A site investigation, risk assessment, and remediation strategy assessment was conducted to evaluate remediation alternatives for re-development options at a former landfill site at Haven Road, The Hythe, Colchester, Essex (the site).

Specifically, the report had the following objectives:-

• Assess the suitability of the land for development as housing, commercial uses and/or public open space;
• Assess remediation alternatives such that the site might be rendered suitable for the development objectives;
• Assess the potential costs of the identified remediation alternatives;

The area of the site requiring remediation (approximately 1.7 ha) was identified as an old landfill (1930s) consisting of brick, clinker, flint, ash, metal, and some timber.

The depth of the fill was estimated at 6.5m to 9m. Based on the age of the fill, the settlement potential and gas activity was likely to be low. The low settlement potential and low gas activity suggested that complete removal of the fill material was not a prerequisite for development, though ground improvement methods, including removal, treatment, and compaction may be required to address structural aspects of construction.

Further, a designed cap, to address direct contact exposures and gas and leachate control would likely be required. Passive gas control systems and protection of buildings against gas intrusion would be required. In this case, active gas control systems were thought not to be necessary.

The remediation costs for different development options, including mixed residential / commercial, public open space, and underground parking were estimated.