Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Laboratory measurements and field measurements

Complete geophysical datasets in some brownfields and polluted sites, laboratory and controlled field measurements have been aimed to:
1) evaluate the time and performances of different geophysical methods
2) create database of physical, geochemical and sedimentological properties of samples from brownfields and contaminated sites and
3) improve the implementation of scaled realistic subsurface models to be used at the test tank facility and in the numerical simulation of geophysical response for data calibration and survey procedure improvement.

The selection of the test sites was performed in cooperation with the end-user partners in order to identify situations that are representative of classes of broad and urgent interest in the field of brownfield rehabilitation. Interaction between numerical simulation, laboratory and controlled field measurements were the core activity towards the development of effective procedures for the extraction of quantitative information from non-invasive records and the reconstruction of reliable subsurface models.

Sandbox tests were performed to provide datasets and subsurface models for development in the field of processing, modelling and inversion. The subsurface models implemented to date and exploited for data acquisition included PVC and metal pipes, fully or partially filled by different types of liquids (hydrocarbons, water, water contaminated by organic and inorganic compounds) fully or partially filled by different types of liquids (hydrocarbons, water, water contaminated by organic and inorganic compounds) and steel balls or clay blocks. Water was injected and drained by the bottom of the box to simulate a varying water table. Part of the experiments was performed with damaged pipes to simulate leakage conditions common in urban areas and industrial plants. GPR controlled datasets were acquired also in polarization mode, testing the performances for different offset and azimuth. Laboratory analyses (EM properties, radioactivity, chemical analysis, grain size and minerals) were done to implement the database of material properties. All the information were organised in a Database that represents the most complete data source available at the moment.

The Database of physical, geochemical and sedimentological properties started from present international bibliography on this argument, which represents the state of art. More than 30 papers concerning acoustic and electric properties of materials were considered. As regards the physical properties of acoustic waves we considered: P or compressional waves velocity, S or shear waves velocity, P waves quality factor Qp, S waves quality factor Qs and density r. For electric properties we collected: the relative dielectric permittivity er, the electrical conductivity s and the magnetic susceptibility c. In addition, sedimentological, electromagnetic, chemical and radioactivity measurements were performed.

A database containing the all the acquired geophysical data was developed. It was exploited in the framework of the project for technology development and test of intermediate solutions and final deliverables. A wide range of subsurface conditions, including migration of contaminants, heaps of industrial and urban waste and industrially utilized areas, was thus considered in the test phase. The main problems at the selected sites range from the assessment of volumes of the materials and the characterization of the types of materials to the determination and monitoring of free-phase Non-aqueous liquids (NAPL). Traditional invasive methods (boreholes, trenches) provide localized information at high costs that is difficult to correlate, primarily due to heterogeneity of the materials and associated rapid lateral variations of their characteristics. Determination and monitoring of contamination and associated hazards for groundwater resources are an even more elusive problem that cannot be effectively tackled by conventional and invasive techniques. The goal of the experiments was not only to obtain a comprehensive dataset for the implementation of the database and the test of the technology but also to verify in the field organization, optimisation and limits of the integrated approach. Experiments were completed at the different test-sites to check the applicability of different integrated geophysical techniques.

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