''MODERATE'' charges have been proposed for landfill dumping to allay fears that the sudden introduction of high levies might encourage polluters to leave waste on roadsides. The proposal was received with reservations by environmentalists and legislators, who were doubtful about the effectiveness of the levy. Spokesman for the Conservancy Association, Mr Gordon Ng Ting-leung, said the Government should conduct a comprehensive review of its waste disposal policy instead of charging polluters alone. The Legislative Council's Environmental Affairs panel was told yesterday that a levy equivalent to 25 per cent of the landfill operation cost will be charged for all privately-collected waste from next July. Charges ranging from $75 for loads carried in a small vehicle to $150. There are three landfills in Hongkong - Tseung Kwan O, Pillar Point Valley and Shuen Wan - which cost a total of $500 million last year. The construction industry, which contributed more than 60 per cent, or 12,000 tonnes, of rubbish, is the main target of the scheme. Figures show that 63 per cent of the dumped materials could be reused. The Government also plans to extend the scheme to householders after discussions with the Urban Council, which oversees domestic disposal. The Principal Assistant Secretary for Planning, Environment and Lands, Miss Mary Chow Shuk-ching, said that the charge should not be too high or it would lead to illegal dumping. The initial charges were criticised by legislators as too lenient. They said the charges might undermine the scheme to promote re-use of construction materials. United Democrats legislator, the Reverend Fung Chi-wood, said there was not enough incentive to reduce the amount of waste. ''If the charge is that low, I don't think constructors would care to make an effort to separate the waste,'' he said. Some legislators also suggested a higher charge for construction waste. Engineer Mr Samuel Wong Ping-wai suggested constructors pay five per cent more than other polluters to encourage the retention of reusable materials in the industry. But independent legislator Miss Emily Lau Wai-hing was against higher charges, saying the Government should not discriminate against industry. A study on how to reduce the amount of rubbish reaching landfills will be commissioned by the Government later this year. Miss Chowtold a seminar yesterday that the Government was looking to broaden its waste disposal strategy from providing landfills.