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1 Dept of Geology, Royal Holloway, Egham, Surrey TW20 0EX
2 Shanks and McEwan, Woburn Sands, Bucks MK17 8TA
Many formations treated as Minor Aquifers for the purposes of resource protection do not meet accepted definitions of aquifers. The Kellaways Sand is a typical example, and modern waste-disposal licences require the installation of an engineered containment system to protect groundwater within it. However, the formation is clay-rich and only 4 to 5 m in thickness, and has a transmissivity of around 1.3 x 10–1 m2day–1. Contained water quality is poor with salinities well above maximum admissible concentrations for drinking water. As the Kellaways Sand does not yield water to pumping wells, the only rational reason for protection is that the formation might contribute to baseflow in the River Ouse to the northeast. However, hydraulic gradients are such that seepage rates to the river will not exceed more than a few cubic metres per year over the length of outcrop adjacent to the river. It is concluded that the installation of engineered mineral liners at the base of brickpits in the Lower Oxford Clay do nothing to reduce the risks associated with waste disposal. Resources spent on protecting the Kellaways Sand could be better used in other areas of environmental protection.
