HR: 0800h
AN: H11D-1283    [Abstracts]
TI: Design of Zero-Valent Iron Fracture Reactive Barriers for Remediating a TCE Plume in a Chalk Aquifer
AU: * Cai, Z
EM: zu.cai@shef.ac.uk
AF: University of Sheffield, GPRG,Department of Civil and Structural Engineering, Sheffield, S1 3JD United Kingdom
AU: lerner, D N
EM: d.n.lerner@sheffield.ac.uk
AF: University of Sheffield, GPRG,Department of Civil and Structural Engineering, Sheffield, S1 3JD United Kingdom
AU: Mclaren, R G
EM: mclaren@uwaterloo.ca
AF: University of Waterloo, Department of Earth Sciences,200 University Avenue West , Waterloo, N2L 3G1 Canada
AU: Wilson, R D
EM: r.d.wilson@sheffield.ac.uk
AF: University of Sheffield, GPRG,Department of Civil and Structural Engineering, Sheffield, S1 3JD United Kingdom
AB: A novel concept, the Fe⁰ fracture reactive barrier (Fe⁰ FRB), is proposed to clean up chlorinated solvent pollution of groundwater in a chalk aquifer. A Fe⁰ FRB is an extended reactive zone where the fractures are partly filled with iron. It can be created by injecting a viscous, biodegradable gel suspended with iron particles into selected fractures via boreholes. To evaluate the feasibility of Fe⁰ FRB as a remediation strategy, we conducted numerical modelling simulations to assess the treatment performance of a Fe⁰ FRB in a hypothetical chalk aquifer. The assessment was carried out using a numerical model for flow and solute transport in a discretely-fractured porous medium coupled with an analytical expression representing degradation by iron. The hypothetical chalk aquifer was represented by a 3-D discrete fracture network model which was developed using data from a number of chalk sites. TCE reactive transport in the Fe⁰ FRB and mass exchange of solute between fractures and the porous matrix were fully accounted for in the model. The model revealed that the success of the remediation technology lies in how to create a highly reactive Fe⁰ FRB without plugging fractures and reducing flow through it. A parametric study of various design parameters for the Fe⁰ FRB suggested that a high treatment efficiency was likely to be achieved, by employing highly reactive nanoscale iron or by using a high proportion of microscale iron fill and fracture enlargement. The model study also provided some preliminary conclusions on the optimal design of a Fe⁰ FRB. A preliminary analysis of the longevity of a Fe⁰ FRB, which contains a small amount of highly reactive nanoscale iron, showed that its lifetime is between 5 and 50 years dependant on the TCE mass flux through the barrier.
DE: 1846 Model calibration (3333)
SC: Hydrology [H]
MN: Fall Meeting 2005