A concise history

The Binnian Tunnel - 1948 - 1952

Stage three of Macassey's original scheme had intended for the construction of a second storage reservoir at Annalong Valley. However, as a result of the difficulties encountered during the construction of the Silent Valley Reservoir and following findings from further geological surveys, plans for the building of a second reservoir were abandoned.

Instead, the Water Commissioners decided, as part of an alternative scheme, that the water from the Annalong River should be diverted into the Silent Valley Reservoir by means of a tunnel through Slieve Binnian.

Sam McMurray, the contractor's engineer standing at the Dunnywater tunnel entrance in 1950

Immense engineering skill was employed in driving the tunnel, which was worked on simultaneously from both ends. Construction methods involved firstly marking the face, drilling, setting explosives, firing, smoke clearing and finally mucking out. Working conditions in the tunnel were pretty dreadful by today's standards. The further they drove into the mountain, the longer it took to clear away the debris. As they neared the middle, the two teams had to travel a mile in near darkness, breathing smoky stale air, laden with granite dust and dynamite fumes.

With a design capacity of 90 million gallons per day, the tunnel is some 2.5 miles in length, approximately seven feet high and eight feet wide. In one week alone, a team of men cut 160 feet of tunnel, which was firmly established as a record on the job. Such precision was undertaken that when the two teams met, there was only a two inch difference on the centre line!

The day the two squads finally met in the middle 6th December 1950

In all 47,000 tonnes of granite were blown out in the construction of the Binnian Tunnel, making use of 100 tonnes of gelignite and 57,000 detonators. The entire scheme was a test to strength and nerve, and without fatality, was finished in record time. The Binnian Tunnel was opened by the Prime Minister of Northern Ireland, Captain the Right Honourable Viscount Brookborough of Colebrook, in August 1952.

There is a large section of "Your Place & mine" devoted to the story of the Binnian Tunnel, where you can read about the task and listen to those who carried it out. Click Here to go to it

Triplicate conduit 1949 - 1956

The time had arrived to make full use of the water available at Silent Valley and thus fulfil Macassey's plans. The capacity of the conduit from Silent Valley to the Annalong Valley was increased and the syphon sections en route to Belfast were tripled allowing for a maximum supply of 30 million gallons per day. Farrans (Construction) Ltd carried out the work, making first use of mechanical equipment since the war.

Farrans stringing pipes across the countryside

The new triplicate conduit crossing a river in the early '50s