A method of slip forming a concrete structure can include using a first slip form mold that travels along a path to form a portion of a concrete structure by delivering a first flow of concrete into the first mold through a first hopper. The first hopper can be configured to receive the first flow of concrete. The portion of the concrete structure can be modified using a second slip form mold different from the first mold by advancing the second mold along the concrete structure and, while advancing the second mold, delivering a second flow of concrete into the second mold through a second hopper that is configured to receive the second flow of concrete.