DIVISION OF TERMINAL CONSTRUCTION. The division of terminal construction, under Rear Admiral H. H. Rousseau, United States Navy, was charged with the design, inspection, and construction of dry docks, shops, coal and fuel oil plants, floating cranes, docks, and other terminal facilities, and the construction of the east breakwater at the Atlantic terminal. Dry docks. The general dimensions of Dry Dock No. 1 are as follows: Length on center line from outside of masonry at entrance, to inside of head.... ...do.... 1, 110. 0 Elevation of top of blocking 4 feet 6 inches high referred to mean sea level....... -35.0 Elevation of miter and caisson sills referred to mean sea level. -39.5 +16.5 Volume of water contained with tide at mean sea level, elevation 0.0, cubic feet.. 5, 265, 000 The dock is founded on rock, which for the most part is hard, but which contains spots, relatively small, where decomposition has occurred. The body of the dock consists essentially of two parallel gravity walls, connected by a semicircular head; the floor of the dock is merely a smooth skin, laid over the rock exposed by the excavation, the minimum thickness of which is 1 foot, increasing to 5 feet where some of the soft pockets occur. The floor is level longitudinally and for the middle 66 feet of its width, but between this level middle part and the side walls, a distance of 23.5 feet, the floor has a fall of 6 inches, making the elevation of the top of the gutter, which is formed at the base of each side wall, -40. The side walls are reinforced at their backs with 70-pound rails, spaced 4-foot centers for the lower portion of the walls, and 8-foot centers for the upper portion to within 13.5 feet of the coping level. The walls average 29.5 feet in width, and are 12 feet thick for the upper 20 feet of their height. The working faces are formed into four altars, each 3 feet wide, the height of the altars beginning at the coping, elevation 16.5, being 20 feet, 4 feet, 4 feet, 8 feet, and 20 feet, to elevation -39.5. The wall for the lower 20 feet is battered 20 on 3. To prevent hydrostatic pressure behind the walls, a drain is formed at elevation -27.5 on the back of each wall, which communicates with the dock body by four 8-inch pipes through each wall. Four stairways are provided from coping to dock floor, one at the entrance, one at the head, and two intermediate. Extending completely around the dock and connecting to tracks on the entrance pier will be a 22-foot gauge track with a 50-ton traveling crane of 87-foot reach. A row of capstans and bollards parallels each side wall at a distance of 40 feet from the coping. The normal closure of the entrance is by a pair of steel mitering gate leaves, identical with the lock gates, except that the bearing surfaces at the miter and quoin ends are to be of Demerara Greenhart, instead of nickel steel as in the lock gates. The miter sill and hollow quoins are of granite. Outside the miter gate sill is a seat for the floating caisson purchased primarily for service at the locks. This seat is faced with granite similar to the gate sill and hollow quoins, and is reinforced by structural steel brackets embedded in the masonry. The dock will be flooded through culverts formed one in the base of each side wall. These culverts communicate with the sea, each by twin openings 8-feet wide by 12-feet high, at elevation -24.5. On the south side the flooding water passes through the pump suction chamber, and on the north side the flooding culvert descends to the lower level after passing the gate recess. The floor of the suction chamber and of the lowest portion of the side wall culverts is at elevation -52, the descent being made on 45° slopes. The suction chamber is 22 feet clear width, 12 feet high, and about 80 feet long. It is expected to flood the dock, with tide at mean high water, in not more than 30 minutes. The flooding intakes are closed by "wagonbody" valves, operated by water at a pressure of 300 pounds per square inch, furnished by an accumulator provided with the pumping plant. The plant for pumping out Dry Docks Nos. 1 and 2 is located at a distance of about 100 feet from the entrance wall, and consists of 4 main pumps, 2 drainage pumps, and 1 bilge pump, all located in a rectangular pump pit about 100 feet long by 35 feet wide. Immediately adjacent to the pumping plant is the permanent compressor plant, which consists of one 2,250-cubic-foot and one 5,500-cubic-foot motor-driven compressors. These are primarily for the shops, but they will also supply air for the various operations around the dry docks. Award was made and a contract entered into for 11,500 cubic feet of dressed granite and 750 cubic feet of rough stone, the former at a cost of $1.90 per cubic foot, and the latter at $1.40 per cubic foot. After advertisement a contract was entered into for the pumping plant at a cost of $133,456. A contract was also entered into for the flooding and sluice valves and accessories for the sum of $49,100. During the year 134,777 cubic yards of material were removed by steam shovel and by hand. Of this amount 102,425 cubic yards were for excavation, at an average cost of $1.2288 per cubic yard, and 32,352 cubic yards at an average cost of $2.3135 per cubic yard. The first concrete was placed on August 17, 1914, in the south wall, and 128,195 cubic yards of mass concrete were placed during the balance of the fiscal year, and 24,675 cubic yards of reinforced concrete; the cost of the former was $3.9744 per cubic yard, and of the latter $6.0304 per cubic yard. There remain to be placed 25,000 cubic yards of concrete. The total amount of fixed iron placed was 312,729 pounds, and 2,251,304 pounds of reinforcing rods and rails were embedded in the masonry. The placing of granite began in May in the miter sill, and this, together with about three-quarters of the hollow quoins were in position at the close of the year. The erection of the steelwork was begun on June 12, 1915, and all of the girders of the two leaves were placed in position on June 23, 1915. At the end of the fiscal year 565.68 tons of steel had been erected at a cost of $6,391.19, or $11.2982 per ton, including the driving of 1,919 rivets. Backfill to the amount of 33,787 cubic yards was put behind the walls, at a cost of $15,430.36, or an average cost of $0.4567 per cubic yard, and work started on the foundations of the air compressor and pumping plant. It was decided during the year not to complete Dry Dock No. 2 and the adjacent repair piers, Docks 10, 11, and 12, until the necessity for one of such dimensions becomes apparent. This dock will be rectangular in plan, with side walls and head walls of gravity section, but only the head wall and south side wall of the dock are being built; the latter wall supports one side of the entrance pier, the other being supported by concrete columns and steel framing. The entrance pier as now building is 59 feet wide by 350 feet long. It will have a reinforced concrete deck slab and will support a 22-foot gauge crane track and two standard gauge tracks. At its west or sea end there is now to be furnished an electric capstan similar to those around Dry Dock No. 1 for use in handling ships entering Dry Dock No. 1. The entrance pier is situated on the north side of the entrance basin. Nearly all the excavation for the pier was completed in the previous year, and but 5,313 cubic yards were excavated during the present fiscal year in preparing foundations, at a cost of $3.4839 per cubic yard. There were 11,232 cubic yards of plain concrete placed at an average cost of $4.2455 per cubic yard and 602 cubic yards of reinforced concrete at an average cost of $8.5610 per cubic yard. Of the above amount of concrete, 10,189 cubic yards plain and 229 cubic yards reinforced concrete are contained in the gravity section of the pier, which will form the south wall of Dry Dock No. 2, should the need of a dry dock of such dimensions become apparent. Shovel work in the entrance basin was continued in connection with the dry-dock excavation. Nearly all of the material was removed at the end of the fiscal year. There was very little seepage through the cofferdam, and the steam pumps which were installed had no difficulty in handling the water. The remaining excavation for the entrance basin, under and outside the cofferdam, will be done in the wet after the completion of the dry-dock gates and the installation of the valves, when water can be put behind the cofferdam. The amount of material excavated during the year in the entrance basin by steam shovel was 8,771 cubic yards at an average cost of $1.0704 per cubic yard. Balboa coaling station. The concrete work in connection with the crane tracks and the docks for the station was continued throughout the year. The supports for the berm crane tracks consist for the most part of steel girders arranged in pairs, supported on concrete piers spaced 25-foot centers. The piers supporting one of the tracks also support the conveying system viaduct which parallels the berm crane travel by means of piers of buttress form extending above the main pier. These buttress piers also support reinforced concrete curtain walls which confine the coal in the subaqueous storage, a length of about 300 feet, and also for a distance of about 200 feet to the west of the subaqueous storage where deep foundations were necessary. For the balance of the unloader travel the total length of which is about 800 feet, the rails are supported on continuous concrete walls founded on rock or rock fill. The unloader wharf (Dock No. 7) will be 1,052 feet in length by 59.5 feet in width. The type adopted in August, 1914, consisted of concrete piers, spaced 25-foot centers, anchored to the rock, extending the full width of the floor of the dock and having a width of 8 feet at the bottom, which is offset to give a width of 6 feet for the upper portion of each pier. These piers carry longitudinal steel girders which support the tracks, the reinforced-concrete deck slab, and the necessary superstructure of the coaling plant. The unloader wharf supports two coal unloading towers, having a travel of 790 feet. At the end of the fiscal year the wharf had been completed to the cofferdam. Eighteen thousand three hundred and thirty-one cubic yards of concrete were placed in the unloader wharf, at a cost of $5.4746 per cubic yard. A general layout for the reloader wharf (Dock No. 6) to be 745 feet in length by 64.2 feet in width was approved in August, 1914. For the substructure 6-foot cylinders with steel forms sunk to rock were adopted, except under the wharf bunker, where 8-foot cylinders will be placed on account of the heavy loads. The deck will consist of steel longitudinal and cross girders, with a reinforced concrete slab. In January, 1915, the construction of a trestle was begun and thirteen 6-foot caissons were set in place. After the work had started the bank started a slow movement toward the canal, and in order to remove the sliding material the bank was sluiced down, first by a hydraulic monitor and later on to better advantage by a monitor installed on the discharge end of a suction dredge. After the move ment stopped, the work of caisson sinking proceeded. At the end of the fiscal year all but 3 of the caissons were in position, 27 had reached rock, and 46 were in the process of sinking. A total of 4,246 feet of caissons were sunk during the year. There were excavated 17 cubic yards of rock and 4,685 cubic yards of earth in the coal pockets. Riprap retaining walls were constructed around the underwater storage area and around a part of the two dry storage areas. At a cost of $5.5669 per cubic yard, 5,393 cubic yards of concrete and 2,799 cubic yards of rubble masonry were placed in the masonry walls and crane supports. The piers supporting the runways for the berm cranes were erected, and the floors of the coal pockets were leveled off, with the exception of the south half of the east area. The four berm cranes, originally used by the Pacific division, for handling concrete, were dismantled and brought to the site and erected on the runways provided. They were remodeled to fit the work for which they are to be used. By the close of the fiscal year 1,097.8 tons of steel had been erected in these cranes, the structural ironwork was complete, and about half of the machinery installed. The unloader towers, which were furnished by the contractor, arrived on the Isthmus in May, 1915, and at the end of the year one tower was in place and bolted up but not riveted. No deliveries of the reloading towers and conveyor system had been made at the end of the year by the contractor. Cristobal coaling station.-During the year the dredging division completed the excavation of the subaqueous coal pockets to elevation 28. The total material dredged for the coaling station was 188,667 cubic yards, at a cost of $0.5836 per cubic yard. Caisson foundations for the south 500 feet of the unloader wharf were completed on January 1, 1915, for the entire unloader wharf on June 4, and for the entire reloader wharf on June 15. Work on caissons for the end wharf commenced on June 5, 1915, and at the end of the fiscal year 8 out of 31 caissons were completed. These caissons are all 6-foot cylinders of one-half inch or three-eighths inch steel plate, and riveted in lengths of from 10 to 50 feet, depending on the depth of the water. Caisson driving started in July, 1914, and excavation work began soon afterward. In all 11,917 linear feet of penetration was made, 15,027 cubic yards of material were excavated, at an average cost of $2.1133 per cubic yard, and 17,953 cubic yards of concrete filler were placed in the caissons during the year, at an average cost of $4.6833 per cubic yard. Most of the caissons were sealed at the bottom while full of water. After this the water was pumped out, the top surface of the concrete was cleaned, and the filling of the cylinders proceeded as in an open form above ground. This method assured a good quality of concrete. Run-of-bank |