Remediation of designated Part 2A gardens, St Helens

Remediation of designated Part 2A gardens, St Helens

FLI QDS were appointed as principal contractor to undertake the remediation of the garden areas of 40 individual domestic properties as part of the Part 2A Contaminated Land Capital Projects remediation programme for St Helens Council.

The properties had been determined by St Helens Council to have significant pollutant linkages with respect to human health under Part 2A of the Environmental Protection Act (EPA) 1990. The subject properties were constructed on the site of a former chemical and glass works in the 1950s when planning controls were less stringent and environmental risk assessment/ investigation less advanced. The works were undertaken to ensure that garden areas were suitable for continued domestic use.

Project Details

Remediation method

The remediation works undertaken by our team required the restoration of front and rear gardens. Properties remained occupied throughout the works. We were working within a tight financial budget and operating timescales. The works required extremely proficient project management skills; treatment and reinstatement timeframes equated to three days per garden. In order to provide necessary cost efficiencies, operations were streamlined and, when possible, multiple gardens were remediated at one time. Works also required intensive management from a health and safety perspective due to the equivalent of half a mile of services intersecting target gardens. Maintenance of trip free access routes for residents was also required along with the control of any dusts generated. Reinstatement of fencing around each garden each evening was a pre-requisite from both a health and safety and security perspective. Works included detailed prestart topographical surveys of site boundaries including brickwork integrity; detailed delineation of contamination facilitating accurate waste classification and streamlining of disposal operations. The remedial scope also included delineation and removal of an area of Japanese Knotweed. Metals/PAH impacted soils were removed from garden areas (600mm layer) prior to the placement of a high visibility break layer and reinstatement with 450mm of approved subsoil and 150mm of topsoil. We also undertook post remediation landscaping including the provision of paths, patio areas and turf. Garden furniture was either reinstated or replaced.

Materials were recycled wherever possible – for example fence panels were re-used if in satisfactory condition and sheds re-erected. Works were delivered under difficult operational conditions, which included very small access points to gardens and the provision of a soil/equipment storage  compound greater than one mile away from the target properties. Works typically required significant amounts of hand digging, so as to avoid services. Excavation works were carefully controlled with appropriate no dig zones implemented, where remediation zones abutted property foundations.

Remediation outcome

The works were completed within required timeframes and successfully validated. In total we excavated and removed from site 2,070 tonnes of non-hazardous soils, 660 tonnes of hazardous soils and 140 tonnes of Japanese Knotweed contaminated soils.

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Remediation of designated Part 2A gardens, St Helens

It was a pleasure to work with QDS on this project. Hopefully we can give you further opportunities to win more awards in the future.

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