THE CHALLENGE:
A 4Ha portion of RAF Tangmere (a former Spitfire airfield during WWII) was being redeveloped to a 125-unit residential housing scheme with private gardens. Site investigations identified sub-surface macadam containing coal-tar bitumen, which presented a risk to the underlying Principal Aquifer from polycyclic aromatic hydrocarbons (PAHs). The site also contained significant in-ground structures and asbestos containing materials including cement fragments, insulation board and lagged pipework below the site.
OUR SOLUTION:
Soilfix implemented a sustainable and cost effective solution in conjunction with idom Merebrook, all in accordance with a Materials Management Plan (MMP) developed in accordance with CL:AIRE Code of Practice (CoP) and an Asbestos Plan of Works (APoW) developed in accordance with CAR-SOIL guidance, including:
- Stabilisation / solidification (S/S) treatment of 4,500m3 coal-tar bitumen contaminated soils to reduce PAH leachability below stringent leachate criteria;
- Additional S/S treatment of unforeseen areas of weathered aviation fuel contamination;
- Targeted removal of asbestos lagged pipework as licensed works;
- Comprehensive breakout of slabs & sub-structures, processing 7,000 tonnes to BS EN 932-1 ‘Type-3’ Specification for permeable paving below development roadways & external areas;
- Hand-picking of asbestos cement debris from made ground soils;
- Cut / fill reprofiling site to development platform levels, incl. lime stabilisation to achieve optimal moisture content; and,
- Lime stabilisation & construction of working platforms for vibro-piling operations.
In spite of numerous unforeseens encountered during the project, Soilfix completed all works in sufficient time to allow unimpeded progress of our client’s construction programme. Of the total 20,000m3 materials subjected to processing, only 785m3 of unsuitable material required disposal off-site, resulting in almost 95% materials recovery achieved. On-site S/S treatment enabled a saving of over £2M compared to hazardous off-site disposal – the regeneration of the site to much needed housing in the local area would not have been commercially viable with such an over-spend.
