MicroWell wellpoint systems from Hoelscher Dewatering have proved to be particularly well suited for dewatering of excavation steps at depths not greater than approx.
6.0 m. These systems are also very useful when dewatering is required for small shallow excavations or on sites where space is at a premium.
Installation requires a borehole approx. 110 mm in diameter which can be sunk by straight-flush rotary drilling or dry drilling to a depth of 8 meters.
A plastic pipe 50 mm in diameter is inserted and centred in the drilled borehole. The bottommost 1 m section of the pipe is perforated with slots 0.3 mm in width. The annular space around the pipe is then backfilled with filter gravel and sealed with clay sealant.
The individual wellpoints are connected by PVC vacuum hoses to a peripheral header main. Powerful vacuum pumps create a vacuum in the header main up to - 0.9 bar
(13 psi). The vacuum on the pump«s inlet side pulls the water through the wellpoints, therefore draining and stabilizing the surrounding soil layers.
When the construction work in the excavation is completed, the plastic pipe is removed and the borehole is backfilled with inert material.
Providing outstanding wash-out resistance over their entire installed length, MicroWell wellpoint systems perform reliably in most types of soil strata.