The Electrification of the Irish Free State
...ield of hydropower for their economic and technical evaluation. They approved the report with some minor modifications. In June of 1925, the Shannon Electricity Act was passed through the Dail and this enabled the project to go ahead. The contracts were signed between Seimans and the Irish Government on the 13th of August 1925 and work began almost immediately. Construction: The River Shannon is an extremely flat river for its size, the only significant fall occurring between Killaloe and Limerick. Hence, the decision to locate the power station at Ardnacrusha, just outside Limerick City. A damn had to built at Parteen Weir, (about 5 miles south of Killaloe) to divert the river down a new man made canal called a headrace. This headrace was to be12.6km long and would end at the power station. A tailrace 2.4km long would then have to be built to return the discharged water back into the old river. The power station it self would have four major parts and I will explain these by showing you some old photographs. (Photo No1). This is a photograph of the construction of the Intake Sluice House. This was a massive structure that spanned the mouth of the headrace. 600,000 tons of concrete was used to construct this damn and it contained the sluice gates, which regulated the flow of water to the turbines. (Photo No. 2) On the other side of the Intake Sluice House were the pentstocks. These were large cyclindrical tubes 6m in diameter, 41m long and set at an angle of 31 degrees. Each pentstock could deliver 100 tons of water per second to the turbines. This photo only shows three but a fourth pentstock was added in 1933 when another turbine was commissioned. (Photo No. 3) At the bottom of each pentstock, you had what was called the spiral casings. These connected the pentstocks to the turbines. They reduced in size to increase the velocity of the water as it entered the turbine rotors. This particular photo also gives you an idea of the construction methods and equipment of the time. (Photo No. 4) Finally, you have the power house itself. This was a steel framed building whose foundations were 98 feet below the intake sluice house. This had to be an extremely strong structure to support the massive weight of the turbines. (Photo No. 5) This is just an overview of the whole power station. You can see the powerhouse in the fore ground and you can just make out one of the pentstocks. In the background you can see the intake sluice house. Logistics: As you can imagine, the infrastructure at the time was extremely poor. The country was just on the back of a civil war, the Free State had just been established and a new and inexperienced government was in office. Seimans faced a massive task to transport the equipment to the various locations on the site. Most of the equipment was to come in through Limerick Docks, so a narrow gauge railway was laid from Limerick Docks to Longpavement. Here, a depot was established and various other railway lines were laid from here to the different locations on the scheme. In total, over 100km of narrow gauge railway was laid. New roads also had to be laid and four new concrete bridges had to be built over the new canals. Two huge cranes were erected in Limerick Docks to unload over 30,000 tones of equipment from the various ships. A list of some of the equipment that came through Limerick Docks included 96 locomotives, 1,350 wagons, several hundred trucks, track laying machines, excavators, dredgers and various other plant and equipment. The project took a total of 3.5 years to complete and finished within time even though it was delayed by three months because of a strike over labour rates. 5,000 people worked on the scheme at its peak. This included 4,000 Irish m...