Excavation & Processing of Asbestos in Soils

Client / Kier Moss/SEGRO Estates
Site / Edinburgh Avenue, Slough
Value / £600k
Timescale / 9 Weeks

Summary

Sanctus was appointed by Kier Construction (Central) (the Client) to carry out the controlled excavation and processing of over 6,000m3 asbestos contaminated soil and demolition rubble historically used to raise site levels at 157 Edinburgh Avenue, Slough.

The site investigation confirmed that the fill material comprised subsoil and demolition type materials, including brick, concrete, stone, sand and gravel. Within this material, Asbestos Containing Materials (ACM’s) were identified, including cement bonded asbestos roof sheets (Chrysotile), asbestos insulation board, asbestos pipe lagging (Crocidolite and Amosite) and asbestos ‘free fibres’.

Due to the variable nature of the Made Ground, Sanctus established a methodology for the controlled excavation and hand sorting of the materials, to segregate the asbestos fragments from the soils and recyclable brick and concrete rubble. The methodology was approved by the HSE, and all works were carried out in accordance with the Health and Safety at Works Act 1974 and the Control of Asbestos Regulations 2006.

Strict controls were in place at all times, including daily perimeter air monitoring and personal occupational air monitoring to ensure the safety of site workers and the general public. The entire operation was carried out in a phased approach as to minimise the exposure of potentially contaminated materials at any one time.

Prior to undertaking the works, a safe working zone was established, with entrance and exit only possible through a decontamination unit.

Made Ground containing asbestos was loaded onto a picking station conveyor belt and sorted by hand using a picking station. ACMs were removed and double bagged for disposal at a suitably licensed facility under full duty of care. Brick and concrete rubble were also picked from the material mix for washing and crushing.

Processed soils were sampled and sent to an independent UKAS and MCERTS accredited laboratory to check for the presence of asbestos free fibres. Materials found to be contaminated by asbestos fibres or fragments of ACM were removed from site for licensed disposal. Recyclable materials, confirmed to be free from asbestos were reused onsite.

Sanctus managed to process and ‘recover’ significant volumes of clean soils and brick and concrete rubble which was crushed and reused onsite.

Sanctus provided the management, supervision, environmental engineers and labour for the project. All operatives involved in the operations had received asbestos awareness training prior to working on the site.

Previous Site Investigation had also identified an area of hydrocarbon contaminated material, as a result of former land use. In addition to the controlled excavation of contaminated demolition rubble, Sanctus excavated grossly impacted materials and subjected them to treatment by Chemical Oxidation under controlled conditions, to enable the disposal of the material as non-hazardous waste.

The project was completed within a tight nine week programme, including the reinstatement of excavations to formation level. The processing and handpicking operation provided a more sustainable remediation option than a simple ‘dig and dump’ operation at landfill, and saved the developer in the region of £400k in landfill disposal costs.