EXPERIMENTAL ASSESSMENT OF SOIL AND GROUNDWATER CONTAMINATION FROM 2 OLD INFILTRATION SYSTEMS FOR ROAD RUN-OFF IN SWITZERLAND

Surface and sub-surface infiltration systems for road run-off at two s ites in Switzerland were investigated by sampling and analysing the ru n-off sludge and soil found in the systems. The infiltration systems w ere between 12 and 45 years old. Measured pollutant parameters include d the heavy metals Cr, Co, Ni, Cu, Zn, Cd and Pb, a number of polycycl ic aromatic hydrocarbons (PAH) and adsorbed organically bound halogens (AOX). Total concentrations were measured to assess the extent of soi l contamination. Further, metal concentrations were measured in equili brated aqueous extracts to simulate naturally occurring concentrations in percolating water. In the infiltration systems the pollutant conce ntrations decreased rapidly to background levels within depths less th an 1.5 m. The potential for groundwater contamination from infiltratio n of road run-off appears to be limited, but soil and run-off sludge f ound in infiltration systems can be heavily contaminated. Noteworthy, the run-off sludge itself plays an important role as pollutant source and sorbent.