A large petrol station located along one of the busiest motorways in northern Italy was undergoing extensive reconstruction, including the demolition of existing buildings, removal of above- and below-ground structures; as well as remediation. The existing underground fuel tanks (USTs) were removed and the contaminated soil surrounding the USTs was excavated to a depth of 5m BGL.

The geology consists of a highly permeable soil comprising sand and gravel to approx. 40m BGL. The average groundwater level is at approximately 4m to 6m BGL, where an extensive contaminant smear zone was observed.

The main excavation was approx. 1,100m2 and 5m deep, with the extent and depth limited by the proximity of the motorway (as well as the presence of groundwater).

The soil at the bottom of the excavation was highly impacted with Total Petroleum Hydrocarbons (TPHs) and BTEX compounds, with concentrations of up to 10,000mg/kg. The groundwater inside the excavation was highly contaminated, with evidence of Light Non Aqueous Phase Liquid (LNAPL) and average concentrations in the range of 500,000μg/L.