title: ZVI-Clay remediation of a chlorinated solvent source zone, Skuldelev, Denmark: 2. Groundwater contaminant mass discharge reduction.
abstract: The impact of source mass depletion on the down-gradient contaminant mass discharge was monitored for a 19-month period as a part of a field demonstration of the ZVI-Clay soil mixing remediation technology. Groundwater samples were collected from conventional monitoring wells (120 samples) and a dense network of multilevel samplers (640 samples). The hydraulic gradient and conductivity were determined. Depletion of the contaminant source is described in the companion paper (Fjordbøge et al., 2012). Field data showed four distinct phases for PCE mass discharge: (1) baseline conditions, (2) initial rapid reduction, (3) temporary increase, and (4) slow long-term reduction. Numerical modeling was utilized to develop a conceptual understanding of the four phases and to identify the governing processes. The initial rapid reduction of mass discharge was a result of the changed hydraulic properties in the source zone after soil mixing. The subsequent phases depended on the changed accessibility of the contaminant mass after mixing, the rate of source depletion, and the concentration gradient at the boundaries of the mixed source zone. Overall, ZVI-Clay soil mixing resulted in a significant down-gradient contaminant mass discharge reduction (76%) for the parent compound (PCE), while the overall reduction of chlorinated ethenes was smaller (21%).
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark, Miljoevej, Building 113, DK-2800 Kgs. Lyngby, Denmark. asfj@env.dtu.dk
authors.forename: Annika S
authors.initials: AS
authors.lastname: Fjordbøge
authors.forename: Ida V
authors.initials: IV
authors.lastname: Lange
authors.forename: Poul L
authors.initials: PL
authors.lastname: Bjerg
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Binning
authors.forename: Charlotte
authors.initials: C
authors.lastname: Riis
authors.forename: Peter
authors.initials: P
authors.lastname: Kjeldsen
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D000077215:Clay; D052918:Environmental Restoration and Remediation; D060587:Groundwater / Q000737:chemistry*; D054879:Halogenation; D014874:Water Pollutants, Chemical / Q000737:chemistry
chemical_list: D000538:Aluminum Silicates; D014874:Water Pollutants, Chemical; D000077215:Clay