Interference between road network and groundwater resources.

The need to protect drinkable groundwater resources has been implemented by European Law for a long time; more recently Italian legislation has taken time of travel (TOT) criterion as a rule for the delineation of the protection areas nearby drinkable wells. However, very often, the fulfilment of this criterion collide with multiple land uses, not only with the pre-existing urban setting, but also with the planning of new public infrastructures which aim is to improve the land use near urban areas. Recently, an emblematic example of interference between different land uses has occurred in the neighbourhood of the city of Torino in Italy, near a well field that ensures about the 22% of the potable water supplied to the municipality of Torino. The well field area is partially interested by the realization of a new road network for the improvement of the accessibility to the Venaria’s Palace; in particular, the planned route falls into some well head protection zones. A very detailed hydrogeological investigation has been conducted in order to understand the position of the well screens, the extraction rates, the piezometric contours, the hydrodynamic properties and the characteristics vulnerability of the intercepted aquifers. The results of the study showed that the interference is unavoidable and therefore, because of the unmodifiability of the highway’s layout, eight wells have to be sealed. Furthermore, severe mitigation procedures connected to the construction and management of the road network shall be adopted in order to avoid contamination towards groundwater resources that have a strategic role for the city of Torino. In order to recover the loss of pumping rate, four new wells will be drilled in areas not interested by potential polluting activities. Anyway, the investigations carried out revealed the need of further analysis to implement an effective protection of groundwater resources used for public supply.