A TEAM of international experts yesterday rejected the Government's original multi-billion dollar sewage plan to dump semi-treated waste into Chinese waters. In its place, they suggested the Government dispose of the effluent inside Hong Kong's own borders, after it was given a higher level of treatment. The three experts went before the Legislative Council's environmental affairs panel to answer questions concerning a government-commissioned feasibility report on sewage treatment options. The report, produced by Pypun Engineering Consultants, was commissioned in the wake of accusations by green groups, legislators and academics that the original plan was outdated and flawed. The experts were brought in by the Government to ensure the study was unbiased and met scientific standards. The $4.8 million study's report suggested nine technological options, but rejected the Government's initial plan to treat sewage with lime and then dispose of it in Chinese waters through a 28-kilometre pipeline. China has protested that it will not tolerate Hong Kong using its waters as a 'toilet'. All the options recommend a pipeline which would dump the treated effluent off Lamma Island. The consultants believe there will be little environmental impact on the surrounding area. The cost of the options varies from $6.5 billion to $12.5 billion. The experts rejected the government-backed plan of lime treatment, due to the amount of space the process requires and the amount of toxic sludge it produces. One of the two options which appear to be most favoured by them suggests using primary treatment followed by secondary biological treatment. But this scheme would cost $10.5 billion to build - $4 billion more than the Government's original proposal. The experts believe water quality might not be noticeably different if the less expensive process of chemically enhanced primary treatment is used. This option would only cost $6.5 billion. It would halve the amount of sludge and dramatically reduce environmental dangers. 'This solution has been successfully used in southern California for a population of 12 million people,' panel member Professor Ronald Harleman, of the Massachusetts Institute of Technology, said. Both the report and the experts agreed that increasing the level of sewage treatment meant a shorter pipeline could be used to dump the effluent within Hong Kong's waters.