Uploaded by Jay Banglos


Group II
Acmad, Aiza Corazon
Banglos, Jay
Bienes Christian Joy
Dagondon, Cyrille
Espejo, Lenra Rose
Juab, Jestonie
Rillera, Romulo
Salcedo, Jackylyn Mae
Salvejo, Mark Lester
Tagupa, Kristine Neña
Among other obstacles faced in the
construction process, water can be one of the
most challenging and costly barriers during
construction. With 71% of the earth’s surface
covered in water, and new construction
beginning every day, cofferdams are proving
to be just as significant today as they were
before the birth of Christ. By definition, a
cofferdam is a work area constructed and
dewatered to temporarily provide dry land for
construction of various types of structures.
What is cofferdam?
A cofferdam is defined as a “watertight
enclosure from which water is pumped to
expose the bed of a body of water in order to
permit the construction for a pier or other
hydraulic work.” In other words, it’s a structure
that is able to retain water and pump it out into
a different area. Whether it stores water or
pumps it in a different location, a cofferdam
ensures a dry area for construction sites.
Cofferdams have been around for centuries, but they
haven’t all looked or worked the same. The history of
cofferdams is interesting and takes us back to the
Persian empire. Here is the timeline of cofferdams used
throughout history and how they have advanced
through the years.
1. Earthen
2. Roman
3. Sandbags
4. Steel
Sheet Pile Cofferdam
5. Aqua-Barrier®
Inflatable Cofferdam
Earthen Cofferdam
The first cofferdams were
said to be used by King
Cyrus of Persia in 539 B.C.
to temporarily divert water
from the Euphrates river,
allowing the capture of
Babylon. This capture of
Babylon ended their rule,
allowing the Medo-Persian
empire to begin.
Roman Cofferdam
The Romans had their own
cofferdam, as well, and it was
made from wood pilings that
they temporarily used in order
to build bridges across the
Danube river in 102 A. D. in
what is now Romania.
In the 1880’s, during the
Napoleonic wars, people
used sandbags to control
water. Initially, these bags of
sand were used for the
protection of the troops
during battle, but eventually,
they were used as temporary
dams and water control.
Steel Sheet Pile Cofferdam
After a hundred years of using
sandbags, a milestone in
cofferdams was introduced
through the steel sheet pile
cofferdam. In the early 1900’s, a
German engineer came up
with an interlocking design of
‘U’ shaped steel to help control
water. This interlocking steel
cofferdam design is still being
used today in some countries.
Aqua-Barrier® Inflatable Cofferdam
Fast forward to 1996 and the
invention of the Aqua-Barrier®
cofferdam. This inflatable cofferdam
features a patented internal baffle
system that not only provides stability
but the ability to use on any terrain,
too. The Aqua-Barrier® is vastly more
effective and efficient than outdate
Where does the word cofferdam come from?
Which points are kept in mind for cofferdam
1. Depth and Flow
 These
conditions change from season to season. Water
World suggests reviewing the timing of the project and
consulting the U.S. Geological Survey (USGS) to gauge
fluctuations in water levels at the site to determine the best
timetable for the project.
2. Permits
 “Turbidity
requirements, contamination concerns, right-ofway restrictions, and time constraints for working in the
water” are all items that may need permits or permission to
conduct construction. Even though it is usually the
responsibility of the project engineer to understand and
obtain these permits, it is important for the contractor to
know these as well.
3. Navigating the Subsurface
 Water
world suggests that knowing, “the silt levels, slopes,
vegetation and composition of the subsurface” to
specifications to meet the projects needs.
4. Contractor Experience
 Because
of the complexity of dewatering projects, it is
important to hire contractors who have experience working
in and around water. Experience affords the contractor the
ability to understand and respond to changing conditions
of the work site. They may have come across overlapping
aspects in previous jobs to determine the best solutions for
the current project.
5. Engineering and Design Criteria
 The
last aspect a contractor needs to know
before beginning the dewatering project is the
right cofferdam technology for the project and if
the cofferdam’s construction cost meets
specifications. “Further, he or she should conclude
if the project calls for Professional Engineer
Stamped Calculations. The contractor should be
well-versed in dam safety protocol and standard
operating procedures and also able to provide
engineering support in an emergency.”
Different Types of Cofferdam
It is the simplest types of cofferdam. It is used when the water depth is
shallow, 1.2 m to 1.5 m and the velocity of water flow is slow.
Earth Cofferdam
In this type of cofferdam, an earth embankment is built around the
area to be surrounded. The top width of the embankment should not
be less than 1m.
Its waterside slope 3/2:1 and the inner side slope is kept at 2:1.
Earth embankment is made from a mixture of clay and sand or clay
and gravel.
Pitching is done by arranging boulder (large stone) on the slope of
the waterside to prevent water damage to the embankment.
Often in the middle of the embankment, Steel sheet piles are inserted
to an impervious level of soil below the embankment, to prevent
water from entering through the permeable layer of soil.
The height of the embankment is kept 0.6 m above the water level for
In the workplace, a drain is kept near the embankment from which
water is pumped out.
Different Types of Cofferdam
This types of cofferdam is useful when the water depth is up to 3.0 in
and the water flow is turbulent. In this type of cofferdam, stones are
used instead of clay in the bed. Such cofferdams are cheaper where
stones can be easily found.
Rockfill Cofferdam
The disadvantage of Rockfill cofferdam is that it is not impervious.
Where the water depth is low, an impermeable layer of soil is spread
over the waterside of the embankment.
Clay particles fill the cavities between the stones and gradually form
waterlogged structures.
The slope of its sides can be kept as wide as 1:1
Often the core wall or steel sheet pile inserted between the
cofferdam and the bottom of the cofferdam to an impervious level of
the soil to prevent water from entering the embankment.
Core walls are made of clayey soil or cement concrete.
Different Types of Cofferdam
This types of cofferdam is made of a wooden cube. The crib is a
framework made of wooden horizontal and cross beam alignment.
The film is filled with stones, gravel, or clay to increase the stability of
the crib against overturning or sliding.
Crib or Braced Cofferdam
The following conditions are favorable for this types of cofferdam:
Less workspace.
The river bed is hard.
If the water depth is high.
The water flow is an eddy type.
Wood is readily available.
Different Types of Cofferdam
This types of cofferdam is used when the area to be surrounded is
small and the water depth is high. Such cofferdams can additionally
be used up to a depth of 25 m water.
Single wall cofferdam
Guide piles are inserted on the periphery of the area to be enclosed.
The spacing of such guide piles is kept at 3m.
Guide piles are usually made of wood. Steel piles can also be used if
the water depth is high. The guide piles are then bolted horizontally
at appropriate distances by means of wooden bolts (Wales) bolts.
Then sheet piles are applied with a strut and bracing. Wood sheet
piles are used for water depth up to 10 m, steel sheet piles for water
depth more than 10 m.
On the inside and outside of the sheet, half-filled bags of sand are
rocked to increase the durability of the cofferdam.
Water is pumped out of the enclosed area and foundation work is
Different Types of Cofferdam
A single wall cofferdam is costly when the enclosure area is large and
the water depth is high. As the double wall cofferdam, the thickness
of the components like sheet piles Strut, Wales, etc. is much more
required to withstand water pressure. In such a situation a double-wall
cofferdam is useful.
Double wall cofferdam
There are two types of double wall cofferdams:
Ohio type cofferdam
Wood or steel sheeting cofferdam with Wales and tie rods
Ohio type cofferdam
This type of cofferdam is called Ohio river type wood sheeting
cofferdam. As it was first used for construction over the Ohio River in
the United States. It can be built very cheaply and quickly.
Wood or steel sheeting cofferdam with Wales and tie rods
It is used in hard layers where erosion is unlikely. Such cofferdams are
suitable for deep water or fast water flow.
Different Types of Cofferdam
This type of cofferdam is useful when the enclosure area is large and
the water depth is high. Cofferdams are used in the construction of
water structures such as boilers, pushes, etc.
Cellular cofferdam
There are two main types of cellular cofferdam:
Circular type cellular cofferdam
Diaphragm cellular cofferdam
Different Types of Cellular cofferdam
In Circular Cofferdam, circular cells are inserted into the ground to a
certain depth above the boundary area.
Such a cell is connected by an arc of a circle. The radius of such an
arc is 2.5 m. The arc forms an angle of 30° to 45° instead of contact
with the circular cell. The cell is filled with clay, sand, or gravel.
Circular type cellular cofferdam
The advantages of Circular type cofferdam are as follows:
Each cell can be filled to the head independently before the construction
of the second cell and in this way, the construction of the second cell is
not distorted so the construction of the cell can be started from a different
Each cell behaves as a self-supporting independent unit.
Less steel per unit length is used in the construction of a circular cell
compared to a diaphragm type cell.
Cellular cofferdam is suitable for heights of 10 to 15 m. The diameter
of the cell is kept from 10 to 15 m and the distance from the center to
the center is kept from 12 to 18 m. The bottom of the river is hard rocky
and the top layer of clay or silt is more suitable for such cofferdam.
Different Types of Cellular cofferdam
Diaphragm type cellular cofferdam
In this type of cofferdam, steel sheet piles are attached to each other
to form a series of arcs. Straight walls are attached to each other with
the arc of sheet piles on both sides. Usually, the radius of the arch is
kept equal to the distance between the two diaphragm walls.
In order to create uniform tension between the diaphragm and the
arch, building materials like sand, gravel etc. are filled in it after
immersing the cell in water to the required depth.
In all cells the filing of material should be done at the same rate up to
the same height so as not to wrap the diaphragm.
How cofferdam installed?
On Cofferdam installation , On-site water is pumped into the two inner fill
tubes causing the dam’s chambers to slowly and evenly inflate, forming
a strong, stable cylindrical tube. As the inner tubes continue to fill and
the water pressure builds, the dam unrolls in a controlled manner to
create the strong and dependable Cofferdam.
Cofferdam Video
Cofferdam Requirements
There are several basic requirements of any cofferdam. It must be
watertight. A cofferdam must remain standing against the pressure of
existing or added water (such as a flood). Existing water includes water
at, above, or below the groundwater table.
Cofferdam Materials
Cofferdams can be made from several different materials, such as earth,
rocks, timber, steel, and concrete. If possible, the selected material
should be relatively easy to dismantle and recycle to reduce
construction costs.
Cofferdam Construction Process
Most cofferdams are constructed using the following 12 general steps:
Pre-dredge and level the area for the cofferdam.
Drive temporary support piles.
Temporarily install a bracing frame on the support piles.
Install steel sheet piles.
Drive sheet piles to grade.
Block between bracing frame and sheets.
Cofferdam Construction Process
Most cofferdams are constructed using the following 12 general steps:
Tie sheet piles at the top.
Excavate, leaving the water inside the cofferdam.
Install internal bracing as the water is removed progressively from the
10. Drive piles as required.
11. Install rock fill.
12. Place tremie concrete seal.
Cofferdam Construction Process Video
Cofferdam Pressures
An engineer determines the best type of cofferdam to use. It needs to be of
a sufficient size to meet the project requirements in the most economical
way possible. The engineer uses standard calculations based on known and
anticipated forces including hydrostatic pressure, soil loads, water currents,
waves, ice, as well as seismic and accidental loads.
Emergency Response
With workers and equipment inside of what is essentially a deep, dry, well,
you need to have an emergency response plan in place. There are several
potential risks when working inside a cofferdam. Obviously, a flood event
causes the cofferdam to fill up with water. But rock fissures and shifting soil
conditions – even vessel traffic – can create unsafe conditions within the
cofferdam. Any emergency response plan should include dewatering
backups that are regularly inspected.
Cofferdam Removal
The cofferdam is meant to be a temporary structure. But you can’t just
pull it out, chuck it out, and be done with it. Removal of the cofferdam
must be planned in advance. A critical consideration is the impact of
cofferdam removal on the structure that was built. In some cases, the
sheet piles are sheared off and the bottoms are left in place. This is to
avoid damaging foundation soils that could in turn damage the new
What is the main purpose of
Cofferdam is commonly used to facilitate the construction or repair
of dams, piers and bridges. The aim of a cofferdam is to be as watertight
as possible to create a dry area in which to complete the required
building works, or at least to limit water ingress to a safe level that can
be pumped away.
A cofferdam is a temporary structure that provides a dedicated
barrier against water intrusion. Many construction sites use cofferdams to
create a temporary dam so they can get on with their project without
having to work in water, or to make the construction project possible in
the first place.
Factors affecting selection of
cofferdams construction
Cofferdams can be of different types. But what kind of
cofferdam to build in which place depends on the following
The area to be protected by a cofferdam
The depth of water to be dealt
The state of water
The overtopping possibility by floods tides etc.
The characteristics of a bed on which the cofferdam is
constructed. Is i.e. a pervious layer or an impervious layer.
The velocity of flowing water.
Factors affecting selection of
cofferdams construction
The availability of construction materials in the vicinity of the site of work.
Transportation facilities are available.
Increase inflow velocity due to obstruction of water flow from the
construction of Cofferdam and the possibility of erosion of bottom
Necessity of cofferdams
The need of cofferdams construction arises in the following situations:
Necessity of cofferdams
When construction is to be done on the banks of a dry or
watery river or between rivers
Necessity of cofferdams
When construction is to be done on the beach
Necessity of cofferdams
When construction is to be done on the middle of the lake or
on the shore
Necessity of cofferdams
When deep excavation is to be done at a place of deep
granular soil
Necessity of cofferdams
When deep excavation is to be done on clay soil
Necessity of cofferdams
When excavation is to be done below ground level
Necessity of cofferdams
When there is a possibility of landslides due to deep
Necessity of cofferdams
When water is likely to seep into the excavation from the
surrounding area
Uses of cofferdams
A cofferdam is used for the main purpose that provides a dry working area for
workers. Cofferdams have lots of applications, it can be used either temporary of
The following are the uses of cofferdam:
To facilitate pile driving operations.
To place grillage and raft foundations
To construct foundations of piers and abutments of bridges, darns, locks,
To enclose a space for the removal of sunken vessels.
To provide a working platform for the foundations of buildings when
water is met with.
To provide space for carrying out the foundation work without disturbing
or damaging the adjoining structures such as buildings, sewers, pipelines,
What is the difference between cofferdam and caisson?
A temporary structure which is
removed after completion of
the work.
The aim of a cofferdam is to be
as watertight as possible to
create a dry area in which to
carry out the required works, or
at least to limit water ingress to
a safe level that can be
pumped away.
built to remain in place as part
of the completed structure.
Typically, a box
like structure made
of materials such
as timber, steel, masonry and r
einforced concrete. It
maybe constructed on shore
then floated to the
required location, where it is
sunk into place,
enabling access to the bed to
undertake works.
Projects that are using Cofferdam technology.
La Mesa Dam Project:
Status: Unknown/ no Document Available
Scope: Pressure Relief Wells, Piezometer drilling and Curtain Grouting
Location: Quezon City, Philippines
Summary: The drilling of Pressure Relief and Piezometer holes inside and
outside of a Cofferdam which was being constructed as the exit
portal for a TBM (Tunnel Boring Machine) in La Mesa Dam.
La Mesa Dam Project Video
Projects that are using Cofferdam technology.
Panguil Bay Bridge Project:
Status: still on going
Scope: Installs First Pre-Cast Substructure Foundation of Panguil Bay Bridge
Location: 3.17-km inter-island bridge that will connect Tangub City and
Tubod across Panguil Bay in Northern Mindanao.
Summary: Undersecretary Sadain, explained that the prefabricated PC
house will be the foundation for the two (2) pylons each with six (6) piles
and piers 17 and 18 with four (4) piles each which are the substructure of
the project’s main bridge or the highest segment where marine vessel
such as ship could pass underneath.
Waterproof sealing are ongoing to ensure the watertightness between
pile and boxlike PC house as this will then filled inside with cast concrete
to act as cofferdam or strong foundation to make them stable against
various forces which are likely to act on the structure, Undersecretary
Sadain reported.
Panguil Bay Bridge Project
The End and Thank You for Listening!!