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-gated at launchThe 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