Glan Agua and MEIC awarded Kilkenny RWSS

Glan Agua/MEIC has recently been awarded the Kilkenny City Regional Water Supply Scheme (RWSS) upgrade contract by Irish Water.

 

Glan Agua/MEIC will deliver this landmark piece of infrastructure for Irish Water over the next two years, and will operate the new plant for a period of 12 months after the issue of the Commissioning Certificate. Glan Agua/MEIC will also assume interim operations of the plant for the duration of the works.

 

The initial phase of the project is now underway, with Glan Agua/MEIC currently carrying out the design services element of the contract. Our Design and Production teams are working closely with Irish Water and the Employer’s Representative (Ryan Hanley) to develop innovative engineering solutions that are tailored to meet the project requirements.

Overview of the Existing Kilkenny City RWSS Scheme

The Kilkenny City RWSS is currently supplied with treated water from two separate water treatment plants (WTP), namely Troyswood WTP and Radestown WTP.

 

Raw water is currently abstracted from three surface water sources, the River Nore, the River Dinin and the Douglas River via the Muckalee Impoundment. Water pumped from the River Nore is treated at Troyswood WTP, while water sourced from the River Dinin and the Douglas River is treated at Radestown WTP. Between September and December 2016, the average daily treated water supply to the Kilkenny City RWSS comprised of:

 

  • From Troyswood WTP, circa 5,800m3/day via the existing Thornback Reservoir (6,800m3 capacity TWL 107.9m Malin).
  • From Radestown WTP, circa 5,100m3/day via the existing Radestown Reservoirs (6,750m3 capacity TWL 109.2m Malin).

The existing Troyswood WTP operates a sedimentation coagulation/flocculation/clarification (CFC) process followed by first stage filtration, disinfection using chlorine gas and fluoridation. The existing Radestown WTP operates a slow sand filtration treatment process followed by disinfection using chlorine gas.

 

Due to the inability of the slow sand filtration system at Radestown to remove THM precursors in the form of dissolved organic carbons from the Muckalee and Dinin sourced surface waters and the high chlorine demand of these precursors, the Radestown WTP has been on the EPA’s Remedial Action List (RAL) since January 2008 for frequent exceedances of the parametric limits for total THMs set out in the Drinking Water Regulations (SI 122 of 2014).

 

The current River Nore intake works, which is located at Troyswood, has the following operational issues:

  • The site at High Flood Risk. Frequent inundation during flood conditions of the entire intake works and associated trackway which prevents pedestrian and vehicular access to the intake for protracted periods;
  • Frequent blocking of the intake works by gravel, sediment, silt and debris deposition;
  • Abstraction difficulties during low river conditions.
  • Difficult to clean and maintain due to access chamber sizes.
  • No operational screens.

Summary of Proposed Upgrade Works at the Kilkenny City RWSS Scheme to be carried out by Glan Agua/MEIC

Glan Agua/MEIC will carry out the complete scope of the project, which is to:

 

  • Provide new raw water intake facilities with a maximum daily abstraction volume of 19.085 Mega Litres per Day (MLD) to match the current abstraction order limit from the River Nore at Troyswood.
  • To increase the treatment capacity throughput at the existing Troyswood WTP accordingly.
  • To upgrade the residuals treatment facility.
  • To supply the service reservoirs at Radestown WTP directly from the Troyswood WTP via a new 2.8km long 450mm diameter rising main to facilitate the decommissioning of the Radestown WTP.

 

To achieve these objectives, the following works will be carried out under the contract:

 

  • Decommissioning of the Radestown WTP and associated raw water sources.
  • The decommissioning of the existing River Nore intake.
  • The construction of a new raw water intake works located 70m upstream of Troyswood Weir.
  • A process upgrade of the existing flocculation system.
  • A process and hydraulic upgrade of the process tanks (existing and proposed) at Troyswood WTP to facilitate the maximum abstraction rate of 19.085 MLD over 18.5 hour-day.
  • A hydraulic upgrade of the existing filter backwash pumps, air blowers and associated.
  • The re-use of the existing clear water tank as the backwash pump sump and filtrate water sump from where filtered water shall be pumped to the new clear water tank.
  • The provision of new second stage duty/ standby variable speed drive pumps.
  • The provision of a new rising main from the existing 450mm diameter main at the outlet from the pump hall (currently supplying Thornback Reservoir) to the new clear water tank.
  • The extension of the existing treatment plant
  • building, including the routing of the foregoing filtrate rising main to the new clear water tank.
  • The provision of duty/ standby UV reactors and ballast/ control panels.
  • A new 2.44 ML clear water tank, complete with baffles, emergency high level overflow, attenuation pond and associated pipework and controls.
  • Provision of multi-barrier disinfection system.
  • Five new high lift centrifugal pumps as the pumping regime within the new treated water pumping room comprising of:
  • 2 No. duty fixed speed pumps on the rising main to Thornback Reservoir.
  • 2 No. duty fixed speed pumps on the rising ma.in to Radestown Reservoir
  • 1 No. standby fixed speed pump to be used to supply either reservoir as required with adequate pumping head to facilitate supply of Radestown Reservoir at this rate.
  • A new section of treated water pumped rising main from the new treated water pumping room to the existing Thornback Reservoirs rising main (outside the existing Pump Hall) including a valved tee connection to facilitate
  • switch over to the new pumping arrangement.
  • The construction of a new treated water rising main between Troyswood WTP and the Radestown Reservoirs which will continue to be used as treated water storage for the Kilkenny City RWSS on the eastern side of the River Nore.
  • Provision of a new residuals treatment system for the new upgraded Troyswood Water Treatment Plant (WTP), including used washwater equalisation and settling tanks, sludge thickening tank, sludge holding tank and sludge dewatering plant building and equipment for clarification of liquid waste residual and associated pumps and pipework.

 

Glan Agua / MEIC look forward to mobilising site in the coming months. We look forward to working collaboratively with Irish Water, Ryan Hanley and Kilkenny County Council on the delivery of this important project, and updates will be provided on our website and social media platforms as works progress on-site.

Date

July 29, 2021