THE CHALLENGE:
Soilfix initially supported CALA Homes with abnormal development costs at the pre-acquisition stage to purchase a 5.2 hectare parcel of this former Army Barracks. Site investigations had detected hotspots of elevated Polycyclic Aromatic Hydrocarbons (PAHs) and asbestos (chrysolite fibres and cement fragments) in the shallow Made Ground.
Extensive soft areas of the site were covered with an imported topsoil—whilst containing some anthropogenic materials and of low organic/nutrient content, the topsoil was confirmed to be chemically suitable for residential end-use if carefully stripped and segregated from underlying soils.
OUR SOLUTION:
To achieve the client’s remediation objectives and return the site to a level suitable for residential development use, Soilfix’s carried out the following works in advance of construction, fully in accordance with CL:AIRE Code of Practice:
- Controlled site strip of 6,000m3 topsoil under watching brief, processing to a <25mm grading with an imported PAS128 compost mulch—comprehensive testing to confirm suitability for re-use in garden / POS areas;
- Further delineation of identified hotspot areas, followed by targeted excavation of contaminated soils under a watching brief;
- Pre-treatment of PAH impacted soils for re-use as sub-capping fill;
- Screening and handpicking visible asbestos cement fragments from 3,000m3 made ground, for re-use as sub-capping fill or disposal (by others) as de-categorised non-hazardous soils & stones; and,
- Close liaison with the consultant who was responsible for sampling and verifying the hotspot excavation to ensure all contaminated soils had either been removed or utilised at suitable locations / depths below capping subsoils.
Soilfix completed the remediation works on programme allowing continued site redevelopment without delay. A total 8,500 tonnes of improved, chemically suitable topsoil was generated by the works to provide a highly sustainable and cost-effective solution to meet all of CALA’s development requirements, saving over £200K in the process.
