Overview
Helping to meet the demands for additional outer London housing, “The Quarry” is the redevelopment of a former landfill site into a 600-home residential complex and 630-place three-form primary school.

Spanning approximately 20 hectares, The Quarry site was originally mined for gravel and loam, subsequently used as a landfill site for bricks, masonry and other inert building materials and finally lay neglected to become overgrown with brambles and invasive Japanese knotweed.

The site is designated a Grade One Site of Borough Importance for Nature Conservation (SINC) and benefits from the Thames Gateway Regeneration Scheme. It therefore has to reflect a careful balance between ecology and development (by providing a generous proportion of play space, open space and ecology areas).

No development is permitted to take place in these ‘ecology rich’ areas, other than the provision of footpaths and cycle-ways and the construction of sustainable drainage features, including wet ponds and swales to manage surface water drainage and promote biodiversity.

What They Did
SDS GEOlight® attenuation tanks, with a combined capacity to store up to 6,070m³ of water, have been installed beneath new wet pond features including three low level lakes and an area of natural grassland and scrub, surrounded by small wooded areas. These ‘wildlife areas’ provide a habitat for notable protected species including newts, lizards and slow worms.

Due to its historic use, the site has a unique topography, with level changes from north to south varying between five metres and 35 metres towards the east and west. This created challenges for access, internal roads and the drainage systems, which were successfully overcome.

Results
SDS GEOlight® tanks were integral to the drainage solution, providing attenuation to meet the very low site discharge rate on a steeply-sloping site with limited space and no opportunity to infiltrate.

Using below-ground storage in conjunction with surface water drainage features facilitated the environmental and wildlife benefits above-ground, while achieving sufficient surface water storage necessary to satisfy planning requirements at this sensitive location.

The 3.5-hectare ecology area will be managed with a “hands-off” approach by a designated management company, protecting the area from further deterioration and allowing its ecological value to be conserved.

SDS helped us to engineer a successful SuDS outcome at an extremely challenging brownfield location.

– Ben Rayner, Principal Engineer, Stomor Group

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