United Utilities (UU) commissioned Sweco to undertake an investigation into 193 Heavily Modified Water Bodies (HMWB) potentially affected by UU’s water abstraction assets.
Client – United Utilities
Location – North West England
Fee Value – £480,000
The Environment Agency (EA) had identified these HMWBs as requiring further investigation as part of the Water Framework Directive objective to meet Good Ecological Potential.
As part of this project, the services provided by Sweco included:
• Hydrometric surveys and hydrological analysis
• Geomorphological surveys and assessment
• Aquatic ecology surveys and assessment
• Solution optioneering
• Cost benefit assessment
• Multi-criterion Environmental Impact Assessment
• Stakeholder management
Sweco were required to investigate whether it was technically and economically feasible to mitigate any impacts on the five drivers against which Good Ecological Potential (GEP) is assessed. The five drivers being:
1) fish passage
2) downstream flow
3) sediment transport
4) downstream water quality
5) lake level modification.
As part of the Stage 3 assessment, Sweco undertook the following:
• Review of the EA’s Stage 2 assessment of the priority for the five drivers at each site.
• Value Management (VM) workshops to agree prioritisation, in terms of high, medium and low priority sites.
• Optioneering for mitigation measures at high and medium priority sites.
• Further VM meetings to agree the cost-benefit analysis outcomes and the preferred mitigation measures.
Outline options were developed for high and medium priority sites. These included the design of fish passages (Driver 1), environmental flow release structures (Driver 2) and the development of sediment management plans (Driver 3). Ecological assessments of available habitat and geomorphological assessments were also undertaken based on downstream hydrometric, geomorphological and fisheries habitat walkover surveys.
Cost benefit assessment and multi-criterion Environmental Impact Assessments were undertaken to analyse whether the mitigation measures were cost effective and to ensure that they did not have wider social and environmental impacts.
Sweco successfully gained agreement from the EA and UU on a preferred solution for each site. Altogether the project reduced UU’s risk by 90% against the £350m total potential expenditure.