Vyrnwy Aqueduct Modernisation Programme
Lake Vyrnwy to Merseyside (via Oswestry WTW to Prescot Service Reservoirs), UK · Ongoing (First constructed 1890, refurbishment program includes AMP5 element with 52km lining programmed to be complete by March 2015, and overall completion by 2028) · £177 million (estimated cost for cleaning and refurbishing the entire 240km aqueduct, as per DWI undertaking); £260 million (overall modernisation programme, as per New Civil Engineer)
The judgement call
Account action unavailableThe use of die drawing technique, jointly developed by North West Water (UU's predecessor) and British Gas in the 1990s, was re-evaluated and adopted for its cost-effectiveness. - Extensive trial areas and hydraulic/PODDS modelling were crucial for validating refurbishment techniques and predicting water quality impacts. - The project emphasized minimizing excavations by locating launch/reception points at existing air/sluice valve locations. - Development of a new specialist end restraint fitting jointly by UU Engineering and Nova Siria improved installation efficiency. - Comprehensive scraping and proving processes were essential to prepare host mains and identify potential restrictions before lining.
Key engineering challenges
Addressing accumulated iron and manganese deposits in century-old pipelines to prevent water quality incidents and discoloration. - Maintaining water supply and quality during temporary outages of sections of the aqueduct for lining. - Implementing innovative relining techniques (thin walled polyethylene lining, die drawing) in large diameter, long pipelines. - Managing complex logistics across urban and rural locations, including environmental considerations (badgers, great crested newts) and public disruption. - Designing bespoke equipment, such as a compact track-mounted 100-tonne capstan winch, for liner installation.
Project facts
- Client / owner
- United Utilities (UU)
- Lead contractor
- Balfour Beatty (Network Construction Partner for Oswestry to Malpas section); Specialist sub-contractors for lining installation.
- Lead designers
- United Utilities Engineering (for Oswestry to Malpas section); Nova Siria (jointly developed new fitting).
- Project type
- refurbishment | upgrade
- Scale
- 3 parallel pipelines (Lines 1 & 2 cast iron, Line 3 steel); 240km total length; diameters ranging from 39" to 42"; transfers up to 210Ml/d of potable water; 52km of thin walled polyethylene lining in AMP5; 139km of pipeline to be modernized (cleaning and slip lining).
- Disciplines
- civil; hydraulic; materials engineering; geotechnical; environmental
- Standards & frameworks
- Drinking Water Inspectorate (DWI) legal undertaking; adherence to relevant UK water quality and engineering standards.
Sources: "Vyrnwy Aqueduct Refurbishment", Kevin Harvey, UK Water Projects 2014, https://waterprojectsonline.com/wp-content/uploads/case_studies/2014/Vyrnwy-Aqueduct-Refurbishment-2014.pdf - "Vyrnwy Aqueduct Modernisation Programme", United Utilities Hub, https://uuhub.co.uk/vyrnwy/ - "How the £260M Vyrnwy Aqueduct modernisation will improve drinking water quality for 7M people", New Civil Engineer, 2026, https://www.newcivilengineer.com/in-depth/how-the-260m-vyrnwy-aqueduct-modernisation-will-improve-drinking-water-quality-for-7m-people-27-01-2026/ - "Vyrnwy Aqueduct Modernisation Programme", OCU Group, https://www.ocugroup.com/case-studies/vyrnwy-aqueduct-modernisation-programme