Petroleum hydrocarbon transport in a fractured clayey till
- GeoSystems Engineering, Lenexa, KS (United States)
- Iowa State Univ., Ames, IA (United States). Dept. of Civil Engineering
Flow through interconnected fractures and fissures in an otherwise tight formation can lead to increased mobility and spreading of contamination. To investigate the potential for increased mobility of gasoline in fractured clayey till, a series of laboratory flexible wall permeability tests (column tests) were performed on undisturbed samples of fractured clayey till at confining pressures equal to the measured in situ lateral earth pressures. The column tests were performed using a CaSO{sub 4} solution, a CaCl{sub 2} solution, and gasoline as the permeants. Results of the tests with CaSO{sub 4} and CaCl{sub 2} solutions indicate that the fractured and fissured till has a hydraulic conductivity on the order of 10{sup {minus}6} cm/s and a breakthrough porosity significantly less than the total porosity, on the order of 0.04 (4%) as compared with the total porosity of 0.30 (30%). Breakthrough porosity represents the porosity (i.e., pore volume of flow) at which the breakthrough of a solute or contaminant is first observed. The gasoline conductivity is approximately equal to the hydraulic conductivity. Results indicate that the gasoline breakthrough porosity is approximately 75% of that for water, about 0.03 (3%), inferring the potential for a significant decrease in first arrival time. Fractured clayey till should therefore not be considered as a significant barrier against groundwater contamination.
- OSTI ID:
- 116337
- Report Number(s):
- CONF-9507173--; ISBN 0-7844-0095-4
- Country of Publication:
- United States
- Language:
- English
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