It is proposed to redevelop a former industrial works with private housing and Cognition have been awarded the contract to carry out remediation works.

The development comprises 115 two three and four storey housing units mostly with private gardens and also limited areas of public open space.

Powder Plant Redevelopment

The site has recently been demolished but was previously occupied by two large operational buildings including a powder plant. The eastern half of the site was rough car-parking, asphalt covered in places. To the south and west of the building was soft landscaping which comprised the natural succession of topsoil over subsoil. The works included 2 above ground fuel storage tanks, 2 metal oxide slurry tanks and 4 underground settlement tanks.

Ground conditions comprise a limited thickness of made ground over glacial sands and clays over Chalk. The site is sub-divided into four zones, on the basis of the ground conditions, patterns of contamination and remediation requirements. Zone 1, in the NE corner of the site was previously hard standing and is characterised by made ground which is slightly contaminated with lead and Benzo(a)Pyrene. Zone 2, also formerly car parking is characterised by a thin layer of construction over either glacial drift or chalk. The construction materials contain PAH and are contaminated with manganese nickel and zinc.

This zone has been contaminated by surface spills of fuel hydrocarbons. Zone 3, the footprint of the former buildings is similarly contaminated as zone 2 with process related metals. Zone 4, the area of former soft landscaping is clean.

There is a zone of hydrocarbon contamination beneath a former 20,000 litre tank some 10mx10m in area extending to 2-2.5m depth which requires remediation. A rubble filled soakaway uncovered by the demolition, contains rubble which is heavily contaminated with manganese, nickel and zinc, the process metals used on site.