¤ Boreholes no longer required for whatever reason need to be made safe and backfilled / sealed to prevent groundwater pollution and flow of groundwater between aquifer units.

¤ The borehole / well should be restored as closely as possible to its pre-drilled condition requiring a variety of materials so that permeable aggregates (eg. pea gravel) are positioned adjacent to aquifer horizons while low permeability materials (cement grout) are positioned adjacent to low permeability horizons.

¤ The top 2 metres below ground level down should be excavated at least 1 metre wider than the diameter of the backfilled borehole and filled with cement.