Limerick Main Drainage Scheme

The Limerick Main Drainage Scheme is a major environmental and infrastructure project to provide a foul water drainage system and treatment facility for Limerick and its suburbs. Up until the project was commissioned, 4 million gallons of wastewater was discharged daily into the Shannon and Abbey rivers from more than 50 outfalls.

The Shannon River Crossing allowed the drainage system on the North side to cross the mighty Shannon River to where the treatment plant was located on its southern banks. The unusual ground conditions of alluvial deposits overlying hard limestone together with the fast flowing waters of the Shannon meant there were many challenges for the project to overcome.

Norfolk Marine Ltd worked in conjunction with the specialist dredging contractor, Marine Blast Ltd, to drill, blast, and excavate a trench through the tough limestone river bed.

A system of guide rails was then laid and secured in place from the south to the north bank whilst another contractor sunk vertical shafts into both banks. Tunneling techniques were used to break through the banks to the shafts, waterproof seals were fitted to the break through points to keep the Shannon’s waters at bay.

Concrete pipe section were then lowered into the shaft and jacked through the seals and along the rails in the trench on the river bed. The pipe was jacked across the river until it penetrated the seal on the far bank. Once across the pipeline was concreted in place.