Leixlip-Ballycoolen Water Supply Scheme

River Liffey Crossing
River Liffey Crossing
River Liffey Crossing 2
River Liffey Crossing

Project Profile

Tuam Regional Water Supply Scheme-Extension to Headford

Value: €17,000,000
Client:

Fingal County Council, County Hall, Swords, Fingal, Co. Dublin Contact: Mr. John Mulcahy Ph.: 01-8905000

Consultant:

Nicholas O’Dwyer Consulting Engineers, Nutgrove Office Park, Nutgrove Avenue, Dublin 14. Contact: Mr. Gerry Cronin Ph.: 01-2969000
Completion Date:

October 2008
Involvement:

Main Contractor / PSCS, 100% participation

Project Description:

This Contract provided for the construction of the following Civil Works:

  • Installation and commissioning of 26,000m of 1000mm diameter Ductile Iron Rising Mains.
  • Construction of 10 No. Reinforced Concrete Valve Chambers for Cross-connections.
  • Completion of 9 No. 1500mm diameter tunnels utilising pipe-jacking techniques.
  • Completion of 2 No. 1200mm diameter tunnels utilising Micro-tunnelling Techniques.
  • Completion of 4 No. river crossings including the 38m River Liffey crossing.
  • Installation of all air-valves, scour valves and associated chambers on the pipeline route.
  • Cross-connection to existing 1000mm diameter pre-stressed concrete main and a 27” diameter steel main on completion of new pipeline.
  • Reinstatement of approximately 650,000m2 of wayleave including golf course, parkland and stud farms.
  • Mechanical & Electrical Subcontract Works (value-€400,000) including telemetry (radio linked):
    Installation and commissioning of 35 No. 1000mm Butterfly Valves and Actuators.
    Installation and commissioning of 2 No. 1000mm flowmeters
    Instrumentation and controls to all valve chambers.

Particular Challenges:

  • We highlight the River Liffey crossing and tunnel construction under the Dublin-Sligo Railway line/Grand Canal combined.
    In order to avoid potential contamination of the River Liffey it was decided to adopt the pre-grouted steel sleeve principal (Contractors Design). Sheetpiled ‘fingers’ 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 sheetpiled fingers were subsequently used to form a cofferdam on either bank to facilitate the connections required at either end of the pipe string.  Long-reach excavators excavated the channel, supervised by a team of divers. The pre-grouted pipe string was 50m long and weighed 55tonnes. A 500tonne crane was used to lift the pipe strings into position.
    All of the Works were supervised by the Eastern Regional Fisheries Board.  Environmental considerations required that all pumped water was pumped to a lagoon area to facilitate settling of sediment. The works are featured on the Fingal County Council website.
  • Three 1200mm diameter tunnels were constructed under the railway and Grand Canal combined. All were driven from one major shaft 12m deep and each was 70m long. The shaft constructed was a sheetpiled cofferdam with top and bottom frames. The tunnels were driven in 150MPa limestone rock. A Herrenknecht micro-tunnelling machine was used.
  • Liaison with numerous stakeholders along the route of the pipeline including South Dublin, Kildare, Meath and Fingal County Council Parks and Roads divisions, ESB, Telecoms, Landowners, etc.; Irish Rail, Eastern Regional Fisheries Board and Natura Ecological Consultants; Businesses such as IBM, Astellas Pharmaceuticals and Tyco Healthcare.
  • Maintaining and diversion of existing live services, as required by the permanent works.
  • Co-ordination with third party construction works along the route of the pipeline including the new Reservoir at Ballycoolin and the Damastown Link Road.
  • Traffic Management on site was the responsibility of Ward & Burke Construction Ltd. 

 

TBM Shaft 1
TBM Shaft

TBM Shaft 2
TBM Shaft 3


Ward & Burke Construction Ltd, Stradbally East, Kilcolgan, Co. Galway, Ireland
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