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.