Silent Valley Explained

The excellent presentation by eminent engineer Dr Philip Donald FICS - The Complete Story of the Silent Valley Dam and Reservoir gave a perspective on the Engineers McCassey and McCullough proposing and constructing the Major Water supply for Belfast together with the troubles encountered. His fascinating material was very well received by members.

In his very detailed account of the building of the Silent Valley Dam and Reservoir. He pointed out that in the 1840 Act the Belfast Water Commissioners were set up to secure an adequate supply of water to Belfast.

In 1874 there were two reservoirs on the Woodburn River near Newtownabbey. In October Luke Macassey was appointed to design and build five more dams which were built by 1890. In 1891, given the growth of the City, he was asked to report on current water supplies to Belfast, future needs and future sources. He proposed a scheme for the Mourne Mountains which could be executed in 2 stages a pipeline supply followed by storage reservoirs. In 1901 he advised on moving the dam site further south. He died of pneumonia in 1908 and didn't see it built. The project was taken over by his assistant Frederick William McCullough who selected a new site and Pearson & Sons were commissioned as contractors for the £1m scheme. However the project ran into difficulties as the boreholes dug did not find the bedrock at the expected level. A row with the contractors ensued, blaming McCullough for the increased costs and delay by selecting the wrong site which went to arbitration with Sir Lynden Macassey KC (Luke's son) appearing for the contractor.

However bedrock was finally found 150' lower, the original report boreholes having hit large boulders glaciated from Scandinavia rather than actual bedrock. The contractors overcame their problems and Belfast got a water supply at a reasonable cost.

Dr Donald reported that he had superimposed drawings to try to ascertain how far the final site was from the original Macassey's proposal and found it was actually right on top of the second revised site and McCullough had been wrongly blamed!

The dam is in the same condition today as when it was built.