Client: Fingal County Council

Location: Dublin, Ireland

Project Value: €22.99m

Description: Installation and commissioning of ductile iron rising main including construction of tunnels via pipe jacking and microtunnelling

This Contract provided for the construction of rising mains to support both the rapid population growth and high level of economic development currently experienced in the Greater Dublin Region.

It was a requirement along the pipeline route to cross the River Liffey and so Ward & Burke proposed a contractor-designed solution involving the use of a pre-grouted steel sleeve.

Mechanical & electrical subcontract works on the scheme included telemetry (radio linked), installation and commissioning butterfly valves and actuators, electro-magnetic flowmeters and, instrumentation and controls to all valve chambers.

The innovative design and construction solution to the River Liffey crossing, as conceived, designed and constructed by Ward & Burke, included the use of sheet-piled ‘fingers’ which were formed in either river bank in the position of the proposed pipeline. The piles installed guided the pipe string into the pre-dug channel. These sheet-piled fingers were subsequently used to form a cofferdam on either bank to facilitate the connections required at either end of the pipe string.

One of the many advantages of this solution was the very significant reduction in pollution risk and the ability for works to take place, without impact on the Eastern Regional Fisheries Board ‘in-stream’ works May-September window. As a result, the majority of works were carried out without the need for in-stream activities.

The solution was fully compliant with specification and resulted in the following positive impacts;

  • Pre-grouting reduced risk of exposure to construction chemicals
  • Pre-fabrication of complete pipe string reduced exposure to manual handling risks
  • Reduction in time on site and associated preliminaries
  • Reduction in future maintenance / whole life costs due to nature of construction
  • Reduction in the amount of constructed pipe elements therefore reducing the risk of individual element non-conformance

As the river is an important salmonid waterway, traditional methods of construction for the River Liffey crossing would have realised significant programme and environmental risks as the in-stream nature of the construction works in the original design presented a significant pollution risk, and the nature of the works would also have meant operational disruption due to the Inland Fisheries Ireland requirements for ‘in-stream’ works to take place from May to September of each year only.

Ward & Burke’s innovative solution negated the need to complete in-stream works which vastly reduced amount of time for operatives being exposed to working over and within water. It also comprehensively mitigated pollution to the salmonid watercourse and reduced the amount of excavation required, thereby contribution to a reduction in the overall embodies carbon for the scheme.