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HK told to drop low tech sewerage plan for cheaper biological option

HONG KONG's government has been urged by an international panel of experts to scrap plans to extend its troubled strategic sewage disposal scheme in favour of alternatives using newer technology.

The six-member group, led by Massachusetts Institute of Technology professor Donald Harleman, said its four alternative proposals were also cheaper than the existing plan.

In a 50-page report, the team said plans for a 17km long sea outfall, discharging effluent into the South China Sea, should be abandoned. Instead, the present chemically enhanced primary treatment should be upgraded to use biological aerated filters supported by a network of shorter discharge outfalls.

Prof Harleman said: 'The question is, 'Is dilution the solution to pollution?' The answer is 'No'.'

His report presents four alternative options for the construction of new tunnels and outfalls and upgrading treatment works.

The estimated cost of each option is £1.3bn-£1.4bn. This compares to the £1.9bn cost of the government's preferred scheme.

Harleman also urged the government to seek finance from the private sector to develop the plants proposed at Lamma, North Point and Sandy Bay.

However, construction of new tunnels and pipelines would have to be publicly funded. He added that the priority was to build the deep tunnels required in all four options to eliminate further delays.

'Privatisation through design, build, finance and operate is very useful for new treatment plants to speed up the construction process, ' said Harleman.

The Environmental Protection Department has already used privatised concessions to develop three landfill sites and a chemical waste incinerator. But this would be the first use for a sewerage scheme.

However, another member of the group, Sebastiano Pelizza, professor of underground construction at Turin University, underlined that extensive site investigation would be needed to reduce the risk of meeting the tunnelling problems found on the first phase of the tunnel network.

Acting secretary of the government's Environment & Food Bureau Paul Tang said public consultation would be held on the proposals. 'We will also need to look at the resource requirements of the options recommended by the review panel, ' he said.

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