February 2018

Category 3 check on Thames Tideway Tunnel

The Thames Tideway Tunnel (TTT) involved the construction of a 25km (16 mile) tunnel running under the River Thames. This will provide an upgraded system to intercept, store and transfer raw sewage and rainwater discharge that currently overflows directly into the river. Construction work commenced in 2016 and the target completion year is 2022.

Rendel was appointed by Ferrovial Laing O’Rourke (FLO) to undertake a Category III Check of the damage assessment carried out on the existing river wall assets at Kirtling Street. The check was limited to the first and second phase construction works which included installation of diaphragm walls, shaft excavation and tunnelling for the Thames Tideway Tunnel project.

Rendel undertook a full desk-top study based on factual ground investigation reports, previous damage assessments and method statements provided by FLO to ascertain the damage expected to occur on the relevant river walls.

Our role included:

  • Development of an independent ground model
  • Assessing the impact of diaphragm wall construction and shaft excavation (Phase 1)
  • Assessing the impact of piling works and acoustic shed construction (Phase 1)
  • Assessing the impact of tunnelling using sprayed concrete lining, NATM and a tunnel boring machine (Phase 2)
  • Developing 2D and 3D geotechnical models
  • Developing 3D structural models
  • CAT III Check Certification and Reporting