Joint solution for rain water management

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Optimally equipped for present and future requirements

In recent years, progressing urbanization – that is, the use of river-adjacent flood zones as residential areas or the sealing of city surfaces – has combined with climate change and repeatedly resulted in significant flood damage. Furthermore, sewers and wastewater treatment plants are not designed for such natural events, nor can they be usefully designed to handle them. Erecting rain drainage structures offers a remedy.

In light of this, ordinances have been in effect in Germany for some time that mandate rainwater retention measures in situations such as constructing a housing development. This can unburden sewers, drainage channels and wastewater treatment plants. As experts in the field, Krohne Messtechnik, Phoenix Contact, VAG Armaturen, Videc and Wilo took up the issue and worked together on a solution for regulating and monitoring rain basins. Rain basins, which offer temporary storage for rainwater in sewerage systems, can control inflow to the wastewater treatment plant or the drainage channel. There are the following types of rain basins:

  • Rain retention basins for mixed and separate systems
  • Rain overflow basins for combined systems
  • Rainwater treatment basins for separate systems

New legal framework conditions and structural changes for operators increasingly require automation and uninterruptible monitoring of structures.

Model of the joint solution for regulating and monitoring rain basins (image source: Krohne Messtechnik)

Continuous monitoring of the drainage volume

During heavy rainfall, excess water from the sewerage system, for example, is temporarily stored in a rainwater basin. Regulating the flow of rainwater to the wastewater treatment plant or drainage channel protects these structures from possible overload and protects the surrounding area from flooding. As soon as the rain ceases, the drainage process for the rain basin begins. Here, the default value – the maximum inflow volume to the wastewater treatment plant or drainage channel – is compared with the flow measurement in the intake channel of these systems, normally designed as a gravity drainage line. This comparison yields the controlled variable for the control valve of the rain basin drainage control system.

Furthermore, the level measurement installed in the rain basin and the flow measurement ensure uninterrupted monitoring of the drainage volume and consequently the load of the basin. An optional conductibility measurement ensures that the state and load of the rain water can be monitored. This allows future analytical measurement requirements to be implemented today.

Simple handling of automation technology

Storage rain gauge on the Wupper (image source: Krohne Messtechnik)

The controlled variable for the rain basin drainage process is controlled and calculated using the installed automation technology. It also connects the measuring equipment to the control room via standardized remote control protocols. The modularity, availability and simple handling of the automation technology play an increasingly significant role in this process. In order to address the issue of user-friendliness, the partners created their solution according to the principle “configuring instead of programming” and implemented it based on the automation library Waterworx from Phoenix Contact, specially developed for water management.

Monitoring important characteristic values – such as the frequency of use of the basin, the drainage volumes and other variables – is also of great significance. As part of the joint solution, the data is stored temporarily in the controller. If the connection to the control room should fail, the PLC transmits the values in the proper sequence after reestablishing communication with the logging system of the wastewater treatment plant, such as Acron from Videc. For monitoring on-site in the structure or via a mobile end device, the solution can be operated using a panel PC on which the HMI/Scada software Atvise is running. Often, mobile technology is used to exchange data since very few operators have routed data cables to the rain basin. To protect the data from unauthorized access and fulfill IT security needs, the solution utilizes an FL Mguard mobile network modem with integrated hardware firewall from Phoenix Contact. This ensures that only authorized personnel can change control parameters remotely and immediately acknowledge reported errors.

High availability of the systems and data

Steel pipe cleaner from Wilo for cleaning the rain basin (image source: Krohne Messtechnik)

The solution also includes an uninterruptible power supply from the Quint UPS-IQ product range as the automation and measuring technology. It ensures high availability of the system and the data. Thanks to IQ technology, the user can see how long the battery will function without error, for instance, even remotely. On-site inspection of the status of the battery cells is no longer necessary as a result, which saves time and money. In the last step of the drainage process, a steel pipe cleaner from Wilo cleans the rain basin. The device functions with a freely adjustable height to prevent contamination and residue in the rain basin .

Consequently, the partners’ joint solution contributes to long-term management of the sewerage system and active protection of waterways. Moreover, the structure is optimally equipped for future technological developments. For example, a central rainwater management system may be designated that implements precautions based on weather data to ensure that there is sufficient capacity in the rain basin if required.

  • Thomas Geiz, Water and Wastewater Treatment Senior Specialist in Industry Management Infrastructure, Phoenix Contact Electronics GmbH, Bad Pyrmont, Germany

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