Specialist in sonic drilling supports search for Griftpark bacteria

The soil of Utrecht's Griftpark was polluted in the past by the Municipal Gas Plant at this location. The contaminated soil under the park was successfully isolated in the 1990s and a system was set up to clean the groundwater in this area over a period of one hundred years. Recent analyses show that a unique group of bacteria significantly accelerates the cleaning process. Reason to start extensive microbiological research into this Griftpark bacteria, for which Sialtech - specialist in sonic drilling - was called in.

The Municipal Gas Works was demolished in the 1960s. "In order to transform the area into a park, the contaminated soil was packed to a depth of 50 meters and the area around the park was remediated," knows Henk Nijmeijers, Managing Director at Sialtech. "Then a system was set up in which the contaminated groundwater was pumped up and purified. The design calculations from the 1990s showed that the groundwater remediation would take at least a hundred years. Now it appears that after just over twenty years, the desired result has already been achieved. This is most likely due to the Griftpark bacteria." 

110 meter depth

According to Nijmeijers, the group of bacteria was discovered by accident several years ago, as the groundwater became cleaner by itself. "It prompted the municipality of Utrecht to start a scientific study together with Utrecht University, Wageningen University & Research (WUR) and Deltares. The aim is to investigate how the conditions for biodegradation can be improved. To this end, we installed so-called multi-level samplers in the area adjacent to the park in the spring of 2021. Using the sonic drilling method, we managed to place the monitoring wells to a depth of 110 meters below ground level. A first for microbiological research, especially at this depth. In this way, the quality of the entire deep groundwater can be monitored, as well as the quality, structure, composition and properties of this deep soil layer. It is also being investigated whether the Griftpark bacteria could live in the deep subsoil. The scientific research will continue until at least January 1, 2023."

Independent

European drilling company "As Sialtech, we are of course proud to contribute to this complex and experimental project," Nijmeijers emphasizes. "Since February 23, 2021, we have also incorporated Geosonic France. We will function as one independent European drilling company within the ABO Group where we will be able to offer almost all common drilling operations and drilling methods. With ten sonic drills, we have a clear specialization in sonic drilling. In doing so, we perform work at various locations and for various research purposes from environmental and construction to exploration, nuclear, geotechnical and archaeology. At home and abroad. For example, in Sweden we are busy sonic drilling for the installation of inclinometers. These gauges are used to determine the lateral movement of the earth or the deformation of existing structures. For this work we are using 6-inch casing and 4.75-inch core barrel to a depth of about 50 meters in a geology consisting of alternating sand, boulders and solid rock."