Prefabricated Vertical (PV) Wick drains, are a synthetic 'band' shaped material approximately 4 inches wide by 1/4 inch thick.  The material is installed vertically into soft soils in order to shorten the path water must travel, in order to expedite the construction process. 

Why use Wick Drains? 

Since water is effectively incompressible, soils must drain pore water in order for the soil skeleton to support the weight of a new loading condition such as a building or embankment.  By shortening the drainage path in fine soils such as silts and clays that can take several years to drain, the water can escape in weeks or months, and the soil can realign into a configuration capable of supporting the new loads. 

Design Guidelines

Nilex has been installing wick drains for over 20 years, and has seen many good, and not so good wick drain designs.  Many engineers have never had the right conditions to incorporate wick drains into the design.  Nilex has compiled some simple guidelines to help the new engineer with constructability and other issues.

Strip Drains

The function of the wick drains is to allow the water to squeeze out of the soil.  If there are no significant drainage layers within the soil strata or at the lower extent of the wicks, the water will be squeezed out of the soil up to the surface.  At the surface the drainage conduit must be maintained in order to prevent 'capping' off the tops of the wick drains.  This can be achieved by a sand/gravel drainage layer, or a synthetic drainage material called a Horizontal Strip Drain.

Equipment

Nilex has pioneered the development of new equipment with greater push force than any other equipment in North America.  In addition to the conventional installation machines, Nilex's 'can do' approach and equipment knowledge, has led us to develop many machines for special applications.

Piezometers

By measuring porewater pressure, piezometers allow engineers engineers to determine that settlement is complete and construction can begin.  Nilex is able to install pneumatic piezometers with the wick drain installation equipment, saving the project the expense of bringing out (and contracting) another drilling company to install the measuring devices.

Download Material and Installation Specifications Here

View Publications and Papers on Prefabricated Vertical "Wick" Drains Here