The Liffey Siphon

The Liffey Siphon was constructed in circa 1900 as part of the original Dublin City Drainage Scheme that removed untreated wastewater discharges from the River Liffey. The siphon runs from Eden Quay (north bank of River Liffey) to Burgh Quay (south bank of River Liffey) and is within the Dublin City centre catchment.
The Rosie Hackett Bridge is a Luas and Bus transport corridor. The bridge was constructed directly over the siphon in 2012 under an NTA/DCC Transport Project. The siphon structure is considered a critical wastewater asset within the Greater Dublin Area (GDA).
The Liffey Siphon, which is an inverted siphon (always submerged with flow), is a single cast-iron pipeline. It is brick lined with an internal diameter of 3 feet 4 inches (1m) and is 210 feet long (64 m).

GMC Utilities Group on behalf of Uisce Eireann will undertake a detailed survey of the siphon, including confined space entry to carry out a sonar and an acoustic survey. This will be one of the first occasions in Ireland where this method will be used to survey a wastewater siphon. The results will indicate the condition of the aging structure and the need for remedial works.