| Non-invasive evaluation of contaminated land
The rehabilitation of brownfields – contaminated land and waste disposal sites – is a key issue for sustainable development. However, the process is costly, and the extent of the decontamination task is often not immediately apparent. Therefore, there is an urgent need for non-intrusive methods of evaluating land prior to urban regeneration. The HYGEIA project addresses this problem, explains coordinator Professor Michele Pipan, through "the development and testing of high-resolution non-invasive technology for subsurface characterisation of contaminated land, based on an integrated geophysical approach".
"Industrial and military decommissioning activities, waste disposal practice and accidental spills have left a legacy of derelict sites," notes Prof. Pipan. "Diffusion of contaminants in the subsurface from such sites poses a severe threat to groundwater aquifers." The approach taken by HYGEIA identifies pollution sources and the links between brownfields and groundwater resources. Dedicated non-invasive methods are important because boreholes cannot provide accurate and cost-effective information, and increase the risk of contamination.
The HYGEIA project is entirely supported by the EU's Fifth Framework Programme (FP5): Energy, Environment and Sustainable Development (Key Action 4). The project consortium consists of two categories of partners: end-users and scientific partners. End-users have experience of the technical problems encountered in site remediation, and benefit from new strategies to tackle the characterisation phase before remediation, which reduces costs and improves safety. The scientific partners have expertise in different geophysical sectors and benefit from the integration of this expertise with that of other scientific partners.
The biggest challenges faced by the consortium have been "the extreme variability of subsurface conditions, which hamper the development of standard techniques, the elusive nature of the target, and the cost constraints that the proposed technology has to satisfy", explains Prof. Pipan. The variability of the target sites means that geophysical prospecting techniques have to be pushed to their resolution limits to obtain the information of interest for remediation purposes.
"Geophysical methods have a tremendous potential for the 3-D evaluation of contaminated ground," claims Prof. Pipan, "but most of the studies performed to date focus on the application of individual techniques." The available geophysical techniques include Ground Penetrating Radar (GPR), High Resolution Seismic Reflection (HRS), Electrical Resistivity (ER) and Electromagnetic Methods (EM). The project partners have developed novel procedures based on combinations of these, to suit particular types of target site.
Among the technical innovations, HYGEIA has developed a high-precision positioning system for GPR surveys, which is necessary for high-resolution 3-D data acquisition, and innovative GPR low-frequency antennas. Seismic sources and sensor deployment devices have also been produced. The hardware being used is cost-effective, portable and transferable between different environments.
The development of innovative software enables geophysical data to be processed and modelled in a form suitable for the analysis of subsurface characteristics and for 3-D visualization. The filtering out of noise, for instance, is crucial in obtaining high-quality data.
The consortium has developed databases of physical and geochemical properties of sample brownfields and contaminated sites, which include pollutants. The resulting information source has facilitated a system of classification for brownfields and contaminated sites, of interest to both end-users and the research community.
Supporting remediation decisions
Guidelines and a Decision Support System (DSS), developed by the consortium, enable end-users to choose an optimal combination of geophysical techniques to evaluate a particular site, and facilitate the effective planning of rehabilitation actions. One outcome of using the DSS might be that no geophysical techniques are considered appropriate, therefore saving costs on unnecessary surveys.
Prof. Pipan regards the main achievements of the project to be "dedicated hardware to tackle the characterisation problem, innovative software that includes processing and modelling algorithms, guidelines and automated decision support system, and databases of physical properties and geophysical data of interest to end-users and the research community".
The successful outcome of the HYGEIA project will minimise costs and reduce the risks of urban regeneration by supplying improved knowledge of subsurface conditions. And it will safeguard the environment by assessing pollution-prone sites and monitoring them by non-invasive means. Finally, it will protect natural resources such as groundwater. More accurate budget estimates of clean-up costs will serve to encourage private investment on brownfields. Another outcome of the project is the development of new technologies and skills, bringing commercial opportunities and the creation of new jobs. The supply of geophysical and environmental services is particularly suited to small and medium-sized enterprises. For example, "a spin-off company is about to be launched by the University of Trieste, which will bring part of the new technology to the market ", notes Prof. Pipan.
"The results of the project will change paradigms in contaminated site management and will have a considerable impact on strategies and expenditure," he concludes. "The solutions that have been implemented fill an important gap in present technologies for the environment."