The remodeling of Georgetown reservoir will be made necessary by the proposed system of coagulation in order to flush out the sediment that will be deposited from the water after treatment at the coagulating plant. The necessity for the preliminary treatment of the water is discussed under the head of "Maintenance and operation," pages 2365 to 2372, Annual Report of the Chief of Engineers, U. S. Army, 1908, where is also explained the necessity of remodeling this reservoir. The work proposed will complete the works for the preliminary treatment of the water supply, for which an estimate of $108,000 is submitted. PARKING M’MILLAN PARK. An appropriation of $2,000 was made in the act to provide for the expenses of the District of Columbia for the fiscal year 1911 for continuing the parking of McMillan Park. For continuing this work an estimate of $8,000 for the fiscal year 1912 is submitted. No money being available, no work of improvement was done during the fiscal year 1910, except in the maintenance of the portion of the grounds used for purposes of the filtration plant, in which case the filtrationplant funds were applicable. In order to complete the work of parking according to the prepared plans it will be necessary to cover the area south of the dam with soil, to seed it with grass, and set out various kinds of shrubs and trees. It will also be necessary to build walks and steps leading from the low to the high areas, to sod all steep slopes, and to build a wading pool. While the area under consideration is now graded to nearly its final lines, its surface is of clay, which will not support a growth of grass, so that it will be muddy in wet weather, dusty in dry weather, and always unsightly until the work is completed. The prepared plans for the parking of McMillan Park also provide for planting of shrubs and trees and for certain changes in roads and sidewalks, etc., north of the dam. The necessity for the prompt installation of meters is explained in the report on "Increasing the water supply of the District of Columbia," House Document No. 347, Sixty-first Congress, second session. The finding in this report that a new aqueduct was not necessary was based on the assumption, among others, that metering of all services in the District of Columbia would be immediately provided for. In the appropriation for the expenses of the District of Columbia for the fiscal year 1911, an appropriation was made to meter the supply to certain public buildings. An estimate of $45,000 is submitted to complete the installation of meters on all the services to public buildings, reservations, or grounds. It is also urged that a large appropriation, as recommended in the House document referred to above, be made for the general installation of meters on all private water services, under the engineer department of the District of Columbia. While the work done by the engineer department of the District of Columbia to detect and prevent the waste of water is highly commendable and the results accomplished are exceptional, a study of the consumption of water in the District of Columbia in its relation to air temperatures has led the officer in charge to conclude that the necessity for the general and complete installation of meters is still very urgent, not only to remove the necessity of an expenditure of $4,000,000 or $5,000,000 for the construction of a new aqueduct, but also to remove the possibility of the consumption of water exceeding the maximum capacity of the aqueduct, which is still likely to happen in case of the recurrence of a period of cold weather similar to that of the winter of 1904-5. The officer in charge has recomputed the consumption of water for weekly periods from January, 1903, to October, 1905, based on the latest information on the hydraulics of the Washington Aqueduct. From the results obtained it appears that the average rate of consumption of water for the month of April, 1904, was 57.2 million gallons per day. The average rate of consumption for April, 1910, was 58.3 million gallons per day. In the investigations of the consumption of water in relation to temperatures it developed that in the months of April and November.the temperatures are such as not to affect the consumption of water, so that the consumption of water during these months forms a fair basis of comparison for different years. It will be noted that the consumption for April, 1910, was slightly higher than for April, 1904. It would be reasonable, therefore, to expect that, if the winter of 1910-11 should be similar to that of 1904-5, the consumption will at least equal the high consumption in February, 1905, when the demand exceeded the maximum capacity of the aqueduct, and a failure of the system to meet the demands was threatened, unless the difference between the present conditions and those of 1904-5 is such as to prevent a recurrence of a threatened failure of supply to meet the demands. These conditions are controlled by the number of water services metered and unmetered, and the probable waste from a metered service as compared with an unmetered service. In 1905 there were 51,931 unmetered and 2,104 metered services. At present there are about 48,038 unmetered and about 15,879 metered services. There are about 3,893 fewer unmetered services and about 13,775 more metered services than in 1904-5. It appears therefore that if the average metered service should waste twentyeight one-hundredths as much as the average unmetered service, then 13,775 metered services would waste as much as 3,893 unmetered services, and under this condition the demand for water during a period of extreme cold weather next winter, similar to that of 1904-5, would equal the demand for water made during the cold winter of 1904-5. That there is waste from a metered service in periods of cold weather is evident from the fact that cities having nearly or all services metered experience the increased demand for water during cold periods, although the demand is not as heavy as it would be if all services were unmetered. It is believed that the waste from a metered service is not less than, and in general is probably more than, twenty-eight one-hundredths of the waste from an unmetered service. It is therefore the opinion of the officer in charge that all services should be promptly metered to reduce the normal consumption of water so that the danger stated above shall be removed. QUARTERS FOR ASSISTANT TO OVERSEER AT GREAT FALLS, MD. It has always been difficult to secure the services of a reliable and intelligent person to assist the overseer at Great Falls in the performance of his duties, owing to the lack of suitable and convenient. habitation for such a person, no suitable building in the neighborhood being available for renting. There is submitted an estimate of $2,500, or so much thereof as may be necessary, to provide the labor and purchase materials of construction not now available in order to provide quarters for the assistant to the overseer at Great Falls. COMPLETING SURVEYS FOR INCREASING THE WATER SUPPLY. A report on the results of the preliminary investigations and surveys for increasing the water supply of the District of Columbia was submitted from this office by Maj. Jay J. Morrow, Corps of Engineers, U. S. Army, July 8, 1909, and was published as House Document No. 347, Sixty-first Congress, second session. Reference to increasing the water supply by use of the Patuxent River as a source is made on pages 4, 5, 7, 8, 84, and 85 of the said report. On page 8 Major Morrow reports: It is estimated that these studies could be made at a cost of $3,000, and that an appropriation therefor should be made at a reasonably early date, as it should be borne in mind that should this project be adopted for ultimate construction the necessary legal preliminaries would add possibly two years to its time of completion over the time necessary to complete the work of providing a new conduit from Great Falls. The present officer in charge of the aqueduct concurs in this opinion, and desires to state that on account of the failure to provide, in the appropriation for the expenses of the District of Columbia for the fiscal year 1911, for the prompt installation of meters on all services in the District of Columbia, as repeatedly urged in the report mentioned above, the necessity for the work provided in this estimate becomes urgent in order to determine as soon as possible the best method of increasing the water supply, with a view to submitting to Congress, as soon as practicable, an estimate for beginning the construction of a new aqueduct. If the prompt installation of meters shall be provided for in the District appropriation bill for the fiscal year 1912, as recommended by Major Morrow in his report on increasing the water supply, there will be no need of submitting to Congress an estimate for a new aqueduct. An estimate of $3,000 is submitted for completing the investigations and surveys to determine the availability and adaptability of the Patuxent River as a source of water supply for the District of Columbia. LINING CERTAIN UNLINED PORTION OF THE AQUEDUCT. There is in the aqueduct a total length of 4,364 feet of tunnel through rock, which is unlined. The best engineering practice of the present day would require all tunnel in rock to be lined for use as an aqueduct. In these unlined sections of the aqueduct there are certain places where the rock is disintegrating and falling from the roofs and sides of the tunnels. Such portions of the unlined sections of the tunnels should be lined for the sake of the stability of the aqueduct, and to remove the danger to the lives of employees engaged in cleaning or inspecting the aqueduct. To do this work it will be necessary to drain the aqueduct between Great Falls and Dalecarlia reservoir, thus interrupting the supply of water from the river. During the time that the supply is thus interrupted the city will draw on the reserve supply, which is limited to such an extent that, for the present average daily consumption of water, it will be possible to keep the aqueduct drained for approximately only four consecutive days. It will then require about fourteen days for the reservoirs to refill. It is therefore estimated that it will be practicable, under present conditions of consumption of water, to work on the lining of the tunnel. only sixty-four days in a year, making allowance for seventy-seven days between the middle of December and the end of February, when it will not be possible to interrupt the supply from the river on account of the probability of excessive demand for water in the city during periods of very cold weather. Under such conditions the work of lining the tunnels will not be continuous, and on this account, and on account of the locations of the sections to be lined and the restricted space in which it will be possible to work, the work will probably extend over more than one fiscal year and will be more expensive than work of the same character under favorable conditions. Under these conditions an accurate estimate can not be submitted, but the cost is not expected to exceed $20,000. An estimate of $12,000 is, therefore, submitted to cover the purchase of the plant necessary and not now on hand, and to do as much work as may be possible during the fiscal year 1912. EMERGENCY FUND. It was not necessary to make any expenditures from the appropriation of $5,000 for emergency use during the fiscal year 1910. Before the custom of making appropriations of $5,000 for use in emergency was established, when a break or other contingency occurred, necessitating any unlooked-for expenditure, it was necessary to stop ordinary operations so as to cover the extraordinary expense. Should, however, a serious break occur during the last part of the fiscal year, the funds available might be inadequate and a disastrous condition result. A continuation of the appropriation of $5,000 is recommended to constitute an emergency fund. CONSTRUCTION OF THE METROPOLITAN SOUTHERN RAILROAD THROUGH THE DALECARLIA RESERVATION OF THE WASHINGTON AQUEDUCT. For the history of this work attention is invited to Annual Report of Chief of Engineers, 1909, page 2316, and Annual Report of Chief of Engineers, 1893, page 4288. Work on this construction was continued during the year by the railroad company (Baltimore and Ohio Railroad), and was nearly completed at the end of the fiscal year. The necessary inspection charges were paid from the deposit of $1,500 made by the company in accordance with the regulations, approved by the Secretary of War, governing the construction of the railway. DREDGING DALECARLIA RESERVOIR. The unexpended balance on July 1, 1910, which was covered by outstanding liabilities, was disbursed. |