This technique for well development comprises a dual pipe eductor system where well water fines and sediment is "hovered" through centre of the eductor pipe to surface and discharged at appropriate location.

A column of air is connected to centre of eductor pipe at prescribed distance set-off the bottom of the eductor pipe displacing well water in the hollow centre of pipe and thereby creating a vacuum for additional well water to enter the base of eductor pipe and continue the process of displacement at surface. This method has advantages over direct air method as larger volumes of water can be displaced and the dual pipe eductor system is more gentle to abstract (ie hoover) fines and sand and sediment from the producing aquifer than direct air method.

All aspects dealing with discharge of water to surface water courses, landowner permission , pipeing system .......bearing in mind the longer the length of discharge pipe the greater the restriction on the water flow needs to be considered. In addition the capacity & impact on any nearby surface drain/river to cope with the volume of water and the presence of silt content in the water must be dealt with adequately in advance of commencing airlift.

Equipment

Air compressor, dual well drill pipe, crane/rig, well head fittings to plumb into airline and accommodate water discharge.

Methods used include:

• Jetting: circulating a high-pressure water jet in the well.
• Surging: Moving a tightly-fitting plunger up and down in the well.
• Bailing: Moving a bailer (a long steel tube with a foot valve) up and down in the well.
• Dual Pipe Air-Lift System: Technique to discharge dissolved, silty water under air pressure through an annular eductor pipe to airline.