A literature review of the environmental impacts of sub-water table quarries and the environmental issues to consider in assessing the sustainability of mineral extraction from below the water table.
Guidance and legislation regarding the quarrying industry and in particular in relation to groundwater has been reviewed. A review has also been undertaken of published information dealing with sub-water table quarries and a questionnaire was circulated within the Environment Agency with the aim of identifying the range of approaches to sub-water table quarrying in different hydrogeological environments. It was found that approximately 45% of the quarries identified have permission to extend beneath the water table and nearly two thirds of these are located in the Thames River Terrace deposits. Approximately one third of the sub-water table quarries are located on Major Aquifers (this reflects a large number of sand and gravel quarries in the Thames area where the Terrace Gravels are classified a Major Aquifer). Results of the questionnaire also indicate that the most common form of water management includes discharge of water to a near by watercourse.