APPENDIX 3.

OFFICE OF THE WASHINGTON AQUEDUCT,
Washington, D. C., December 31, 1894.

GENERAL: In a letter to the Secretary of War the Commissioners of the District of Columbia on the 21st of September last requested to be furnished with a list of the water mains which come within the purview of section 1803, Revised Statutes, forbidding the tapping of any mains laid by the United States in the District of Columbia, excepting by permission of the Chief of Engineers. This letter was referred to me on the 24th September for report (E. D., inclosure 2 of 7307), and in compliance with this direction I have to state the following list of the mains laid by the United States in the District of Columbia:

In Four-and-a-half street west from College street to the new reservoir, near Howard
University

In the Conduit road from the distributing reservoir to Foxall road; in Foxall road to Canal
road; in Canal road to M street north; in M street north to New Hampshire avenue; in New
Hampshire avenue to R street north, and in R street north to Fourth street west.
In New Jersey avenue from L street north to Fourth street west; in Fourth street west to
Florida avenue; in Florida avenue to Linden street; in Linden street to Four-and-a nalf
street west, and in Four-and a-half street west to College street..

In the Conduit road from the distributing reservoir to Foxall road; from Foxall road to the
Canal road at College Pond; in the Canal road to M street north; in M street north to
Pennsylvania avenue; in Pennsylvania avenue to L street north, and in L street north to
New Jersey avenue*,

In New Jersey avenue from L street north to B street north; through the Capitol Grounds to
East Capitol street, and in East Capitol street to Eleventh street east...
In the Conduit road from the distributing reservoir to Foxall road; from Foxall road to the
Canal road at College Pond; in the Canal road to M street north; in M street north to Penn-
sylvania avenue; in Pennsylvania avenue to Washington circle; through this circle to K
street north; in K street north to Massachusetts avenue; in Massachusetts avenue to
Mount Vernon Square; through this square and in Massachusetts avenue to New Jersey
avenue, and in New Jersey avenue north to L street north and south to B street north...
In Eighteenth street west from K street north to L street north..
In Eleventh street west from U street north to K street north..

In New Jersey avenue from L street north to K street north, and in K street north to Eleventh
street east.

In B street south from Tenth street west to Sixth street west; in Sixth street west to Maine avenue; in Maine avenue to the Botanical Garden; through this garden to the Capitol Grounds; through these grounds to the intersection of New Jersey avenue with B street north, and in B street north to Eleventh street east...

In Seventh street west from G street north to F street north; in F street north to Eighth street west, and in Eighth street west to Pennsylvania avenue.

In Four-and-a-half street west from Pennsylvania avenue to D street north, and from Maine
avenue to the Arsenal...

In Twenty-fourth street west from Pennsylvania avenue to the old Naval Observatory.
In Florida avenue from Linden street to Fifth street west..

In the Conduit road from the distributing reservoir to Foxall road; from the Foxall road to
the Canal road at College Pond; in the Canal road to M street north; in M street north to
Pennsylvania avenue; in Pennsylvania avenue to Fifteenth street west; in Fifteenth street
west to Pennsylvania avenue; in Pennsylvania avenue to First street west; in First street
east from B street north to Pennsylvania avenue; in Pennsylvania avenue to Eighth
street east, and in Eighth street east to the navy-yard..

In Pennsylvania avenue at Rock Creek Bridge to Twenty-ninth street west; in Twenty-ninth
street west to P street north; in P street north to Thirty-second street west, and in Thirty-
second street west to the high-service reservoir in Georgetown.
In Seventh street west from Massachusetts avenue to G street north..

* This main was laid by the United States, but its cost was borne entirely by the cities of Washington and Georgetown.

For the safety of the 48-inch main in M street, Georgetown, the portion of this main which is below a valve inserted in it just above M street in 1891, is not to be used and the valve is to be kept closed.

The foregoing list is as accurate as can be made from the plats in this office, which, in respect of the mains laid from the completion of the Washington Aqueduct in 1863 to the laying of the 36-inch main in 1871-72, are probably not entirely conclusive. The list does not include the water pipe supposed to have been laid by the United States to supply the Capitol from a spring that is now in the bed of the new reservoir near Howard University, or any other water pipe laid for the special service of any of the public buildings.

Although all the mains in the table apparently come within the purview of the law referred to by the Commissioners, the United States has, as a general rule, not been at any expense on account of the mains 12 inches in diameter and under for many years. They have probably been considered and used as belonging to the general distribution system of the District of Columbia and have been cared for at the

expense of the District. The District authorities, with but one exception, as far as I am informed, have therefore not applied for or been granted authority for any of the thousands of taps that probably exist in these mains.

I know of no reason why, with three exceptions, they should not all be formally turned over to and be accepted by the District of Columbia, as, by authority of the Secretary of War in 1891, was done with the large number of valves placed by me on the outlets from the 48-inch and other large mains laid by the United States under the act of August 2, 1889, or, if this be not deemed advisable, why general authority should not be given the Commissioners to tap the small mains referred to.

These exceptions are, that part of the 10-inch main in Georgetown mentioned in a note to my tabular list of mains and for the reasons stated in the note, the 12-inch main on the Conduit road between the distributing reservoir and Foxall Hill, and the 12-inch main on the Canal road.

The 12-inch main on the Conduit road between the distributing reservoir and Foxall Hill is parallel to and near the 48-inch, 36-inch, and 30-inch mains. It is very deep (18 feet on a part of its route); it is very expensive to get at the main for tapping, and the great excavations required for this purpose endanger the large mains. The land on both sides of the road is being built upon, and improvement in the vicinity and applications to tap the main are likely to rapidly increase in number by reason of the probably early construction of the Washington and Great Falls Electric Railway, recently chartered by Congress. If the District authorities should lay a small distributing main on this road between the points mentioned, no further tapping of the 12-inch main on this part of its route except for connecting it with the suggested distributing main would be required, and the danger to which the large mains are now subject would be avoided.

The 12-inch main on the Canal road is also very deep, and for a considerable distance the 48-inch and 36-inch mains lie between it and the houses on the north side of the road, so that it is now necessary, whenever additional houses are to be supplied with water, to run the service pipes from the 12-inch main under these two large mains, for the reason that the top of the 48-inch main is so near the surface of the ground that service pipes if carried over the main would be likely to freeze in very cold weather. This practice endangers the water supply to the city. Some time since I found a plumber, acting under the authority of a permit given by the District water office to tap the 12-inch main for the supply of a row of houses of narrow fronts on this road, excavating, apparently without any supervision, a scries of tunnels (one for each service pipe) under the 48-inch main, leaving it supported only by narrow benches of not very compact earth. The internal pressure on the mains on this part of their routes is about 43 pounds per square inch (nearly 40 tons to the running foot of 48-inch main), and the plumber was ignorant or regardless of the fact that if either of the 48-inch or 36-inch mains had settled and broken at its joints by a failure of the benches of earth to support it, not only the supply to the city through the main would have been cut off, but the damage to the road, the houses in the vicinity, and the Chesapeake and Ohio Canal on the south side of the road, would have been enormous. There is therefore also required a small distributing main along the Canal road between Foxall Hill and the foot of M street at the Aqueduct (Arlington) Bridge for the supply of the houses on this road, and if this be laid no further tapping of the 12-inch main on this part of its route except for the supply of this distributing main would be necessary.

In view of the foregoing, I have to make the following recommendations: First. That the Commissioners of the District of Columbia be tendered a transfer to the District of all the United States mains in the District of 12 inches in diameter and under, with the exception of the 10-inch main in Georgetown between its valve just north of M street and the Rock Creek Aqueduct Bridge at Pennsylvania avenue; the 12-inch main on the Conduit road between the distributing reservoir and Foxall Hill, and the 12-inch main on the Canal road; or if this be deemed not advisable, then I would recommend that general authority be granted to the Commissioners to tap any of these mains at their pleasure, with the exceptions just mentioned.

Second. That the Commissioners of the District of Columbia be requested to lay a distributing main on the Conduit and Canal roads between the distributing reservoir and the foot of M street at the Aqueduct (Arlington) Bridge across the Potomac, and that if this main be laid and it be requested by them, permission be granted the Commissioners to tap the 12-inch main for the supply of this distributing main. An earlier report on the letter from the Commissioners has been prevented by the uncertainty as to accuracy of the plats of the old United States mains and by my other duties.

The letter is herewith returned.

Very respectfully, your obedient servant,

GEORGE H. ELLIOT,

Colonel of Engineers.

Chief of Engineers, U. S. A., Washington, D. C.

Brig. Gen. THOMAS L. CASEY,

APPENDIX C C C.

IMPROVING THE DALECARLIA RECEIVING RESERVOIR, DISTRICT OF COLUMBIA.

REPORT OF COL. GEORGE H. ELLIOT, CORPS OF ENGINEERS, RETIRED, OFFICER IN CHARGE, FOR THE FISCAL YEAR ENDING JUNE 30, 1895.

OFFICE OF THE WASHINGTON AQUEDUCT,

Washington, D. C., August 1, 1895. GENERAL: have the honor to transmit herewith report of operations for the improvement of the Dalecarlia Receiving Reservoir, District of Columbia, for the fiscal year ending June 30, 1895.

Very respectfully, your obedient servant,

Brig. Gen. Wм. P. CRAIGHILL,

GEORGE H. ELLIOT, Colonel of Engineers, Retired.

Chief of Engineers, U. S. A.

This reservoir is partly in Montgomery County, Md., and partly in the District of Columbia. It was constructed with a capacity of about 170,000,000 gallons of water.

In this my final annual report on this improvement, I think it proper to restate its object and the project for the work.

Its object was to divert from the reservoir the water flowing from its watershed, which has an area of about 4,000 acres.

When the reservoir was constructed by the late General Meigs about thirty-five years ago for the storage and settling of Potomac water from Great Falls, the land comprising its watershed being then sparsely settled and largely occupied by woods, and its cultivated land being mainly used for grazing purposes, the water from it was not excluded from the reservoir, and, mixed with Potomac water, which entered the reservoir through the "north connection," it was used in the Washington water supply for more than twenty-five years. In time, however, as the country surrounding the reservoir became more populated, the water flowing from it into the reservoir became more and more contaminated, and frequent complaints by citizens and in the press led to the reservoir being thrown out of service about seven years ago.

The water from the watershed entered the reservoir by three streams, viz, Little Falls Branch, Mill Creek, and East Creek, these streams having drainage areas of about 2,700, 900, and 225 acres, respectively.

The project for the improvement of the reservoir* provided for the erection of dams across the valleys of all of these streams just above their mouths and taking the water of East Creek (the stream farthest to the east that polluted the reservoir) from behind its dam and conducting it by an open channel around the margin of the reservoir, together with the water flowing directly into the reservoir from the hillsides between East Creek and Mill Creek, into Mill Creek above its dam. The combined waters of both streams and the water falling directly into the reservoir from the hillsides between Mill Creek and Little Falls Branch were to be carried by a proportionally larger chan nel, still following the margin of the reservoir, and a short tunnel into Little Falls Branch. Finally the water of the entire watershed thus collected was to be turned into a shaft to be excavated in the valley of the latter stream above its dam, and from the bottom of this shaft a tunnel about 1,000 feet long, to be excavated under Dalecarlia Hill and under Washington Aqueduct Tunnel No. 4, was to carry the water to a natural water course below the reservoir in which it would flow off into the Potomac.

At the commencement of the last fiscal year the tunnel under Dalecarlia Hill and the shaft in the valley of Little Falls Branch, which is 51 feet deep (56 feet to the bottom of its water cushion), had been essentially completed and work had been suspended until the new appropria tion should become available.

In the act of August 7, 1894, Congress granted an appropriation of $52,500 for continuing the work, and operations were resumed on the 15th of that month. The excavation of the tunnel through the hill east of Little Falls Branch was then commenced and it was soon carried to the limits of the Government land. By reason of the delay of the district attorney for Maryland then in office, in reporting on the validity of the title to the land purchased for the remainder of this tunnel, its excavation was suspended from the 4th of September until the 18th of December. This unfortunate and unlooked for delay hav ing come to an end, the excavation of the tunnel was resumed and work was carried on night and day with three shifts of workmen at each end until the 16th of January, when the headings met.

In addition to the appropriation just mentioned, the sum of $37,500 was appropriated for the work in the act of March 2, 1895, and by the terms of the act the money was made immediately available.

Under these two appropriations as large a force of workmen has been constantly employed as could be worked to advantage, the number for several months past averaging from 150 to 250 men.

In addition to the excavation and lining of the tunnel about 400 feet long through the hill east of Little Falls Branch, the following work has been done since my last annual report:

Grading the slopes and completing the walls of the channel leading from Wasteweir No. 2 of the Washington Aqueduct at the mouth of the new tunnel under Dalecarlia Hill; the construction and paving of the open channels around the reservoir, of which the aggregate length is 4,869 feet, or nearly 1 mile; the excavation and paving of gutters on the hillsides above these channels to prevent erosion of the banks of the channels; the construction of the following earthen dams, viz, the dam across the mouth of Little Falls Branch, 230 feet long and 10 feet high, its crest being at reference (157); the dam across the mouth of

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A plan of the works and a map of the watershed of the reservoir were printed in the Annual Report of the Chief of Engineers for 1893, pages 4308-4309.