The frequency of heavy rain events and flash floods is increasing more and more due to climate change. This is also the case in Rastatt. In order to be prepared for this, one of the largest construction projects of the coming years in the baroque city started in September 2022: In the industrial area at Rauentaler Straße 12/12A, a new stormwater overflow basin will be built to meet environmental specifications and replace the existing three stormwater overflows. At the same time, sewers will be renewed, Rauentaler Strasse will be rehabilitated and bicycle protection lanes will be 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 rain, the underground sewers quickly fill up. In the worst case, the wastewater then flows directly into the Murg. Stormwater overflow basins relieve the sewage system and wastewater treatment plants during heavy rain. They retain dirt particles so that combined sewage is not discharged unfiltered into rivers. If it does not rain, the wastewater is discharged directly to the wastewater treatment plant. When it rains, on the other hand, 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 stormwater overflow basin prevent basements from filling up and streets from being flooded during heavy rains?
Yes and no. During normal continuous rainfall, the 500-cubic-meter stormwater overflow basin can intercept and drain the water volumes. During heavy but short heavy rain events or even during floods of the Murg river, the water first accumulates on the road surface and only gradually reaches the sewage system. Suitable safeguards against surface water penetration and backwater protection are still urgently recommended for property owners. However, since the sewer pipes will also be doubled in diameter, particularly in Rauentaler Straße, the underground storage for stormwater runoff will be increased overall and water pressure will be reduced.
Where exactly will the stormwater overflow basin be built and what is the cost of construction?
The stormwater overflow basin is being built at 12/12A Rauentaler Strasse, 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 cost of the pool, the technical equipment and the sewer work is around seven million euros, plus around 1.2 million euros for road rehabilitation.
What restrictions should residents and businesses expect during the construction period?
Since a large part of the roadways will have to be torn up due to the underground work, Rauentaler Straße will be thoroughly rebuilt between the junction of Alte Bahnhofstraße and the junction of Lochfeldstraße. In addition, the road surface will be rehabilitated from the Lochfeldstraße intersection to Im Steingerüst Street. The project is divided into four construction phases. Work will start in July at the level of Alte Bahnhofstraße. There will be full closures of Rauentaler Straße in sections. However, deliveries by trucks will still be possible - either coming from the south or the north. During the construction period, a replacement bus stop will be set up at Niederwaldstraße 1.
How many and which construction phases are there?
- Construction phase 1a, September 2022 to December 2022: Reconstruction of the manhole in Rauentaler Straße at the Alte Bahnhofstraße level: Full closure of the Alte Bahnhofstraße junction, passage in the direction of Rauentaler Straße is still possible.
- Construction phase 1b, December 2022 to February 2024: New construction of the stormwater overflow basin including technical equipment and spillway into the Murg: Full closure of Rauentaler Straße in the south as far as the sidewalk and bike path. The sidewalk and bike path will remain open to vehicles coming from the north via Rauentaler Straße or from the east via Alte Bahnhofstraße.
- Construction phase 2, March 2024 to August 2024: Reorganization of the sewer system in front of the stormwater overflow basin: Full closure between Rauentaler Straße 12 to 16, sidewalk and bike path can only be used by residents coming from Alte Bahnhofstraße during construction phase 2 (dead end).
- Construction phase 3, September 2024 to June 2025: New inlet channel to the stormwater overflow basin; pipe jacking underneath the industrial tracks will be constructed: Full closure of Rauentaler Straße in the north, sidewalk and bike path can still be used by vehicles coming from the south via Rauentaler Straße or from the east from Alte Bahnhofstraße for the period.
- Construction phase 4, July 2025 to August 2025: Pavement rehabilitation from Lochfeldstraße to Im Steingerüst/Hardbergstraße: Closure of Rauentaler Straße between the railroad crossing and the junction with Hardbergstraße.
All information without guarantee. Due to weather conditions and depending on the delivery situation, there may be changes in the time schedule.
When roads are rehabilitated, bicycle protection lanes are also built. What effect do these have on traffic?
On the one hand, the city hopes that the traffic in Rauentaler Straße will be calmed down by narrowing the roadway. On the other hand, it wants to improve the traffic situation for cyclists in general. However, this also eliminates some free parking spaces at the edge of the roadway, which were used in particular by rail commuters. In this context, the city refers to the directly adjacent park-and-ride lots of Deutsche Bahn, which offer sufficient capacity. Citizens also suggested extending the 30-mile zone to the stormwater overflow basin. The administration wants to examine the suggestion.
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