A chemical company wanted to develop a former site in western Germany for commercial and residential use. Although the plant had ceased operation in the 1990s, it had a long working history and residual soil contamination persisted, which poses a risk to humans. The company was prepared for multimillion-euro active remediation. However, before work began, it learned of a much more cost-effective alternative from RSK Alenco: monitored natural attenuation (MNA).
RSK Alenco applied its alternative remediation programme to the site demonstrating to the regulator that the groundwater contamination was being naturally attenuated and active measures such as cost-intensive pump-and-treat systems were not necessary. To do this, the RSK Alenco team developed a detailed, risk-based MNA concept. The contaminants and hydrogeological conditions were investigated, and a network of 19 boreholes monitored the groundwater contamination levels, but low-flow rates prevented the use of standard groundwater sampling methods. To overcome this, the team persuaded the regulator to allow low-flow sampling using specialist micropurge equipment with bladder pumps.
The results demonstrated that the contaminant plume was not spreading and natural attenuation was controlling it. The regulator agreed to the MNA concept, thereby avoiding the costly active remediation. More than 15 years of monitoring has confirmed the initial assessment that the contaminated soil is better contained and poses no risk to residents’ health.
RSK’s tailor-made solution was the correct approach for the client, and it saved the client substantial costs. By persuading the regulator to allow MNA to continue, the chemical company avoided remediation measures that otherwise would have cost tens of millions of euros.