How to lay geotextile and install wick drains (PVD)

Why they go in together

On soft, water-logged ground the two are a team. A geotextile separation/drainage blanket goes down first, then wick drains (PVD) get driven through it to shorten the drainage path and speed consolidation. The geotextile carries pore water sideways to the edge; the wick drains move it up out of the deep clay. Lay them in the wrong order and the working platform silts into the subsoil before you've installed a single drain.

Laying the geotextile blanket

Spread the geotextile flat over the prepared platform with overlaps as specified, forming a separation and drainage layer at the base of the working pad. Cover it with a sand drainage blanket. This pad does two jobs at once: it carries the rig, and it channels the water the wick drains expel away from the fill instead of letting it pond under the embankment.

Wick drain installation

A mandrel rig pushes each PVD core into the soft soil on a triangular or square grid — commonly 1.0–1.5 m spacing — down to the firm layer. The core is anchored at depth with an anchor plate, the mandrel withdraws, the drain is cut above the sand blanket, and the rig steps to the next point. Spacing and depth come straight off the consolidation design, not off what's quick on site; tightening or skipping points to save a day shows up later as settlement that misses tolerance.

Surcharge and acceptance

Once the drains are in, a surcharge fill — often with vacuum preloading — drives consolidation, and you monitor settlement until the target degree is reached. Accept the work against installed depth, grid spacing and the verticality logged for each drain; a drain installed short of the firm layer drains nothing. Tell us the platform area and grid and we supply matched wick drain and blanket geotextile together.