|
|
History of the C&D Grain Elevators
The elevators being demolished were first constructed around 1900. They are designated as elevators "C" and "D" based on their location along the row of other elevators nearby. Elevator "A" which is still in use is a twin sister of the "D" elevator. There is a good aerial photo of the elevators on the Port website The oldest of these structures is the "D Center Annex". It is the first slip formed concrete silo structure built in the US. Reinforcing steel bars as we know them today had not been invented yet when this was built. Instead, steel strapping was inserted into the concrete and served to act as a form of barrel hoop to hold the concrete in place. There are roughly 800 miles of reinforcing steel in the whole project. The concrete aggregate included river rock up to 2-3" in size as well as sandstone chips from 3/4"-5". The "D" headhouse was built around 1906 and was constructed of simple clay tile. The lower machinery floor consisted of poured concrete pillars roughly 25' tall with 2" steel rod for reinforcement. Above this, clay tiles were laid in intersecting circles in much the same way as a honeycomb. These formed the separate silos for grain storage. The tiles were stacked upwards for roughly 100' with no steel reinforcement other than cross tie rods. A solid floor was poured on top of the silos and a steel frame structure with clay tiles for an outer wall was constructed. This upper area housed all of the machinery for weighing, screening, and sorting the grain. As grain was delivered to the elevator by train or truck, it was lifted to the top of the elevator by a conveyor belt equipped with hundreds of buckets, each holding a small armload of grain. The grain would fall by gravity through the different holding bins, weighing hoppers, screening machines, and be directed to individual silo pockets by chutes. When a ship arrived to load, gates beneath the silo pockets were opened. The grain would flow onto a horizontal conveyor belt, dropped at the bottom of the vertical bucket conveyor, raised once again to the top of the building, and then directed to a chute down into the waiting ship. The "C" elevators and headhouse were built in the 1920's and the "D" west annex was added in the 1930's. The elevators were built on low land in the middle of the Duluth Harbor with rail access over a track built on pilings. Each building was built after driving upwards of four or five thousand wooden pilings into the harbor. Over the years, the "C" east building began to shift into the harbor. The top of the building had moved roughly 18" towards the harbor by 1998. The middle of the building had a dip of 3-4" relative to the ends. Cargill Corporation donated the entire complex to the Duluth Seaway Port Authority in the early 1990's and demolition was begun in 1998. Do you have any photos or interesting story's about the C&D site that might interest others? Email me about it and I'll put in a new section for it! |
