APPENDIX V V. MAINTENANCE AND REPAIRS OF WASHINGTON AQUEDUCT—INCREASING WATER SUPPLY OF THE CITY OF WASHINGTON-ERECTION OF FISHWAYS AT THE GREAT FALLS OF THE POTOMAC. REPORT OF MAJOR G. J. LYDECKER, CORPS OF ENGINEERS, OFFICER IN CHARGE, FOR THE FISCAL YEAR ENDING JUNE 30, 1887, WITH OTHER DOCUMENTS RELATING TO THE WORKS. IMPROVEMENTS. 1. Washington Aqueduct. 2. Increasing the water supply of the city of Washington. 3. Erection of fish-ways at the Greet Falls of the Potomac. OFFICE OF THE WASHINGTON AQUEDUCT, SIR: I have the honor to transmit herewith reports of operations on the Washington Aqueduct; increasing the water of Washington, D. C.; and erection of fish-ways at Great Falls of the Potomac, for the fiscal year ending June 30, 1887. Very respectfully, your obedient servant, The CHIEF OF ENGINEERS, U. S. A. G. J. LYDECKER, Major of Engineers. V V I. WASHINGTON AQUEDUCT. Operations under the appropriations for the Washington Aqueduct have for their object the maintenance and general repairs of the aqueduct, with its accessory structures, and also of the Government supply mains by which the water is brought to the system of distributing mains in Washington and Georgetown. The principal elements of the whole combination are: (1) The aqueduct, 114 miles long, by which the water is conducted from the Great Falls of the Potomac to the distributing reservoir. (2) The masonry dam, 2,877 feet long at the Great Falls, at which place are also a gate-house, where the flow of water into the aqueluct is regulated, and a keeper's dwelling. (3) The receiving reservoir, with its influent and effluent gate-houses, sluice-tower, waste-weir, and keeper's dwelling. (4) The distributing reservoir, with its influent and effluent gate-houses, screen-well house, and keeper's dwelling. (5) The high service reservoir in Georgetown. (6) The Government mains by which the water supply is taken from the distributing reservoir to Georgetown and Washington. (7) The bridge over Rock Creek (at the crossing of Pennsylvania avenue), through the arched ribs of which the water supply for Washington passes; adjoining this bridge, on the Georgetown side, are the aqueduct office building, stable, and workshop. The history of operations presents but little variety from year to year, as it is ordinarily a record of routine work, and current repairs of a minor character; such was particularly the case during the past year. The Government mains were regularly flushed, and the numerous gates and stops by which the supply is regulated were kept properly oiled and packed, thereby maintaining them in good working order; the usual precautions were observed to prevent ice, drift, fish, etc., from getting into the aqueduct; the grounds about the reservoirs were kept in good, cleanly condition, and every effort made to prevent the introduction of any objectionable substances into the water supply; the fences around Government property at the Falls and the reservoirs, aggregating about 16,500 feet in length, were whitewashed, and about 3,000 feet thereof were renewed or repaired; ruts in the macadam covering of the aqueduct were filled, embankments repaired where washed or cut, and the culverts and ditches along the line of the aqueduct road all cleaned out and kept in good shape. Most of the work above indicated is of a purely routine character, and is done under the immediate supervision of the keepers along the line of the aqueduct, each of whom is charged with the care of certain specified sections, and all of whom receive their instructions in relation thereto from the superintendent of the aqueduct. In the nature of what may be classed as special or unusual repairs, I have to report: (1) The replacing of the roadway of the bridge over Rock Creek, to which purpose 12,533 feet, B. M., of Georgia heart-pine was applied. (2) The placing of riprap backing against the new dam spanning the Virginia Channel of the Potomac at the Great Falls, to which end a small scow (40 by 14 feet) was constructed and a force put at work in the quarry that had been opened on the Government property on the Virginia shore; the amount of stone quarried, boated to the dam, and leveled off was about 2,016 cubic yards. (3) The conduit road was widened at places where the embankments were dangerously narrow, such as to barely admit the passage of meeting vehicles; the aggregate length of road so widened was about 15,800 feet, the increase of width varying from 10 feet to 20 feet, providing in this way a roadway whose least width is 20 feet. (4) The doors of all gatehouses were sanded down and painted; the iron cornices and beams of the gate-houses were painted, as also were the keepers' houses. (5) About 1,500 linear feet of paved gutter was built along the conduit road where it passes by the distributing reservoir, thereby improving the surface drainage at that place. (6) The poles of the aqueduct telephone line on Thirty-fifth street, Georgetown, were removed to the new curb line of the street in response to a request from the Commissioners of the District. (7) In addition to scattering repairs to the macadam of the conduit road, a layer of stone 6 inches deep and 11 feet wide was spread over a length of about 2,000 feet and thoroughly rolled; and I would note that the maintenance of a good stone roadway over the aqueduct is of the greatest importance as a guard gainst injury to the conduit from the deep cuts made by heavy traffic luring certain parts of the year, especially in the spring-time. Three ld wooden culverts on the line of the road were rebuilt in stone, and ne new pipe culvert. At the close of the fiscal year the general conlition of everything about the aqueduct was as good as the means vailable could make it. The outflow of water from the distributing reservoir, as measured luring the 24 hours ending at 6 a. m. June 25, 1887, was 26,878,424 gallons, being 1,335,918 gallons more than the outflow as measured bout the same time in the year preceding. (See Table 1.) The water supply as it passed the effluent gate-house of the distribut ng reservoir was clear on 256 days, slightly turbid 39, turbid 32, and very turbid 38; the supply in this respect being an improvement on hat of the previous year, during which clear water passed the effluent on only 147 days. (See Tables 2 and 3.) The water-level at the inlet to the aqueduct at the Great Falls has varied from a maximum of 3 feet to a minimum of 0.7 feet above the rest of the dam. This, it will be observed, is the first in a long series of years that the water level has not fallen below the crest of the dam, he natural result of its extension and completion to the Virginia shore. See Table 2.) The average water pressure for the year in the supply mains at the rossing of Rock Creek, as recorded daily at 9 a. m., was 31.03 pounds >er square inch; the maximum 9 a. m. pressure was 35 pounds, and he minimum 28.5 pounds. The average pressure during 1886 was 32.04 pounds. (See Tables 1 and 4.) The following tables, from which the items above noted were deduced, vill furnish more detailed information in relation to the same points: TABLE 1.—Showing hourly flow from distributing reservoir for the twenty-four hours euding June 25, 1887. The outflow during twenty-four hours, as measured in the latter part of June, for the past fourteen years is as follows: TABLE 2.-Showing for each day in the year, (a) condition of water at Great Falls' res ing reservoir, and distributing reservoir; (b) heights of water over dam at Great Fa (c) 9 a. m. pressures at Rock Creek. Calculated from 148 feet, height of new dam; formerly calculated from 146.80 feet, height of old dam |