INCOME - Improved management of contaminated urban aquifers by integration of source tracking, monitoring tools and decision strategies , TP A.4.2 Direct push techniques and source identification procedures (EU)

The EU has a long history of environmental pollution linked to industrial development and economic growth of member states, with over 300 000 potentially contaminated sites identified in Western Europe. The number of contaminated sites is probably considerably larger if Eastern European sites are also considered. A result of this ongoing development is an increased pressure on available resources, particularly a contamination of groundwater. Many countries in Europe rely heavily on groundwater for drinking water and irrigation water supply purposes. Identifying, monitoring and reducing the environmental impact of human activities on groundwater resources and ensuring long-term supplies to meet the development needs of the EU is therefore a major problem and fundamental task. Throughout Europe and worldwide numerous technical tools, guidelines and directives are available with respect to subsurface investigation as well as identification, monitoring and remediation of groundwater contaminants. However, new investigation, risk-based monitoring, remediation and administrative tools as well as combination of tools are still strongly needed for urban aquifers with challenging conditions such as missing alternative water sources, very high transport velocities, mighty thickness, high hydraulic conductivity and heterogeneity, multiple contaminant sources and plumes which are difficult to be detected due to their geometry etc. Under such conditions the contaminant concentrations are highly variable in time (in the order of months), and the required time for administrative response, decisions and measures in case of groundwater contamination is very short. Therefore, the project was aiming at providing a cost-efficient innovative set of tools to optimize subsurface investigation, evaluation, monitoring, protection and management of contaminated groundwater in urban areas with complex aquifer and contamination conditions. Innovation of current scientific, technical, economic, and administrative methodologies was tackled. The achievements of the project are beneficial to other parties, which are not participating, but which are facing similar problems of urban groundwater pollution.

In subtask A.4.2, applying numerical backtracking procedures and inverse modelling methods, a delineation of potential contamination source zones had to be achieved. Backtracking procedures and algorithms had to be further developed to include reactive transport modeling and mass flow rates and contaminant distributions measured at control planes as boundary conditions. Direct-push based monitoring fences can provide possibilities to obtain these boundary conditions with a high resolution. After backtracking and contaminant source zone delimiting, direct-push based measurements at the predicted source zone locations, contaminant fingerprinting and innovative methods based on passive sampling, the estimation of isotope composition and fractionation can then further increase the accuracy of the source zone and polluter identification. Here, consultancy had to be provided with respect to monitoring strategies and numerical model based positioning of the direct-push boreholes, probes and monitoring wells, as well as with model based backtracking and contaminant source zone delimiting.