Stradbally 225OD HDPE Outfall, Stradbally, Co Waterford

Challenges presented

  • 100M of rock breaking within the outfall trench alignment
  • Outfall location

Sorensen Civil were assigned as principal contractor for the Stradbally Waste Water Treatment Plant. This project and outfall pipeline was part of upgrading the exiting treatment system for the area. Once again Sorensen Civil appointed Foyle & Marine Dredging as the contractor to construct and install the outfall 120M 225OD HDPE outfall pipeline.

The complex location of the proposed outfall provided limited option for the trench to be installed via floating plant methods.
Foyle & Marine executed the trench excavation and rock breaking work via a 45T and 20T Hitachi excavator. A temporary revetment was developed alongside the proposed trench alignment to conduct rock breaking and trench excavation during tidal ranges. The 45T was equipped with a Prolec Pcx dig system for accuracy.

The 120M outfall included 30No anchor block and a single point diffuser was installed over two tides. The marine section was floated off the beach, connected to the shore end and lowered into the pre-dredged trench in a controlled manner. On completed outfall installation, a dive survey was conducted prior to backfilled the pipe with existing material.
The treatment plant was successfully commissioned later that year.

Stradbally Outfall

Waterford County Council

Sorensen Civil Engineering Contractors

Stradbally, Co Waterford

120M of 225OD Outfall Trench Excavation & Placement

4 Weeks April 2015 – May 2015