Some aspects of the state of the art of contaminated sites remediation in Italy

Abstract

The remediation of contaminated sites has been faced in Italy and elsewhere in the world with a series of works originated by the availability of specific technologies for the recovery of soils and groundwater quality, acting in accordance with the principle of sustainability. A framework of rules (target values and type of intervention) and a summary of the quality of soil and groundwater in Italian contaminated sites must be mentioned first. The design of the remediation was also permitted by the improvement of the site characterization, with specific equipments addressed for example to identify the stratigraphy of the contaminants, the presence of volatile compounds, the sampling of water of significant groundwater quality, etc.. The text describes some interventions relating to physical and hydraulic barriers that involve substantial capital and O&M costs and also the consumption of natural resources. Subsequently they are also considered important in situ interventions that resulted in a reduction in the concentration and significant recovery of the pollutants mass. The evolution of the residual concentration in the groundwater must be considered by monitoring natural attenuation. Despite the recovery of the mass of pollutants even up to 90-99%, values of cleanup (expected concentrations of the order of μg/L) which are established by national legislation have not been achieved. It can be stated that the scientific community is considering the new paradigm expressed by the “order of magnitude of the flow of pollutant mass” to replace the old paradigm consisting in the “limit value of final concentrations”.

Stochastic analysis of the efficiency of coupled hydraulic-physical barriers to contain solute plumes in highly heterogeneous aquifers

“…These issues have been documented in multiple analyses presented in the past (e.g. Bayer and Finkel, 2006;Beretta, 2015;Britton et al, 2005;Kaleris and Ziogas, 2013;Khandelwal et al, 1997;Pedretti et al, 2011;Russell and Rabideau, 2000;Wu et al, 2016;Xanthakos, 1979).…”

“…A well-known approach is for instance the use of pumpand-treat technologies combined with vertical cutoff walls (e.g. Bayer and Finkel, 2006;Beretta, 2015;Pedretti et al, 2013a). The accurate hydraulic design of combined pump-and-treat systems (CP&Ts) requires a reliable parameterization of the hydrogeological properties of both the physical barriers and the surrounding aquifer.…”

Heterogeneity-controlled uncertain optimization of pump-and-treat systems explained through geological entropy

“…Scenario "C" was chosen as an intermediate scenario between A and E, being a common simple geometry for physical barriers widely adopted in countries such as Italy (e.g. Rolle et al, 2009;Pedretti et al, 2013bPedretti et al, , 2017Beretta, 2015). The total length of the barriers, 𝑙 𝑏 , was assumed to be three times the width of the sources (𝑙 𝑏 = 3𝑊 𝑆 ).…”

“…Pump-and-treat (P&T) is a widespread technique for solute plume management (e.g. Mackay and Cherry, 1989;EPA, 2005;Pedretti et al, 2013b;Beretta, 2015). Despite the decadal use of this technique and the emergence of alternative solutions for remediation purposes (e.g.…”

How Can We Make Pump and Treat Systems More Energetically Sustainable?

“…SINs are mostly large industrial districts with complex contamination and most of the expense for SINs remediation is related to the operation of P&T systems [42]. Up until 2009, an investment of 604 M€ was made to contain and treat contaminated groundwater in 17 SINs; of that amount, 248 M€ were invested to install P&T systems that treat 45 Mm 3 per year at an average operational cost of 2.40 €/m 3 [44].…”