New Ross WWTP

T J O’Connor & Associates were engaged by Wexford County Council in connection with the provision of a new Waste Water Treatment Plant in New Ross. The WWTP has a capacity of 16,000 PE and treats flow to a secondary standard before discharging to the River Barrow.

The treatment works was constructed as a DBO Contract and included the main pumping station, which lifts the sewage to the new WWTP via a 2km long, 600mm diameter sewage rising main. The WWTP provides treatment to a secondary standard with Sequencing Batch Reactors used to provide the required 16,000 PE capacity.

The works also included storm water holding tanks, SCADA systems, preliminary treatment works, sludge dewatering using two centrifuges and an acceptance plant for importing and dewatering liquid sludges from other (smaller) works in the vicinity of the New Ross plant.

Difficult ground conditions associated with deep alluvial deposits were experienced in the construction of the WWTP. A  geotextile reinforced ‘earth mattress’ was constructed over the existing soft alluvial deposits. Settlement of the mattress was accelerated by the construction of a vertical drainage system comprising ‘wick’ drains at 1m centres, and surcharge loading. The system used successfully accelerated primary settlements (pore water extrusion) for around 6 months.

The works also included two marine outfall pipes to the Barrow estuary. The first carries treated effluent from the WWTP via a 150m long, 900mm diameter pipe. The other provides for emergency discharge from the main pumping station to the Barrow, below the low water mark, via a 1,050mm diameter pipe. The work was facilitated under a foreshore licence and separate consultations with the New Ross Harbour Commissioners. An Environmental Impact Statement was prepared by T J O’Connor & Associates and planning approvals for the main pumping station were obtained through the Part 8 (local authority) procedure based on planning documents prepared by TJOC.

Start/End Date:

Aug 2007 – Dec 2009

Contract Value:



Consulting Engineers and Client’s Representative providing full Engineering Services for all stages of the project & PSDP

Key Features:

  • 16,000 PE WWTP based on Sequencing Batch Reactors with a new outfall discharging to the River Barrow
  • Sludge reception and dewatering
  • Preparation of an Enviornment Impact Statement
  • Commissioning of site investigation works
  • Mathermatical Modelling (HydroWorks) of the sewerage system including flow and rainfall survey and model verification
  • Prepartion of Tender Documents using FIDIC Orange Book for the WWTP IEI 3rd Edition (CONDOC) for the pipelines contract
  • Preparation of foreshore licence applications
  • Part 8 planning documentation
  • Detailed design of sewerage works including works to upgrade existing Combined Sewer Overflows (CSOs)
  • Project Supervisor Desgin Process duties under the Health and Safety Regulations
  • Tender evaluation and report and recommendation on tenders received
  • Construction Management and Supervision

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