Clamshell excavation of a permeable reactive barrier
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Nowadays, permeable reactive barriers (PRB) are one of the most widespread techniques for the remediation of contaminated aquifers. Over the past 10 years, the use of iron-based PRBs has evolved from innovative to accepted standard practice for the treatment of a variety of groundwater contaminants (ITRC in: Permeable reactive barriers: lessons learned/new directions. The Interstate Technology and Regulatory Council, Permeable Reactive Barriers Team 2005). Although, a variety of excavation methods have been developed, backhoe excavators are often used for the construction of PRBs. The aim of this study is to describe the emplacement of a full-scale PRB and the benefits deriving from the use of a crawler crane equipped with a hydraulic grab (also known as clamshell excavator) in the excavation phases. The studied PRB was designed to remediate a chlorinated hydrocarbons plume at an old industrial landfill site, in Avigliana, near the city of Torino, in Italy. The continuous reactive barrier was designed to be 120 m long, 13 m deep, and 0.6 m thick. The installation of the barrier was accomplished using a clamshell for the excavation of the trench and a guar-gum slurry to support the walls. The performance of this technique was outstanding and allowed the installation of the PRB in 7 days. The degree of precision of the excavation was very high because of the intrinsic characteristics of this excavation tool and of the use of a concrete curb to guide the hydraulic grab. Moreover, the adopted technique permitted a saving of bioslurry thus minimizing the amount of biocide required.
KeywordsPermeable reactive barrier (PRB) Clamshell Zerovalent iron (ZVI) Biopolymer slurry Guar gum
The authors would like to acknowledge Stephanie O’Hannesin, Andrzej Przepiora, Jennifer Son from E.T.I., Hermann Schad from I.M.E.S., and Steve Day from Geosolutions Inc. who provided technical guidance during the different phases of the project; Lorenzo Buonomo and Studio Buonomo Veglia who participated, with Studio Bortolami e Di Molfetta, in the design of the remediation project; Stefano Marconetto, Chiara Ariotti, Raffaella Granata and all the staff who worked hard during the installation of the PRB.
- Clement TP (1997) RT3D—a modular computer code for simulating reactive multispecies transport in 3-dimensional groundwater aquifers. Battelle Pacific Northwest National Laboratory. PNNL-SA-28967, RichlandGoogle Scholar
- Di Molfetta A, Sethi R (2005a) Progettazione e realizzazione di barriere reattive permeabili. In: Gestione di Siti Contaminati a cura di Studio Aglietto s.r.l. Edizioni “Osservatorio Siti Contaminati”Google Scholar
- Di Molfetta A, Sethi R (2005b) Barriere reattive permeabili. In: Bonifica di siti contaminati. Caratterizzazione e tecnologie di risanamento. A cura di Luca Bonomo, McGraw Hill, New York, ISBN 88-386-6278-9Google Scholar
- ITRC (2005) Permeable reactive barriers: lessons learned/new directions. The Interstate Technology and Regulatory Council, Permeable Reactive Barriers TeamGoogle Scholar
- Mountjoy KJ, Blowes D (2002) Installation of a full scale permeable reactive barrier for the treatment of metal-contaminated groundwater. In: Gavaskar AR, Chen ASC (eds) Remediation of chlorinated and recalcitrant compounds, 2002. Proceedings of the third international conference on remediation of chlorinated and recalcitrant compounds, Monterey, CA, May 2002. ISBN 1–57477-132-9, Battelle Press, ColumbusGoogle Scholar
- Orth Fellow A, Dauda T, McKenzie DE (1998) Reductive dechlorination of DNAPL trichloroethylene by zero-valent iron. Pract Periodical Hazard Toxic Radioact Waste Manage, July, 123–128Google Scholar
- Sethi R (2004) Barriere reattive permeabili a ferro zero-valente: modellazione dei fenomeni di trasporto e degradazione multicomponente, Ph.D. Thesis in Environmental Geoengineering. Politecnico di TorinoGoogle Scholar