A controversial 'superjail' complex on Hei Ling Chau, housing more than 7,000 inmates, came closer to reality yesterday when legislators approved a $46 million feasibility study. The decision came amid objections from green groups who have expressed concern at the environmental impact of the project and its associated works, such as reclamation and a bridge between Hei Ling Chau and Lantau Island. A Security Bureau paper submitted to the Legislative Council's Public Works Subcommittee yesterday admitted that the project might have a potentially adverse impact on the environment and water quality in the area. It said key environmental concerns include the potential impact on Hei Ling Chau's marine life, bathing beaches, fishing grounds, the nearby fish farming area, its natural coastline and ecologically important habitats for the rare Bogadek's Burrowing Lizard. Sixteen legislators yesterday voted in support of conducting a $46.7 million feasibility study and site investigation. Four other legislators objected. It was the first time legislators had given their blessing to the development since the idea was first debated by Legco's security panel in December 2000. Two years of discussion ended with the scaling down of the original proposal to build a $28 billion, 120-hectare jail for 15,000 inmates after legislators expressed fears it would pose security and management problems. The scaled-down proposal will provide 7,220 places and bring the total Hong Kong prison capacity to 13,860. It will replace eight of the existing 24 prisons, putting real estate worth billions of dollars on to the market. If the project is given the green light, construction is expected to start in 2006 and finish in 2012 . Security officials told legislators yesterday that the scaled-down project would cost $12 billion, not $16 billion as earlier estimated. The feasibility study approved yesterday will cover land use, planning, traffic studies and an environmental impact assessment. The Security Bureau plans to seek the $46.7 million needed for the study at a Finance Committee meeting on April 11 and commence the study in May if the funding is approved. Democrat legislator Wong Shing-chi, who voted in support of the study yesterday, said he would only continue to throw his weight behind the project if the government settles the concerns of green groups. 'What we worry about is that this project will be a repeat of the Long Valley incident,' Mr Wong said. Long Valley has been in the spotlight since the KCRC revealed plans to build its Lok Ma Chau line across the area's wetlands in 1999. But the plan was dropped after it failed to win government approval on environmental grounds. The KCRC plans instead to build a 7km rail tunnel under the area. The director of the Conservancy Association, Ng Cho-nam, said the government should not have chosen the Hei Ling Chau site before conducting the environmental impact study. 'The best way to minimise the environmental impact is avoidance and if a site is already chosen, you can only minimise such an impact through mitigation measures, and this is not ideal,' Mr Ng said. Frontier legislator Cyd Ho Sau-lan, who voted against the feasibility study, agreed that the government should have conducted the study on a variety of shortlisted sites. She also raised doubts about the economic benefit of vacating the eight existing prison sites.