A programme of geotechnical investigations have started along the proposed route for the Central Inceptor, a new wastewater tunnel in New Zealand.
The programme will involve drilling holes to the depth of the future tunnel and trial pits near the access shafts that will be constructed to build the new pipeline.
The estimated completion date for this work is early May 2015.
The geotechnical investigations will influence the final design of the tunnel which is expected to be approximately 13km in length and lie between 22m and 110m below surface level.
The proposed route will run between Western Springs and the Mangere wastewater treatment plant, crossing the Manukau Harbour at a depth of approximately 30m below the seabed.