The project capitalised on the already undulating landscape. By accentuating the existing valleys and hills, the project established three lakes to detain and treat the rainwater from large parts of the town.
The local utility company excavated three existing hollows on a 7-hectare land area to make them deeper. A total of 54,000 cubic metres of soil was excavated and then added to the existing hills.
The climate adaptation project turned the three hollows into "the retention ponds at Tallerup", where the terrain slopes slightly from the first, southernmost pond to the northernmost pond.
The lakes retain surface and rooftop runoff from parts of the town through a separate sewer system. They also retain drainage water and rainwater from a production forest located on higher ground outside of the town.
The water runs from the first, southernmost lake via a meandering channel to the middle lake and further onwards via a winding channel to the northernmost lake. From the northern lake, the water is led via a culverted waterway into the Brende Å watercourse.
The system includes sand and oil traps installed in the lakes. This is to treat the water before it is led into Brende Å.
The three lakes are one metre deep and contain approx.
4,400 cubic metres of water. During heavy downpours, the water level increases considerably. Together the lakes can hold as much as 22,000 cubic metres of water.
During intense or long rainfall, the three lakes spill over and become one large lake. In these situations, a "dry lake" located close to the three lakes will also fill up with water.
The "dry lake" was established as a way of visualising the impact of weather and climate on the surroundings for local inhabitants, school students, etc.
The rainwater runs freely from one lake to the next. Because of the large volumes of drainage water that also need to pass through the lakes, it was decided to establish a stormwater outlet structure fitted with holes at various levels and of varying size.
At a later stage, the structure will be fitted with sluices to regulate the amount of water that is led from the lakes into Brende Å.
All three lakes and the culverted waterway leading into Brende Å will also be fitted with water-level data loggers.
With the final system is in place, the rainwater that used to flow uncontrolled and untreated into Brende Å will be detained, treated and controlled in its flow towards the watercourse.