REBUILDING LOCK GATES, MILAN SECTION OF ILLINOIS AND MISSISSIPPI CANAL, DURING SEASONS OF 1910-1911

BY

Mr. J. C. MCELHERNE
Assistant Engineer

The Milan Section of the Illinois and Mississippi Canal at Milan, Ill., connects with and extends from the head of the lower rapids of Rock River to the Mississippi River at the mouth of Rock River— its length being 411⁄2 miles. There are three locks on this reach: No. 35, a guard lock at its head; No. 36, 3 miles below, and No. 37, at its lower end. The difference in elevation between the normal stage of water at its upstream end, Rock River Pool, and the low water of 1864 at its lower extremity is 18 feet. This fall is overcome by a 6-foot lift at Lock No. 36 and a 12-foot lift at No. 37, thus making navigation possible between the Mississippi River and the Illinois River near Hennepin, Ill., via Rock River Pool, and thence through the longer portion of the Illinois and Mississippi Canal, a total distance of 75 miles.

The locks are of concrete, 35 by 170 feet long between quoins, and their gates, built of wood in 1894, range, except a 10 2-3 foot pair, from 142 to 23% feet high, and are all 20 1-3 feet long. The much decayed gates of these three locks are now being rebuilt, and the work is almost completed. The lumber used in construction is oak, with pine sheathing, and was, last season, first all framed and creosoted at our canal boatyard, then distributed to the different locks, where, to prevent its warping, it was without delay correctly assembled, as most convenient, near the lock walls-there being no other available room for the purpose. Next the old gates, in pairs, were taken out intact; the large castings, rods, and other irons removed, repaired or renewed as needed, and neatly fitted into the new gates, which latter were then installed as herein described.

In reference to the method of performing the work: A set of five

timbers, 6 by 12 inches 40 feet long, was first laid across the lock, close to each end of the gate recesses to serve for supporting purposes and as a passage way. A large oak jack-timber, 30 feet long, was then blocked on upper edge of the old gate in place in its recess, and over it were fastened chains passing underneath the gate, near each end; and down through this timber and some of the upper longitudinal ones of the gate, about 712 feet each way from center, an iron rod with washers and nuts for both ends was run and securely tightened to help strengthen and steady the combination in different positions, after which two cribs of light blocks were started and gradually built at each end of the gate recesses,

Fig. 1. Old Milan Gate, Illinois and Mississippi Canal, Raised Preparatory to Removal

as the gate itself was being jacked up. These two cribs were to sustain its weight and there were others in rear of the recess to serve as stands for the men and bases for the car jacks used in lifting the load (Fig. 1). When the gate was raised to the required elevation, or about half its own height, two sets of planking, of sufficient thickness, were spiked on its back to fully protect the valves, their rods, connections, etc.; and stout knees were also so fastened into and against the gate on the same side as to lap over on top of the lock wall and thus prevent any sliding down of the gate while it was being pulled backwards down over skidways and on bottom rollers, as needed. It was then stripped of its top jack-timber, chains, and rods, and of its own irons, etc. (Fig. 2.)

A new gate when fully assembled and provided, exactly like the

old one, with the same jack-timber, chains, and rods, was next placed between the same afore-mentioned lock cross-timbers-its jack-timber being shaped to rest and travel on them. The gate was then forced, on rollers, with lines and pinch bars, well out over the lock chamber onto temporary cribs erected on a barge in the lock. The bottom edge, only, of the gate was then lowered to the barge by means of jacks, and the cribwork carefully removed, while the gate in the meantime was being continually forced still farther over so as to make it finally clear the barge (Fig. 3). This having been done, the barge was withdrawn, leaving the gate suspended vertically on the lock cross-timbers. It was then, with a dolly under each end of the jack-timber, very easily drawn back into its recess, let down on its pintle, and finally securely fastened in its proper position."

The work of removing the old gates and substituting new ones at Lock No. 35 was completed just before the close of and without interfering in any way with navigation, and that on the other two was carried on throughout the entire winter with the loss of only twelve days, seven of which were spent on work elsewhere. The cost of renewing these lock gates, including material, creosoting, labor, and office expenses was, for Lock No. 35, $2,499.80; Lock No. 36, $2,174.75; and Lock No. 37, $3,391.70. Total amount, $8,066.25.

THE DISCHARGE OF UNPURIFIED SEWAGE INTO THE HUDSON RIVER NEAR YONKERS*

BY

Col. W. M. BLACK
Corps of Engineers

As a step in the agitation for a cleaner harbor by the City of New York, and following closely upon the action taken in the case of the Passaic Valley Trunk Sewer, the Department of Justice of the Federal Government proceeded against the Commissioners of the Bronx Valley Sewer, seeking to restrain them from discharging untreated sewage into the waters of the harbor. In a letter from the Attorney-General to the Secretary of War, dated July 21, 1910, it was requested that the engineer officer in charge of the district be directed to report upon the proposed sewer as affecting "the pollution and sanitary results to commerce which may hereafter develop on the Hudson River or other navigable waters, from said plans, in addition to what may be termed ordinary statutory obstructions to navigation."

In this connection reference is made to a report of the writer dated June 21, 1909, on the same subject, submitted to the Adjutant-General, Department of the East. In paragraph 3 of that report, the general extent of the project for the Bronx Valley Sewer is described, and it is stated that it is proposed to discharge the sewage through two cast-iron pipes into the Hudson River, in depth of about 42 feet, about 236 feet beyond the bulkhead line established by the Secretary of War in 1897. This line, at the point of outlet, is about 170 feet outside of the low, water shore line." The proposed outlet is located about 300 feet north of the northern limit of the City of Greater New York and about 2 miles north of the entrance to Spuyten Duyvil Creek.

In November, 1910, the outlet pipes had been laid from the shore to a point some distance inside of the bulkhead line and connected with a tunnel which is being constructed under the high land from a point about 500 feet distant from the shore to connect with the

* From a report submitted to the Chief of Engineers, December 27, 1910.