The false abutment of the bridge at Lebanon should be removed and the draw lengthened to reach to the abutment originally intended for it. It should be the duty of the State of Delaware to compel the making of these improvements. I am not at present aware of any other structures erected or in process of erection which "do or will interfere with the free and safe navigation" of any of the navigable waters in this district. Very respectfully, your obedient servant, To the CHIEF OF ENGINEERS, U. S. A. WM. F. SMITH, LETTER OF THE BOARD OF PORT-WARDENS OF THE HARBOR OF WILMINGTON, DELA WARE. [Board of port-wardens, city of Wilmington, Del.] NOVEMBER 28, 1884. DEAR SIR: I was directed by the board of port-wardens, at a meeting held November 26, 1884, to communicate with you stating that the sunken pier in the Christiana River, in the line passing through harbor line stones 5 and C 7, is regarded by the board as a very dangerous obstruction to navigation, and that it will be very gratifying to the board if it please you to incorporate in your report to the Secretary of War such mention of this matter as may result in the removal of the pier by the United States Government. Yours, etc., General WM. F. SMITH. FREDERIC H. ROBINSON, Secretary. REPORTS OF MAJOR PETER C. HAINS, CORPS OF ENGINEERS. (1) LONG BRIDGE ACROSS POTOMAC RIVER. UNITED STATES ENGINEER Office, Washington, D. C., September 10, 1884. SIR: In compliance with General Order, No. 13, Headquarters Corps of Engineers, July 23, 1884, I have to report, for the information of the Secretary of War, that the structure known as "Long Bridge," spanning the Potomac River from Washington, D. C., to Alexander's Island, Virginia, was first built by the Washington Bridge Company, under an act of incorporation provided by act of Congress approved February 5, 1808, entitled "An act authorizing the erection of a bridge on the Potomac River within the District of Columbia." In 1834 the Government of the United States purchased the rights of the Washington Bridge Company and the remains of the original structure, which had been partly destroyed in 183 by a freshet. It was afterwards rebuilt by the Government and maintained by it until June 21, 1870, when by act of Congress the Baltimore and Potomac Railroad Company was authorized to take possession under certain conditions. It has remained in the custody of said railroad company since that time, and is used and occupied by it as a railway bridge, and by the public as a wagon and foot bridge. It interferes now with the free and safe navigation of the Potomac River, and will do so in a greater degree when the improvements now in progress on the river front approach more nearly completion. The draw of this bridge is only 70 feet wide, and, consequently, in times of freshets or high winds, does not afford a free and safe opening for large vessels. Besides, it is never opened at night at all, so that the bridge constitutes a complete barrier to all navigation through it after dark. The bridge, however, will become a serious obstruction as the work of improving the river front advances. Congress has already appropriated $900,000 for the improvement of the Potomac River in the vicinity of Washington, baving reference to the improvement of navigation, the establishment of harbor-lines, and the raising of the river flats. A part of this money has already been spent, and the work is now well under way. The necessity of rebuilding Long Bridge is referred to by the Board of Engineers in its report of February 18, 1882. The report includes among its recommendations that The Long Bridge shall be rebuilt at an early period, during the progress of the improvements, with wide spans upon piers offering the least possible obstruction to the flow of water. Other engineers have at various times called attention to the neces sity of a new bridge. The location of the present bridge is faulty, its construction more So. Above the bridge the channel of the river curves well over to the Virginia shore, so that at the site of the bridge the channel current, in the ordinary stages of the river, sets towards the Washington side, making, with the axis of the bridge, on obtuse angle. The piers are set parallel, or nearly so, with the current in such stages. In times of freshets, however, the direction of the current is more direct; the water takes a shorter cut across the shoals to reach its proper level. The piers of the bridge being located to best suit the low stage of the river, they stand obliquely to the current in times of freshet, making the obstruction greatest when it should be least. The bridge thus acts as a partial dam in times of freshets, checking the flow of water above and causing the deposition of the material that is rolled along the bottom or held in suspension. The spans of the bridge are too narrow, requiring a greater number of piers than would otherwise be needed, consequently the flow of water is proportionately obstructed. While the number of piers is unnecessarily great, and their direction with reference to the freshet current objectionable, a still more formidable objection exists in the construction of the piers themselves. They are built of stone on a pile and grillage foundation, and to the ordinary observer would appear unobjectionable except in respect to number, height, and location with reference to the freshet current. The pile and grillage, however, reaches to about the level of low water, and is not ordinarily seen; but, in order to make the foundation secure, a large quantity of riprap stone has been deposited around each pier, so that while each pier seems to be narrow, it pratically spreads out like a cone beneath the surface of the water. The bottom chord of each span is too low, being only 10.7 feet above low water. The adjacent flats are to be filled to a height of 3 feet above the freshet slope of 1877, which will make them at the site of the bridge about 12 feet above low water. The bottom chord of the bridge is, therefore, only a little more than 13 feet above the level of the freshet slope of 1877, and nearly 13 feet below the proposed grades of the flats when they are reclaimed from overflow. The effects of logs, trees, etc., swept down the river and against the bridge in such a freshet can readily be imagined. It was practically destroyed in 1831 by such a freshet. The improvements now in progress contemplate the closing of the Washington Channel at the site of Long Bridge; hence, all the water that now finds its way down the river by that route will be forced into the Virginia Channel. The capacity of the latter must, therefore, be increased. This is now being done above the bridge, and it will be done below it, by dredging. To secure the required area of cross section through the bridge would require dredging to be done between the piers, which, it is believed, is not practicable to the extent required. without endangering the structure. The best and only satisfactory way of correcting the defects of this bridge is to build a new one several feet higher, on fewer piers, with wider spans. The piers should be set as nearly as practicable in the axis of the freshet current, and should rest on the rock or hard-pan, which it is believed will be found to underlie the softer strata of mud. In any case, the body of each pier should extend to a depth below the surface of the water equal to the ruling depth of water above and below the bridge. No riprap protection should be allowed around the piers to reach a level above that of the general bottom of the river channel in the neighborhood of the bridge. Very respectfully, your obedient servant, To the CHIEF OF ENGINEERS, U. S. A. PETER C. HAINS, (2) POTOMAC AQUEDUCT. UNITED STATES ENGINEER OFFICE, SIR: In accordance with General Orders No. 13, current series, Headquarters Corps of Engineers, United States Army, I have to report that the bridge known as the "Aqueduct," that spans the Potomac River between Georgetown, D. C., and the Virginia shore, is an obstacle to the free and safe navigation of the Potomac River. The bridge is an acqueduct for the Washington and Alexandria Canal, which is here carried across the Potomac River. The piers of the bridge are built of stone, the superstructure being of wood. There is ample width between the piers for the largest vessels that come to Georgetown to pass, and the depth of water is over 20 feet at low tide. At mean high tide there is only a clear space of 25 feet between the timber supports of the lower chords of the truss and the surface of the water. As a consequence, none but the smallest of steam-boats can pass under it, and practically it renders navigation above the bridge impracticable for anything but small tugs and flat-boats. Paragraph 2550, Revised Statutes, provides that the collection district of Georgetown shall extend to the head of the navigable waters of the Potomac River, which is near Little Falls. Between the latter place and the Aqueduct Bridge, a distance of more than 3 miles, there exists a deep, navigable channel, obstructed only at two places by shoals, which have over them a depth of 16 and 19 feet, respectively, at mean high tide. On the Georgetown side of the river there is over 19 feet at high tide for a distance of 3,000 feet above the bridge. In a commercial point of view, that part of the river would be of great value if the way to it was not barred by this bridge. It is an obstruction in another respect. The piers, abutments, and causeway reduce the width of the river from about 1,600 feet, its natural width between the lines of high water, to about 950 feet. This re duction causes an abnormal rise in the surface of the water in times of freshets. The bridge can best be altered so as not to interfere with the free and safe navigation of the river by discontinuing its use as an aqueduct, and providing a draw through which vessels can pass. This would necessitate the entire rebuilding of the superstructure, and the modification of one of the abutment piers to serve as a draw-pier. Other interests may be involved in such a change, but a discussion of them is beyond the province of this report. The bridge interferes with the free and safe navigation of what would doubtless become a very important part of the river were it not there, and the only satisfactory way of removing this interference is to dispense with the aqueduct portion and rebuild the superstructure as a highway bridge, with a suitable draw for the accommodation of vessels of the largest class that visit Georgetown. Very respectfully, your obedient servant, To the CHIEF OF ENGINEERS, U. S. A. PETER C. HAINS, REPORT OF CAPTAIN F. A. HINMAN, CORPS OF ENGINEERS. UNITED STATES ENGINEER OFFICE, Norfolk, Va., October 31, 1884. GENERAL: In accordance with General Order No. 12, Headquarters Corps of Engineers, U. S. Army, current series, relative to sections 2 and 8 of the act of July 5, 1884, making appropriations for the construction, repair, and preservation of certain public works on rivers and harbors, and for other purposes, I have the honor to submit the following final report on all the matters known to me in this district covered by the foregoing: The following bridges are considered obstructions to the free navigation of the waters that they cross, for the reasons specified below, viz: The Norfolk and Western Railroad bridges over the Eastern and Southern branches of the Elizabeth River (shown on the accompanying map*) and the wagon bridge over Town Creek, North Carolina, 33 miles above its mouth. Each will now be referred to in detail. (1) The Norfolk and Western Railroad Bridge over the Eastern branch of the Elizabeth River.--The present draw-opening is at the extreme northern end of the bridge at the right bank. It is 40 feet in the clear, and has a depth through it of 13 feet at mean low water. The approaches to this draw are as follows: The upper approach is very crooked and shallow from the main channel to the draw-opening. On a line perpendicular to the draw-opening, and about 300 feet above it, is a shoal with but 1 feet of water on it at mean low tide. The lower approach has been lately dredged by the United States, and, so far as depth is concerned, is satisfactory. The draw-opening should be at least 50 feet wide, and placed near the middle of the stream, where the deep channel is, between the piers marked A and B, with suitable guide-piles above and below for safety of navigation through it. (2) The Norfolk and Western Railroad Bridge over the Southern branch of the Elizabeth River.-The river at this point has been contracted by Map omitted. earthen causeways, terminating in masonry bridge abutments on either side, that on the east side being 88 feet long and that on the west side 256 feet in length. The present draw-opening is at the extreme eastern end of the bridge, is 40 feet, in the clear, and has a depth through it of 8 feet at mean low water. The approaches to this draw are on a curve, and hard for vessels, particularly those with tows, to make, es pecially when the wind blows from certain quarters. I quote as follows, relative to this bridge, from report dated January 30, 1872, of the late Capt. C. B. Phillips, Corps of Engineers, found in report of the Chief of Enginers, 1872, page 719: Below the lock of the Dismal Swamp Canal no difficulty is experienced in the navigation of the Elizabeth River. A deep and unobstructed channel exists up to this point and, in fact, to a point about 2 miles farther up the river. The above remark should be qualified by stating that the Norfolk and Petersburgh Railroad Bridge, which crosses the river about threefourths of a mile above the Dismal Swamp Lock, causes considerable annoyance to shipping, much of which is taken up and down the river in long tows. As many as five schooners sometimes constitute a single tow. The draw of the bridge referred to is badly located. It is nearly over to the right bank of the river, away from the deepest water, and out of the course which shipping would take were it not for the bridge. This evil, however, it appears must continue to exist, as litigation has, I understand, failed to correct the matter. (The Norfolk and Petersburgh Railroad is now a part of the Norfolk and Western Railroad.) The draw-opening should be at least 60 feet wide, and placed near the middle of the stream, where the deep channel is, between the piers marked C and D, with suitable guide-piles above and below, for safety of navigation through it. (3) Bridge over Town Creek, North Carolina.-I quote as follows regarding this bridge, from report dated August 4, 1884, of the late Mr. W. H. James, assistant engineer: Town Creek, North Carolina, for the improvement of which $1,000 was appropriated by act approved July 6, 1881, and expended under my charge, for an account of which work reference is respectfully made to Appendix K 17, of the Annual Report of the Chief of Engineers for 1883, is obstructed 34 miles above its mouth, on the west side of the Cape Fear River, 8 miles below Wilmington, by a common county-road bridge, belonging to the county of Brunswick, North Carolina. This bridge has no draw. The creek is navigable for the improved distance of 19 miles from its mouth for small steam-launches drawing not over 34 feet of water. These boats, in passing under the bridge, have to lower their smoke-stacks, and, for want of a draw, none but very small, low boats can pass at all. I am informed that if compelled to put in a draw or abandon the bridge, the county would probably remove it and close the road. It is manifest that there should be either a proper draw-opening in this bridge or else it should be removed. It is believed that the southern abutment or causeway (shown on accompanying map*) to the county bridge that formerly crossed the eastern branch of the Elizabeth River interferes with the free and safe navigation of said river to the extent described below, for which reasons the structure should be removed. * Map omitted. |