Ballynahinch WwTW, Co. Down

Ballynahinch WwTW was originally constructed in the early 1960’s, with a major upgrade completed in 1995. It was designed to treat a Population Equivalent (PE) of 6,000.

Doran Consulting were designers for the BSG/ WIS JV for the Design & Build upgrade of the Treatment Works, for NI Water, to meet the Urban Waste Water Treatment Regulations (NI) 2007 and increase its capacity to 14,600PE.

Design services comprised: 

  • Process Design
  • Civil Design
  • Structural Design
  • Hydraulic Design
  • Geotechnical Design 

and included new Archimedes screw pumps, inlet works screens, storm tanks, anoxic tanks, two new primary tanks, sludge holding tanks and sludge thickeners as well as a bespoke tertiary rapid gravity sand filtration plant and new control buildings. Construction work was all carried out within the boundaries of the existing site which required careful phasing to maintain the quality of the output. Where possible existing assets were incorporated into the proposed design and refurbished as part of the new works, in particular the two oxidation ditches and the two existing clarifiers.

This Plant is now reliably meeting the new standards of 9mg/L BOD, 15mg/L SS, 2mg/L ammN and 2 mg/L Total P, and is capable of meeting a Total N standard of 15 mg/L.