Chemical and geochemical characterisation of a disused red brick factory area of central Italy

Abstract

Characterisation and remedial actions are proposed for a polluted site enclosed within a red brick factory, located in central Italy. Approximately 22,000 t of chromium containing tannery sludge were introduced as ‘secondary raw materials’ for reuse in red brick manufacture. Preliminary geo-electric tomography was carried out on the waste bank, followed by the perforation of 14 boreholes into the bottom geological stratum. Heavy metals [B, Crtot, Cr(VI), Hg, Pb, Cu, Sn, V, Zn] and polycyclic aromatic hydrocarbons [benzo(a)pyrene; phenanthrene; dibenzo(a,h)pyrene; pyrene] were determined on solid samples. Carrots were sliced to give samples from different depths in the waste bank. The following samples were determined in the waste leachate: 1,1,2trichlorethane, phenol, 2,4,6trichlorphenol, hexachlorhexane, dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE). During characterisation, laboratory experiments were also carried out on lime-treated and untreated carrot sections to evaluate heavy metal release and potential migration in the subsoil. Pollutant exposure pathways were set up, based on application of the Risk-Based Corrective Action (RBCA) model, followed by the evaluation of potential environmental and sanitary targets for site-specific risk evaluation and the proposition of scientifically based restoration scenarios. Surface capping, coupled with lateral belting of the site, were selected for the site recovery operations after extensive cost–benefit evaluations.