Wick drains

Also known as Prefabricated Vertical Drains, wick drains provide drainage paths to remove pore water out of soft compressible soil to consolidate it much more quickly than it otherwise would.

Prefabricated geotextile filter-wrapped plastic strips with molded channels are vertically inserted in a grid pattern, and these artificial drainage paths can reduce soil consolidation times from years to weeks.

Wick drains are applicable to fine-grained soils such as silts, clays, organic silts, organic clays, peat, sludges and dredge fills.

As a means of essentially squeezing water out of soil, wick drains can be very useful in the construction of road and railway embankments. The technique is also suitable in making green and brownfield areas suitable for construction.

“As water gets squeezed out of soft soils into a wick drain, the soil becomes densified.

“By driving the wick drains at one metre centres, an alternative path is created for the water.

“Once that water’s squeezed out, other water can’t get back in.

“What was previously a strata which couldn’t safely and steadily support any sort of heavy structure then can.

“The great advantage of wick drains are their high-speed installation, and the fact that their accelerated drainage can in turn speed up construction schedules.”

Terry Donnelly