Closed-Loop Boreholes   Boreholes usually drilled to depths of between 100 and 150 metres below ground level. Boreholes typically drilled in 120mm (4 ¾ inches) diameter. Polyethylene collector pipe installed to depth of borehole. Pipe usually either 32mm or 40mm in diameter with u-bend at the final depth of the borehole. Boreholes backfilled with grout to surface (backfill specification determined by designer and/or installer).   Open-Loop Boreholes   Boreholes drilled to target productive aquifer, usually to depths of between 60m and 200 metres below ground level. Boreholes sometimes drilled to greater depths to target abandoned coal mine workings. Boreholes drilled in larger diameters to 300mm (12 inches) or greater. This can help to maximise the water abstraction potential. Liner installed within the borehole to final depth, to restrict sediment infiltration. Submersible water pump, electric cabling, riser pipe and other equipment installed within borehole. This equipment will be specified based on a target rate of groundwater abstraction. Separate borehole(s) will be required to re-inject the (cooler) water back into the same aquifer.