THE WATER SUPPLY OF THIS CITY
现在很快熟悉的旧水库在40 -second street will have become a thing of the past, and its place taken by the new Public library. It is thought that, as the work of laying down the two forty-eight-inch mains in Fifth avenue from the Central Park distributing reservoir to Twenty-first street is so nearly completed, the water may be flowing through them in December next. Before the reservoir can be abandoned, however, not only must these mains have been laid, but also the four-foot main from Twenty-first street to Fourth street, where it will connect with existing pipes— smaller ones extending to the Battery. Connections from these new four-foot feeders have already been made into crosstown pipes at Thirty-fourth street and other places below; the crosstown pipes being small ones. One of the two three-foot outlet pipes from the Forty-second street reservoir has already been disconnected, and in all probability the other one will be disconnected in the near future—probably before the new fourfoot mains are ready to receive water.
Chief Engineer Birdsall is ruthority for the statement that, when the new feeder mains are fully connected and filled, the pressure below Thirty-fourth street, particularly farther downtown, will be increased equivalent to one-story ” during the day time and about normal pressure during the night time. He predicts that the water consumption will be increased about 15,000,000 gallons per day, while Chief Engineer Fteley places the probable increase at 25,000,000 gallons daily. The approximate delivering capacity of the two new feeders will be 50,000.000 gallons daily under full pressure, and Mr. Fteley states that, if full pressure is let into the feeders, one-half their capacity will be consumed. ‘File daily consumption of water at present is about 225.000.cxt0 gallons, which is not in excess of last year, and the fact is due to the continued falling of the pressure with the growth of the city. The highest consumption reached during the past summer was 240,000,000 gallons daily. ‘I here is no reason to expect the completion of the new Cornell reservoir before the time fixed five years hcrce. When that structure is completed, the estimated yield of the Croton system is officially fixed by Mr. Fteley at 280,000,000 during dry years. That reservoir will add a storage capacity equal to some 60,000 000 or 70 000,000 gallons daily, so that until its completion that quantity should be deducted from the calculations of safety, as estimated at 380.000,000 gallons. The Bronx watershed furnishes approximately 15,000,000 gallons daily, which is Independent of the Croton watershed. Owing to the unusual rainfall duting 1897 the reservoirs arc approximately two-thirds full at present; and Mr. Birdsall estimates that 35,000,000,000 gallons of storage will be carried over into 1898, which will equal a daily supply of from 75,000,to 90.000,000 gallons. The rainfall in the Croton valley during 1897 has lreen forty-five inches up to the present time average yearly rainfall having been forty eight inches in twenty-five years. The average for November and December is about eight Inches, which shows five inches excess thus far in i8g7The rain fell mainly after July 1, being thereby absorbed by the ground and augmenting the natural flow of the Croton river. One hundred and thirty million gallons is now being drawn from storage daily, the river furnishing the balance—95,000,000 gallons. In 1896 at this time some 175,000,000 gallons was being drawn from storage,and in 1895 over 200.000,000 was being drawn. In addition to tha two four foot mains down Broadway.a thirty-six-inch main has this year been laid down Eleventh avenue from Ninety-sixth to Thirty-eighth street. No estimate of increased pressure and consumption is made on account of that main.
With respect to the Forty-second street reservoir the following particulars are interesting: When full, its greatest depth is thirty-six feet. Its elevation above mean tide-water, when full is in feet, which is four feet lower than the Central Park reservoir when full. The lowest stage of water in Fortysecond street is about twenty-five feet, and that occurs about 2 p. m. every Monday, and continues with slight variations, during the night all of the week. About midnight on Sundays the water rises to thirty-two feet, and begins at that time to fall gradually until it reaches its lowest stage, as above stated, about 2 p. m. on Mondays. About 8 a. ra. every week day the stage of the water is about thirty one feet, six inches; but it drops during the day to nearly twenty-five feet. –
The pipes leading into this reservoir are two thirty-six-inch mains coming down Fifth avenue from the Central Park reservoir. These are the two original inlets. There is an additional thirty-six-inch pipe leading into the rese.voir from the forty-eight-inch* main which runs^crosstown through Forty second street, from Tenth avenue to Second avenue,and acts as an equalizer of pressure and supply. The outlet pipes of the resetvoir arc two thirty-six-inch mains from the Fortieth street side of the reservoir—one of them to, and down through Fourth avenue, and the other, to, and down through Fifth avenue These pipes are the original city distributing mains. They are reduced in size as they extend down town. One of them continues from Washington square direct down to the Battery; the other goes over, and down Avenue A, supplying the East Side. Of the 100,000,000 gallons of water used daily below Forty-second street, 25,000,000 gallons pass through the Forty-second street reservoir. This reservoir fills about 4,000,000 gallons each week day night, and about 7,000,000 gallons on Sunday nights. H itherto,therefore,it has been of some value as a gauge and equalizer for all that part of the city supplied by the two thirty-six-inch mains extending to the East Side and downtown.
