Why use PVD over sand drain

• PVD’s have high discharge capacities, typically 30 x 10-6 m3/sec to
  90 x 10-6 m3/sec compared to a Ø 0.35 sand drain with a discharge capacity of 20 x 10-6 m3/sec (Van Santvoort, 1994).



• When installed with purpose designed mandril, smear effects are much smaller for PVDs than for the large diameter sand drains. Zone of smear is directly proportional to the diameter of mandril used for installation.



• PVD’s (prefabricated vertical drains) are consistent factory produced whereas sand drains are subject to quality variance of naturally occurring sands.