| 摘要 |
<p>The specification discloses a system for recovering groundwater from a subterranean aquifer (12) through an extraction well (20) having a perforated casing (28) extending down to the water table (14) and a drop-tube (24) within the casing (22) to define an annular area (23) between the casing (22) and the drop-tube (24). A vacuum pump (26) is connected to the drop-tube (24) for inducing a flow of liquid up the tube (24). An aperture (48) is provided through the wall (40) of the drop-tube (24) to enable gas from the annular area (23) to enter the drop-tube (24) to mix with liquids flowing upwardly through the tube (24) and reduce the density of the flowing column (56) so that it is more easily lifted to the surface. The aperture (48) also provides a self-priming feature which avoids start-up problems associated with known vacuum dewatering methods.</p> |
