Scope of the Works included:

• Pipelaying:
  • 5,800m, 100-450mm diameter watermain
  • 5,130m, 225-900mm diameter surface water
  • 9,400m, 225 & 300mm diameter foul sewer
  • 3,000m of House Connections
• 4No. Pumping Stations
• Major Estuary Crossing. Quay wall construction and repair
• Extension to the existing Treatment Works - new Clarifiers/Settling Tanks, Sludge Thickening Tanks, Buildings

Particular Challenges:

• River Moy Crossing: This element of the work involved crossing a tidal channel with twin 400mm diameter rising mains and numerous utility ducts. The channel was subject to a 2m tidal variation. The length of the crossing was 250m.
  A pipe string 250m long, consisting of a 900mm steel sleeve, inside which was placed the twin rising mains and utility ducts, was fabricated and sealed on one bank. Construction space was restricted, with a quay on one side and woodland on the other.
  Trench excavation was carried out in rock from embankments constructed of imported fill extending into the tidal channel from each bank (see Data Sheet photos). The fill level was such as to allow us to take full advantage of tidal variation. Underwater rockbreakers were used and long-reach excavators completed the trench excavation. Levels were monitored by a team of divers.
  The pipe string was floated across the channel upstream of the embankments [which acted as a guide]. The flow in the channel aligned the pipe string into the correct position. The Pipe string was submerged in a controlled fashion with the aid of divers.
  The embankments were then used as backfill and were removed progressing from the middle of the channel to the banks.
  All the work was undertaken under the supervision of the Western Regional Fisheries Board. Incorporating the pipes into a pre-grouted single sleeve [Contractors Alternative Design] avoided potential contamination by concrete surround in an open channel in this important salmonoid river.

• Pumping Station/Quay Wall Construction: Crocketstown Pumping Station was constructed adjacent to the River Moy, in the tidal zone, at a depth 8.7m and required the construction of sheetpiled cofferdams, repair and construction of the adjacent quay wall.  The river crossing (above) terminated at the pumping station. Breeches in the quay wall to accommodate the pipeline and pumping station construction were significant parts of the construction operations in this location.

• Full road/street reconstruction in an urban environment which involved: all aspects of traffic management; maintaining and diverting existing live services during the Works; liaison with Local Authorities, Service Providers, local businesses and residents.
  Bespoke precast manholes, manufactured at our Precast Yard, allowed immediate carriageway reinstatement.

• Liaison with numerous stakeholders along the route of the pipeline including Mayo County Council divisions, National Parks and Wildlife, Fisheries, local businesses and residents/landowners, ESB, Telecom, etc.