David joined the Amberg team in Sri Lanka on the troubled Uma Oya project as their Chief Site Supervisor. The TBM in the 15km headrace tunnel was stopped in May 2016 to carry out grouting works. The initial post grouting works was completed in December 2016.
At one stage there was nearly 400l/s of water ingress. This has now reduced to about 150l/s but the water pressure has increased to over 5 bar.
Over 1000 tons of cement were injected and the TBM started again in December 2016. However conditions continued to be difficult requiring extensive pre-excavation and post grouting to allow the tunnel excavation to be completed.