GNGTS 2015 - Atti del 34° Convegno Nazionale

GNGTS 2015 S essione 1.3 151 in different sedimentary bodies separated by erosional surfaces with areal range development, representing the main elements of the succession (Bonsignore et al. , 1969; Dela Pierre et al. , 2007). This sedimentary succession rests on the “villafranchian succession”, comprising deltaic deposits (Lower Complex) and fluvial deposits (Upper Complex), referred to Piacenzian and Calabrian respectively, separated by an unconformity (Cascina Viarengo Surface) (Carraro Ed., 1996; Forno et al. , 2015), and deep marine clay deposits (Lugagnano Clay) with littoral sandy deposits (Asti Sand) referred to Zanclean (Festa et al. , 2009). Hydrogeological setting of the Turin city. This study focuses on the shallow aquifer hosted within the fluvial deposits. The shallow aquifer is mainly supplied by direct rainfall and rivers at the outlet of the valleys in the plain. This aquifer has a thickness generally ranging between 20 and 50 m; in spite of the variable thickness of the aquifer, it has a high productivity and has a regional importance. The water table generally follows the topographic surface. The bottom of the shallow aquifer is generally well marked by a textural variability of the deposits. The local presence of thick and relatively continuous layers of silt or clay-rich deposits allows a clear separation between the shallow aquifer and deep aquifers, hosted mainly in marine and permeable horizons of the villafranchian succession (Canavese et al. , 2004; Bove et al. , 2005; De Luca and Ossella, 2012; Irace et al. , 2009). Technical characteristics of the geothermal open-loop system. The project, object of this research, corresponds to an open-loop system constituted by two wells (P1 and P2 in Fig. 1B), extraction well and re-injection well, for heating-cooling and hot water health. The wells are placed at a distance of 20 m. Both wells were drilled up to 45 m depth from ground level and together intercept a shallow aquifer. The reintroduction of thermal water therefore, occurs in the same aquifer from which it was extracted for the operation of the open-loop system. Fig. 1 – Sketch of north-western Piedmont Region (A); satellite view of the study area (B); monitoring parameters: static level and temperature of the aquifer (C); simplified stratigraphic cross section of the subsoil (D).