Section 2112. Wick Drains
B. Wick drains consist of a band-shaped plastic case which permits continuous vertical drainage, wrapped in a filter material, installed in the subsoils by displacement methods, and spaced and arranged as shown on the plans.
two weeks prior to construction, submit wick drain samples and certification
indicating the source and material properties of the drain materials. At the Preconstruction Conference, submit to the
Engineer for review and approval
details of the sequence and method of installation, including installation equipment,
anchoring, manufacturer’s splicing method, certification indicating source of
wick drain material, drain layout, and numbering plan. Approval
Review by the Engineer does not relieve
the Contractor of the responsibility of installing the wick drains according to
the contract documents.
wick drains consisting of a plastic drainage core encased in or integrated with
a filter jacket.
Ensure it is band-shaped with
an aspect ratio (width divided by thickness) not exceeding 50. Prefabricated
wick drains meeting this specification are listed in Inspection and acceptance of wick
drain materials will be according to Materials I.M. 442.01.
Meet the following requirements:
· Provide continuous vertical drainage.
· Continuous plastic material (excluding splice area) fabricated to promote drainage along the axis of the vertical drain.
a. Install a jacket that allows free passage of pore water to the core without loss of soil material or piping. Meet the following requirements for jacket material:
· Manufactured from a synthetic non-woven geotextile capable of resisting all bending, punching, and tensile forces imposed during installation and during the design life of the drain.
· Sufficiently rigid to withstand lateral earth pressures due to embedment and surcharge so that the vertical flow capacity through the core will not be adversely affected.
· Sufficiently flexible to bend smoothly during installation and induced consolidation settlement without damage.
· Comply with the following specifications:
Table 2112.02-1: Wick Drain Jacket Specifications
Minimum Average Roll Value
Grab Tensile Strength2
ASTM D 4632
ASTM D 4533
ASTM D 4491
Apparent Opening Size (max.)
ASTM D 4751
60 sieve (250 µm)
2 For bonded drains, tensile strength test may be conducted on assembled drain using ASTM D 4595.
3 For bonded drains, trapezoidal tear test is waived.
b. Do not allow the jacket material to be subject to localized damage (for example, punching through the filter by sand/gravel particles). Ensure the jacket material does not undergo cracking and peeling during installation of the drain.
3. Assembled Drain.
Meet the requirements below. The Engineer may reject material that is damaged during shipment, storage, or handling, or which does not meet the minimum requirements of the drain material.
· One single type of assembled drain used on the project, unless the Engineer approves otherwise.
· Mechanical properties (strength and modulus) of the assembled vertical drain equal to or greater than those specified for the component jacket and core.
· Resistant against wet rot, mildew, bacterial action, insects, salts in solution in the groundwater, acids, alkalis, solvents, and any other significant components in the site groundwater.
Minimum discharge capacity of
3500 cubic feet per year (100 m3/yr)
1.5 gallons per minute
(9.46 x 10-5 m3/s ) when
measured under a gradient of one at a minimum
lateral confining pressure of 25 psi (172 kPa) according to ASTM D 4716.
· Ensure it is band-shaped with an aspect ratio (width divided by thickness) not exceeding 50.
· Minimum equivalent diameter of 2 inches (50 mm) using the following definition of equivalent diameter:
dw = (a+b)/2.
dw = diameter of a circular drain equivalent to the band shaped drain (inches (mm)).
a = width of the band shaped drain (inches (mm)).
b = thickness of the band shaped drain (inches (mm)).
· Drain material labeled or tagged in such a manner that the information for sample identification and other quality control purposes can be read from the label. Ensure, as a minimum, each roll is identified by the manufacturer as to lot or control numbers, individual roll number, date of manufacture, manufacturer, and product identification of the jacket and core.
· Ensure during shipment and storage the drain is wrapped in heavy paper, burlap, or similar heavy duty protective covering and according to the manufacturer’s recommendations.
1. Install wick drains using equipment of a type that will cause minimum disturbance of the subsoil during the installation operation.
the wick drains using a mandrel. Push (in one continuous movement) the mandrel
through the sand blanket (if required by the
contract documents) and into the soil.
or driving are options if the Engineer approves. Obtain the Engineer’s approval for
use of vibratory methods. Driving or jetting installation methods are not
permitted. Ensure the mandrel:
· Protects the wick material from tears, cuts, and abrasions during installation,
· Is rectangular or rhombic in shape and of a cross sectional area not to exceed 10 square inches (6500 mm2), and
· Is provided with an “anchor” rod or plate at the bottom to prevent soil from entering the bottom of the mandrel during installation of the drain and to anchor the bottom of the drain at the required depth at the time of mandrel removal.
A. Familiarity with site conditions and the available
geotechnical information is a necessity.
to installation of the wick drains, demonstrate the equipment, method, and
materials produce a satisfactory drain installation. Drill at least two borings
within the area designated on the plans in order to sSelect the equipment, method, and materials:
1) suitable for the existing site conditions; and 2) capable of producing a
satisfactory drain installation to the minimum elevation. Installation of up to ten trial drains may be
required in each of two to four test locations designated by the Engineer.
Compensation will be made for each trial drain if the installation satisfies
the requirements of the contract documents. No compensation will be allowed for
installing unsatisfactory trial drains. This may require the contractor to
drill additional soil borings. Demonstrate the equipment, method, and materials
produce a satisfactory drain installation by installing a trial drain at the
location of the first production drain.
B. The Engineer’s
review of the method and equipment used
to install the trial drains does not constitute acceptance of the method for
the remainder of the project. If the Engineer considers that the method of
installation does not produce a wick drain that satisfies the requirements of
the contract documents, alter the method or equipment, or both, in order to
D. Install the wick drains following placement of the sand blanket (if required by the contract documents). Install a granular blanket of sufficiently coarse material and compact to provide a stable working surface.
E. Locate, number, and stake wick drains. Take all
reasonable precautions to preserve the stakes. Ensure drain locations vary by
no more than 3 inches (75 mm) from the locations indicated on the drawings.
Two weeks prior to construction, submit drawings to the
Engineer for approval showing the method of field locations, drain layout, and
F. Auguring or other methods may be used to loosen
stiff upper soils prior to the installation of the drains, provided such
operations do not extend more than 2 feet (600 mm)
below the bottom of the sand blanket into underlying compressible soils. After the wick drain has
been satisfactorily installed, fill all holes or voids created by such
operations with sand.
G. Check the installation equipment for plumbness prior to advancing each drain. Ensure the plumbness of the mandrel does not deviate more than 1/4 inch per foot (50 mm per meter) from vertical. Install the drains to the minimum elevation as shown on the plans. If the penetration shown on the plans is more than 1 foot (300 mm) into the underlying foundation layer and difficulties are encountered prior to achieving the indicated depths, install the drains to a depth of 1 foot (300 mm) below the bottom of the soil layer(s) being improved by wick drain installation as shown on the plans.
H I. The
Engineer will reject wick drains that vary from their proper location by more
than 6 inches (150 mm) at the ground surface, drains that are damaged during
installation or subsequent construction, or drains that are improperly
completed. No compensation will be allowed for any materials furnished or for
any work performed on such drains.
J K. Splices or connections in the wick drain material
will not be allowed. Provide splices with structural and hydraulic continuity of the drain.
A maximum of one splice, constructed according to manufacturer’s splicing
method, per drain is allowed. Ensure manufacturer’s splicing method is
compatible with installation equipment.
K L. When
obstructions that cannot be penetrated by the drain installation equipment are
encountered below the working surface, notify the Engineer and complete the
drain from the elevation of the obstruction to the working surface. At the
direction of the Engineer, attempt to install a new drain (maximum of two
attempts, as directed by the Engineer) within an 18 inch (450 mm) radius from
the obstructed drain. The Contractor will be compensated for each obstructed
drain unless the drain is improperly completed, in which case no compensation
will be allowed.
After installation, cut each drain horizontally such that approximately 6
inches (150 mm) of drain material extends above the top of the sand blanket or as otherwise specified by the contract documents.
Engineer Contractor will shall keep a daily log which lists for each
drain the date of installation, top elevation, tip elevation, and pay length. A
copy of each daily log will shall be provided to the Contractor Engineer.
A. Measurement for Wick Drain (including trial wick
s) will be feet (meters)
installed according to the contract documents, calculated from measurements
taken from the top of the drain to the tip elevation of the drain.
· Field staking for the location of wick drains, and
· All labor, equipment, and materials necessary to complete the installation according to the contract documents.
E. The cost of
borings drilled to select the equipment, method, and materials suitable for the
existing site conditions to produce a satisfactory drain installation is
incidental to the price bid for Wick Drains.