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Water Projects : Water Supply
| Project Name |
- Inishbofin Public Water Supply
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| Client |
- Atkins was appointed by Galway County Council to undertake an assessment of the water supply on Inishbofin in response to problems with water quality and source yield. The island is located 3 miles off the west coast of Ireland and has a permanent population of 210 which rises sharply during the summer months due to tourists.
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| Project Development |
- The source for the scheme is a natural water body located in a depression in the central part of the island and which is recharged entirely by rainfall. The abstraction is by means of an intake pipe extended along a jetty and feeding into an infiltration chamber. The water is treated by slow sand filtration and chlorination. There is a raw water tank with a capacity of 56.8 m3 and a clear water tank of 113.6 m3.
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| Scope |
- A demand analysis was made for the island under both normal and peak demand scenarios. Pressure loadings resulting from tourist demand accounts for much of the pressure placed on the raw water source during summer months. A water audit was carried out under peak demand conditions which estimated unaccounted for water to be in the order of 30%.
- The exposed nature of the lake means that it is prone to contamination. A serious contamination incident occurred in 1996. The efficiency of the disinfection equipment was verified and measures recommended to ensure adequate chlorine residuals were detected within the system.
- The possibility of reusing some of the many dug wells which supplied the island prior to the commissioning of the public supply was assessed. Many are located near to septic tanks which compromises their suitability for reuse.
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| Recommendations |
- Recommendations were made to extend the operational life of the water treatment and storage infrastructure, which are in need of remedial structural works, especially given their exposed condition.
- Short term recommendations for the scheme included the complete fencing in of the lake, the installation of meters to allow the abstraction to be monitored, the rehabilitation of the slow sand filter which was found not be operating at maximum efficiency, regular flushing of the distribution network and increased frequency supplied water quality sampling.
- Longer term recommendations included a detailed yield study of the lake, the construction of a bund to increase lake storage, provision of a second sand filter to allow filtration to continue during maintenance of the main filter, relocation of the chlorine dosing point, redesign of the intake point to maximise the volume of water abstracted and a condition assessment of the distribution network part of which is constructed above ground.
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