Physical modelling of a dissolved contaminant in an unsaturated sand

1991 ◽  
Vol 28 (6) ◽  
pp. 829-833 ◽  
Author(s):  
B. Cooke ◽  
R. J. Mitchell
Keyword(s):  
Contaminant Transport ◽  
Scaling Laws ◽  
Physical Modelling ◽  
Saturated Soils ◽  
Test Results ◽  
Centrifuge Modelling ◽  
Geotechnical Centrifuge ◽  
Partially Saturated ◽  
Partially Saturated Soils ◽  
Viable Approach

Computer solutions to the problem of dissolved contaminant movements in saturated soils are readily available. However, for partially saturated soils, extreme nonlinearity of some variables and difficulties in determining values for other variables make computer solutions predicting the movement of dissolved contaminants highly unreliable. Physical modelling in a geotechnical centrifuge is presented as a viable alternative to numerical modelling. Scaling laws for physical modelling are presented in this paper, and dimensional analysis is used to identify potential difficulties in application of model test results to prototype situations. Preliminary results of experimental work are presented. These results indicate that centrifuge modelling may be a viable approach to the evaluation of dissolved contaminant transport in partially saturated soils. Key words: contaminant transport, centrifuge, unsaturated.

scholarly journals Numerical Modeling on Fate and Transport of Pollutants in the Vadose Zone

2020 ◽  
Vol 2 (1) ◽  
pp. 34 ◽  
Author(s):  
Giacomo Viccione ◽  
Maria Grazia Stoppiello ◽  
Silvia Lauria ◽  
Leonardo Cascini
Keyword(s):  
Vadose Zone ◽  
Contaminated Soils ◽  
Fate And Transport ◽  
Transport Processes ◽  
Saturated Soils ◽  
Saturated Porous Media ◽  
Campania Region ◽  
Partially Saturated ◽  
Partially Saturated Soils ◽  
Method Approach

Soil contamination is an issue of paramount importance to assess human health (HHRA) as well as ecological (ERA) risk assessment. To analyze risk scenarios related to contaminated soils, the identification of sources, either of primary or secondary type, as well as the assessment of propagation and fate processes is needed. Although many studies refer to the transport of pollutants in fully saturated porous media, little efforts have been made concerning the case of partially saturated soils so far. The matter is of interest as the contamination in the fully saturated region may take place as a result of the percolation in the vadose zone. Governing equations ruling fate and transport processes in partially saturated soils are here solved numerically by means of a finite element method approach. Richards equations are adopted to describe flow dynamics through the hydraulic conductivity coefficient Ks, while contaminant fate is mainly described by the sorption coefficient Kp. As for the boundary conditions, we consider a local and continuous spill of contaminant at the upper ground of variable thickness. Precipitations are given as step functions whose intensity is derived by considering pluviometric data at the station of Gròmola, Campania Region, Italy. Benzene and tetrachloroethylene (PCE) are taken into account. A comparative analysis is carried out for permeability Ks and distribution Kd coefficients in the range [10−6, 10−4] m/s and [10−5, 10−3] m3/kg. Results are then compared and discussed.

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