The Irish Water 2017-2021 Investment Plan identified 52 No. Wastewater ‘Above Ground’ treatment projects where upgrade works are to be implemented through Irish Water’s gateways from conceptual design, on to construction and project closure.
For the purposes of delivery, IW combined these Wastewater projects into works packages and the Wastewater Treatment Plants (WwTP) that are included in this project under Tobin Consulting Engineer’s remit include:
- Banagher WwTP, Co.Offaly
- Stamullen WwTP, Co. Meath
- Clogherhead WwTP, Co. Louth
Fine Bubble Diffuse Aeration (FBDA) systems are proposed to replace existing surface aerations systems on two of the WwTP’s so to reduce the energy consumption of the WwTP’s. Sludge Drying Reed Beds (SDRBs) are also proposed at Banagher WwTP which will eliminate the current energy consumption of sludge dewatering by mechanical means.
At tender stage for all of the sites, award criteria for the project will place significant weighting on the overall energy consumption and efficiencies of the equipment proposed by tenderers.
The Sludge Drying Reed Beds proposed for Banagher WwTP are intended to eliminate the need to remove and dispose sludge off site from the WwTP. The negative effect on the environment of the operation of a SDRB system is seen as quite limited compared to traditional sludge treatment systems such as mechanical dewatering and drying, as this removes the need for use of chemicals; incineration; direct deposition on landfill sites, etc.
The proposed specification of pre-fabricated units for the treatment processes will limit the volume of construction traffic during the project. New onsite sludge thickening and treatment is proposed at the Clogherhead and Banagher sites which will reduce the collection of sludge from the site and also reduce trips over the lifetime operation of the plant.
Rising mains for the proposed pipeline for the Stamullen pump away option are designed as a full welded high pressure main suitable for the variable ground conditions encountered along the route. This is designed to minimise maintenance and repair of these materials. On all sites, in off road locations, it is proposed that backfill material will be taken from surround on-site materials, as opposed to imported materials.
A main driver of the project is to improve the receiving water quality through investment in wastewater treatment infrastructure. The proposed WwTP upgrades will enhance the level of treatment achieved by each of the WwTP’s and eliminate the discharge of untreated wastewater by ensuring adequate stormwater storage and augmented treatment is provided at each of the plants.
In order to assess the potential impact on the natural habitats and the local environment, screening for appropriate assessment will be carried out at detailed design stage for each site.
The proposed wastewater treatment plant upgrades will support each area in meeting the wastewater treatment needs for its population and that of its rural hinterland. Each plant is to be upgraded to accommodate the incoming wastewater flows up to the year 2040.