Skibbereen Regional Water Supply Scheme

Irish Water was required to propose and advance remedial actions to resolve these water quality issues in the Skibbereen region. In conjunction with Irish Water, RPS planned and designed a rationalised regional water supply scheme centred on the treatment of drinking water at two water treatment plant sites.

The existing public water supply in the Skibbereen region derives from five separate water sources and treatment plants. There is an insufficient level of treatment at three of these plants and consequently these supplies are listed in the EPA’s Remedial Action List.

Key details

Project name

Skibbereen Regional Water Supply Scheme

Client 

Irish Water

Location

County Cork, Ireland

Services provided

  • Data collection and data management
  • Surface water source yield assessment
  • Preparation of water abstraction order documentation
  • Asset data collection and asset condition/performance assessment
  • Energy audits of water treatment plants and pumping stations
  • Site investigation specification, procurement and management
  • Site & route selection
  • Flood risk assessment
  • Environmental Impact Assessment Screening
  • Appropriate Assessment Screening
  • Invasive Alien Species surveys
  • Fire safety and disability access assessments and reports
  • Preparation of planning applications
  • Preparation of land acquisition, wayleave and compulsory purchase order documentation
  • Attendance at compulsory purchase order oral hearing
  • Asbestos surveys and reports
  • Detailed Design of water treatment plants and distribution networks
  • Contract documents preparation
  • Tender assessment
  • Contract management and site supervision

Challenge

The initial challenge was to develop a project that balanced the requirements to provide improved levels of treatment while considering the longer term demand for water in the region and the yield of the existing sources.  Two broad options were developed, the first proposing the redevelopment of the five existing treatment plants, while the second considered the creation of a rationalised regional water supply scheme centred on the two largest existing treatment plants.

Once the project scope was defined, the most significant challenge was to advance a large and regional scheme with multiple sites through the statutory water abstraction, planning, and land acquisition processes.

In addition, optimisation of the water treatment processes to maximise the removal of natural organic matter and minimise the production of disinfection by-products such as Trihalomethanes (THM) as a key challenge.

Skibbereen reservoir tanks - Plan for Irish Water

Solution

Through the development of concept designs and cost benefit analysis, the development of a rationalised regional water supply scheme centred on the treatment of drinking water at two existing plants, allowing the decommissioning of the remaining three existing plants, was identified as the optimum solution.

Upgrades to two retained water treatment plants were designed, as were distribution network extensions and enhancements to facilitate the bulk transfer of water to the supply areas where plants were being decommissioned.

Robust site and route selection processes, allied with extensive environmental studies and appraisals, were critical in successfully completing all statutory processes.

Comprehensive water sampling, jar testing and THM formation potential analysis was undertaken to ensure the enhanced coagulation, flocculation and chlorination processes designed can sufficiently remove the pre-cursors to disinfection by-products.  Ultrasonic algae control was specified in one of the retained sources to reduce the effect of algae on the treatment process.

Project statistics

7,000
People will benefit from improved drinking water quality and supply
7.4
Million litres of drinking water per day provided by upgraded plants
37
Kilometres of water-mains to be constructed
1.45
Million litres of additional treated water storage at four reservoir sites

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