grading and paving of area around dock; placing of concrete walk around pump and compressor house; installing fittings at dock coping, and check valves in culverts to prevent "geysers" at coping drain down spouts which enter flooding culverts. Pump pit was also made water-tight and cut-off wall added to bulkhead at station 10 to prevent seepage into backfill around dry dock. The miter gate operating machinery was completely installed and wiring completed. These electrically operated machines have proven a remarkably successful innovation for dry docks, being duplicated from the lock gate operating machinery. Capstans and bollards were completely installed and capstans accepted after minor alterations thereto. The capstans have operated satisfactorily. Handrails were completely installed and have proven satisfactory. The blocking system, with some modifications, was installed as originally designed, and presents a new feature in dry dock installations, as regards the holding-down device for the docking keel blocks, which was described in the last annual report. The device has proven practical and securely holds the blocks in any desired position. The 50-ton locomotive crane was completely erected, tested, and accepted, having met the tests satisfatcorily except in a few minor points. The crane was furnished by the American Hoist & Derrick Co., of St. Paul., Minn. The design, fabrication, and erection of steelwork for wharf C-D-E was completed and the decking installed by the municipal engineering division. The pumping machinery was completely installed, tested, and accepted, proving entirely satisfactory after minor adjustments had been made. The machinery is efficient and the plant is a very satisfactory installation. Dry Dock No. 1 and all its accessories have been in satisfactory operation, and practically no work remains to be done except main tenance. The construction of Dry Dock No. 2 was not advanced beyond the limits contemplated at the close of fiscal year 1916. The basin formed by cofferdam on north and dock wall on south side was opened for entrance of small craft. COALING PLANTS. Erection was completed. The official tests were run and the machinery accepted, subject to the operation of guaranty bonds required of the contractors. The plants are satisfactory except for some defects and the closing up of contract matters is in progress. EAST BREAKWATER, COLON. C. C. Snedeker, Superintendent. The following is a report of operations on the Atlantic breakwaters for the months of July to December, 1916, to complete the work at the east breakwater: Dry Fill.-Derrick barges Nos. 156 and 157 continued the work of placing concrete blocks in the top section and to finish the fill. From July to October there were placed 10,055 blocks, containing 81,156.1 cubic yards, as follows: Number of Number of blocks. cubic yards. Walker & Torbert contract, size 7 feet, 12.3 cubic yards.... .per block.. Totals..... 10,055 81,156. 1 The unit cost for placing, by means of derrick barges, a total of 147,056.1 cubic yards of concrete blocks to complete the east breakwater was $0.3318 per cubic yard. Wet fill. The dredge Marmot, working at the Cristobal coaling station, excavated 46,350 cubic yards of material classified as earth, small rock, and blue rock. This material was dumped on the harbor slope of the extension by scows, and the wet fill was completed August 14, 1916. Coco Solo production of concrete blocks.-One thousand three hundred and fifty-six concrete blocks containing 12,204 cubic yards, size 6 feet 3 inches, 9 cubic yards per block, were manufactured at the Coco Solo mixing plant to complete the requirements of the east and west breakwaters. In addition to this, 1,000 blocks, containing 9,000 cubic yards, were made for permanent storage. A total of 2,356 blocks were manufactured from July 1 to October 30, the mixing plant working 81 days of eight hours each, or an average of between 29 and 30 blocks per working day. On account of rough weather during the first week of November it was decided to be more expedient and economical to unload and store 143 blocks which had been put into barges to be placed by derrick barges in the east breakwater fill than to hold the floating equipment inactive until smoother weather prevailed. Therefore the number of blocks in storage at the Coco Solo yard for future use, if required on the Atlantic breakwaters, is 1,143, containing 10,287 cubic yards. Derrick barges Nos. 156 and 157 were then transferred to the Panama Railroad for use at Pier No. 6. The unit cost of manufacture at Coco Solo for a total of 6,000 blocks, containing 54,000 cubic yards, was $33.4379 per block, or $3.7152 per cubic yard. The unit cost of producing and putting into the east breakwater fill a total of 196,468.8 cubic yards of concrete blocks was $3.9813 per cubic yard. Miscellaneous. From July 1 to November 30 work was continued in tearing up and removing the temporary trestle on the east breakwater, using derrick barge No. 161 and crane No. 61. Approximately 10,726 linear feet of single-track_trestle on the harbor (seaside) extension and "L" were removed. The work of salvaging the trestle was completed on November 30. The log sawmill sawed 953,273 feet b. m. of lumber from salvaged trestle material. This mill was transferred to the fortification division on December 31, 1916. WEST BREAKWATER. During the months of August, September, and October, 1916, 812 concrete blocks, containing 9,666.6 cubic yards, were manufactured, as follows: These were placed on the west breakwater to complete the repairs made necessary on account of damage done by the 1915 "northers." This portion of the work was finished on October 10, and the unit cost of producing and placing these blocks was $4.2758 per cubic yard. General. The cleaning up of the work on the Atlantic breakwaters at Coco Solo was commenced in November and completed during the following month, the floating equipment, consisting of derrick barges, rock and sand barge, launch, and locomotive cranes, being transferred to other divisions. The property and material were also transferred and the accountability of the superintendent closed. The average daily force from July to close of the work in December was 22 gold and 159 silver employees. The remainder of the force at Coco Solo was disbanded and the work at the east breakwater completed. Respectfully, JAY J. MORROW, Engineer of Maintenance. Col. CHESTER HARDING, United States Army, |