3D scanning of subsoil should make it faster, cheaper and easier to clean up contaminated soil without the use of excavators.

This is the concept behind the innovation project Guided Injection Remediation (GIRem) that Ejlskov A/S, Aarhus University and Airborne Instruments ApS have joined forces to realise.

Subsoil scanning will ensure that biotechnological cleansers, such as bacteria and activated carbon, will be precisely injected into contaminated soils and enable real-time monitoring of the distribution of the agents in the subsoil. This will add a new standard to the advantageous in-situ method, where the contamination is broken down without having to move the soil.

Danish innovation fund Innovationsfonden, has invested DKK 17 million in the project.

In Denmark and in the rest of the world, authorities face major challenges in cleaning up contaminated sites as required by legislation. The remediation of toxic soil is incredibly costly, partly because in many places around the world, the contamination continues to be removed by excavating the soil and transporting it for treatment elsewhere. Remediation projects are postponed again and again, because the excavation may require that operations at the site are paused or installations must be removed, leading to enormous costs.

This means that biotechnological solutions that break down contamination directly in the soil (so-called in-situ remediation), without causing major disturbances to the daily operations at the site, have excellent potential.

In-situ remediation is typically done by injecting microorganisms and agents (e.g. bacteria and activated carbon) into the contaminated soil. Even though the method is often simpler and cheaper than excavation, in-situ remediation can be optimised even further. With current methods, soil and groundwater must be sampled several times after injection to ensure that the cleaning agents have penetrated throughout the contaminated area. And there may be a need to inject the soil once again. 

Management of both goals and agent

During a 3-year project, researchers from Aarhus University in collaboration with Ejlskov A/S and Airborne Instruments ApS, will make the in-situ method even more competitive. In a collaboration between research and commercial innovation, the participants will develop new geophysical tools that make it possible to measure how biological cleaning agents are distributed in the soil when using different injection techniques. The process is similar to when a doctor uses ultrasound to guide a needle when injecting an anaesthetic into a patient’s shoulder, only in this case, induced polarization (DCIP) is used to analyse the subsurface.

Researchers working at the HydroGeophysics Group (HGG), which is part of Arhus University’s Department of Geoscience, are world leaders in the development of geophysical instruments and the collection and visualization of geophysical data.

Ejlskov A/S already uses in-house developed 3D visualization software, which, using data from advanced drilling and measurement systems, can build a detailed illustration of the contamination in soil. Now, this software shall also be able to capture data directly, from the injection process to the treatment of the contamination. This requires developing and linking technologies and instruments that do not yet currently exist. And here the partners in the project complement each other well.

“The goal is to develop a tool that guides the injection of cleaning agents into the soil and enable us to observe it all on a real-time 3D model. This will mean we need less of the expensive cleaning products and are able to continuously monitor the distribution of injectate to ensure it is correctly distributed to break down the contamination. This will really provide the market with a highly sought after alternative to expensive and cumbersome excavation,” says CEO at Ejlskov A/S Palle Ejlskov.

“The technologies, tools and software packages for data handling that we are now developing will move the technology into a higher gear and make it more useful in soil cleanups. With the latest measuring instruments, algorithms and machine learning, we can form 3D images of the contaminated soil layers and their interactions to depths of 20 metres - and create better images of what happens when Ejlskov injects its remediation agents. And the technology shall then be operationalised so that it can be used in practical situations,“ says Professor Esben Auken of Aarhus University’s HydroGeophysics Group.