Client: Buro Happold

To design, fabricate and install a Limpet Dam to a dock redevelopment

Kaymac were approached by Buro Happold Engineering for our design, fabrication and installation of a Limpet Dam expertise.

A limpet dam is a large steel structure which is positioned on the side of a quay wall or dock below the water line. By removing the water from within the limpet, the external water pressure against the structure creates a water-tight seal that allows essential repairs to be undertaken in a safe, dry environment. In this instance, the Limpet Dam was needed for the dock wall adjacent to Brandon Yard which was being redeveloped for residential use. As part of this redevelopment, the installation of a 600mm diameter drainage pipe through the dock wall was required below the Floating Harbour water level.

The suitability of the harbour wall for the limpet dam installation was ascertained by a pre-works diving survey carried out by Kaymac.  Once the wall was wall was examined, the Limpet Dam was designed by in-house engineers and fabricated in Kaymac’s workshop.

The Kaymac team carried out the civil engineering works to install the manhole and outlet pipe, for which the limpet dam is required. Operative’s core drilled a hole for the pipe through the wall from an excavation on the landward side. To facilitate this, a limpet dam was attached to the wall and the water pumped out prior to the commencement of drilling operations. The limpet dam was then used to gain access for making good to the annulus between the hole and the pipe. The limpet dam was delivered to site by road transport in two sections and was lifted off the road transport using the Kaymac civil engineering team’s 13t excavator, using suitable certified lifting chains, slings and shackles, and set down at the southern end of the site adjacent to the dive location.

The excavator was then positioned above the section of wall where the limpet dam was required.

The lower section of the limpet dam was then lowered over the harbour wall and down until it touched the harbour bottom. A diver then entered the water via the steps ladder from the pontoon where he was pulled by the tender along to the limpet dam where he proceeded to descend and check to ensure there is no debris or detritus trapped between the limpet dam seal and the wall.

The lower section of limpet dam was then raised into position and the invert level of the limpet dam was checked against the level of the top of the harbour wall where the client’s representative confirmed once the line and level of the limpet dam was correct. Once fixed into place, a diver descended to check around the seal and establish the position of any leaks, Waterplugs were then used where needed to seal any leaks between the limpet dam and the harbour wall.  The Limpet Dam was successfully sealed to the quay wall and dry working area achieved. 

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