"Promoting construction excellence through                     


                                  constant attention to the details"


Caisson Construction

Webster’s dictionary defines a “caisson” as ”…a watertight box for underwater construction work.”  Municipal Builders utilizes this type of construction to construct a deep structure in an area with either tight site constraints or poor soil conditions.  This method of construction is usually used as a cost effective alternate to the need for “sheeting” as a soil retention system.  This method is only cost effective if an open hole is not a viable option for the construction of the structure.  In general structures utilizing this method are 25 to 70 feet deep or deeper.  Sewage lift stations are the most common structure of this type.  Drawing off John’s experience with Barbarossa and Sons, a pioneer in this type of construction, Municipal Builders started pursuing caisson work early in its history.

Here is how this method works:

Cutting shoe1)

A structure is designed with the inside   dimensions desired by the design team.  The structure is designed with an open bottom and “cutting shoe” which forces all of the earth below the structure to the inside as it “sinks” to its desired elevation.  The structure is poured in manageable vertical lifts and the structure is excavated from the inside utilizing a clam bucket on a crane.   


As the structure sinks more vertical lifts are added and the sinking operation continues.  The ground water is allowed to seek its own level within the structure and the vertical excavation continues thru the groundwater within the structure.  No dewatering is necessary.


Once the structure is sunk to the proper elevation a concrete plug or “trieme” is poured in the bottom of the structure below the water which is left in the structure at its static level.

Finished floor with piping4) 

Once the “trieme” or concrete plug has cured the water is pumped out of the structure and a finished bottom is poured on top of the trieme plug.  From this point on conventional construction practices are used.


As stated above this method of construction becomes cost effective only when conventional “open cut” methods of construction is not possible due to site constraints or poor soil conditions. 

Municipal Builders has extensive experience in this type of construction.  We possess the experience required to be responsible for the design and implementation of the processes used to correctly construct a structure in this manner. 

Potential difficulties include:

  • Keeping the structure straight as it sinks into place.

  • The ability to advance the structure to its desired elevation and stop it once you achieve the correct elevation.

  • The ability to provide a watertight structure upon completion.