This category is for a geoenvironmental scheme - as a standalone project or part of a larger development - that stands out in terms of its credentials in innovation, quality, sustainability, health and safety and value engineering. Projects shortlisted into this category have a major focus on contaminated land remediation or specialist environmental protection as part of a geotechnical scheme.
Arcadis Consulting UK
Chapelcross Nuclear Power Station
Overall project value: £1.8M
Geoenvironmental value: £1.8M
chapelcross nuclear power station
Chlorinated solvents used in 1950s and 1960s maintenance of generator armatures had entered the underlying glacial till and penetrated Triassic sandstone aquifer. Earlier excavation of impacted till had not removed a contamination plume that extended at least 400m beyond the site boundary. Ten years of monitoring data indicated the plume was probably stable, but not diminishing and natural degradation had stalled.
Arcadis’ investigation strategy included rock mass structure analysis and depth discrete assessment of hydraulic permeability and phreatic conditions, soil vapour surveys and guide targeted drilling.
Assessment of characterisation monitoring, borehole and geophysical data culminated in a detailed conceptual site model depicting a sinking plume reaching to >50m depth. Full scale remediation of residual source and near source plume using enhanced natural degradation is now underway.
GEA and Regenesis
Runcorn bus depot
Overall project value: >£2M
Geoenvironmental value: £80,000
The redevelopment of a former bus depot in Runcorn posed unique and complex challenges, where each step in the solution process had a follow-on effect.
The site was located on a mound of industrial waste known as Galligu resulting from the Leblanc process to make soda ash and had several metres of Galligu above a black ash layer which was underlain by cohesive glacial till. Contaminated groundwater was seeping out of a steep slope adjacent to a canal and polluting the waterway.
GEA and Regenesis’ solution involved a soil/cement mixed panels to support the structures, with a soil/cement mixed mattress under roadways. Installation of these panels altered the groundwater flow, which was modelled to ensure the contaminant treatment could be targeted accurately.
The groundwater was raised and channelled towards the panel “wall” at the boundary and would funnel through gaps at a higher velocity. A liquid activated carbon substrate was used to integrate with the panels and provided effective treatment in the bio-toxic environment created by Galligu. This subsurface carbon-filter entirely prevented contaminant from the leaving site.
Davyhulme Modernisation Project
Overall project value: £144M
Geoenvironmental value: Project costs saved as a result of the geoenvironmental design: £70M
Opening in 1894, Manchester’s Davyhulme Wastewater Treatment Works started life as a “sewage farm in the countryside”. It has been at the forefront of innovation and is one of the biggest wastewater treatment works in the UK serving the entire western side of Manchester.
The cost of disposing of 282,000m³ of contaminated spoil off site was estimated to be £75M, so United Utilities assessed the ground data and introduced a remediation strategy to reduce the amount of material requiring disposal to just 280m³.
The site investigation strategy included 95 monitoring boreholes to assess the ground gas risk and impact on ground water to enable United Utilities to appraise the remediation options and present these to the local authority and Environment Agency.
The cost of remediation was reduced to around £6M, delivering a cost saving of just under £70M compared to the cost of disposal.
Sighthill Transformational Regeneration Area
Overall project value: £10.79M
Geoenvironmental value: £10.29M
A complex project to transform a 50ha area into new residential and amenity parkland in Glasgow, saw VHE Construction implement earthworks to deal with contaminant remediation, ground improvement and waste minimisation.
The site had been subject to upfilling with 1Mm3 of Galligu waste from soda ash production at a former chemical works. The manmade product that cannot be classified geotechnically or chemically and could impact ground water and potentially generate hydrogen sulphide gas, so remediation was needed for the redevelopment to progress.
The ground model for the site was complex due to material having been historically imported, relocated, mixed and exposed to different elements over time, VHE’s solution was to develop a strategy allowing different materials to be placed in different locations both on plan and in elevation. This required a significant pre-classification exercise with extensive planning, materials management, tracking and verification.
Drayton Garden Village
Overall project value: Confidential
Geoenvironmental value: £2M
WDE Consulting was appointed to manage the geoenvironmental aspects for the redevelopment of the RAF West Drayton for redevelopment to create 773 residential and commercial units.
The firm undertook ground contamination and engineering work at the site to satisfy the regulatory authorities and stakeholders. This included the remediation of 20,000m³ of hydrocarbon impacted soils and associated groundwater plume, backfilling of a 15,000m³ void from a former basement with an engineering fill and the reuse on site of a further 100,000m³ of site won materials.
The work had to be completed in phases to prevent delays in the overall project completion, which required careful co-ordination with a number of different contractors. In additional WDE had to provide general advice on foundations and drainage parameters as well as the mitigation measures that were required to provide appropriate protection to the sensitive receptors.