David has been appointed to supervise a crew from Mainmark Civil at Arncliffe to carry out post grouting of the tunnels. The role required defining the scope of works, designing the extent of the grouting and completing the task to achieve an acceptanle water ingress of 6 l/min/100m.

The New M5 is twin motorway tunnels in Sydney 9km long, from Kingsgrove to St Peters, and are part of the West Connex project. The tunnels at Arncliffe are 17m wide and 8m high, and 30m below surface, and pass under the Cooks River. 

Grouting and Foundation Works Australia has been awarded Best Ground Treatment Service Provider in NSW  in the Australian Enterprise Awards 2017

David Lees has registered to study his PhD at Peradeniya University in Sri Lanka. His research into "The effects of tunnelling on the near surface and deep level aquifer in the Uva Province" is directly related to his work as Chief Site Supervisor on the 15km headrace tunnel for the Uma Oya project

David was appointed by Amberg Engineering as Chief Site Supervisor for extensive grouting works and completion of the excavation of the 15.2km headrace tunnel excavated by TBM and a 3.7km drill and blast tunnel linking the two dams.

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.