Client: Barratt David Wilson Southern
Date: 2014 (13 Weeks)
Nature of Works: Landfill remediation, re-engineering & restoration
Contract Value: £297,000 NEC Option A (Lump Sum) Contract
The Milford Hospital site is being redeveloped to a prestigious residential housing scheme by Barratt David Wilson in partnership with the HCA. Localised sources of lead, PCB and TPH contamination required remediation. A former landfill used for tipping of incinerator ash, hospital wastes and oily residues required more significant remediation work. In addition to presenting a risk to end-users, leachable contaminants from the landfill presented a risk an adjacent brook and the underlying Principal Aquifer, as well as housing stands of Japanese Knotweed infestation. Initial options considered at the design stage included wholescale excavation and processing of the landfill (~15,000 tonnes) or capping – the latter option would have required a steel palisade fence to prevent unauthorised access.
Soilfix developed an alternative, more cost-effective, sustainable and aesthetically attractive option to manage potential risks to controlled waters and future site users. No wholescale excavation of the landfill was required and more than 96% of materials were re-used on site.
The Soilfix solution demonstrated both best practice and innovation in the sustainable re-use of materials, in accordance with a Materials Management Plan (MMP) developed fully in accordance with CL:AIRE Code of Practice (CoP). Following targeted remediation of Japanese knotweed infested areas, the upper portion of the landfill was excavated, screened / sorted and re-engineered to form a low-permeability cement stabilised capping layer. This layer was overlain by a drainage geo-composite layer, erosion matting on side-slopes and a 600mm thick layer of site-won subsoil which was subsequently seeded. In doing so, the majority of landfill materials could be left in-situ without requiring significant disturbance and the remediation works could be completed on a limited footprint to enable early commencement of construction works adjacent to the landfill.
This Soilfix project was Highly Commended at the 2015 Brownfield Briefing Awards for the category of Best Re-use of Materials.
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