Faced with more than two miles of retaining wall to form and pour, Minneapolis contractor Jon Oster of Oster and Pederson, Inc. took time out and compiled some time studies. One finding of this study proved nothing short of depressing: while his pouring operations were proceeding at a speed comparable with similar retaining walls jobs, for 35 percent of the time concrete pouring rested at an absolute standstill. Why? The specifications of the Minnesota Highway Department, which are similar to other states, dictate that concrete cannot be dropped into a form more than four feet. As a consequence nothing happened while: the concrete bucket was unhooked from the crane, the crane was swung over the hooked onto the hopper; and the hopper with its tubes was slowly hoisted out of the form. Oster designed, built and is now using a concrete hopper with a telescoping tremie. The hopper has a winch with a handle and ratchet control. Cables extend down through the hopper to the bottom telescoping section. As concrete slowly fills the forms, a man at the hopper gives a twist on the handle from time to time to raise the tube. The tube rises as the concrete mass rises, with not one minute of lost time.