Although the last of Crossrail’s tunnelling spoil set to be excavated next month, the work on developing a new bird sanctuary using the waste will continue for another 10 years.
The Royal Society for the Protection of Birds (RSPB) has said that it needs a further 8M.t of clean soils to complete its work on the Wallasea Island Wild Coast Project in Essex.
The new bird sanctuary has taken 3M.t of waste from Crossrail and the reclaimed land is already being colonised by wildlife thanks to efforts to ensure fill material meets environmental criteria.
Since tunnelling on Crossrail started in November 2012 significant environmental testing has been undertaken to ensure the waste presented no risk to its future inhabitants.
According to ESG, who worked with Atkins on the assessment work, the material had to be chemically characterised for typical ‘brownfield’ contaminants and more specialist compounds derived from the injection of grout and polymers used when tunnelling.
However this was not a straightforward task as the intellectual property rights of the polymer manufacturers meant that the actual chemical make up of each polymer used was not revealed to ESG, Atkins and the contractors. To aid assessment ESG developed a methodology of the polymer chemisty and used specialist techniques, such as inductively coupled plasma – optical emission spectroscopy and gas chromatography – flame ionisation detector.