An enviornmental group is squawking over a plan to bring duck boats to Manhattan. Transportation Alternatives contends in a lawsuit that the state erred when it issued two permits to New York Waterways, which wants to build a ramp at Pier 78 on the Hudson River so the amphibious vehicles can move from land to water."These ducks will greatly disrupt the use of the greenway by pedestrians, joggers, bicyclists and Rollerbladers," said Transportation Alternatives lawyer Michael Gerrard.New York Waterways said the suit is without merit. The Department of Environmental Conservation said it followed proper procedures.