Three final stages of Hong Kong’s troubled strategic sewage disposal scheme could be undertaken as build-own-operate concessions, according to an independent panel.

A six-member group is investigating the controversial US$2bn first phase and its planned further stages.

Professor Donald Harleman, Ford Professor of Environmental Engineering at Massachusetts Institute of Technology, said: “We will look at experience elsewhere and at the pros and cons, but not details of the financial arrangements or how funds should be raised.” The panel, appointed by Hong Kong government chief executive Tung Chee-hwa, will submit a final report by November.

The three follow-on stages include a long-sea outfall discharging into Chinese waters south of Hong Kong and a deep tunnel sewer collector system under Hong Kong Island.

The panel’s investigation coincides with a two-week shutdown of a Robbins TBM being used by Skanska to excavate one of the phase-one tunnels between Tsing Yi and Stonecutters Island. Technicians are replacing cutterhead seals.

Work on the tunnel was already proceeding slowly because of poor ground conditions caused by the 100m Tolo Channel fault which crosses the tunnel at about 90 degrees. Skanska excavated just 26m in April before tunnelling halted on April 26, and 15.8m in March, figures from the client, Hong Kong’s drainage services department, show.

The TBM is under container terminal 7 at the Kwai Chung port, a sensitive area on reclaimed land carrying part of the world’s biggest container shipping harbour.

So far three of the six tunnel drives have been completed. The Paul Y/Seli joint venture has completed more than 86% of its 4.83km drive from Chai Wan to Kwun Tong, but the project has caused subsidence in Chai Wan.

The TBM is nearing the Eastern Harbour Crossing, a combined three-lane and two-lane immersed tube tunnel.

Gammon/Kvaerner has also bored about 78% of its drive from Kwun Tong to To Kwa Wan.

The three contractors were appointed after the government sacked the original contractor, Campenon Bernard/Maeda, in December 1996. That dispute is the subject of an arbitration expected to last into July.

The project is believed to have doubled in cost and is unlikely to be finished until late 2001, four years after it was due for completion.

The phase one scheme was designed by Montgomery Watson with Mott Connell as tunnel design sub-consultant.