Controls on dense non-aqueous-phase liquid transport in Permo-Triassic sandstones, UK
Published:January 01, 2006
D. C. Gooddy, J. P. Bloomfield, 2006. "Controls on dense non-aqueous-phase liquid transport in Permo-Triassic sandstones, UK", Fluid Flow and Solute Movement in Sandstones: The Onshore UK Permo-Triassic Red Bed Sequence, R. D. Barker, J. H. Tellam
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The Permo-Triassic sandstones are geographically and lithologically diverse, and exhibit large variations in porosity (ф), pore-throat size, gas permeability (k) and mineral phases. These parameters influence considerably the flow and transport of contaminants. The aquifer is susceptible to contamination by a range of pollutants from both contemporary and historic sources as it outcrops in a number of large industrial towns. One such class of pollutants are chlorinated hydrocarbons, which have been used extensively for years in dry-cleaning and metal degreasing. The physical, chemical and biological properties of these dense non-aqueous-phase liquids (DNAPLs) make them a particular cause of groundwater contamination. Standard physical property measurements, along with a weak nitric acid extraction to determine dominant minerals, were carried out on consolidated sandstones. A laboratory method was developed to produce pressure–saturation curves for a DNAPL–water-sandstone system. Entry pressures were found to be lower than predicted from theoretical considerations, which could be explained in part by the relative amounts of calcite and dolomite present in the pore space. Calculations on relative permeability show that at roughly 60% DNAPL saturation no water flow occurs. Understanding the controls on DNAPL transport can greatly assist the need for appropriate remedial action.
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Fluid Flow and Solute Movement in Sandstones: The Onshore UK Permo-Triassic Red Bed Sequence
Sandstone aquifers are common worldwide: they contain a significant proportion of the Earth’s fresh water supplies. However, because of their textural complexity and the frequent occurrence of both matrix and fracture flow, prediction of flow and pollutant migration is still a considerable challenge. This volume contains a collection of papers summarizing current research on an example sandstone aquifer: the UK Permo-Triassic Sandstone sequence. These red bed, organic-poor sandstones are of fluvial and aeolian origin, are often strongly textured, and are cut by discontinuities of a wide range of permeabilities. Matrix flow often dominates, but fracture flow also occurs. The papers in the volume deal with research on saturated and unsaturated flow, and solute and non-aqueous-phase liquid movement. They cover investigations from laboratory to regional scale, and involve a wide range of approaches, from petrophysical through geophysical and hydrochemical to modelling.
The book is intended to be of interest to researchers and practitioners involved in water resources and groundwater pollution, and to hydrogeology, water engineering, and environmental science students.