Derwent Valley Aqueduct – Derbyshire

Bridge management services including planning and executing inspections to 74 pipe structures, high pressure pipeline testing/residual life assessment and asset management and strengthening repair services.

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The challenge

The Derwent Valley Aqueduct is one of Severn Trent Water’s most important assets, forming part of its strategic water grid it supplies more than 590,000 people with 200 million litres of treated water per day. It consists of 180km of large diameter pipeline, 16km of single 1.9m diameter tunnel, 1,000 valves, 74 bridges and culverts, and 307 other structures and chambers.

In 2014, Severn Trent Water put a team together to deliver the Derwent Valley Aqueduct Strategic Life Extension Project. Inertia Consulting Ltd was appointed as the Bridge Engineering Consultant. The project trialled a new Severn Trent strategy aimed at delivering projects 30% faster and more productively, with cost savings of 20%.

Engineering Consultancy

Project tasks included:
• Surveying all the structures along the 180km aqueduct length to ascertain their life expectancy and condition, using standardised Bridge Condition Indicator methods.
• Identifying structures requiring minor works and those needing further survey and developing work-scopes by prioritising spend to maximise efficiency and benefits.
• Carrying out the minor works and surveys, which often required specialist access techniques such as roped access and the use of speedboats, pontoons and MEWPs.
• For the major projects, using a traditional scoping approach to design and deliver schemes to strengthen and refurbish priority structures within tight timescales.

“Inertia are an extremely professional company providing an excellent service which always delivers highly accurate detailed surveys with cost effective solutions. They only use highly skilled competent staff that always put the needs of the client first.”

John Wing, DVA Resilience Project Facilitator, Severn Trent Water plc

Many of the structures requiring major projects were in environmentally and logistically challenging locations which could have significantly increased costs. Through close collaboration and the sharing of resources, the team were able to keep costs down.

The project team

Severn Trent Water plc – the Client
Beale Engineering Services – the Project Manager
Inertia Consulting Ltd – the Bridge Engineering Consultant
Bagnalls Building Maintenance – the Principal Contractor

The outcome

The timely, strategic and innovative intervention by the close-knit team enabled the project to be successfully delivered. We also achieved Severn Trent’s goals of faster project delivery, improved productivity and 20% cost reduction.

Reviews carried out before and after the project’s completion highlighted that our management approach considerably improved the network risk profile, revitalised the asset and increased its lifespan by decades.