UK Project with a Geotechnical Value of between £500K and £1M

This is for a ground engineering scheme (as a standalone project or part of a larger development) with a contract value of between £500K and £1M that stands out in terms of its credentials in innovation, sustainability, health and safety and value engineering.

AtkinsRéalis, Thames Water, MWH Treatment & Keller
Hampton Reservoir Leakage Remediation Works

Seepage through the Hampton Reservoir was identified using state-of-art geophysical ‘Willowstick Survey’. Due to challenging site constraints such as working space and ecological sensitivity, conventional piled cut-off wall was not a viable remedial solution. An alternative measure using permeation grouting was carried out to create low permeability flow barriers. The project has adopted the latest technology for grouting work in terms of the grout mix and grout monitoring, allowing the use of real time data to make quick decisions on the next steps and focus on specific treatment areas which ultimately allows works completion ahead of schedule. The success of the project also relied on an effective communication chain between the Client, Designer and Contractors, who made informed decisions collaboratively based grouting results. The project demonstrates the best practise of applying grouting technique in reservoir leakage remediation, which could be a good case as a reference for similar projects.

Victoria Heights, Exeter

A local, rural site in Exeter, Devon, uncovered a deeply complex geological and historical past when detailed desk-based research and investigation identified a hidden, buried 10m deep valley that was infilled with Made Ground in the 1960s. The ground conditions at the site posed a substantial engineering challenge to this ‘local’ site, and initial feasibility by others had suggested a substantial quantity of soils would require to be disposed off-site, requiring vast quantities of imported fills. Collaborative, cost-effective and sustainable solutions were developed between CGL and the Client and Engineering Teams to re-use the landfilled Made Ground to minimise soil disposal to landfill. The versatile and dynamic UK and internationally-based team overcame many geotechnical challenges on this project, and utilised a combination of desk-based studies, GIS systems, engineering assessment and detailed analysis to justify the acceptability of the proposed measures.

Mott MacDonald Bentley
Newthorpe & Heanor Milnhay Sewage Treatment Works AMP7 Upgrades

Severn Trent Water AMP7 infrastructure upgrades in Nottingham require decommissioning of the aging Heanor Milnhay Sewage Treatment Works (STW) for future residential growth. Flows will be transferred to a new treatment works extension at Newthorpe STW. Mott MacDonald Bentley (MMB) was appointed to deliver this £30M investment through detailed design and construction. Significant geotechnical challenges included: construction in problematic alluvial soils; managing high groundwater; mitigating legacy mining risks and construction over a 1960’s opencast colliery. MMB have delivered significant embodied carbon and commercial savings by adopting a ‘back to basics’ pragmatic design approach, alongside challenging existing client standards. Following principles of PAS2080, MMB have delivered a ‘build better’ solution by re-servicing existing structures; utilising digital solutions to best develop ground models in order to design out risk and adopting site won materials for reuse to construct biodiverse wildlife habitats, avoiding unnecessary carbon-heavy and costly off-site disposal.

Network Rail & BakerHicks
Geohazards Assessments – Scotland’s Railway

BakerHicks have been working in partnership with Network Rail (NR) to undertake Geohazard Assessments on outside party slopes. The scheme required Geohazard assessment on a huge scale and is one of the largest Geohazard Assessments in the UK to support the safe operation of the railway. NR already have robust processes for managing their own assets within the railway boundary. This unique workstream is a new agreed process required to assess the risks from earthworks assets outside the boundary which Network Rail do not own. Unmanaged and unpredictable outside party slopes are particularly susceptible to failure during adverse/extreme weather. Such an examples have occurred at Loch Eilt and Loch Treig. Geohazard Assessments for 1752 miles of railway was completed which considered the risk to the line from failure modes such as landslides, rock falls, earth flow etc.

Speedeck Foundations
Clay Cross Piled Rafts

Speedeck designed and built piled raft foundations for a residential development on a former opencast coal mine and landfill area. The ground conditions were challenging due to the extreme variability in the depth to bedrock and the thickness of overlying landfill materials which included large obstructions. Foundation zoning and identification of risk issues was carried out early in the design, with additional ground investigation scoped to reduce the risk. An efficient piling solution was developed and construction proceeded without significant issue. Some obstructions to piling were encountered with designs revised to add alternative pile locations to the affected rafts. This ensured construction could continue without interruptions, and completed plots were handed over to the client on programme.

United Utilities & Soil Engineering Geoservice
Yeoman Hey IR - Maintaining aging assets

The project is confidential so no summary was provided.

Sturminster Newton Embankment Stabilisation

A well considered geotechnical solution delivered against the challenges of working alongside a major river prone to flooding and breaking its banks during the autumn and expected flooding season. Works had to be completed during the autumn window as the A357 is one of the county's major trunk roads and extensively used by tourists in season. Working collaboratively with the Clients representatives, designers and framework contractor, VSL worked jointly to improve the buildability and durability of the geotechnical works. VSL also supported the project team liaising with the EA, local residents and other stakeholders. Extensive planning and a meticulous project delivery ensured the project was completed on time, to budget and safely. Feedback from the Clients representatives and from the wider project team has been universally positive.

A357 Sturminster Newton Bank Stabilisation

The stabilisation of the bank of the River Stour on the A357 at Sturminster Newton is to rectify stability issues that have persisted for more than 60 years. Soil nailing was adopted to stabilise the slopes to minimise impacts to the highway and river during construction while maintaining the historical aesthetic of the site. This required significantly less materials than other potential options thus offering carbon savings. The presence of soft materials within the riverbank above hard limestone beneath the road presented a challenge to the design of the soil nail system. Following additional ground investigation and design development, this was overcome using the TECCO® mesh system. Construction was safely completed within the specified timeframe, minimising impact on the local economy and within the necessary ecological working windows. Localised flooding and very high-water levels in the river were managed and did not delay completion of the works.