the present invention relates generally to precast cantilevered retaining walls and methods of using and forming precast cantilevered retaining walls . more specifically , the present invention relates to a cantilevered concrete retaining wall having a base shear key and blockouts for receiving a material that substantially impedes the wing wall from sliding or other inadvertent movement , to a method of retaining a soil embankment with a cantilevered concrete retaining wall , and to a method of manufacturing a precast concrete cantilevered retaining wall .