Even if there are no visible electrical installation works on the construction site of Pumping Station Oberhausen yet, the electrotechnical equipment ist making bis steps forward. At the factory acceptance test in Finland, two out of the 10 frequency converters of the "small" and "large" sewage pumps were successfully tested and approved by the manufacturer as the first components of the powerful drivelines. These are frequency converters with a nominal voltage of 690 V and a rated current of 1.180 A, respectively 1.700 A, which corresponds to a rated output of 900, respectively 1.250 kW. The high demand on the network repercussions with limit specifications to the harmonic, inter-harmonic and, for the first time, also to the supra-harmonic currents, required the frequency converters to install active line filters and correspondingly large-sized line reactors. These are, like the actual power electronics of the frequency converter, cooled by water. Each frequency converter consists of 5 control cabinets, with each frequency converter being approx. 3 m wide. Helmut Mangelmann heads the Electrical Engineering Department at DAHLEM and works in the team of the design consortium (Planungs-ARGE) of Pumping Station Oberhausen: "We have planned and built quite a lot in the field of electrical engineering, but these dimensions go far beyond the previous performance levels. In the low voltage sector, they are at the limits of what is technically possible in terms of circuit and transmission technology."
On October 12th, 2022, the Prime Minister of Kosovo, Albin Kurti, officially inaugurated the new fully biological wastewater treatment plant of the municipality of Peja. The wastewater treatment plant was handed over on time and on budget by DAHLEM on a turnkey basis and has already been in operation for one year. The plant is operated by the regional water and wastewater company Hidrodrini. Together with the German and Swiss ambassadors as well as the mayor of Peja and many other guests, the completion of the wastewater treatment plant was celebrated. The entire project was financed mainly by KfW, in cooperation with Kosovo. Likewise, the Swiss State Secretariat SECO and the municipality made substantial contributions to the 23 million euro investment costs, which include not only the treatment plant but also an extension of the sewerage network. WWTP Peja offers a strong contribution to the environmental protection and health care for south-western Kosovo.
You can read more about the Peja sewage treatment plant in the article below.
The KEYS research project, which began in 2017 under the leadership of ISAH Hannover, with the participation of DAHLEM and in cooperation with TSINGHUA University Beijing, has now been brought to a conclusion. Various German-Chinese cooperation projects for sustainable water management were developed for the national "Sponge City Concept" in China. In the period 2018-2020, DAHLEM collaborated on two sub-projects in the greater Beijing area, focusing on an implementation-oriented approach of sponge city concepts. Together with the ISAH and the Berlin Water Competence Centre in Germany, project experiences were transposed into an element catalogue showing needs-based solutions of the sponge city concept for the local metropolitan area. For China, the implementation of the sponge city approach is an important and recognised step to make cities fit for the future. Sponge City elements as a combinatorial overall concept help to mitigate urban heat island effects and flash floods, improve groundwater recharge and quality as well as the structural diversity of urban spaces. They basically follow the natural model and impress with their simplicity and efficiency.
Download the brochure ”KEYS–Demonstrations for a smart Sponge City”
It has been completed: The new construction of the Mörscher Wald waterworks, for which the ground-breaking ceremony took place in November 2018. Commissioning is currently underway and the official inauguration will take place in July 2022. The new waterworks is equipped with state-of-the-art technology and now replaces the 70-year-old plant in the immediate vicinity on a directly adjacent plot of land. After commissioning of the new plant, the existing one will be completely dismantled. For species protection reasons, demolition will not take place until September 2022 and the area will be reforested. In future, the new waterworks will ensure the vital supply of potable water for the city of Karlsruhe and the surrounding communities. Calculations of the potable water demand until 2040 showed that, due to climate change and the predicted population growth, a capacity of 60,000 m³/d or 3,000 m³/h will have to be maintained in the future as the maximum capacity for raw water extraction and treatment. The architectural design of the building provides for a harmonious integration into the greenery. As a partner in a consortium, DAHLEM has been commissioned with the planning of the civil engineering works, the building interiors and the outdoor facilities. A BIM-oriented 3D model was created for the building design.
Heavy rainfall events have caused considerable damage throughout Germany in recent years. Municipal decision-makers see themselves more and more obliged to assess the flood risks and derive precautionary concepts in the short term. The flow path analyses used so far for large-scale rough analyses have methodological limitations. Our colleague, Dipl.-Ing. Tim Schneider from Darmstadt, developed on a freelance basis "SplashTool" - software that no longer has many of these limitations. SplashTool was used for the first time for a volume-based flow path analysis and rough analysis over an area of 200 km² for the city of Kaiserslautern and is now used as a tool in numerous projects for heavy rainfall risk management.
Figure l.: Map generated with the help of SplashTool
Further information on SplashTool:
Heavy rainfall hazard maps of the city of Kaiserslautern:
Article in the trade journal wwt Water Management Water Technology dfv.de,
March 2022 issue, p.36 - 39
As part of the Emscher Conversion generation project, the Emschergenossenschaft redesigned also the Katernberger Bach stream, which, for the most of part, has been flowing through the Katernberg district of Essen since the 1960s. Along a stretch of 1,100 metres, the stream was given new space next to the old watercourse route and is now running open along 1.2 kilometres. The opening of the stream and the separation of clean and wastewater as well as the renaturation of obstructed drainage profiles enable an ecological improvement of the watercourse. In addition to the river engineering plans, bed slides, fords and a bridge as well as several culvert structures have been implemented. Accompanying measures along the ecologically revitalized watercourse enhance the green corridor and create a high recreational quality for the Katernberg district. The Emschergenossenschaft commissioned DAHLEM with the project planning, structural design, technical equipment and construction management for the watercourse conversion.
The illustration shows a visualisation of an accompanying measure:
Waterside playground (Hoff Landscape Architects, Essen).
The construction work is complete, wastewater is being delivered via the upgraded sewer systems and treatment has begun. A new, central, fully biological wastewater treatment plant now receives and processes the sewage from the western Kosovan city of Peja. The contractual acceptance date was 1st February 2022 and the local water supplier has now taken over responsibility for operation and maintenance. Planning for the new plant with an initial treatment capacity of 81,000 population equivalents began in February 2018 and WWTP Peja is now one of the first of its kind being operated in Kosovo. The new facility will make a huge contribution to improvements in the quality and the sustainability of both precious local water resources and the living conditions of the Project area’s residents, as well as many of those living downstream. In addition to the treatment, an anaerobic-mesophilic digester stabilises the sewage sludge and CHP units (converting the gases produced to heat and electricity) satisfy much of the plant’s power demand. In the urban areas of Kosovo, sewage systems for wastewater collection are very often available but the country lacks municipal and industrial sewage treatment plants. This means the direct discharge of untreated waste to the environment is widespread, a problem now overcome in Peja. The extensive sewage collection and treatment measures implemented as part of this Project were financed by KfW, SECO, local funds from the municipality and the government of the Republic of Kosovo itself. The total costs for the design and construction of around 8 kilometres of new sewage collection and conveyance systems, stormwater overflows and the wastewater treatment plant amounted to around € 23 million. HIDRODINI engaged DAHLEM to provide the planning, tendering and procurement and construction supervision services for both the sewage treatment plant and the additional sewers.
Additional ward buildings are to be impplemented on the Clinic for Trauma Surgery hospital campus in Frankfurt by summer 2026, in line with the requirement to limit the discharge volume into the public combined sewer system. In the future, the existing drainage system on the campus will therefore discharge a large part of the rainwater separately and let it infiltrate on site. In order for a reduced discharge to take place, temporary intermediate storage of the resulting combined sewage is necessary on the Clinic grounds. A large part of the additional rainwater is fed into an infiltration ditch with a storage volume of around 1,000 m³. The modular design of this system has proven to be particularly advantageous as it guarantees rapid installation and the cubature can be flexibly adapted, especially with regard to the old tree population to be preserved and the ongoing clinic operations. The Clinic commissioned DAHLEM with the restructuring and renovation of the drainage system at the property. Within the scope of the planning, DAHLEM will provide services related to the engineering structures - from preliminary design to construction, including the construction supervision on site. As a special service, a flood analysis is being carried out for the entire property.
Article in the specialist magazine B_I umweltbau:
Heavy rainfall and urban flash floods will pose major challenges to our society in the future. In cooperation with the environmental office of the City of Frankfurt a.M., DAHLEM developed heavy rain hazard maps, which were created as part of an overall concept for protection against heavy rain and are now available online in the geodata portal. Dipl.-Ing. Tim Schneider, employee of the Darmstadt office, managed the concept. He has been a DWA-certified specialist planner for heavy rainfall prevention since 2019 and has been working intensively at DAHLEM on the topics of heavy rainfall and urban flash floods since 2010. He sees protection against heavy rainfall as a joint municipal task and was particularly pleased about the publication: "The fact that the heavy rain hazard maps produced by DAHLEM are available online to all citizens is an important step in the context of climate change adaptation. The environmental agency has done a very good job with the publication of the maps. In addition to the main results of the analysis, plenty of further information on related topics is also available."
It was a historic moment when Pumping Station Oberhausen was commissioned on Friday, 20 August 2021, in the presence of the North Rhine-Westphalian Prime Minister Armin Laschet. For it is only with the start-up of the enormous pumps with a delivery rate of up to 16,000 l/s that the approx. 60 km long Emscher underground sewer (AKE) between Dortmund and Dinslaken also takes on its function of transporting wastewater. Previously, the Emscher served as the "cesspool of the Ruhr" for over 170 years and was long considered the dirtiest river in Germany. The project of the century to renaturalise the Emscher took many years and was completed on time. For the realisation of Pumping Station Oberhausen alone, more than ten years of planning and construction are behind the parties involved, in addition to, for example, Emschergenossenschaft‘s various planning offices, experts, construction companies and approval authorities. Emschergenossenschaft commissioned DAHLEM with the design of the almost 50-metre deep pumping station of Pumping Station Oberhausen, which also sets architectural standards in the part above ground. In addition to the design, DAHLEM, as part of a joint venture, was responsible also for the construction supervision of the complex process, control, energy and machine technology.
At Chausseestraße in Berlin-Mitte, the construction of an approximately 17,000 m3 underground stormwater overflow basin, designed by DAHLEM on behalf of Berliner Wasserbetriebe, has begun. The basin is intended to temporarily store stormwater during heavy rainfall in order to sustainably relieve the sewage system and the Spree River. It is part of Berlin's large-scale storage programme and "disappears" completely under the square on the banks of Süd-Panke. Apart from the operations building, which is architecturally adapted to the neighbouring wastewater pumping station, only a striking steel chimney rises 30 meters above the ground. If the basin is completely flooded within 30 minutes by heavy rain, the exhaust air escapes through this chimney high above the rooftops of Berlin. Currently, a circular diaphragm wall - double excavation pit, with a depth of around 30 m, is being built on the construction site in the immediate vicinity of the headquarters of the Federal Intelligence Service. The completion of the stormwater overflow basin, including the operations building, is scheduled for 2026.
Two new digesters, a post-thickener and a powerhouse went into operation at Wastewater Treatment Plant Mergelstetten in Heidenheim on 15 July 2021. Together with the City of Herbrechtingen and the municipalities of Gerstetten, Steinheim and Nattheim, the City of Heidenheim has invested six million euros in this project over the past two years. The sewage sludge from the municipalities involved will be treated in the wastewater treatment plant in Mergelstetten. The new technology will enable more digester gas to be extracted from sewage sludge in future, thus increasing the plant's own electricity and heat generation. The methane gas produced from the sludge digestion process is used in the two CHP units to generate thermal and electrical energy. The heat is used to heat the digesters and the operating buildings; the electricity flows into the treatment plant for its own use. The two digesters, each with a volume of 1,400 cubic metres, replace the previous sewage sludge treatment facilities, but can work in independent as well as combined operation. As a partner in a consortium, DAHLEM was commissioned with the planning of the engineering structures (Service Phases 1-4).
New technology for the environmentally friendly wastewater treatment is now to be installed: By the end of 2022, the Eifel-Rur Water Association is investing around 4,00 million Euros in the conversion of four secondary settling tanks at Wastewater Treatment Plant Aachen-Soers in order to effectively relieve the polluted water load. The ozonation plant has already been built and, as the largest in Europe, integrated into the existing wastewater treatment system. The wastewater treatment plant has been treating the wastewater of the city of Aachen since 1913 and is dimensioned for 458,300 population equivalents. By 2022, four secondary settling tanks will be upgraded step by step with new stainless steel central structures and height-adjustable inlet structures. The DN 700 return sludge pipes will be replaced by new stainless steel pipes. The optimization of the secondary clarification system is expected to increase the capacity by approx. 20%. A joint venture with DAHLEM as lead company has been commissioned with the project and specialist planning. The state of NRW is funding both the large-scale technical implementation and the accompanying research on the entire project of the wastewater treatment plant.