Five-Year Vapor Monitoring for Risk Management at a Hydrocarbon-Polluted Site

Soil remediation (excavation and off site disposal) was partially carried out in 2005 at a site in Milan (Italy), leaving a residual volume of soil polluted with petroleum-derived hydrocarbons. Indoor air, outdoor air, crawl-space air and soil gas samplings have been carried out since January 2009. In March 2011 the monitoring network was upgraded to its final configuration (18 indoor, 7 outdoor and 4 crawl-space sampling locations, 60 soil gas probes at four different depths from ground surface); after that, one monitoring campaign a season was performed till November 2013, fractionating hydrocarbons according to a modified version of the Massachusetts Department of Environmental Protection approach. In order to permanently keep risk below acceptable levels, a mitigation system of the contaminated source was installed in December 2013 and it is still working. Three monitoring campaigns of ambient air have been performed since then. Although not strictly necessary in terms of time-averaged health risk, the mitigation system allowed to extract significant amounts of mono- and light poly-cyclic aromatic hydrocarbons. This has helped manage worries about future uncontrolled exposure of people working at the site