We have ascertained groundwater contamination from hexavalent chromium around the former Sabena Technics building. The chromium leaked into the soil during the galvanizing of aircraft parts. To convert the toxic chromium into a solid form, we placed a grid of 71 injection filters filled with a chemical composition on the site. By converting hexavalent chromium into trivalent chromium, the pollutant could no longer spread underground.
However, after 18 months, we found that the injected reagent had not worked adequately. So, during the 2018 Spring and Easter holidays, we launched a new pilot test with an adjusted dosage. If the project is successful, we will apply this method to the entire area.
In 2017, Cecoforma won a public tender to operate two mobile petrol stations airside.
At the end of each contract, a soil audit is carried out. When soil contamination is found, it must be remediated by the party that caused it − and a new soil audit is conducted. That second test released a definite fuel smell. About 30 m3 of soil contains mineral oil and elevated concentrations of ethylbenzene and xylene to a depth of 1.5 metres. The decontamination will be performed along with the infrastructure works in this area. We’re also taking preventive measures to protect the soil more effectively in the future.
On the grounds around building 212, there is historical contamination that includes mineral oil in the soil and in the groundwater. In 2016, the core of the contamination was completely excavated; and for the treatment of the remaining pollution, we started a pilot project based on biodegradation. However, this method proved insufficient in breaking down chlorinated hydrocarbons.
So, a second pilot test, based on chemical oxidation, was conducted and was indeed successful: the concentrations of the pollutants decreased significantly. Brussels Airport has now decided to employ this technique to decontaminate the remaining pollution.
How does chemical oxidation work?
The undeveloped site next to apron 9 will soon be used as an area for ground handling equipment. During the preparation of the site, we dug up a former dumping ground. The waste consists of lime sludge, mixed with residual hazardous waste. The lime sludge is probably a by-product of the chemical plant that stood in this area in the 1960s.
The works were immediately stopped to identify the contamination. As soon as the soil audit has been completed and we find a proper way to remove the waste, we’ll resume the works. Because the pollution extends beyond the current project zone, we’re also starting a new soil remediation project. The waste will be disposed of at an Indaver landfill.