Table giving amount of work performed on the Washington Aqueduct Tunnel for the fiscal year ending June 30, 1899.

Expense on Washington Aqueduct Tunnel for fiscal year ending June 30, 1899.

BBB 3.

INVESTIGATING THE WATER SUPPLY OF WASHINGTON, DISTRICT COLUMBIA.

This work is being conducted under an act approved June 30, 18 which contains the following clause:

To enable the proper officer of the Government having charge of the Washing Aqueduct and the water supply of the city of Washington to make an investigat of the feasibility and propriety of filtering the water supply of Washington and submit to Congress a full and detailed report thereon, and to meet all necess expenses of said investigation, three thousand dollars. Said report shall be acco panied by a detailed estimate of the cost of the work required, and in making investigation and in the preparation of this report the Chief of Engineers, Uni States Army, shall be associated with the proper officer of the Government in charge of the Aqueduct as consulting engineer.

In addition to the above appropriation of $3,000 an additional app priation of $5,000 was given by an act making appropriations to p vide for the expenses of the government of the District of Columb for the fiscal year ending June 30, 1900, and for other purposes:

For additional amount to enable the proper officer of the Government havi charge of the Washington Aqueduct and the water supply of the city of Washin ton to make an investigation of the feasibility and propriety of filtering the wa supply of Washington, and to submit to Congress a full and detailed report there and to meet all necessary expenses of said investigation, five thousand dollars, be immediately available.

The work for the fiscal year has consisted in the collection of da and information in relation to filtration of water supplies in this a foreign countries.

The methods of filtration adopted and in operation generally are: First, slow sand filtration, the method adopted generally in Engla and the continent of Europe, more especially in Germany.

This method having been first adopted and developed by the En lish is frequently designated as the English system.

Second, rapid sand filtration. This method has been developed this country and has been designated as mechanical, or the America system.

The slow sand or English method consists of passing the raw wat through a layer of fine sand, supported by coarser material, and conducted generally at a rate of from 2 to 2 million gallons per ac per diem.

The mechanical or American system consists in passing the wat rapidly through a coarser sand than in the English system and the u of some chemical, generally sulphate of alumina, as a coagulant. Th rate of filtration by this method is about 128,000,000 gallons per die per acre, or about fifty times the rate of the English method.

In order to ascertain the results of these methods of filtration wit Potomac water, two filters have been erected, one on the English sy tem and the other embodying the recent improvements on the Amer can system. These experiments are being conducted with a view 1 showing the reduction in turbidities, the bacteriological results, an the safe rate of filtration to be adopted in the special case of the Pot mac water.

The report required by Congress will be submitted as soon as suf cient data have been obtained to deduce a fair conclusion.

Money statement.

INVESTIGATING WATER SUPPLY OF WASHINGTON, D. C.

Amount appropriated by act approved June 30, 1898......
Amount appropriated by act approved March 3, 1899......

$3,000.00

5,000.00

8,000,00

1,916.63

6, 083.37 78.60

,6, 004.77