STRAIGHTENING THE MOHAWK RIVER.

STRAIGHTENING THE MOHAWK RIVER.

E. BABCOCK, civil engineer, of Little Falls, N. Y., has recently surveyed the Mohawk river with a view to its being straightened. He believes that the improvement can be made and that the cost, including the land to be taken, will be within the limit of $150,000 named by the statute. His report on the subject is very exhaustive.

The survey was made from the Black river railway bridge on the west or upper end down to the N. Y. C. & H. R. RR. bridge located east of the city of Utlea— a distance of six miles and flfteen-hundredtlis of a mile. Mr. Babcock found out to his surprise that the river is not of uniform channel. On the contrary, it has two natural submerged dams or rifts, each about five feet deep—one 700 feet below the Genesee bridge, in Utica, the other at the lower end of Oxbow bend. At the Black river bridge the bed of the river is nearly four feet lower than at the first rift; at the upper end of the proposed new channel it is some inches lower, showing that the first rift, 700 feet below the Genesee bridge, is a submerged dam of practically five feet depth. At the second rift, at the east end of the Oxbow bend by the tracks of the N. Y. C. & H. R. RR. tracks, the river bed is over three feet lower than at the first rift, and other variations of a similar kind are to be met with between the given points named. The result of changing the channel, therefore, will simply be the removal of one dam of five feet depth and lowering the level of the surface of the water two feet in depth, without appreciably affecting the water surface or the velocity below. It will not effect the overflow of the country below or create any accelerated velocity over and altove that which formerly existed. The lower dam will now servo a useful purpose, Instead of being us before an annoyance and a detriment, and, by lowering the flow below, will avoid any claims for damages by floods, freshets, etc.

These freshets have sometimes caused a large overflow of water and been the source of considerable local damage, aggravated by the ice, logs, and timber that floated down and lodged against the various bridge obstructions. When the river is straightened at Utica the tendency to ice and timber jams fMr. Babcock points out) due to the piers of the Genesee and Miller roadbrldges will have been removed, and bridges spanning the entire width of a straight channel substituted at both places, correcting the obstruction evil in front of the city.

Mr. Babcock in his report conveys a vast amount of Information, locally interesting, ns to the rainfall and the comparative height of the various floods and freshets, and gives muny formula; tor determining the volume of water and the rate of flood-flow on such occasions. Using these, he found the flood-discharge to be as follows; Mohawk river at Utica, 13,811 cubic feet the second; at Little Falls, 37,010; at Meehanicsvilie, 09,707. Roughly stated, the flood-flow of the Mohawk is 7,000,000 g&llous a minute, which reduced is 15,597 cubic feet the second.

As to the work required, Mr. Babcock makes the following estimate. As the new channel must be of such size, character, and capacity as to protect the property of the citizens of Utica from floods and inundations, and as the territory bounded by the present river and the new channel has been made part and parcel of the city of Utica, suitable embankment will require to be made and carried round the bend of the river from the upper end of new channel to the Black river railroad on the west, and the east end of the new channel along the east side of the Oxbow bend to the tracks of the N. Y. C. RR. company. TheN. Y. C. RR. tracks at the east [end of the Oxbow bend, are at an elevation of 406,804-1000 at Miller bridge crossing; 408.91 J00 at Black river railroad; at carpenter shop, 407.204-100; under side of ncedlebeams of Black river bridge, 409—bottom of deck-bridge truss at lower N. Y. C. RR. crossing, 401.493-1000—all taken on track No. 4 ; and elevations all given above the Utica city datum, which makes the steppingstone of entrance to the D. L. & W. R. passenger depot, 409.210-1000 feet above mean tide in New York city. Taking into account the N. Y. C. tracks at Genesee street and the Black river bridge opining, it is apparent that the bank must be carried round at an elevation of 409, from the Genesee street crossing to the Black river railroad; and it is presumed that the N. Y. C. RR. company will, or, at least should raise, theBlack river tracks, t>o as to have them as high as at Genesee street. South of Genesee street an elevation of 407 carried round to the N. Y. C. RR. tracks at the lower end of the Oxbow end will just lit the elevation of track at this point, and the work has been so plotted and estimated. The total cubic yards required above Genesee street, exclusive of the embankment shutting off the present river at Station O is 72,999 yards—while for Genesee street east to the N. Y. C. RK. tracks at the lower end of the Oxbow bend,exclusive of the river filling,48,175 yards will be required. From Genesee street north on the north side’ * * * the level of the meadow or flat through which the new channel runs is two to four feet lower than the present river bank just adjacent to the channel. Full plans [must be prepared] for the construction of good and sufficient embankments for the same, together with proper dykes, dams, and other erections for conducting the waterof said river in such new channel and confining the same therein. And to save possible litigation, and to protect properly the new channel from drawing the soil dpwn on the upper side and cut out or change the shape of the new banks, and to protect properly these lands and to dispose of a portion of the waste material of excavation, this bank it is proposed to be carried to an elevation of 409 through the past Station O to Station 4, and then following along the west division line of G. M. Weaver north to an elevation of 409 at the foot-hills. An embankment will also be constructed at an elevation of 407 on the north side, from the Miller road, west to the highlands, as shown on plans, all disposing of 88,151 cubic yards of embankment. Along the stretch from Genesee street west to Station O and Miller bridge, the high ground, there are a number of ditches running at about right angles with the proposed new river channel. These ditches serve the useful purpose of draining away the water sent from the foot-hills at the north of the flats. In order that they may still continue to work and serve the purpose for which they’ are intended, it is proposed and provided for in the specifications that pipe drains shall run through the banks, and at the outer edge, shall be regulated by check-valves, so that,when the water in the river raises up level with the flats, they will shut down and prevent the water from flooding the land—or, if it is desired, they may be held open and water allowed to flood the flats. At Genesee street and the Miller road two newbridges will be required. * * * It is proposed to make each bridge a single span without any pier. Instead of building expensive abutments, changing the shape of cross-sections at the two crossings to nearly vertical walls, the plan is to place the abutments buck from the top line of excavation for the new river channel in the solid earth, going down nine feet and bringing the tops up level with the under side of trusses at the streets with suitable frost walls. By adopting this plan of construction, quite inexpensive masonry or concrete will answ er all the requirements, and the difference in cost as between first-class expensive masonry, protecting itself from floods and inexpensive masonry underground, will twice over pay for the additional length of spans. The bridges will require to be 180 and 176-foot spans respectively, nearly tilling the full width of streets, and with two ten-foot sidewalks and a thirty-foot roadway.

These bridges should be heavy structures, so as to accommodate

probable loads of at least 100 pounds the square foot of floor and two concentrated weights of 10,000 pounds each, six feet apart at right angles with the direction of the bridge, and two electric car tracks, and with buckle-plate, concrete and brick pavement,and buckleplate, concrete and stone sidewalks. No change in elevation of the roadway or sidewalks will be required at Genesee street; while at the Miller road the bridge will be about four feet higher than the present roadway,allowing the top or pavement of bridge truss to set three feet higher and under side just clearing the level of the top of the proposed new bank on the south side of the new channel. This will necessitate grading the road for a distance each side of the bridge,all as shown on the maps and plans, and calls for an embankment of 4,000 yards. The embankment requirea for the upper river crossing will be 15,671 yards, while the embankment required at the lower end will be 7,888 yards.

The material excavation used in embankment will aggregate 551,785 yards,including thirty-six-inch pipe and back-tilling, 501 yards and seventy-two-inch pipe and back-filling, 855 yards. Deducting the material used in embankment, 187,281 yards, the surplus left to be wasted is 364,504 yards.

The structures call for 374 cubic yards rubble masonry ; 693.5 cubic yards slope and pavement wall; 823 yards abutment masonry, 41.3 cubic yards coping; 335 yards riprap paving; 24.46 tons cast iron pipe; 165,912 B. M. sheet piling; and various othersmull items. At Reil creek, the level of the bottom of the new channel will be 17 5-10 feet lower than the present bed of Reil creek back on a grade, a distance of 100 feet, and protecting this portion of Reil creek with a heavy quarry stone pavement, in cement, both sides and bottom—-as also abutments and a short span bridge to take the place of one already existing, but located within the lines of the new’ channel.

This improvement will admit of the construction of a large trunk or intercepting sewer to be constructed from the foot of Genesee street to the lower end of the Oxbow bend, of sufficient cross-sectional area to carry off all the sewer and surface storm water and at such an elevation as to preclude the possibility of any backing up of sewage water into the cellars of the lower portion of the city. But until such time as this shall be done, provision will of necessity require to be made to pass the sewer and city storm water down through the present channel and out into the river at the lower end of the new proposed channel. In order to accomplish this, provision is made for two seventy-two-inch steel riveted pipes laid through the new shut-off river bank, while at the upper or west end, provision is made for one thirty-six-inch cast iron pipe with shut-off valve and manhole in new upper bank, both pipes being set or laid so that the tops will be under mean low summer flow. The thirty-six-inch pipe under one foot head will allow 68,000,000 gallons a day to pass through diluting and flushing out the sewage water in the old river bed. The two seventy-two-inch pipes will allow 836 cubic feet a ‘second to pass through under one foot head. The permanent trunk sewer should be laid in the old bed of the river, down to the narrow head of the Oxbow bend, and then, cutting through that, terminate at the lower end of the Oxbow bend. It must be large enough to pass the storm and sewage water of that portion of the city of Utica tributary thereto in times of maximum high water in the river, as well as at times when the city storm water passes off before the river has raised to the top flood height. The trunk sewer should be proportioned for a prospective water consumption of [at least 15,000,090 gallons a day in addition to storm water. The tributary district in the city limits is 1,677 acres, while the watershed of Ballou creek adds 2,240 acres, making a total of 3,917 acres. There are two water company reservoirs on this stream and ordinarily these reservoirs will store and take care of the bulk of heavy storms, but the only safe plan is to estimate, assuming these reservoirs are full and that the storm water of Ballou creek practically all passes off past and forming a part of the water the trunk sewer must make provision for. Taking all these matters into consideration * * * using the Jackson East India formuhe, it calls for a flood, flow of 671 cubic feet the second. * * * A trunk sewer eleven feet in diameter, if circular orits equivalent cross-sectional area of 95 .033-1000 square feet, will be needed to meet all requirements. I offer the suggestion of a culvert of ten-foot span, four and one-half-foot side-walls, bottom curved to a versed sine two feet, and arch with versed sine five feet, which gives a cross-sectional area of 95 44-100 square feet. The bottom should be made of concrete,and its curved form will concentrate the low summer flow and prevent stoppage and dams forming better than with a level bed, and is in every way preferable. In conclusion I desire to state that there are no difficulties,either theoretic or practical, in the project of changing the river channel, and, when once accomplished, the wonder will be why it has not been done years ago. I also desire to say that the bug-bear of damages accruing to property below by reasons of the change is merely a menace without any solid claim as a basis, as will be readily seen by carefully weighing the facts presented in detail in the preceding portions of this report; that the river-straightening project will enable the New York Central & Hudson River Railroad company to make provision for an adequate modern passenger depot and grounds; that it will enable them to change and concentrate the handling of the immense freight traffic, now so much congested in inconvenient and unsuitable buildings and surroundings * * * An overhead crossing at Genesee street or Bagg’s square, not interfering materially with Bagg’s square, is another inestimable benefit possible of accomplishment from the improvements ; but the opening up of the large tract of practically level vacant ground, some 3,000 feet wide and 7,000 feet long, between the present and the new proposed river channel, all properly protected from high water, with the improved facilities for passenger and freight traffic as a necessary sequence of the completion of the project, must present great attractions for newmanufacturing enterprises, and it does not seem to me visionary to prophesy, that in ten or twenty years as a limit the entire north side will be a teeming industrial settlement that will add so much to the taxable value of the city of Utica that the expenses of the improvement will never be felt and will seem comparatively a mere bagatelle.

A bill has been introduced by Mr. Fowle into the assembly at Albany, N. Y., amending the penal code so as to penalize interference with a stream, creek, or other body of water that has been dredged or cleared at public expense.

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