Cofferdam Burning in Portland Harbour

This month Commercial and Specialised Diving have been carrying out underwater burning works on cofferdams all over the country. For our October newsletter we will be reviewing the works at a site in Portland Harbour removing a cofferdam following the construction of a hydraulic ramp

coffer inside
View from inside the cofferdam before it was flooded

Cofferdams are temporary enclosures, typically constructed of mild steel sheet piles. The watertight enclosures are pumped out of any water creating a dry work environment for construction. Once the construction works have been completed, the area is flooded and divers are called in to cut out the redundant sheet piles using underwater burning equipment. We recently wrote about some cofferdam burning works we conducted at the RNLI college in Poole Harbour.

Underwater burning requires experienced operators to utilise oxy-arc cutting equipment which cuts steel by creating an arc between the metal to be cut and the electrode, with temperatures reaching in excess of 2000°C. All works were completed on time and to the client’s satisfaction.