At the forefront of sewer separation

In connection with the expansion of production in Troldhede, Troldtekt has decided to separate rainwater and wastewater on the entire factory site. It took some detective work to map the old pipelines, but significant benefits have been achieved in the form of a reduced load on the local wastewater treatment plant and less impact on the aquatic environment.

Troldtekt, CSR report 2017

When heavy rain falls on the rooftops in Troldhede, the sewage system and wastewater treatment facility are tested to capacity. This is because the rainwater flows along the same sewers that carry the effluent from the town’s toilets, drains and kitchen sinks. And due to increasing rainfall, the existing sewage system is struggling to keep up. This can lead to overflows, where an unsightly mixture of rain and sewage flows out into lakes and waterways.

Therefore, municipalities and utilities across Denmark are busy separating rainwater and wastewater into separate pipes. However, it also means that companies and private citizens need to separate the water on their own plots. So far, sewer separation has not yet come to Troldhede, but in connection with the expansion of the factory, Troldtekt has independently decided to ensure separation of rainwater on the entire factory site.

“Following the expansion of the factory, we will be adding a further 30,000 square metres where rainwater is collected. Channelling all this water into the sewerage system would represent a significant waste of resources, and also the local wastewater treatment plant would have difficulty dealing with it. We therefore entered into a dialogue with the municipality to find out whether it didn’t make sense to separate the grey and black water from the rainwater now,” says Poul Erik Pedersen, the architect behind the expansion project.

Troldtekt, CSR report 2017

On the trail of old pipes
The Municipality of Ringkøbing-Skjern and the water utility Ringkøbing-Skjern Forsyning liked the idea, and it was agreed that Ringkøbing-Skjern Forsyning would install a new rainwater pipe to Troldtekt’s plot. This means that a number of existing rainwater basins can be done away with as the water will now be led away from the plot, circumventing the wastewater treatment facility, to a new rainwater reservoir established by the utility.

The separation will not only cover the new area, but also existing buildings etc. However, it soon became clear that getting an overview of all the existing pipes and drains was no simple task.

“The factory has been added to several times over many years, so it was quite a big job mapping all the piping in the ground. Today, you are obliged to map and register all new pipes, but that wasn’t the case in the past. Considerable time and money has therefore been invested in preparing for the separation. This means that the registration is now fully under control, and the utility is saving a lot of resources for water treatment,” says Poul Erik Pedersen. 

Less wastewater in watercourses
Ringkøbing-Skjern Forsyning is also pleased with the cooperation with Troldtekt, and the prospect of the wastewater treatment plant having to deal with less rainwater. It benefits the utility’s operating economy, and makes it easier for the utility to live up to the Environmental Protection Act (Miljøbeskyttelsesloven) and the Order concerning Waste Water Discharges (Spildevandsbekendtgørelsen).

“Separating the water cuts the costs of treating it, and also reduces the risk of overflows during cloudbursts. The wastewater contains organic matter and bacteria, and if it ends up in the natural environment, then oxygen consumption in streams and lakes will rise concurrently with a deterioration in water quality,” says Hans Schmidt, a project manager with Ringkøbing-Skjern Forsyning.