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Field Tracer Test for the Design of LNAPL Source Zone Surfactant Flushing.

Robert, Thomas; Martel, Richard; Lefebvre, René; Lauzon, Jean-Marc; Morin, Annie (2016). Field Tracer Test for the Design of LNAPL Source Zone Surfactant Flushing. Groundwater Monitoring and Remediation , vol. 36 , nº 2. p. 68-82. DOI: 10.1111/gwmr.12164.

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Résumé

La transcription des symboles et des caractères spéciaux utilisés dans la version originale de ce résumé n’a pas été possible en raison de limitations techniques. La version correcte de ce résumé peut être lue dans le document original.

A field tracer test was carried out in a light nonaqueous phase liquid (LNAPL) source zone using a well pattern consisting of one injection well surrounded by four extraction wells (5-spot well pattern). Multilevel sampling was carried out in two observation wells located inside the test cell characterized by heterogeneous lithology. Tracer breakthrough curves showed relatively uniform flow within soil layers. A numerical flow and solute transport model was calibrated on hydraulic heads and tracer breakthrough curves. The model was used to estimate an average accessible porosity of 0.115 for the swept zone and an average longitudinal dispersivity of 0.55 m. The model was further used to optimize the relative effects of viscous forces versus capillary forces under realistic imposed hydraulic gradients and to establish optimal surfactant solution properties. Maximum capillary number (NCa) values between injection and extraction wells were obtained for an injection flow rate of 16 L/min, a total extraction flow rate of 20 L/min, and a surfactant solution with a viscosity of 0.005 Pa⋅s. The unconfined nature of the aquifer limited further flow rate or viscosity increases that would have led to unrealistic hydraulic gradients. An NCa range of 3.8 × 10−4 to 7.6 × 10−3 was obtained depending on the magnitude of the simulated LNAPL-water interfacial tension reduction. Finally, surfactant and chase water slug sizing was optimized with a radial form of the simplified Ogata-Banks analytical solution (Ogata and Banks 1961) so that injected concentrations could be maintained in the entire 5-spot cell.

Type de document: Article
Mots-clés libres: nonaqueous phase liquids; performance assessment; recovery mechanisms; micellar-solutions; polymer-solutions; remediation performance; LNAPL remediation; porous-medium; sand column; aquifer
Centre: Centre Eau Terre Environnement
Date de dépôt: 28 nov. 2019 16:52
Dernière modification: 28 nov. 2019 16:52
URI: http://espace.inrs.ca/id/eprint/4708

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