ABSTRACT
Vacuum well-points comprising slotted PVC plastic pipes, 38mm up to 152mm diameter and about 200mm long (or sometimes longer), are often gravel packed for greater efficiency. The screened or slotted sections of a well-point should have holes or slots fine enough to keep soil or backfill out but sufficiently open to let the water enter freely. Such systems offer a flexible dewatering facility for fine sands and silts where the quantities of water to be pumped out are not large. A typical pumping capacity of a 38mm diameter riser pipe is approximately 1 litre/s.
