Engineering the Chicago Sanitary and Ship Canal
The Chicago River flows southeast from Chicago into the Lake Michigan, which is the only one of the five Great Lakes that is completely based in the United States. In the 1800s the rapid expansion of Chicago led to pollution of the Chicago River from sewage, industrial pollutants, and the activities of the inhabitants. This pollution went into the river and thence to Lake Michigan, which was the source of water supply for the expanding city. This led to fears of epidemics and spurred the formation of the Chicago Sanitary District in 1889.
Origin and Ideas for the Canal
By 1887 ideas had formed to reverse the flow of the Chicago River so that it would not pollute the water resources of the lake. An engineer named Isham Randolph came upon the fact that a ridge twelve miles from the shore of the lake divided the watersheds of the Great Lakes and the Mississippi River. The Mississippi River basin led into the Gulf of Mexico and was fed by the Des Plaines River, which was very close to the Chicago River. So cutting through the ridge and leading the water into the Des Plaines River could effectively divert the Chicago River and prevent any pollution reaching the water source, which was Lake Michigan. The distance was seen as something not too great and in the realms of possibility for any canal construction.
Image Source: Wikimedia: Diversion of River
Civil Engineering Details of the Canal
Plans were drawn up to construct a canal 28 miles long, 202 feet wide and 24 feet deep connecting the Chicago River and the Des Plaines River. Locks were also planned at the two places where the Chicago River met the Michigan lake so that water inflow in to and out of the lake could be controlled. Besides river dredging and canal building, the work also involved construction of roads and bridges. A fifteen mile stretch of the canal was through rock and had to be removed by dynamite. Steams shovels mounted on rails were used to remove the debris from the blasting operations.
Altogether 43,000,000 cubic yards of stone and dirt were excavated over a period of eight years from the main canal itself and at a cost of $70 million. Most of the labor used on the project involved people of African-American origin; at least that is what photographic records of the day seem to suggest. Equipment used was mechanical shovels and excavators and even ropeways to remove the dirt and stones. A lot of the techniques perfected by the engineers of the time were used in operations for making the Panama Canal following the completion of this canal. The Army Corp of Engineers had responsibility for most of the works on the canal.
Thirteen bridges were also built over the canal. They were all movable bridges so that canal boats could pass through. Seven sluice gates each thirty feet wide were built at Lockport to regulate the amount of water flowing through the main canal. A 160-foot dam that was also movable was part of this construction.
The vertical height of the dam was 17 feet, and it consisted of two huge iron sheet plates joined by hinges. The lower plate was firmly anchored, while the upper one could be raised or lowered according to requirement. The power used for this mechanism was through special conduits and valves that used the power of the water current. This ingenious mechanism was a source of wonder to engineers the world over.
Image Source: Wikimedia: Canal and Bridges
Rudolph Hering and the Chicago Canal
Rudolph Hering was Chief Engineer of the Drainage and Water supply Commission of Chicago during the years that the canal was completed and commissioned, and his name features as having pioneered and helped much of the work. He is also famous as an environmentalist. The Chicago Sanitary and Ship Canal has been named one of the monuments of the millennium by the American Society of Civil Engineers. Rudolph Hering was a very active member of this society and is credited with many research and engineering activities. Rudolph Hering and two of his assistants were appointed by the city council of Chicago in 1886 to study the sewerage systems and suggest remedies or alternatives that ultimately culminated in the Chicago Sanitary and Ship Canal.
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