Seeing the invisible in 3D to rebuild the future

In Wallonia, SPAQUE relies on Esri solutions to clean up soils, rehabilitate brownfield sites, and support their redevelopment. An integrated GIS strategy that aims for precision and optimizes costs.

Founded in 1991, the Société Publique d’Aide à la Qualité de l’Environnement (SPAQUE) has a mission as noble as it is unique in Belgium: it cleans up polluted soils from brownfield sites and landfills in Wallonia. “In the beginning, it was about identifying and treating emblematic sites that posed serious environmental and health issues, such as the landfills of Mellery and Anton,” recalls Annick Jaspar-Herbillon, geomatics specialist at the Support Functions Department. These two sites, decontaminated in the 1990s, had caused great concern for public health and marked the start of the company.

Since then, the roadmap has expanded. To the landfills were added the rehabilitation of complex industrial sites and the development of renewable energies. Some capped landfills now host photovoltaic plants: three are in operation, two are in progress, and three additional units are running on post-management sites. Moreover, the selection of sites is no longer based solely on environmental criteria, but also on economic redevelopment. “Some are selected because they are strategically located for future investors, with multimodal accessibility,” explains Thomas Christophe, also a geomatics specialist at SPAQUE.

Funded by the Walloon Region, the Liège-based company employs around 85 staff. Since 2000, nearly 165 sites, covering more than 1,000 hectares, have been returned to the Walloon economy. “What makes SPAQUE unique is that we intervene on land that no one wants, often bought for the symbolic euro, because they are too polluted or have no identified owner,” notes Annick Jaspar-Herbillon.

Each project follows a genuine intervention chain in which GIS plays a key role. It all begins with archival work: compiling old maps and industrial records, identifying potential sources of pollution (SPP). This is followed by designing a sampling plan and collecting field data. The pollution is then mapped—first in 2D, and now in 3D. Once the contaminated areas are precisely identified, excavation can be planned in a 5 by 5 meter grid, until a final assessment confirms that all accessible contamination has been treated.

Present since the late 1990s, GIS gained traction at SPAQUE with the arrival of Annick Jaspar-Herbillon in 1999, followed by Thomas Christophe 13 years ago. “At first, I worked alone,” recalls the geomatics specialist. “With two of us, we were able to set up an internal geoportal and give visibility to GIS among all colleagues.” This openness marked a turning point: GIS gradually moved from a specialized tool to an essential component of the global information system, recognized within the IT service (PIC). “This prevents us from being seen as an isolated discipline. GIS is integrated into SPAQUE’s digital strategy,” emphasizes Thomas Christophe.

As for the choice of Esri solutions, it came naturally. “I used their tools from the start of my studies at the University of Liège,” says Annick. “In the late 1990s, there were almost no alternatives.” Today, SPAQUE has a full range: two Advanced licenses of ArcGIS Pro and seven Standard licenses, ArcGIS Enterprise, Geodatabase Enterprise, and extensive use of Field Maps and Experience Builder. “We have evolved according to our needs, and we are not blocked: we have virtually the full panel we require,” adds Thomas Christophe.

The operation of GIS relies on a central link: WalSols, an internally developed SQL database. “All staff encode their technical and environmental data there: drillings, samples, analyses, site inventories… Designed with the help of an IT specialist, WalSols has a web interface that constantly interacts with ArcGIS. “Data circulates in both directions,” confirms Thomas Christophe. “We can visualize WalSols data in GIS, but also integrate it into the web application.” This integration strengthens the reliability and continuity of information and also serves as an archive. “Each project leaves behind a usable record for future works. GIS allows us to go back, compare interventions, and build on accumulated experience.”

Five years ago, SPAQUE took the step into 3D. “Until then, many interpretations of pollution were made in 2D. 3D brings the notion of depth and allows us to precisely delineate polluted areas before excavation,” explains Annick Jaspar-Herbillon. On her screen, the geomatics specialist shows the grid of a former glassworks in La Louvière: 5 by 5 meter squares colored dark green or red. “In red, the analysis concluded there is a pollution problem. We must continue remediation there before carrying out further analyses. In green, it means the area is clean or our work is complete.” The 5x5 dimension is no coincidence—it corresponds to the space needed for a machine to go underground.

Thomas Christophe stresses the importance of this approach: “The more precisely we locate the pollution, the less unnecessary soil we move. And every excavation is expensive. The goal is to achieve the best possible simulation, forecast costs, and build an archive useful for future projects.” This use of 3D in this domain is still unique in Belgium. Visualization and sharing of 3D data also facilitate communication with engineers, decision-makers, and partners. “3D makes the invisible visible. It is a mediation tool that makes it possible to show concretely where the pollution is and what we are doing to fix it.” Finally, the representations are integrated into ArcGIS dashboards to ensure global monitoring.

The connection between field and office is ensured by Field Maps. There are two main uses. First, the solution is used for visualization in managing piezometric wells for water sampling. Teams can thus more easily locate and check these wells, monitor their condition, and ensure maintenance. More recently, Field Maps has been used for data collection on specific issues, such as detecting invasive plants like Japanese knotweed. “Agents draw a polygon around the area, take a photo, and everything is automatically mapped and integrated into the database,” illustrates Thomas Christophe.

For surveys requiring centimeter accuracy (XY coordinates and Z altitudes), SPAQUE calls on external surveyors. “We must use public procurement, which imposes a strict framework and renewable three-year contracts. We ensure that the delivered formats, often Excel files, are compatible with our GIS,” says Annick Jaspar-Herbillon. As a public company, SPAQUE operates within a constrained regulatory framework. The Walloon specification of best practices requires regular updates, once or twice a year. Concretely, a modification can lead to the relocation of dozens of drillings or an increase in the number of samples to be collected.” These precise data are then fed into WalSols and cross-referenced with ArcGIS information.

Beyond the technical aspects, the two geomatics specialists have also carried out significant internal awareness work. “We had to show our colleagues that GIS is not reserved for geomatics specialists, but that it can help them in their daily work,” continues Jaspar-Herbillon. Thanks to the geoportal and the web applications developed with Experience Builder, each employee can access maps, track project progress, and interact with the data. This internal diffusion is also built over time. “For nearly twenty years we have regularly participated in Esri Days. These events allow us to stay in touch with developments but also to convince colleagues internally of the value of new features,” the geomatics specialists explain.

SPAQUE is now looking to the future. The geomatics team plans to enhance these 3D approaches towards true digital twins of the subsurface, integrating socio-economic data and redevelopment scenarios. Other avenues are being explored in collaboration with Esri Belux: augmented reality to visualize networks and pollution on site, immersive technologies to better communicate with partners, and even real-time simulations. “We want GIS to remain a transversal tool, at the heart of decontamination and rehabilitation projects, but also of economic recovery,” concludes Annick Jaspar-Herbillon.