| Title: | Combining steam injection with hydraulic fracturing for the in situ remediation of the unsaturated zone of a fractured soil polluted by jet fuel |
| Author(s): | Nilsson B; Tzovolou D; Jeczalik M; Kasela T; Slack W; Klint KE; Haeseler F; Tsakiroglou CD; |
| Address: | "Geological Survey of Denmark and Greenland, Oster Voldgade 10, 1350 Copenhagen K, Denmark" |
| DOI: | 10.1016/j.jenvman.2010.10.004 |
| ISSN/ISBN: | 1095-8630 (Electronic) 0301-4797 (Linking) |
| Abstract: | "A steam injection pilot-scale experiment was performed on the unsaturated zone of a strongly heterogeneous fractured soil contaminated by jet fuel. Before the treatment, the soil was stimulated by creating sub-horizontal sand-filled hydraulic fractures at three depths. The steam was injected through one hydraulic fracture and gas/water/non-aqueous phase liquid (NAPL) was extracted from the remaining fractures by applying a vacuum to extraction wells. The injection strategy was designed to maximize the heat delivery over the entire cell (10 m x 10 m x 5 m). The soil temperature profile, the recovered NAPL, the extracted water, and the concentrations of volatile organic compounds (VOCs) in the gas phase were monitored during the field test. GC-MS chemical analyses of pre- and post-treatment soil samples allowed for the quantitative assessment of the remediation efficiency. The growth of the heat front followed the configuration of hydraulic fractures. The average concentration of total hydrocarbons (g/kg of soil) was reduced by approximately 43% in the upper target zone (depth = 1.5-3.9 m) and by approximately 72% over the entire zone (depth = 1.5-5.5 m). The total NAPL mass removal based on gas and liquid stream measurements and the free-NAPL product were almost 30% and 2%, respectively, of those estimated from chemical analyses of pre- and post-treatment soil samples. The dominant mechanisms of soil remediation was the vaporization of jet fuel compounds at temperatures lower than their normal boiling points (steam distillation) enhanced by the ventilation of porous matrix due to the forced convective flow of air. In addition, the significant reduction of the NAPL mass in the less-heated deeper zone may be attributed to the counter-current imbibition of condensed water from natural fractures into the porous matrix and the gravity drainage associated with seasonal fluctuations of the water table" |
| Keywords: | *Environmental Restoration and Remediation Gas Chromatography-Mass Spectrometry *Hydrocarbons Pilot Projects Poland Soil Pollutants/*chemistry Steam; |
| Notes: | "MedlineNilsson, Bertel Tzovolou, Dimitra Jeczalik, Maciej Kasela, Tomasz Slack, William Klint, Knud E Haeseler, Frank Tsakiroglou, Christos D eng Research Support, Non-U.S. Gov't England 2010/10/30 J Environ Manage. 2011 Mar; 92(3):695-707. doi: 10.1016/j.jenvman.2010.10.004. Epub 2010 Oct 27" |
