Aalborggade, Randers

In the centre of Randers, residents had been plagued by periodic flooding caused by capacity problems in the area's sewers. In addition, outflow from an overflow structure in Aalborggade had caused excessive load on Tyvdalen. The area has combined sewerage and a number of low-lying basements that are sensitive to high water levels in the sewer system. MOUSE calculations were conducted and, based on the results, it was proposed that the main sewer be relaid so that a plastic pipeline of varying dimension should be laid in Aalborggade, between Vorup Boulevard and Bøsbrovej, parallel with the roughly 240 metres of existing ø300 mm concrete pipeline. Approximately 80 metres of the new pipeline is an ø1200 mm pipe basin positioned midway along the 240 metres of existing pipeline. Flow from the pipe basin is controlled in two places as follows:

• roughly halfway into the pipe basin was an overflow structure (ø1600 mm) with flow control in the drainage to prevent it from exceeding the capacity of the downstream pipeline, which is roughly 110 l/s. The flow regulator, a Mosbaek double baffle, was installed in an overflow wall. In addition, drainage to Tyvdalen was possible via overflow to a ø110 mm pipeline.
• At the outlet from the pipe basin, there was also an ø1600 mm manhole. This manhole contained a double baffle with a 130 l/s capacity, also installed in an overflow wall.

The flow regulators and overflow walls in the two structures ensured ideal utilisation of the pipe basin's volume. Selecting this solution made it possible to reduce the number of basement-flooding incidents.

The project dates from 1999 and the consulting engineers were Carl Bro A/S.