped in Flanders: in 2020, the licensed flow was 63 million m³. That is as much as the licensed volume for agriculture or industry (70 and 55 million m³/year respectively). 
  2. We drew up a list of all sampling of drainage water, checked the values against the standards and fed back the results to the responsible authorities. This shows that we cannot simply consider the quality of drainage water to be pure. 
  3. The project results were echoed by politicians, the media (Radio 1, De Standaard, VTM, etc.) and the field (webinar VCB, Vlario). We also made a video report focusing on two construction sites where water glass injection and return drainage are used to drain less water.
  1. Much more is being pumped than thought. The volumes of groundwater pumped out are significant in the groundwater balance and of the same order of magnitude as the licensed volume for industry and agriculture. Commitment to more sustainable drainage is therefore certainly not a drop in the ocean. 
  2. The quality of groundwater during drainage is not always good enough for reuse. Standards are often exceeded. Therefore, we do not want to explicitly encourage reuse (certainly not for private individuals), but rather integrate it into projects at the request of cities and municipalities. 
  3. It is important to elaborate on the conclusions of this project and disseminate the information as widely as possible. Knowledge sharing around interesting techniques such as water-glass injection and return drainage is also necessary. Buildwise and Embuild are currently working on this through the COOCK project. 
  4. The existing purification techniques for drainage water are limited in availability, very expensive and hardly applied. Further technological development in that area is of great importance.

What will the future bring? 

Through the COOCK project, Buildwise and Embuild are continuing to disseminate knowledge on good drainage techniques. Aquafin is examining whether the yard water platform can be further used to put available drainage water and rainwater to good use. The drainage working group within Aquafin is continuing its efforts to reduce drainage and also convince the rest of the stakeholders of this.

Watch a summary of the project in this video.

Aquafin NV

Partners VUB, Werfwater

Website

https://www.aquafin.be/en

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