In the River

Much of the waste created by the works will be 'clean' (i.e. uncontaminated) materials, excavated from the river or from cut and cover excavations but surplus to requirements on the construction contract. It is known, however, that some of the surplus materials could be contaminated. Surplus materials dredged from the immersed tube tunnel trench may be disposed of at sea. This will fall under the strict control of the Department for the Environment, Food and Rural Affairs (DEFRA) from whom licences would need to be obtained.

Alternatively, surplus river dredgings could be sent to licensed landfill sites in the region. If a licence were granted by DEFRA, approximately 140 000 m3 of unsuitable materials could be disposed of at sea. There are ongoing consultations between the TWPTA's advisors and DEFRA on this matter.

Approximately 160 000 m3 of sand and gravel will be dredged from the tunnel trench line and other construction areas. This may be temporarily stored adjacent to the river at the current RMC site at the former Mercantile Dockyard. Once the tunnel sections have been put in place approximately 150 000 m3 of sand and gravel would be used to refill the trench. The balance could be deployed elsewhere on the project or made available for sale on the open market.

The re-use of excavated aggregates within the construction project will reduce the need to bring in such construction materials from off-site.


Cut and Cover

The excavation of the cut and cover trenches will also give rise to significant volumes of surplus material. Approximately 332 000 m3 of material would be excavated during these operations. Of this total, 167 000 m3 would be backfilled into the trenches, while the remainder (165 000 m3) will require disposal at licensed landfill sites.
Landfill disposal of surplus excavated material will mean a considerable number vehicle movements on the local road network.

General

General construction waste including concrete and mortar residues, packaging, damaged (unusable) materials and office wastes will be generated. In relation to the surplus excavated materials, the volume of construction waste would be very small.

Opportunities for waste avoidance, re-use and recycling will be explored and implemented where practicable. Non-reusable construction waste would be sent off-site for disposal at a licenced landfill.