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A experimental modelling activity was developed to characterize the hydraulic behaviour of water bearing fracture in crystalline rocks. Four conservative tracers have been injected into two packed off sections of the same well 69 m deep in a granite formation, and recovered by pumping from an isolated section of a second borehole (46 m deep, 14 m apart). Before using the tracers in the field, their behaviour was studied in the laboratory under controlled conditions. In each section an ionic spike was associated to a dye. Iodide and fluorescine were injected in one section, and eosine together with Bromide 79 in the other section. The test lasted 27 days after which around 50% of the injected masses were recovered. The analysis of the breakthrough curves revealed different recoveries for fluoresceine (60%) and iodide (45%). However, fitted advective transport parameters from a homogenous model appear quite similar. Thickness porosity 1.8E-2 m and longitudinal dispersivity 1.0 m. Eosine, injected separately, showed lower recovery (43%), greater thickness porosity (4.5E-2 m) and a longitudinal dispersity of 1.5 m. Isotopic Bromide 79 was not recovered probably for a nonquantified loss of tracer during the injection.

Additional information

Authors: D'ALESSANDRO M ET AL, JRC Ispra (IT);GUIMERA J ET AL, Universitat Politècnica de Catalunya, Barcelona (ES);GARCIA M, Centro de Investigaciones Energéticas Medioambientales y Tecnólogicas, Madrid (ES)
Bibliographic Reference: Article: Journal of Contaminant Hydrology
Record Number: 199610036 / Last updated on: 1996-02-16
Original language: en
Available languages: en