Cofferdam work – Includes pile driving, excavation and masonry or concrete work up to completion of the substructure only.           

Shaft sinking – Includes pile driving, excavation, concrete work or lining.

Code 6252 applies to employers engaged in all operations involving shaft sinking for bridge footings, piers or foundations.  The operations involve the removal of earth from a hole with a relatively small diameter and usually from a considerable depth as compared with its diameter.  To prevent cave-ins, wooden or steel sheeting may be driven into the shaft by hand or power apparatus.  This classification contemplates these operations as well as any pile driving, and concrete work connected herewith.   This classification is also applied to specialist contractors engaged in all operations involving pneumatic caisson work for bridge or pier foundations.

Pneumatic caissons are closed casings in which air pressure is maintained equal to the pressures of water or soil on the outside.  This classification includes all employees working under air pressure, others engaged in or upon the caisson or the apparatus connected therewith as well as any pile driving, excavation, masonry or concrete work.

This classification is also applicable to specialist contractors engaged in all operations involving non-pneumatic caisson work for bridge abutment, pier and underwater foundation construction up to the completion of the subbase or sub-foundation.  This classification contemplates the driving of steel piling to the desired depth to form compartments of the required size and the removal of earth and water by clamshells or pumps.  This classification also contemplates the pouring of concrete into the shell and the removal of the piling.  Non-pneumatic caisson work in connection with dam or lock construction falls within the scope of this classification but only with respect to the construction, maintenance or removal of the caisson.  Additionally, this classification applies to specialist contractors engaged in all operations involved in non-pneumatic cofferdam work.