CONSTRUCTION. Cost of supervision, including subsistence and services of boats. Cost of Red River Dam this season Total...... $4,283.54 9, 915. 44 14, 336. 90 1,282.34 15, 558. 39 2, 152.82 6, 063.43 911.86 2, 180.29 56, 685.01 Value of 15,400 rations furnished, cooked, and served...... 8, 222.98 (Cost per ration, 53 cents.) Cost of launch Alaska while in commission, including fuel, material, etc., 6 days, at $12.90 per day ..... Cost of dredge Pah-Ute while in commission: Excavated in Lower Old River, 23,002 cubic yards, at 3.5 cents... Cost of steamer Ruby while in commission, including fuel, material, etc., 207 days, at $15.90 per day. Cost of tug Comstock while in commission, including fuel, material, etc., 107 days, at $20.89 per day 2,235. 10 3, 291.93 77.39 Excavated a total of 41,923 cubic yards, at 3.16 cents.. Cost of dredge Menge while in commission: Excavated in Lower Old River, 54,291 cubic yards, at 3 cents..... .... 813.87 511. 48 1,325. 35 1,628. 60 1, 347. 31 Excavated a total of 171,689 cubic yards, at 1.73 cents. Cost of repairs to dredge Total..... (Cost per cubic yard, 2.3 cents.) Cost of work done for New Orleans Harbor............... Value of rock transferred to New Orleans Harbor... Total..... Cost of rock for Plaquemine, La Previous cost.. Total..... Cost of labor and services of boats for Plaquemine Value of subsistence store transferred. Value of fuel transferred.... Value of material transferred. 2, 975.91 977.52 3, 953. 43 45.27 7,874.52 8, 919.79 276.80 15, 879.90 16, 156. 70 144.78 173.02 210.00 1,238. 24 1,766. 04 Very respectfully, your obedient servant, G. ED. MOTT, Assistant Engineer. Total..... Lieut. JOHN MILLIS, Corps of Engineers, U. S. A. ENG 92-202 NEW ORLEANS HARBOR. The city of New Orleans, with its various suburbs, lies on both banks of the Mississippi River at a distance inland of 104 miles from the South Pass. This pass is the only one of the numerous mouths of the river having sufficient depth of water to admit seagoing vessels of deep draft, and it therefore is the entrance from seaward to the Mississippi River and the harbor of New Orleans. The city is the metropolis of the South, and besides being the most important seaport on the Gulf of Mexico, it stands first among the towns on the Mississippi in the commercial importance of its river traffic. It ranks seventh among the ports of the United States in the value of its imports, while in the value of its exports it is only exceeded by New York City. The New Orleans Harbor, as at present developed, consists solely of a length of about 13 miles of the Mississippi River, which here has an average width of about 2,200 feet, and it comprises four comparatively straight reaches of various lengths and four curves or bends. Two of these bends, the one at Algiers Point and the one at Carroliton, are quite abrupt, the radius of curvature in the former being about equal to the width of the river, and the change in direction being more than 90°. The depth of the river is, in general, ample for the purposes of navigation. The entire country in the vicinity is of alluvial formation and is consequently low and flat, being highest along the river bank and having a gentle slope back toward the swamps. During floods the river reaches a height of 5 or 6 feet above the highest ground in the city, and the levees, which are essential for the prevention of overflow, are as a rule necessarily built close to the river bank in order to meet the requirements of the various interests along the water front. The construction of regular docks, or slips and piers, along the water front is as a rule impracticable, owing to the variation in height of water, the unstable nature of the banks, the swift current, and the tendency to deposit large quantities of silt. The water front is therefore occupied principally by continuous wharves, to which vessels must moor alongside; and since there are no good anchorage grounds, owing to the current and the great depth of water, the conditions generally in the harbor are such as to require an unusual development of water front to accommodate a given amount of shipping. Although the condition of the river and of its banks here is one of comparative stability when contrasted with the extraordinary changes which often occur further upstream, the damage that results from even slight changes of the river in a port like New Orleans becomes serious. In general the action of the river is to erode or cut away and cause caving or sliding down of the banks in the concave shore at the bends and for some distance below them, resulting in the destruction of wharves, levees, streets, and sometimes of sheds and buildings. Where this action occurs on one bank a deposit of sediment and consequent shoaling and damage to the water front on the opposite shore usually takes place also. In certain localities similar destructive effects have been produced in the straight reaches also by the caving of the banks, due partly to the weight of masses of sediment deposited during high water, which when deprived by the falling river of the support which the water afforded during flood time, causes large portions of the bank to crack off and slide down. This action usually takes place only during falling water, but the destructive effects in the bends goes on to a greater or less extent at all stages of the water, and in addition to the immediate damage on the water front there is the danger of much more serious disaster resulting from the breaking of the levee during high water and the flooding of the city. The object of the works of improvement in New Orleans Harbor is to check and if possible prevent the detrimental action of the river as above described, and to maintain the river bed and banks in a condition of permanency. Under the approved project the work now in progress to accomplish the above objects, consists in the construction of submerged inclined spur dikes along the caving banks, which extend out normally to the bank line at intervals of from 500 to 1,600 feet. Each spur dike rests on a wide mattress made of willows, brush, and timber, which is sunk in place by being loaded with stone, and which is intended to prevent any scouring action on the river bottom by eddies or local currents which may be produced by the dike. On this mattress the dike is built up by sinking successive layers of mattresses or cribs of diminishing widths, the construction of which is similar to that of the foot mattress, except that they are made thicker. The work is so planned that the top of the completed dike at the shore end will be below low-water line, and the crest of the dike has an approximately regular slope of about 3 horizontal to 1 vertical, its outer end resting on the river bottom in deep water. In the vicinity of wharves and docks the crest of the dike is placed low enough so it will not interfere with vessels; but in other localities the crest has been continued up to and united with the crest of the levee or the bank by an earth embankment paved with stone. These structures are designed to check the velocity of the current along the shore, and thus diminish the erosion and caving of the bank, and cause deposit of sediment and the restoration of the bank line. In certain localities their direct effect in bracing up the bank, and so preventing the caving which is liable to take place during the falling of the river, is also believed to be beneficial, at least locally. When this form of structure is used, where the existing slope of the submerged portion of the river bank is not steep, the foot mattress probably becomes the inost important part of the spur, and the dikes act more as an interrupted bank re vetment. The following work of improvement, in general accordance with the project as above outlined, had been done prior to July 1, 1891: A continuous mattress, about 400 feet in length, had been placed just above the caving bank in Carrollton Bend, but this form of protection was afterwards abandoned. Three spur dikes had been built in the Carrollton Bend, two in the Greenville Bend, six in the Gouldsboro Bend, and four in the Third District reach. Surveys to determine the condition of work already completed and for the preparation of plans for continuing the work had been made, and several of the barges and other portions of the plant had been repaired or extensively rebuilt. All the completed work remained in place and served the purpose for which it was constructed, except that considerable local caving took place in Carrollton Bend, after the completion of Dikes 3, 4, and 5, and an eddy seemed to be formed between Dikes 4 and 5. A portion of the wharf and shed of the Louisville, New Orleans and Texas Railroad, at the head of Dike No. 4, was destroyed by the caving. During the high-water season in March, 1891, a large crevasse occurred in the levee between the two dikes in the Greenville Bend, but so far as can be ascertained by soundings, no injury resulted to the dikes. At the beginning of the year operations were resumed in the Third District reach, in accordance with the plan submitted in pursuance of the general project and approved by the Commission. Four spur dikes had been built in 1889, on the left bank near the Ursuline Convent. In this locality, and for some distance above, the levee is immediately on the river bank, and a street passes along parallel to the river and just back of the levee. In several places, caving had taken place, necessitating the construction of " run-arounds," or "horse-shoes," in the levee, projecting into the street. A complete interruption of the street and the ultimate destruction of buildings and wharves, was threatened. The project for continuing the work contemplated, building six more dikes, covering that portion of the river front between the uppermost of the dikes built in 1889, and Clouet street. These dikes were located opposite the points of the bank most threatened, and were to be built in the order that they seemed to be most urgently required to arrest the caving. A quarterboat with a force of men and an outfit of tools was sent to the mouth of Thompsons Creek near Port Hudson to cut willows for the work. The force continued work at that point until October 11, 1891, when it was moved down to Profit Island. Willows were supplied both to the New Orleans Harbor work and to that at Plaquemine. A sufficient quantity of rock for the immediate needs of the New Orleans Harbor work was on hand, stored on the bank near Southport, and a considerable amount of rock ballast was purchased in the harbor during the season; but toward the close of the season's work it became necessary to borrow 2,532 tons from that stored at Turnbull Island. This was afterwards returned at the expense of the New Orleans Harbor allotment. Repairs to the quarterboat were not entirely complete at the beginning of work, and a vacant building in the Third District was rented for quarters and office accommodations. Mattress and crib construction began July 23, and sinking of mattresses on Spur Dike No. 1 was commenced September 28. The dike was completed October 2, at a total field cost of $9,593.49. It contains 262,305.6 cubic feet of work. Spur Dike No. 5 was next built. Sinking of mattress began October 13 and all mattresses and cribs were sunk by October 16. The field cost including cost of shore protection was $8,962.84. The total number of cubic feet of work was 202,449.6. Spur Dike No. 2 was the next one undertaken. Sinking began October 30 and was finished November 5. Its field cost was $9,343.52, and it contains 253,713.36 cubic feet. Spur Dike No. 3 was the last one built in this locality. Sinking began Septem ber 9 and was completed November 16. It contains 264,321.6 cubic feet of work, and the total field cost was $11,502.02. Dikes 4 and 6 have not yet been built. The intervals between Dike 5 and Dike No. 1, of 1889, and that between Dikes 3 and 5 are greater than should exist if the caving and erosion were general and active along this front. The current is not very strong, however, and the sections of the river bottom show that the slope of the bank is not on an average much steeper than 3 base to 1 perpendicular. It is quite possible that the completed work will be sufficient to arrest the encroachment of the river and that the intermediate dikes will not be necessary. After completing the four dikes in the Third District reach the plant was removed to Southport to continue work in the Carrollton Bend. The caving that had taken place here since the completion of Dikes 3, 4, and 5, indicated that the intervals between the dikes was too great for this locality, where the curvature of the bank is such that the dikes, being normal to the bank line, may, perhaps, have sufficient convergence to increase the tendency of the water to form eddies or whirls in the intervals. In order to diminish the intervals and break up eddies, the Commission directed that two intermediate dikes, Nos. 3 and 4, be constructed, and that the gap between Dike No. 4 and the bank line which had formed by the caving be filled with a mattress. Dike No. 6 was also to be built if sufficient funds remained after completing the above. Construction work in Carrollton Bend began November 19. Sinking of mattresses on Spur Dike No. 44 began January 27, and the dike was completed January 30. The total field cost was $11,673.95, and the total cubic feet of work was 286,542. Sinking of Spur Dike 34 began February 13, and was finished February 16. The field cost was $11,941.38. The dike contains 297,342 cubic feet. A mattress 80 feet by 90 feet and 2.16 feet thick was built and sunk at the head of Spur Dike No. 4 to connect it with the shore. Its cost was $716.16. The long season of unusually low water and good weather was very favorable for the work, but during the latter part of the season the dikes in the Carrollton Bend were finished under much less favorable conditions, the river having risen, producing a swift current and much trouble from drift. Serious caving in the vicinity of the French Market took place in October and November, and a survey of the bank and river bottom in the vicinity was ordered. It was found that the balance of the allotment available would not be sufficient to complete the construction work undertaken and the survey, and the Commission therefore approved the transfer of $8,000 from the allotment for the Red and Atchafalaya work to New Orleans Harbor. The damage near the French Market was caused by settling of the river bank, and cracks appeared about 200 feet back from the outer crest of the bank or "levee" and the surface began to go down over a considerable area involving a large wharf, the tracks of the Louisville and Nashville and Southern Pacific Railroads, and a few small buildings. The settling was gradually progressive in amount and in superficial extent until it practically ceased about the middle of November. At that time it had extended along the river front for a distance of about 1,600 feet, between St. Ann and Esplanade streets, and its extreme width was about 250 feet. Over the area affected there were several large cracks and the surface was quite uneven and broken, but the general settlement was from 5 to 10 feet. No noticeable change has taken place since and the portion occupied by the railroad tracks has been filled up and the levee restored. In February à careful survey was made in the locality. Seven sections were sounded between St. Ann and Barracks street and map submitted. Three sections indicate that there has been in general a deepening of the river since the survey of 1878, but otherwise no material change has taken place. The slope of the bank at the cave is practically the same as it was in 1878 and does not average steeper than 3 base to 1 perpendicular. Borings made under direction of the city engineer of New Orleans showed a depth of about 50 feet of stiff clay, with an underlying stratum of sand of about the same thickness. Erosion and caving still continue on the left bank from the completed work in Carrollton Bend down to Exposition Wharf, and during the past year the local authorities have built two new pieces of levee in anticipation of the destruction of the old levees in front. The upper levee extends from Leonidas street to Carrollton avenue and the lower to Exposition Wharf, beginning at Broadway street. These works necessitated the removal or abandonment of a large number of buildings and great loss of property. A number of buildings were also thrown outside the new levee built during the year under direction of this office at Southport. There has been no material change since the last report in the condition of the caving places in the vicinity of the Soraparu Market. NEW ORLEANS HARBOR, Money statement. July 1, 1891, balance unexpended... Transferred from Red and Atchafalaya rivers allotment May 31, 1892, amount expended during fiscal year to date.... $72, 961.56 $69, 719.54 8,000.00 77,719.54 $1.00 9.35 10.35 72, 951. 21 June 1, 1892, balance unexpended. Amount that can be profitably expended during the fiscal year ending 4, 768. 33 4,768.33 200,000 The work in New Orleans Harbor has been under the immediate charge of Assistant Engineer William Garvin during the year. His report is as follows: NEW ORLEANS, LA., May 18, 1892. SIR: I have the honor to submit the following report on the work of improving the harbor at New Orleans, La.: At date of last annual report, June 1, 1891, the condition of the work was as follows: The plant was at laying-up quarters at Exposition Wharf, all necessary repairs to barges had been completed, and seven of them were sent to the quarries on Ouachita River. New crib ways were being built and general preparations for the resumption of spur-dike construction were in progress. On July 20, 1891, the tug moved the plant from laying-up quarters to the Third District Bend. At this time the quarter-boat was on ways being repaired, and a house was rented to serve as office and quarters during the construction of the spur dikes in the Third District Bend. On July 20 the steamer General Newton arrived with three barges of willows. The mattress for Spur No. 1, Third District Bend, was commenced July 23 and completed August 5, but owing to the barges being engaged transporting willows it was not sunk until September 28, fifty-four days after completion. The mattress was built in four sections, 100 by 120 feet each; the head block or upstream frame was built of 3 by 6 inch lumber, all other frames of 2 by 4 inch lumber, with stanchions or uprights 26 inches long and 5 feet between centers. The frames were spaced 10 feet between centers. They extend from bank out in stream or at right angles to the current. The first layer of brush was securely nailed to frames, the second, a thick layer, parallel to frames, and the third of selected willows placed across frames and spaced 2 feet distant. Lines of poles were placed across top of frames 20 feet distant to give additional strength and stiffness and to prevent rock shifting, there being but little current; few rods were used for strengthening frames at toggle pins. The dimensions of the mattress were 120 by 400 by 2.16 feet, and the cost and material were: |