Finding Dublin’s deeper side – Alexandra Basin

When you talk about Alexandra Basin, you are talking about the dreams of one young man: Bindon Blood Stoney. He was the assistant engineer who had considerable vision, and conceived of much larger ships one day arriving in Dublin port. Today all of the new quays and docks that were designed and built by him are still able to take the biggest ships that are capable of entering the port.

Stoney had answered an advertisement in 1856, to work with the Inspector of Works, or chief engineer, the famous George Halpin.

Stoney had a radical idea to build the principal works on the deep water berth using Portland cement to help construct foundation blocks, which would be floated into position and lowered to the seabed. His ideas were in contrast to the traditional method of using cofferdams and manually laying stonework within.

William Gladstone visited the works in progress and he was shown around by Stoney. The Prince and Princess of Wales visited Dublin in 1885 and officiated at the naming ceremony for the new deep-water docks. Princess Alexandra broke a bottle of wine and christened the dock ‘Alexandra Basin’, the name it still bears. There is a contemporary illustration from the ‘Illustrated London News’ that shows the Prince and Princess at the naming ceremony with Bindon Blood Stoney in attendance and the diving float and bell in the background. While there, they were given a demonstration of the shear-float laying one of the blocks.

In 1861, when the ideas were developed, he met with opposition from his senior, but Halpin’s retirement in 1862 left the way open for Stoney and the Ballast Board to work together on the new design. When the Ballast Board was reconstituted in 1869 as the Dublin Port and Docks, Stoney was its chief engineer, a post he held until his retirement in 1898.

Stoney achieved many things. He designed improved dredging techniques; for rebuilding works on the Essex and Carlisle Bridges; and the construction of the first Beresford (or Butt) Swing Bridge.

He is also associated with converting half the quays along the Liffey into deep-water quays. His work on the quays included the new method of underwater construction which he had first encouraged in 1861. Massive concrete blocks, weighing 350 tons each, were made on a block wharf located on the north side of the basin, and then moved to their destination by means of specially designed floating shears. The blocks were lowered into position on the river bed, which had been previously levelled by workmen using a special diving bell which Stoney devised for this purpose, and which still survives today on Sir John Rogerson’s Quay.

Diving Bell - Dublin — Diving Bell – Dublin

The fame of Stoney was not based on the methodology itself, but rather the size and scale of the blocks he designed and used. Harland and Wolff in Belfast built the shear float, and Grendon and Co. of Drogheda built the diving bell. The foundation blocks were cast on the specially built block wharf and allowed to cure for several weeks. Large cast iron girders were incorporated into the bottom of the blocks and wrought iron lifting bars were attached to these.

In preparation for the foundation blocks, the overburden would be dredged prior to the positioning of the diving bell. A six-man crew would work inside the bell, levelling the ground surface to ensure that the caissons would be lie accurately.

As of 2019, there are plans to redevelop the basin. Dublin Port Company wants to develop the port’s infrastructure in accordance with a framework established in its “Master-plan 2012 to 2040”. A central objective of this master-plan is to cater for at least a doubling in cargo volumes over the coming three decades.

The project includes the implementation of the master-plan which involves the following
Construction of 3km of quay walls
Dredging of 6.4m m3 of material to deepen the port’s entrance channel by 2.2metres over a distance of 10km
Remediation of 0.5m m3 of contaminated dredge spoil and its reuse in the port as infill
Works to conserve and interpret the port’s Victorian industrial heritage