May 12, 1909: Municipal Journal and Engineerarticle. Inverted Sewer Siphon. “The accompanying drawing illustrates a rather unique piece of sewer work, designed by Mr. C. D. Hill, Chief Engineer of the Sewer Department of the Board of Local Improvements of the City of Chicago, to carry the Kedzie avenue sewer under the Illinois and Michigan Canal.
The Kedzie avenue sewer is a 9-foot circular brick sewer, being built to serve the rapidly growing southwestern section of the city. It empties directly into the drainage canal. The Illinois and Michigan Canal runs parallel to the drainage canal and about 900 feet from it. The problem confronting the engineers was to provide means for carrying the sewage under the canal in such a manner that during the dry weather flow there would be no serious deposit in the siphon and so that the storm water flow would be readily handled. It is estimated that the dry weather flow in the sewer will be from 20 to 30 cubic feet per second, while the storm water flow may reach 250 cubic feet per second, which is under the estimated maximum carrying capacity of the 9-foot sewer. It was feared that, if the 9-foot sewer were carried under the canal, the small velocity of the dry weather flow, calculated to be one foot per second, would result in considerable deposit. A further consideration in the matter was that this canal is not a particularly clean stream, and that the discharge of greatly diluted sewage into it in time of flood would not seriously pollute it [Well, that is obviously not true.]. A design was therefore worked out which would keep the siphon clean during dry weather flow and permit the discharge of excessive storm water into the canal, although lesser amounts will easily be carried through the siphon.”
Reference: “Inverted Sewer Siphon.” 1909. Municipal Journal and Engineer. 26:19(May 12, 1909): 847-8.