Wick drains, also known as Prefabricated Vertical Drains (PVD) are prefabricated geotextile filter-wrapped plastic strips with molded channels. These act as drainage paths to take pore water out of soft compressible soil so it consolidates faster, often from decades to months.

Wick PVD drains technique illustration

Common uses

Typically used in soft, saturated fine-grain soils, such as silts, clays, peat, sludges, mine tailings and dredge fills, with big pore capacity and normally filled with water (fully saturated)
Accelerate drainage
Consolidate tailing ponds and leach pads

Process

Wick drains or PVDs consist of a prefabricated strip which is ideal for water transportation. The flexible core is typically manufactured of polypropylene and both sides have grooves allowing water to flow unimpeded. The core is wrapped in a strong and durable geotextile filter fabric with excellent filtration properties, allowing free access of pore water into the drain. This also prevents piping of fines from adjacent soils without clogging.

The drain is fed down through a hollow mandrel mounted on an excavator or crane mast, connected at the bottom to an expendable anchor plate. A vibratory hammer or static method is used to insert the mandrel to design depth. It’s then removed, leaving the wick drain in place. The wick drain is then cut at the ground surface, a new anchor plate connected to it, and the mandrel moved to the next location. A pattern of installed vertical wick drains provides short drainage paths for pore water, which accelerates the consolidation process and the construction schedule.

Advantages

High-speed installation
Accelerated drainage and in turn construction schedules

Quality assurance

We can ensure quality through:

  • Automated data acquisition to record all installation parameters
  • Trial area monitoring to prove design assumptions
  • Surcharge monitoring