How can we stop our pond liner lifting?
Gillian Dunnett, by email
MATTHEW SAYS A lifting liner can occur around the edge of a pond above the water line, where there is nothing to push back on the liner should air or water get underneath. This can happen through the natural movement of subsoil, with some soils less stable than others – shrinkable clay is particularly unstable. It is unusual, however, for a liner to lift at the bottom of a pond, as the water’s weight should hold it in place. Perhaps a change in the ground water beneath is pushing up the liner. The best thing is to carefully lower some large paddle stones onto the troublesome areas to weigh down the liner.