The frequency of heavy rainfall events and flash floods is increasing due to climate change. This is also the case in Rastatt. In order to be prepared for this, one of the largest construction projects in the baroque city in the coming years started in September 2022: a new stormwater overflow basin is being built in the industrial area at Rauentaler Straße 12/12A to meet environmental requirements and replace the three existing stormwater overflows. At the same time, sewers are being renewed, Rauentaler Straße is being renovated and cycle lanes are being built. Construction is expected to take three years. The total cost of the construction project is around 8.2 million euros.
What is the purpose of a stormwater overflow basin?
During heavy rainfall, the underground sewers quickly fill up. In the worst case scenario, the wastewater then flows directly into the Murg. Rainwater overflow basins relieve the sewer system and sewage treatment plants during heavy rainfall. They retain dirt particles so that mixed water is not discharged unfiltered into rivers. If it does not rain, the wastewater is routed directly to the sewage treatment plant. When it rains, however, the water is temporarily stored in the basin and only then discharged into the Murg.
Why is the construction of a new stormwater overflow basin necessary?
Does the rainwater overflow basin prevent cellars from filling up and streets from flooding during heavy rainfall?
Yes and no. During normal continuous rainfall, the 500 cubic meter rainwater overflow basin can intercept and drain off the water volumes. During heavy but short periods of heavy rainfall or even when the Murg river floods, the water initially accumulates on the road surface and only gradually enters the sewer system. Suitable protection against the ingress of surface water and backwater protection is still strongly recommended for property owners. However, as the diameter of the sewer pipes, particularly in Rauentaler Straße, will also be doubled, the underground storage capacity for rainwater runoff will be increased overall and the water pressure reduced.
Where exactly will the stormwater overflow basin be built and how much will it cost?
The stormwater overflow basin is being built at Rauentaler Straße 12/12A, directly behind the train station. It has a length of around 50 meters, which is roughly the length of a swimming pool, and a width of six meters. The pool will be built completely underground with several access openings so that it can be retrofitted if necessary. The costs for the pool, the technical equipment and the sewer work amount to around seven million euros, plus around 1.2 million euros for the renovation of the roads.
What restrictions should residents and businesses expect during the construction period?
As a large part of the carriageway has to be torn up due to the underground work, Rauentaler Straße will be completely resurfaced between the junction with Alte Bahnhofstraße and the junction with Lochfeldstraße over the next three years. In addition, the road surface from the Lochfeldstraße junction to Im Steingerüst will be renovated. The construction project is divided into four construction phases. Work will begin in July at the Alte Bahnhofstraße. Rauentaler Straße will be fully closed in sections. However, deliveries by trucks will still be possible - either coming from the south or the north. An alternative bus stop will be set up at Niederwaldstraße 1 during the construction period.
How many and which construction phases are there?
- Construction phase 1a, September 2022 to March 2023: Reconstruction of the manhole in Rauentaler Straße at Alte Bahnhofstraße: full closure of the Alte Bahnhofstraße junction, passage in the direction of Rauentaler Straße is still possible.
- Construction phase 1b, March 2023 to May 2024: New construction of the stormwater overflow basin including technical equipment and relief channel into the Murg: Full closure of Rauentaler Straße in the south up to the footpath and cycle path. The construction of the road from the junction of Alte Bahnhofstraße to the south of the stormwater overflow basin will be brought forward to mid-November 2023 to allow residents to drive and park until "construction site free".
- Construction phase 2, May 2024 to March 2025: Reorganization of the sewer system in front of the stormwater overflow basin: Full closure between Rauentaler Straße 12 to 16, footpath and cycle path can only be used by residents coming from Alte Bahnhofstraße during construction phase 2 (dead end).
- Construction phase 3, March 2025 to August 2025: New inlet channel to the stormwater overflow basin; pipe jacking underneath the industrial tracks will be carried out: Full closure of Rauentaler Straße in the north, access to the footpath and cycle path will continue to be open to vehicles coming from the south via Rauentaler Straße or from the east from Alte Bahnhofstraße during this period.
- Construction phase 4, August 2025 to October 2025: Road surface renovation from Lochfeldstraße to Im Steingerüst/Hardbergstraße: Closure of Rauentaler Straße between the level crossing and the junction with Hardbergstraße.
All information without guarantee. Due to weather conditions and depending on the delivery situation, there may be changes to the schedule.
Cycle lanes are also being built when roads are renovated. What effect do these have on traffic?
On the one hand, the city hopes that traffic on Rauentaler Straße will be calmed by narrowing the lane. On the other hand, it wants to improve the traffic situation for cyclists in general. However, this also means that some free parking spaces on the side of the road, which were used by rail commuters in particular, will be removed. In this context, the city refers to the directly adjacent Deutsche Bahn park-and-ride parking spaces, which offer sufficient capacity. Citizens also suggested extending the 30 km/h zone to the rainwater overflow basin. The administration intends to examine the proposal.