Hydraulic and chemical property correlations of the Triassic sandstone of Birmingham
Hydraulic conductivity (K), porosity and cation exchange capacity (CEC) were determined
at the laboratory scale on samples of the Wildmoor Sandstone and Kidderminster
Formations of the Birmingham Triassic sandstone.
The impact of the rock colour was considered in a semi-quantitative manner using the
Munsell Colour System. SEM, flushing experiments and image analysis of thin-section
photomicrographs were used to assess the role of rock fabric in the development of
hydraulic and chemical properties. The image analysis was carried out on colour images
using a custom-written code. XRD, point counting and geophysical methods were utilised
to assess the mineralogical variation between samples, the presence of iron and manganese
oxides within the sandstone was quantified.
The study found significant negative correlations between porosity and CEC in all
samples, while a correlation between K and CEC was only observed in samples with a
lower colour saturation. A significant role for manganese oxides in the development of
CEC in the Triassic Sandstone of Birmingham has been identified.
The study has concluded that a significant part of the CEC within these rocks is due to the
presence of a reducible phase. This has significant implications for migration of
contaminants, particularly those entrained in a reducing plume.