Campbell Reith won Best conceptual design for remediating a former shipyard in Southampton, which began regeneration of the area
This 12.5ha site former Vosper Thornycroft (VT) shipyard was acquired by SEEDA to promote regeneration of the area. It is located along the mudflats and eastern bank of an estuary, adjacent to a special protection area and Ramsar site, in a sensitive environment and prestige development location. The remediation and civil engineering project took a year and included:
- Land quality appraisals including extensive investigations, risk assessments and specialist surveys, plus a full remediation package
- Demolition/crushing of buildings, hardstanding and shallow ground obstructions for reuse
- Excavation and screening of 250,000m3 of soils for reuse, with only 1% of material removed from site
- Hydrocarbon bioremediation and treatments for asbestos contaminated soils, with field and lab trials of remediation techniques
- Continuous multi-channel tubing (CMT) groundwater monitoring and risk assessment modelling to determine remedial actions for water contamination
- Re-profiling of the site to provide engineered capping layers
- Soft engineering to reconstruct the shoreline and engineered marine terraces and extend the ecological footprint available.
Best rather than good practice
The guiding principle throughout the project was to integrate the engineering design with the intended redevelopment and minimise off-site disposal of contaminated soils, to achieve cost-efficient, sustainable remediation. Close professional relationships meant the re-profiling and remediation works accommodated the desired levels of the coming redevelopment and avoided waste.
Of particular importance was establishing the most economic and appropriate method of addressing asbestos contamination in soil in an area of the site used to dump materials affected by asbestos and the intended location of a deep basement for a new residential tower.
A remedial trial was implemented by HBR to evaluate ways to separate asbestos from the soils using complex soils screening and washing techniques. Meanwhile, research began to develop appropriate methods to analyse asbestos in soil and associated risks, to give transparent remedial objectives.
This latter aspect was implemented by the health and safety laboratory in Buxton with the Environment Agency, which is reviewing methods for establishing remedial targets for asbestos in soils. The work generated a numeric assessment risk model for human health that considered the asbestos contamination and demonstrated that remediation was viable.
A highly sustainable scheme was achieved. The soils treated for asbestos and other contaminants were validated and then placed (under a horizontal capping layer) according to the sensitivity of the proposed end use. Use was made of fluvial gravel deposits and the Brackelsham Beds as general fill (following geotechnical stabilisation and drainage). All crushed concrete was washed and reused.
"This project showed excellent attention to detail." Duncan Sanders
