title: Characterization and quantification of pneumatic fracturing effects at a clay till site.
abstract: Environmental fracturing offers assistance to remediation efforts at contaminated, low-permeability sites via creation of active fracture networks, and hence, reduction of mass transport limitations set by diffusion in low-permeability matrices. A pilot study of pneumatic fracturing, focusing on direct documentation of fracture propagation patterns and spacing, was performed at a typical basal clay till site. The study applied a novel package of documentation methods, including injection of five tracers with different characteristics (bromide, uvitex, fluorescein, rhodamine WT, and brilliant blue), subsequent tracer-filled fracture documentation via direct and indirect methods, and geological characterization of the fractured site. The direct documentation methods consisted of Geoprobe coring, augering, and excavation. A mass balance and conceptual model have been established for the distribution of the injected tracers in the subsurface. They reveal that tracer was distributed within 2 m of the fracturing well, mainly in existing fractures above the redox boundary (2 to 4 m.b.s.; 5 to 10 cm spacing). Spacing of observed tracer-filled fractures was large (>1 m) at greater depths. The number of fractures induced/activated could possibly be increased via adjustments to the fracturing equipment design.
authors.affiliation: Institute of Environment & Resources, Technical University of Denmark, Bygningstorvet, DTU-Building 115, DK-2800 Kgs. Lyngby, Denmark. cac@er.dtu.dk
authors.forename: Camilla Maymann
authors.initials: CM
authors.lastname: Christiansen
authors.forename: Charlotte
authors.initials: C
authors.lastname: Riis
authors.forename: Stine B
authors.initials: SB
authors.lastname: Christensen
authors.forename: Mette M
authors.initials: MM
authors.lastname: Broholm
authors.forename: Anders G
authors.initials: AG
authors.lastname: Christensen
authors.forename: Knud Erik S
authors.initials: KE
authors.lastname: Klint
authors.forename: Judith S A
authors.initials: JS
authors.lastname: Wood
authors.forename: Peter
authors.initials: P
authors.lastname: Bauer-Gottwein
authors.forename: Poul L
authors.initials: PL
authors.lastname: Bjerg
mesh_terms: D000538:Aluminum Silicates; D000077215:Clay; D055593:Geological Phenomena; D005844:Geology; D014872:Water Movements; D014873:Water Pollutants; D014881:Water Supply
chemical_list: D000538:Aluminum Silicates; D014873:Water Pollutants; D000077215:Clay