IMPROVEMENT OF THE POTOMAC RIVER AT WASHINGTON; RECONSTRUCTION OF THE AQUEDUCT BRIDGE AT GEORGETOWN, AND CONSTRUCTION OF BRIDGE ACROSS THE EASTERN BRANCH OF THE POTOMAC AT WASHINGTON. Officer in charge, Lieut. Col. Peter C. Hains, Corps of Engineers. 1. Potomac River at Washington, District of Columbia.-Before the improvement was commenced the channel to Georgetown was narrow, crooked, and had not sufficient depth to accommodate commerce. Vessels drawing 16 feet frequently grounded at high water above Long Bridge, and to maintain this depth frequent dredging was necessary, and even then the channel was narrow, as the appropriations for dredging were only sufficient to make a narrow cut through the bar. The Washington Channel was not only shoal, but narrow, and wholly inadequate to the wants of commerce. The flats in front of the city were large in area, sometimes covered, sometimes not covered, by the water of the river, which was polluted by the mixture of the sewage of a large city. The sewer at the foot of Seventeenth Street discharged its contents on the flats, rendering some parts of the city in that vicinity very unhealthy. By act passed August 2, 1882, Congress adopted a project which had for its object the improvement of the navigation of the river by widening and deepening its channels, the establishment of harbor lines beyond which no obstructions should be built, and at the same time the filling of the flats or marshes on the city front, so that they would not be overflowed by ordinary high tides, the material to be dredged from the channels to be used in filling the flats. The project provides for such depth of channels as will accommodate the largest class of vessels that can reach Arsenal Point, with such additional depth at the wharves as will enable vessels to receive full cargoes without grounding at low water; for filling the flats above Long Bridge to a height of 3 feet above the flood-slope of 1877, and that part of the flats below Long Bridge to the same height along the middle line, but sloping on each side of it to 6 feet above mean low tide at the margin; that in order to purify the water of the Washington Channel, which will be cut off at the upper end from the Virginia Channel, a tidal reservoir or basin be established between the sewer canal and Long Bridge, this reservoir to be filled by water from the Virginia Channel on the flood tide, and discharged into the Washington Channel on the ebb. The plan also contemplated the removal of Long Bridge or its rebuilding with longer spans during the progress of the work, and the interception of all sewage now discharged into the Washington Channel, and its conveyance to the James Creek, but neither the reconstruction of the bridge nor the building of the intercepting sewer were included in the estimated cost of the improvement. The amount expended up to the close of the fiscal year ending June 30, 1888, is $1,247,494.90. At that time the Washington Channel had a depth of 20 feet at mean low tide, and a width of 350 feet; the Virginia Channel below Long Bridge had a depth of 20 to 24 feet at mean low tide, and width of 350 to 500 feet; the same channel above Long Bridge had a depth of about 17 feet at mean low tide, and width of about 550 feet. This part of the channel had originally been dredged to 20 feet, but had partly filled up by the deposit of material brought down in freshets. Of the total area of the flats 544 acres had been raised above overflow at ordinary high tide, some of which was up to grade, and of the total amount of material needed to fill them to the required grade a little more than one half had been deposited on them. About three fourths of the tidal reservoir had been dredged, and the foundation of the outlet constructed. The expenditures of the past year have been devoted to the improvement of navigation by widening the Washington Channel at its lower end, and removing the shoal at its junction with the Virginia Channel, so that the distance from the wharves along the river-front below Long Bridge to Georgetown has been materially shortened, the material so dredged being deposited on the lower end of Section III; to raising the embankments along the margin of the fill wherever necessary, and along the sewer-canal, protecting the same by means of riprap, and continuing the construction of the reservoir outlet. The latter work has been one of exceptional difficulty owing to the great depth of soft material comprising the bed of the river at its site. On the 2d of June there occurred the greatest freshet in the Potomac River of which there is any authoritative record. The Potomac at Harper's Ferry rose to the height of 34 feet above the low stage. The water was at one time 2.8 above the rails of the Baltimore and Ohio Railroad on the bridge, and 6.8 higher than the freshet of 1877. The freshet attained its maximum height at about 10 a. m. on June 2. It was within 3 feet of that height for a period of about twenty-four hours, and within 6 feet of it for about thirty hours. The highest point reached by the water at the Sewer Canal, at the foot of Seventeenth street, was 13.26 feet. The actual damage to the reclaimed land on the river front was not great. Section I was protected by a heavy growth of willows which retarded the flow of water over it. The water swept over Section II from near the mouth of the Sewer-Canal toward the Washington Channel with considerable velocity, and as the material consists largely of saud many cubic yards were washed into the tidal reservoir. Section III was not badly damaged, as the current below Long Bridge was not nearly so swift. Considerable lumber and tools were lost at the Reservoir Outlet, but the masonry of that structure was not damaged; $25,000 would cover the loss by washing away of material from the flats. The channels of the river, however, suffered considerably. The Virginia Channel above Long Bridge was filled up to such an extent that there is now not more than 14 feet in many places where there was 20 feet. Recent examinations have been made and from them it is estimated that not less than 600,000 cubic yards of material have been deposited in the dredged channel above Long Bridge. Perhaps one-third of this amount was the deposit of prior freshets, there having been a number of them since the channel was dredged to 20 feet. The same channel below Long Bridge did not fill up to any great extent, except at its junction with the Washington Channel, where a deposit of about 3 feet took place. At the upper end of the Washington Channel there was a deposit of about 4 feet, which fell off to nothing at the upper end of the Arsenal Grounds. In the Tidal Reservoir the deposit varies from about 4 feet in some places to less than 1 foot in others. It is estimated in round figures that there was not less than 1,000,000 cubic yards of material brought down the river and deposited in places where it is injurious to the channels of the river and will have to be removed in order to restore them to the condition they were in prior to the freshet. Long Bridge.-The necessity of early action in respect to the rebuilding of Long Bridge is emphasized by this freshet. Had it occurred when the river was full of ice a gorge would in all probability have formed at the bridge, which would have thrown much more water into the city and done a much larger amount of damage. Attention has often been called to the necessity of rebuilding Long Bridge, and this necessity increases as the work advances. To delay it longer is to put vast interests in jeopardy. July 1, 1888, amount available.... Amount appropriated by act of August 11, 1888. July 1, 1889, amount expended during fiscal year, exclusive of liabilities outstanding July 1, 1888.. July 1, 1889, outstanding liabilities.. July 1, 1889, amount covered by existing contracts. July 1, 1889, balance available.. $23, 124.70 300,000.00 323, 124.70 $174, 298.70 17, 188. 87 81,743.39 52, 303.74 Amount (estimated) required for completion of existing project...... 1,141,365.00 Amount that can be profitably expended in fiscal year ending June 30, 1891..... Submitted in compliance with requirements of sections 2 of river and harbor acts of 1866 and 1867. (See Appendix K 1.) 600, 000, 00 2. Reconstruction of the Aqueduct Bridge, Georgetown, District of Columbia.-Congress by act approved June 21, 1886, appropriated the sum of $240,000 for the purchase of the Aqueduct Bridge, an unsafe wooden structure over the Potomac, and its approaches, and the construction of a free bridge upon the existing piers. The work was assigned to Lieutenant-Colonel Hains in December, 1886. At the close of the year ending June 30, 1888, the work of reconstruction was about completed, and the new bridge was open to public travel. The operations during the past year consisted of the execution of minor details necessary to a completion of the project. On September 15, 1888, the custody of the bridge was transferred to the District Commissioners in compliance with a requirement of the District appropriation act of July 18, 1888. The matter of the condemnation of the north abutment has been adjudicated, the amount to be paid by the United States being fixed at $10,000. July 1, 1838, amount available July 1, 1889, amount expended during fiscal year, exclusive of liabilities outstanding July 1, 1888 July 1, 1889, outstanding liabilities.. July 1, 1889, balance available (See Appendix K 2.) $11, 128.86 $5, 242. 28 7.33 3. Bridge across the Eastern Branch of the Potomac River, District of Columbia. This bridge is located at the foot of Pennsylvania avenue, southeast, in the District of Columbia. It was authorized by act of Congress approved February 23, 1887, by which an appropriation of $110,000 was made. On September 20, 1887, a contract for the construction of an iron bridge resting on masonry piers was made with the Groton Bridge and Manufacturing Company of Groton, New York. The total price being $105,000. The original plan provided for a 90foot through span at the west end of the bridge, over the tracks of the Baltimore and Potomac Railroad Company. When the contractors commenced the excavation for the foundation for the west abutment, they were forcibly interfered with by the railroad company, which claimed that the abutment encroached upon the company's right of way. Subsequently the railroad officials expressed a desire to move their tracks about 187 feet to the eastward of their existing location. By act approved May 14, 1888, Congress authorized the Secretary of War to make such changes in the plan of the bridge as would best accommodate the traffic over and under it, and appropriated $60,000 to provide for the cost, coupling there with a proviso that the railroad company should pay its fair and just proportion of the cost of the changes at the west end of the bridge. It was difficult to fix upon modifications acceptable to the Government and to the railroad company, and which the contractors would agree to adopt for a reasonable price, and at the close of the fiscal year, 1888, operations were practically at a stand. In July, 1888, however, the matter was adjusted, and a supplemental contract made with the Groton Company for the erection, at the west end of the bridge, of two through spans of 151 feet each, in place of one 90foot through span and two 112-foot deck spans as originally designed. The additional price to be paid the contractors is $40,000. At the close of the year ending June 30, 1889, nine iron deck spans were erected and their piers completed, the embankment for the eastern approach was nearly completed, and the contractors were engaged in the construction of the two 151-foot through spans and the piers which are to support them. The west abutment was nearly completed. July 1, 1888, amount available July 1, 1889, amount expended during fiscal year, exclusive of liabilities outstanding July 1, 1888 July 1, 1889, outstanding liabilities.. July 1, 1889, amount covered by existing contracts... July 1, 1889, balance available (See Appendix K 3.) $51, 154, 74 $45, 198. 10 15, 846. 76 EXAMINATION AND SURVEYS FOR IMPROVEMENT TO COMPLY WITH REQUIREMENTS OF THE RIVER AND HARBOR ACT OF AUGUST 11, 1888. The required preliminary examinations of the following localities were made by the local engineer in charge, Lieutenant-Colonel Hains, and reported by him as not worthy of improvement, with facts and reasons for such opinion. The Chief of Engineers concurring in the conclusions reached in these instances, has given no instructions to make further survey with the view to their improvement: 1. Eastern Branch of the Potomac River, Maryland.-(See Appendix K 4.) 2. South Branch of the Potomac River, West Virginia.-(See Appendix K 5.) 3. Great Cacapan River, West Virginia.-(See Appendix K 6.) IMPROVEMENT OF PATUXENT RIVER AND OF THE HARBORS OF BRETON BAY AND ST. JEROME'S CREEK, MARYLAND—OF THE CHANNEL AT MOUNT VERNON-OF RAPPAHANNOCK RIVER AND YORK RIVER, VIRVINIA OF TRIBUTARIES OF THE LOWER POTOMAC AND OF CERTAIN RIVERS IN VIRGINIA AND NORTH CAROLINA. Engineer in charge, Mr. S. T. Abert, United States Agent; division engineer, Col. William P. Craighill, Corps of Engineers. 1. Patuxent River, Maryland, from Benedict to Hill's Landing.-Two only of the five bars between Benedict and Hill's Landing have been surveyed. These are Swann's Point and Bristol bars, respectively, 43 and 46 miles from the mouth of the river. At Swann's Point Bar the least depth within the limit of the proposed channel was found to be 7.2 feet at low water. At Bristol Bar the least depth was 4.7 near the county wharf. Steam navigation on both bars is impeded at low water. The improvement consists in dredging a cut 200 feet wide and from 12 to 13 feet deep, which will give, when completed, a channel of about 100 feet wide and 124 feet deep at low water. Bids received for dredging were excessive (probably on account of the small appropriation and the difficulty of finding convenient dumping-grounds) and were rejected. An attempt will be made in the autumn to secure reasonable bids. Up to June 30, 1889, $255.29 has been expended. Amount appropriated by act of August 11, 1888 . $5,000.00 July 1, 1889, amount expended during fiscal year, exclusive of liabilities outstanding July 1, 1888..... 255.29 July 1, 1889, balance available... 4,744.71 Amount (estimated) required for completion of existing project.... 75,000.00 10,000.00 (See Appendix L 1.) 2. Channel at Mount Vernon, Virginia —Previous to the commencement of this improvement there was a depth of but 4 feet at low water over the wide flat between the wharf at Mount Vernon and the main channel of the Potomac River, a distance of 1,900 feet. The present project, adopted in 1879, and amended in 1888, is to excavate a channel from deep water of the Potomac to the wharf at Mount Vernon which shall have when completed a width of 200 feet and a depth of from 9 to 10 feet at low water, with a turning-basin of 200 feet radius. The amount expended to June 30, 1889, is $13,971.44. The channel has been dredged a distance of 2,300 feet from the wharf to the main channel of the Potomac. It has a width varying from 60 to 100 feet, and the basin a width of 360 feet. The depths in the channel and basin within the limits mentioned vary from 9 to 12.8 feet. As stated in the Report for 1888, no instrumental examination has been made from 1881 to June 30, 1888. The superintendent of Mount Vernon reported that the channel had filled about 10 per cent. (in depth). Upon this representation was based the statement that $8,500 would complete the improvement. A survey under the last appropriation showed that the basin was nearly obliterated, and that the work required to complete the channel would be increased by the deposit. Amount appropriated by act of August 11, 1888. July 1, 1889, outstanding liabilities.. July 1, 1889, balance available..... $6,000.00 $5,466.44 5, 471.44 528.56 Amount (estimated) required for completion of existing project..... (See Appendix L 2.) 2,500,00 2,500.00 |