All beaches on Hong Kong Island could face closure within two decades unless a much-needed sewage disposal scheme is implemented, an official warned yesterday. Principal Environmental Protection Officer Dr Malcolm Broom issued the warning after officials briefed lawmakers on Phase II of the strategic sewage disposal scheme. The project, to be built in four stages over 10 years at a cost of between $11 million and $26 million, is a comprehensive sewerage system to dispose of treated sewage in deep ocean currents south of Hong Kong. Although treatment was provided at Stonecutters Island, an international review panel has recommended that an environmental impact assessment study be carried out on alternative locations. A new expert group on sewage disposal, led by the Hong Kong and Macau Affairs Office and the Planning, Environment and Lands Bureau, was set up in July to continue the discussions. Mainland authorities found the four shortlisted options for treatment acceptable. But they disliked the option to build an outlet on southeast Lamma which would affect mainland waters. Deputy Secretary for Planning, Environment and Lands Kim Salkeld said the Government would ensure pollution problems would not be transferred to the mainland. He said the current proposals involved discharges at sites ranging from east or west Lamma to southeast Lamma.