Tideway Tunnel AMP6 Modification
We were appointed under an NEC 3 option B subcontract to supply all necessary labour and plant to remove the spoil from the drive shaft, reception shaft and siphon tunnel for the Thames Tideway AMP6 Modification.
Works were carried out over a 41-week programme with arisings being disposed of from each shaft simultaneously. We were responsible for supplying the frontline supervisor to manage the muck bays and ensure that there was always sufficient space for stockpiling the arisings.
Arisings consisted of (but were not limited to):
- Made ground
- Alluvium
- Lambeth group
- Harwich Formation
- River Terrace deposit
Challenges
During the disposal phase, the spoils moisture content increased due to the addition of polymers which resulted in the spoil not being suitable for transportation. Subsequently, we managed the waste by adding lime to the spoil until a suitable moisture content was achieved for safe transportation. This also involved additional chemical testing to ensure that the pH limit was within the receiving site’s import criteria.
