Full scale application of a PRB in Torino

Permeable reactive barriers (PRBs) are one of the most widespread technique for the remediation of contaminated aquifers. Over the past 10 years, the use of iron-based PRBs has evolved from innovative to accepted standard practice for the treatment of a variety of groundwater contaminants (ITRC, 2005). The aim of this study is to describe the first full scale application of a zerovalent iron permeable reactive barrier in Italy. The PRB was designed and realized to remediate a chlorinated hydrocarbons plume at an old industrial landfill site, in Avigliana, near the city of Torino, in the Piemonte Region. The dimensioning of the PRB was conducted by means of a three dimensional flux and multispecies contaminant transport model based on column degradation test. The installation of the barrier was accomplished using a clamshell for the excavation of the trench and a guar-gum slurry to support the walls. The performance of this technique was outstanding and allowed the installation of the PRB in 8 days. The degree of precision of the excavation was very high because of the intrinsic characteristics of this excavation tool and of the use of a concrete curb to guide the hydraulic grab. The final configuration of the site is characterized by a wide car park, a ciclo-cross track and a green capping to prevent the infiltration of water from the ground surface to the shallow aquifer.