Supports for the new double-decker Pier 15 are beginning to rise in the East River near Maiden Ln., and pile driving should finish there next month, the city said this week. When Pier 15 is scheduled to open in 2012, it will have a maritime education center and a cafe on the bottom level, along with historic ships and charter boats. The upper level will be mostly open space, with green lawns and few plantings. Design features by SHoP Architects include a red-painted roof on the lower level that will filter light down from the upper level, and trees planted on the lower level that stretch up into the top level. Pier 15 is part of the city’s $150 million East River Waterfront Project, primarily finded by the Lower Manhattan Development Corp..