Water movements on Combe Down are largely controlled by the geology. Water percolates the permeable surface rocks of the Combe Down plateau and emerges as springs on the valley sides above the impermeable Fullers Earth.
The Great and Inferior Oolite formations provide effective aquifers (rock in which water can be stored and pass through and which is then deemed suitable for use as drinking water) for public and private water supplies. The Combe Down Mines lie above a Grade 1 aquifer and the area is a Source Protection Zone because of the potable water supply. Water for public and private use is extracted from the springs that issue at the base of these units, in particular at the Prior Park, Whittaker and Tucking Mill springs.
It was important that the stabilisation project did not affect the quality or quantity of water emerging at these springs, and that any changes in groundwater flow did not cause instability in the slopes of the plateau.
The British Geological Survey (BGS) worked with Bath & North East Somerset Council to ensure no adverse impact was associated with the stabilisation project.