Würmtal townships make a wise decision
rehabilitation by regeneration
Diana Klose, Steinzeug-Keramo GmbH
Ever since 1960, the townships of Gauting, Krailling, Planegg, and Gräfelfing that make up the Würmtal community, located just southwest of the Munich city limits, have had a central wastewater drainage system. Originally constructed by the Würmtal Water Board, it has made a major contribution to stopping the ever deteriorating quality of the waters of the Würm river. Today the water board feeds off the separated wastewater via a sewage system with a total length of about 200 km, with a spread of around 10,000 house connections with an average connection length of approx. 5 m; almost 185 km of the sewage system is accounted for by vitrified clay pipes.
Planegg renews 370 m of sewage pipes and 28 connections
In the Planegg township with its some 11,000 inhabitants, the next stage of the project was to regenerate the wastewater pipes and the house connections in the Bahnhofstrasse. “Rehabilitation by regeneration” was the approach chosen by the Würmtal Water Board as the client and operator, not least for reasons of economy: regeneration guarantees a substantially longer service life than simply rehabilitation, and the excavation of the pipeline system also enabled other technical installations to be done at the same time. The planning took four years, and the final planning of the installations started in the autumn of 2013. Over a period of 5½ months, the Wadle Bauunternehmung GmbH company installed about 370 m of vitrified clay pipes in the DN 250 and DN 300 diameters in the Bahnhofstrasse construction site. To keep the construction time as short as possible, at the same time the house connections were renewed, in most cases using the bursting method. The construction activities were designed not to interfere with the local traffic, since the Bahnhofstrasse is the main shopping street in Planegg.
Gräfelfing follows Planegg’s lead
The situation in the neighbouring township of Gräfelfing with its 13,000 inhabitants is similar to the one in Planegg: Gräfelfing is also part of the Würmtal community whose sewage disposal is taken care of by the Würmtal Water Board; here too, the wastewater system was in need of renewal, and in three streets all at once. “Rehabilitation by regeneration” was the call of the day here, too, also taking advantage of the new construction approach to improve the hydraulic efficiency by enlarging the cross-section of the pipe system. Although the project was planned in 2011/2012, due to overlaps with other construction measures and the re-routing of the road traffic that these measures involved, the start had to be delayed until 2014.Over a period of 3½ months, the Richard Schulz Tiefbau GmbH & Co. KG company installed about 370 m of vitrified clay pipes in diameters of DN 200 to DN 400 in the Pasinger Strasse, the Immelmannstrasse, and the Drosselgasse. Here, too, the work was carried out without interfering with the road traffic – a specially challenging situation, since as a feeder road for the highway and a designated diversion route for highway traffic the Pasinger Strasse has a very high traffic volume. The passage of the pipeline beneath the nearby Würm river made it necessary to install the pipes at a depth of as much as 5 meters.
Conserving the value for both townships
The “rehabilitation by regeneration” approach is a wise decision in both cases: on the one hand it is a farsighted option with a long-term impact, and on the other hand, it goes a long way to preserving the assets of the water board: unlike a typical rehabilitation project, regeneration is not just for an indefinite period of time, but instead an approach that benefits this and many other generations to come – after all, everything is new!
Planegg Client and planning: Würmtal-Zweckverband, Planegg | Construction: Wadle Bauunternehmung GmbH, Altheim/Landshut | Construction-materials supplier: BayWa AG, Straubing
Gräfelfing Client and planning: Würmtal-Zweckverband, Planegg | Construction: Richard Schulz Tiefbau GmbH & Co. KG, Neuburg a. d. Donau | Construction-materials supplier: BayWa AG, Augsburg