In May 2013, a train accident in Wetteren (Belgium) led to toxic water in the sewer system next to the track. 2000 people had to vacate their houses for several days due to toxic fumes in the sewer. Furthermore, high levels of of acrylonitrile were also found in the soil and groundwater. There was, unfortunately, one fatality. To ensure this doesn’t happen again, Flanders Environment Agency (VMM) decided to create an online web map, tracing toxic wastewater in the sewage system to avoid it flowing into open water.
How it works
Sewers and watercourses are combined to prevent flooding when heavy rainfall means the sewage system is overflowing. This water is normally rather clean and could safely flow into recreational water but, naturally, this has to be avoided in the case of toxic wastewater!
With the web app tracing the wastewater, if any overflow containing polluted wastewater is detected, the sewers can be closed immediately. The overflow is then directly guided to a wastewater treatment plant. Thus, potential environmental damage or health issues are prevented.
Use of different datasets
To set up the web app, VMM uses hydrography data from all surface waters like creeks and larger rivers, data from the sewer system, and an algorithm for up- and downstream tracing (going back to the source of the water and all the way to its end point). The algorithm is compatible with European INSPIRE standards for network data (INSPIRE Generic Network Model). The algorithm will also be tested in Delfland (the Netherlands) and it can be expanded to other countries. Public authorities in the Czech Republic and Portugal have already expressed an interest in the algorithm.
Besides avoiding environmental damage and health issues, this pioneering compilation of information will help first aid responders and authorities to get an overview of a precarious situation. Rather less urgently, the algorithm will also help sewer managers to better understand their part in a larger sewer network , allowing them to see the bigger picture and their potential impact on neighbouring networks.
The algorithm can also help with the planning and renovation of the sewer infrastructure. Namely, the app traces the amount of water passing through the sewer network and indicate the complete existing infrastructure. Based on this information the network can be maintained and expanded.
Pilot of the BE-GOOD project
The development of the wastewater tracing system is one of the European project BE-GOOD’s 11 pilots. BE-GOOD is a pioneering project aiming to unlock, re-use and extract value from Public Sector Information (PSI) to develop data-driven services in the area of infrastructure and environment. By making the wastewater tracing algorithm open source, it can easily be used and adapted by others. The use of the INSPIRE standard in the tracing algorithm makes it especially suitable for the European context.
The capitalisation: the sediment tracer (new economic sector)
The tracing algorithm has been integrated in the sediment explorer to trace sediment and their loads through the sewer system. The sediment tracing solution is implemented as part of the Sediment Explorer which is hosted by DOV, a collaboration within the Flemish Government to gather, distribute and communicate data on the (sub)soil of Flanders.
The Sediment Explorer brings together all relevant data layers and functionalities related to sediment use cases. Furthermore, some data layers and functionalities are available for certain users or organizations only. As the Sediment Explorer has a growing number of users, this tracing functionality will become available for more and more users and organizations with different core activities: agriculture (erosion), pollution in water courses or soil, waste water, dredging, etc.
The sediment tracing allows to trace up- or downstream on water courses and the sewer system from multiple starting points. Buffers around the tracing route and overlapping catchment areas can be added to the output of the tracing and assist in analyses for specific use cases. Once calculated, the tracing network can be consulted directly on the map in the Sediment Explorer. Adding additional data layers to the map, e.g. erosion maps, water levels,... allows for an integrated view in the analyses. The tracing network can be used as search area for the other data layers.
For each tracing analysis, the expected total amounts of numerous parameters like sediment load, phosphorus, lead, etc. will be calculated. This information can be consulted in an online tracing sheet. The tracing sheet includes the departure point(s), settings (up- or downstream, weather conditions, buffer, etc), the traced network visible on a map and a table with calculated parameters within the traced network. The parameter table is interactive and allows to visualise different sectors (e.g. households, industries,...) and filtering to narrow down on more detailed areas, e.g. catchment areas. For more advanced geospatial analyses, the outcoming tracing geometries can be downloaded.
The sediment tracing will be introduced in operational processes within VMM, the Department of Environment and Spatial Development and within the agricultural sector.
Want to know more?
Partner: Flanders Environment Agency
Contact: Katleen Miserez