THE CHICAGO DRAINAGE CANAL.
(Specially written for FIRS AND WATER.)
CHICAGO, ILL., Feb. 10, 1900.
LOCKPORT, ILL., where the water of the Chicago river enters the drainage canal, is about thirty miles south of the city, and by an arrangement with the municipal authorities of Chicago, will afford water-power equal to 25,000horse-power, whereby the city’s pumping stations and electric lighting plants will he operated at the rate of $4 a year for every horse-power unit geuerated. This rental will be paid first after July, 1901, by which time, it is expected, the water power will be developed.
The flow of the Chicago river, since the opening of the canal, is no longer towards the lake, but towards Lockport, which is the largest town on its banks, and has only 3,000 inhabitants. There are situated the works which control the flow of the water into the canal. The artificial channel of the south part of the river is virtually a portion of the canal itself. It begins at Robey street and flows southwards—a distance of twenty-eight miles—till it reaches Lockport. Here this channel broadens out to a width of some 500 feet—enough to admit of the large lake vessels turning and being manoeuvred in. From the mouth of the Chicago river to the controling works at Lockport the fall is barely seven feet, and the flow is really upstream, as the phrase is generally understood. The flow of water and its rapidity are, therefore, altogether eontroled by the beartrap dam and the controling works. South of these works the fall is very abrupt and about forty feet in the next four miles. Consequently, these controling works can both turn the water down to the valley by the mere opening of the great gate-valves and also as suddenly turn it off in case of emergency.
In order to make these controling works efficient, seven metal sluice gates, with the requisite bulkheads, and one beartrap dam had to be built. The opening of these sluice-gates is thirty-two feet; the vertical flow is twenty-seven feet. The opening of the beartrap dam, over which flows 100,000 cubic feet of water a minute, is 160 feet; the oscillation is seventeen feet vertically. Two great metal leaves hinged together and working between metal bulkheads essentially compose the dam, to whose heavy foundation the downstream leaf is securely hinged, with the upstream leaf so fixed as to oppose a barrier to the water. Water admitted through conduits constructed for the purpose and closed by valves lying beneath these leaves operates the structure. The water,which is let in from the upstream side, raises the dam’s crest—the discharge being shut off until the required height is reached, when the valves are so adjusted that the volume of water underneath the leaves is constant. By drawing off the water beneath the leaves till the required height is obtnined, the valves are again so arranged as to keep up a constant flow of water, and thus the crest of the dam is lowered.
The fact that, as far as Lockport, the drainage canal is at the present time a ship canal wide enough and deep enough to accommodate ocean steamers drawing twenty-three feet of water has sufficed to convert the valley people from being its foes into its friends They see money in it for themselves. Besides that, certain river towns, such, for instance, as Joliet, will be benefited in the way of water power. Joliet, owing to the dam and tailrace constructed by the sanitary district in the Desplaines river, will become possessed of waterpower representing a capitalization of nearly $200,000. Ottawa and other cities will have a volume of water which will make possible the development of valuable water power, which will act as a stimulus to manufacturing enterprises. Already Ottawa is considering a plan for the development of valuable water-power, and her citizens believe that the opening of the channel will ultimately result in her great advantage commercially.
At the same time, until the canal has been in good working order for some time, the disadvantages incidental to its construction can only be guessed at, or discovered by experience, just as the remedies to he applied to counteract these disadvantages must be the result of experience. It is claimed, for instance, that the building of the canal will destroy a vast amount of valuable land along the Illinois river, which in flood times is totally submerged, as well as are great plantations, whose owners spend thousands of dollars yearly in pumping water from their lands. A rise of two or three feet in the level of the Illinois river undoubtedly means the destroying of untold acres of land which are now corn-bearing. Accordingly, hundreds of property owners are bitterly opposed to the drainage channel, and stand ready to sue the district for damages the moment their lands become flooded. The interest represented by this class has all along insisted that before the water was turned into the channel the State dams at Henry and Copperas creek should be removed. In order to appease this element a clause was placed in the law creating the sanitary district, which made it imperative that thesedams should be removed before the water was turned in. Owing to injunctions obtained by, among others, the Illinois and Michigan canal commissioners, who in the name of the State filed a bill seeking to enjoin their removal—their reason being that to do so would destroy navigation—their removal has not taken place.
Then again, there is the danger from the formation of ice gorges. Such a gorgedid form in the Desplaines river during the last two or three days in January, and the water spread over a mile of territory, flooding railroad tracks. It was broken on the 31st of February with dynamite. There will be more or less trouble from ice whenever the weather becomes very cold. A remedy will he devised to prevent this as much as possible before next winter. The drainage problem is so large that all defects in the construction of the canal and changes in the river arising from it, cannot be corrected in a short time.