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FRENCH DRAIN
The French drain is intended to provide drainage away from a foundation when that
foundation experiences problems due to the unwanted presence of water. A trench
is dug from the lowest point of the foundation in a downhill direction. Permeable
geofabric lines the trench and a layer of washed stone is laid in the bottom of the
trench. A corrugated pierced plastic pipe is placed at the top of the initial layer of
washed stone, which is then covered over with washed stone.
SAND DRAINS
A sand drain is a simple process, employing a column of at least 10 inches in width
augered into ground to be surcharged and consolidated. The column is then filled
with sand and connected to a free-draining blanket of granular soil. The purpose
of a sand drain is to allow shorter drainage paths and relieve increased pore
pressures during surcharging and consolidation of a weak soil strata, thus decreasing
the required consolidation time.
WICK DRAINS
Wick drains are composed of a PVC shell with filters composed of paper or polyester.
The filters vary in permeability by size of soil material and an investigation of prevalent
site soil types should be undertaken prior to choice and installation of the wick drain.
Wick drains are installed by various methods (e.g., vibratory pile hammer or mandrel)
depending again upon onsite soil material. Fill placement over wick drains must be
monitored for lift thicknesses and time intervals between placement to avoid rupture
of lateral displacement of weak soils, which will cause kinking of the wick drain and
a corresponding loss of effectiveness. Wick drains provide an alternative to sand
drains and are used for the same purpose of reducing time required for consolidation
and preloading of weak strata prior to construction.
SAND-WICK DRAINS
The sand-wick drain is a unique patent-pending process developed by Barrier
Geotechnical Contractors, Inc. The sand-wick drain combines features of both the
sand and wick drains and is used for the same purpose, reducing the time required
for consolidation and preloading of a weak bearing stratum prior to construction.
The sand-wick drain is between 4 and 10 inches wide, filled with sand, in which a
wick drain is placed.Once installed the drain is connected to a free-draining blanket
of granular soil and surcharging may begin. |
