The opening of New York City's memorial to the Sept. 11 terrorist attacks has been pushed back by two years until 2011, the agency building it said Tuesday. Officials had said for years that the "Reflecting Absence" memorial would open on Sept. 11, 2009. The memorial will set two waterfall-filled pools just above the twin towers' footprints, surrounded by a glade of oak and sweetgum trees. A museum set below street level was expected to open a year later. Steve Plate, who oversees the rebuilding of the trade center site for the Port Authority of New York and New Jersey, outlined the latest construction schedule at a committee meeting Tuesday. By 2009, the steel for the memorial pools would be built up to street level, he said.