Ballyboden Covered Reservoir Progress Update

Coffey Construction (I) Ltd are currently undertaking the Ballyboden Covered Reservoir Project for Irish Water.  The project commenced in May 2017 with Commissioning programmed to take place in May 2018.

The Project comprises the provision of a covered reservoir and associated works to store treated water, and decommissioning of and modifications to the existing open reservoir.

A new disinfection plant and bulk storage silo tanks will be provided, with a contact tank and a dosing/control building integrated with the covered reservoir. It will replace the existing chlorine gas system with a sodium hypochlorite dosing system.

The existing treatment plant and treated water open storage reservoir has remained operational during the construction work with minimum outages of supplies to facilitate commissioning. The construction works are being carried out in two stages. The newly covered reservoir and associated disinfection plant shall be completed, tested and commissioned first, followed by the draining down and subsequent modifications to the existing open storage reservoir.

The works comprise in summary: –

Construction of a 16,000m3 capacity concrete reservoir for storage of treated water.  The new reservoir has two compartmentalized cells and a contact tank.  The new reservoir is 60m by 80m in plan and has 5.5m high walls.  The in-situ base comprised 2,300 m3 of concrete and 350Te of reinforcement which was completed in 4Nr separate pours.  The 5.5m high in-situ walls comprised 1,000m3 of concrete and 100Te of reinforcement and were carried out in 36Nr separate pours.  The roof of the new reservoir was constructed using precast columns, spine beams and double-T sections.

Construction of a Washwater Tank for the outlet of the filter wash from the existing water treatment plant.  The Washwater tank is 20m by 15m in plan and has 3.9m high walls.  The Washwater tank was constructed using a hybrid twin-wall precast system with in-situ base and wall infills.

The undertaking of several connections to the existing water main network to allow the diversion of flows to the new storage reservoir.  The connections to the existing 600mm diameter water mains were carried out in close partnership with Dublin City Council who operate the existing Water Treatment Plant as the connections required temporary shutdowns to the supply and operation of the Plant.

The installation of approximately 1.3km of 600mm and 450mm diameter associated water main pipework.

Current Progress

At present the current progress in summary: –

  • The in-situ concrete base and walls of the new reservoir tank have been completed.
  • The precast roof sections are 95% complete with the final sections being lifted in to place on 09/03/18.
  • The water tightness test of the new tank is due to take place in the coming weeks.
  • The Washwater tank has been completed and the water tightness test has been carried out.
  • All connections to the existing network are now complete.
  • Currently, 25% of the installation of new water main pipework has been completed.