What’s a wick drain, and how do they work?

The term wick drain is a misnomer because these clever devices do not actually wick away water. Wick drains, more accurately called prefabricated vertical drains (PVDs), consist of synthetic band-shaped material that is installed vertically into soft soils to accelerate preconstruction preloading programs.

The drains are approximately 102mm wide by 6mm thick and are composed of a plastic strip with drainage channels, wrapped in a geotextile filter fabric. Once the PVDs are installed, a sand layer is placed covering the wicks, followed by a surcharge load (usually dirt) that compresses the water into the porous sand and encourages soil consolidation. The process can shorten soil consolidation from years to weeks.