Stevenage Road, Fulham, London
Tel: 01483 310600
Octagon Developments Limited
- Data Review
- Ground Gas and Groundwater Monitoring
- Remediation Strategy Plan
- Verification Reporting
The development is located close to the River Thames and Craven Cottage, the Fulham FC stadium. The site was part of Petroleum Wharf which was once occupied by Redline Motor Spirit Company and later used as an oil distribution depot before being developed into a day centre for the elderly. The surrounding area has had a varied industrial history including coal and oil handling facilities plus asbestos cement works.
CGL was instructed to conduct a review of available information for the site and subsequently to scope and supervise a series of intrusive investigations that included four rotary boreholes and five window sampler boreholes. Ground gas and groundwater monitoring visits were undertaken from six monitoring installations.
CGL’s investigations identified contamination in the soil and groundwater that posed a risk to human health and controlled waters including hydrocarbons, BTEX and lead, with free product encountered in one corner of the site. Generally low concentrations of ground gases were present, however bulk gas/vapour analysis identified that elevated methane readings in two positions were influenced by the presence of hydrocarbon vapours in the soil and groundwater and not as a result of the biodegradation of organic matter. One position showed varying flow conditions including relatively high negative flow conditions. This was investigated by local excavation and shown to result from a broken sewer pipe.
Based on risk assessment and in liaison with the local Environmental Health Officer, CGL prepared a remediation strategy for the development. The scope of the remediation was designed to integrate with the construction programme, including works for an extensive basement covering the majority of the site.
The remediation works included:
- Hotspot removal with localised pump and treat of free product and groundwater.
- Characterisation of materials and identification of waste disposal routes.
- Confirmation that imported material complied with acceptability criteria.
- Gas protection of buildings, including investigation and removal of the anomalous gassing source enabling reassessment of the gas regime and a reduction in gas protection measures.
- Use of appropriate piling methodologies to mitigate the potential of a migration pathway into the underlying aquifer.
- Protection of underground services by specification of appropriate materials.
- A watching brief and discovery strategy for potential previously unidentified contamination.
As works have progressed, CGL has provided technical support on remediation details working in close liaison with the Local Authority Environmental Health Officer, architect, remediation contractor and main works contractor. CGL has also observed the remediation works and provided third party Verification Reports as evidence for the Local Authority to discharge the relevant planning conditions.