What are Cofferdams and How are They Used?

have you ever looked at a large bridge

or other structure whose foundation was

rooted underwater and wondered how

engineers ever went about constructing

it or will ever fix it when construction

needs to take place somewhere that it's

submerged underwater engineers use a

series of large driven piles into the

water bed called copper dams to create a

dry workplace the piles of a cofferdam

are driven deep into the earth in

whatever formation necessary to a

specific depth when water is on one side

of the wall and water is pumped out of

the other side of the wall

this creates a hydraulically unstable

system which can cause water to seep

through the ground without getting too

complex into the geotechnical

engineering of this hydraulic phenomenon

there is a depth at which a wall can be

driven into the ground that will keep

water from seeping up into the other

side of the wall this depth is typically

defined by soil type and the surrounding

water table the piles used in coffer

dams for construction are usually driven

into the surface at a minimum of this

calculated height in order to keep water

out once the entire cofferdam is in

place pumps are used to extract the

water interior to the dam structure

ultimately this creates a dry work place

inside sometimes getting the piles that

make up the cofferdam to a necessary

depth on a lake ocean or river floor is

simply too expensive or impractical in

cases like this a series of pumps are

set in place to constantly pump out

excess water as it seeps into the

cofferdam structure these structures are

very commonly used when constructing

dams piers for bridges or other forms of

aquatic engineering while it may seem

that having such a large work area under

the surrounding water level may be

dangerous and it is it's not as

dangerous as you might think

work inside of copper dams is usually

only allowed under the most pristine

conditions when the water is generally

static in these states failure modes of

the pile dam are slow and predictable in

nature to help fight against these slow

failures as well a series of primary or


can kick into overdrive to help keep the

inside of the cofferdam dry until crews

can evacuate it also may seem like

creating these large copper dams are

very expensive and they are engineers

avoid using any forms of underwater

construction at all cost

but when it's needed coffer dams are

much safer than other methods of

underwater construction like using

divers coffer dams are also a more

permanent solution when continued

projects need to take place on the edge

of lakes or oceans as soon as a project

is completed water is pumped back inside

the coffer dam and the piles are removed

in terms of temporary construction

workplaces giant coffer dams may be one

of the coolest and most impressive