The 2nd trunk line represents a significant extension of the existing S-Bahn system and includes the construction of an additional tunnel section running about 7 kilometres under Munich's city centre. This tunnel runs parallel to the existing main line and creates an important connection between the main station and the Ostbahnhof. The aim of this project is to relieve the existing S-Bahn line and improve public transport in Munich.

The implementation of the project poses some unique challenges, including construction under existing long-distance lines, underground lines and in close proximity to important buildings such as Munich's main railway station and historic structures such as the Frauenkirche in the city centre.

To ensure that our project partners and everyone involved keep their feet dry during construction, we rely on extensive dewatering measures. These include around 6 km of penstocks, 170 groundwater drawdown wells and 18 infiltration wells, as well as around 150 control gauges in conjunction with a real-time monitoring system. In addition, we operate four plants with sedimentation basins for sediment separation and pH neutralisation for the purification of day-stratified and groundwater from the open dewatering wells. Since March 2019, we have been responsible for all the dewatering activities in this project.
Our task is to ensure the smooth running of the project while protecting the environment and existing infrastructures.

Hardly any other project will be as important and "the talk of the town" in Germany in 2022 as the construction of the LNG terminal from Wilhelmshaven to Etzel. Understandably so, because there is a lot at stake: Germany's first floating LNG terminal (LNG stands for Liquified Natural Gas), independence from Russian gas and around 30 kilometres of pipeline route. The Wilhelmshaven Link Pipeline, often simply called WAL, connects the floating terminal in Wilhelmshaven with the storage facilities in neighbouring Etzel.

Especially the short-term and time-limited construction of the terminals and connection lines poses great challenges for the client Open Grid Europe GmbH (OGE) as well as for politicians, authorities and participating companies. Right in the middle: Hölscher Wasserbau. For the so-called "Lot 2" with a length of 13km, we were commissioned to carry out the dewatering and environmental engineering. All in all, the 30 colleagues involved milled 11 kilometres of pipe trenches, drilled 500 wells with a depth between 8 and 12 m, laid 25 km of pipelines and realised about 60 open dewatering operations.

We are pleased that Hölscher Wasserbau was able to actively support the realisation of the new energy infrastructure and demonstrate its know-how.

Translated with www.DeepL.com/Translator (free version)

In the course of the construction activities for the large-scale Stuttgart S 21 project, groundwater is pumped, transported via a pipeline system to the treatment plants and purified there. To support the deeper-lying natural mineral water sources, a large part of the purified groundwater is infiltrated again near the construction pits. Excess groundwater is discharged into the Neckar River. The entire groundwater management system is continuously monitored and automatically controlled.

Over many years, the chemical PFOA (perfluoctanoic acid) has leaked into the groundwater through a nearby industrial park. Several tonnes of the harmful substance have entered the groundwater via the air and seepage water. In the Öttinger Forst area, drinking water for the surrounding communities and towns is drawn from the groundwater layers that have PFOA contamination. In this way, the chemical has also been absorbed by local residents and could even be detected in blood plasma. Hölscher Wasserbau was commissioned in October 2019 to set up appropriate drinking water treatment plants to restore drinking water quality in the region. PFOA must be filtered out of the water so that the drinking water can now be used again without concern.

The European gas connection pipeline EUGAL runs in two pipeline strings over a length of around 480 kilometres from the Baltic Sea through Mecklenburg-Western Pomerania and Brandenburg to the south of Saxony and from there across the border into the Czech Republic. Due to the different geological and topographical conditions, dewatering is a complex undertaking to prevent the trench walls from collapsing again.

Hölscher Wasserbau was commissioned with the dewatering and groundwater management for half of the extensive construction project. For this, work was carried out simultaneously on 3 construction sites with 6 drilling rigs and a total of 60 employees.

To lower the groundwater level, about 2,000 wells were drilled along the pipeline, some of which had to cope with a water volume of 60 bathtubs per hour. In addition, drainage was milled over 44,660 linear metres and 3,500 linear metres of vacuum filters were installed.

In the course of the construction of the Elzmündung retention area, the state of Baden-Wuerttemberg, represented by the Freiburg Regional Council, is planning the construction of wells and pressure drainage lines as well as electrical and control lines. The project is part of the Integrated Rhine Programme (IRP), aiming at the construction of the infrastructure for an extensive groundwater retention facility.

The large-scale FOUR project involves the construction of four new high-rise buildings with underground parking in the banking district in the middle of Frankfurt am Main. The skyscrapers are to reach a height of 100-228 metres and have a shared four-storey underground car park. The skyscrapers are to be converted into over 600 flats as well as the highest office floors in the country, a hotel and a day-care centre. The Construction will take place between Junghofstraße, Neue Schlesingergasse and Große Gallusstraße.

A new laboratory building for the Osnabrück University of Applied Sciences is to be built in Lingen. In the process, the contamination of the groundwater with cyanide was discovered. Hölscher was commissioned to prevent the cyanide contamination from spreading into the groundwater so that construction work on the campus could continue.

The Cityringen metro in Copenhagen is a 15.5 kilometre long, twin-tube tunnel system with 17 underground stations and an underground maintenance depot. The Cityringen line consists of two tunnels, each 5.78 metres in diameter. The tunnel tubes run at depths of up to 25 metres below the earth's surface, mainly through Copenhagen limestone. In addition to the TVM drives, 22 shafts with a depth of up to 30 metres were built.