LAMMA residents were assured yesterday that the disposal of sewage around the island would not have a major impact. The assurance was given as legislators on the environmental affairs panel were informed of recommendations by the three independent experts on the Government's Sewage Strategic Disposal Scheme. One recommendation was to adopt chemically enhanced primary treatment to help disinfect the sewage before it was discharged into the harbour. But the chemicals used could stagnate the water, damaging marine ecology and increasing bacteria. The enhanced treatment would allow the sewage to be dumped in Hong Kong waters instead of adjacent Chinese waters as originally planned. China had vehemently attacked the original plan as immoral and unscientific. Principal Environmental Protection Officer Vic McNally told legislators the disinfected sewage discharged into the water near Lamma Island would not have any 'appreciable effects' on residents. Deputy Secretary for Planning, Environment and Lands Tony Cooper denied the Government's original scheme had been aborted or that the Government had changed from a long-term policy to a piecemeal approach. He argued that there had only been a change in some water quality objectives. The Government will decide which proposals will be adopted after a six-week public consultation period beginning next month and after environmental impact studies on possible sites were completed. The Government is also examining potential sites for secondary treatment plants on Lamma Island and Green Island reclamation, in addition to the primary treatment plant on Stonecutters Island.