The current estimated total bulk volume of excavated material is 7.3 million cubic metres split as follows:
Westbourne Park Western tunnelling site—1 million cubic metres;
Central stations and shafts—3.1 million cubic metres;
Limmo Peninsular Eastern Tunnelling site—2.3 million cubic metres; and
Plumstead Portal/Woolwich Station—0.9 million cubic metres.
At the peak it is estimated that approximately 200,000 cubic metres (bulked) of excavated material will be produced per month across all the Crossrail sites. This peak is predicted to occur in late 2012. The need to reduce the number of such movements during the periods of the Olympic and Paralympic Games is recognised and is being actively considered by Crossrail Ltd in consultation with the Olympic Delivery Authority. As the detailed design develops, the programme and rates for individual sites will be determined.
Excavated material from the tunnel drives from Royal Oak will be removed by rail, while that from the tunnel drives from Limmo will be removed by boat. Excavated material from other sites, including the central stations and Plumstead portal will be removed by road.
It is intended that this material will either be recycled or transported to Wallasea Island in Essex to create a nature reserve for the RSPB. Other sites being considered for this material include South East of England Development Agency regeneration sites in Kent. Eighty five per cent of the excavated material from the tunnel drives will be removed by rail and boat, removing an estimated 500,000 lorry movements from the streets of London during the life of the project.
The majority of the Crossrail works are being built on land that has previously been developed. At some locations, previous uses, such as industrial processes, may have led to contamination of the ground. However, virtually all of the 7.3 million m3 of excavated material is expected to be clean and non-contaminated and can be reused elsewhere.
The Environmental Impact Assessment process identified sites where there was a high, medium or low risk of contamination (referred to as Category 1, 2 and 3 respectively). These sites are specified in the Specialist Technical Report on Assessment of Contaminated Land, which supported the Environmental Statement. Both are available from the Crossrail web site: http://www.crossrail.co.uk/.
Control and mitigation measures, applicable to design and construction, for Contaminated Land are given in section 8 of the Crossrail Construction Code. For higher risk sites (Category 1), these require ground investigation and assessment in accordance with the Model Procedures for the Management of Land Contamination (CLR11) published by Defra and the Environment Agency. For medium-risk sites (Category 2), generic procedures have been developed and agreed with the local authorities and the Environment Agency. Low-risk sites do not require further investigation.
The assessments (site specific or generic) will determine the measures required to deal with contamination. For high and medium risk sites, contractors will be given information from ground investigations that provide an indication of ground quality and the presence of contamination. When the contractors undertake excavations, they will carry out tests on excavated materials to comply with Duty of Care Regulations and to determine the destination of these materials.
The specification for the sprayed concrete lining will be finalised when the contractors are appointed. Approximately 0.4 per cent by volume of the sprayed concrete to be used by the project is estimated to be steel residue.
Sprayed concrete lining residue will not be used for the creation of the land form at Wallasea Island; however, the sprayed concrete lining residue material may be used to create some of the footpaths to allow pedestrian access.
Lord Adonis: Crossrail Ltd’s procurement strategy for removing excavated material is currently being developed and contracts are expected to be let in 2010. The exact scope and specification of each contract, including who will be responsible for the testing of contaminated waste, is still subject to further work. Virtually all of the 7.3 million m3 of excavated material is expected to be clean and non-contaminated and can be reused elsewhere.