EXTENSION OF TROY WATERWORKS
(Continued From Last Week.)
THE QUACKENKILL SYSTEM was built to provide an additional supply for the high-service of the city, and contemplated the full development of about 17 1/2 square miles of the drainage of the headwaters of the Quackenkill. The work thus far done on this system consists of the budding of a small diverting dam and appurtenances on the Quackenkill—about one-half mile westerly of Quackenkill village, and laying a conduit from this dam to the Brunswick reservoir, a distance of about six miles. In connection with this work, the 20-in,, high-service main, was extended from the old distributing reservoir, about 9,000 feet, to the Vanderheyden, .and a new intake-gatehouse was built there. The diverting dam on the Quackenkill consists of a concrete spillway and gatechamber, and an earth embankment, with concrete core. Although only one conduit has been laid from the dam to the storage reservoir, the proper connection, valves, etc., were built into the dam for a second one, when it shall be needed. The conduit already laid consists of 29.550 feet of 16-in. and 3,167 feet of 12-in. cast iron pipe designed to have a carrying capacity of 5,000,000 gallons per twenty-four hours. The outlet of this conduit is taken some distance into the reservoir, as shown by the photograph. The water front the diverting dam on the Quackenkill flows into the Brunswick reservoir. From the Brunswick it passes into the Vanderheyden reservoir, from which it is separated only by a narrow embankment. On the Vanderheyden the new high-service intake-gatehouse above referred to was built. This gatehouse is built of vitrified paving brick, below the high-water line, and of ordinary hard burned building brick above that line. The conduit extending from this gatehouse to connect with the old high-service system, takes the place of an open channel, in which the water formerly flowed, and also gives an increased head of about ninety feet. The full development Of the Quackenkill watershed, as contemplated, will include the rebuilding of the dam at Long Pond and the building of two new storage regervoirs between the Long Pond and the divertmg dam. With this development completed, it is expected that a supply of about 8,000,000 galions per day can be obtained from this source.
THE TOMHANNOCK SYSTEM is by far the most important part of the work for procuring additional supply. This will also be a gravity supply, and wilj enable the city to abandon the present pumping plant, which is becoming very old and inefficient. It will also very largely increase the supply to the low-service. The area of the a rolling and mountainous character, lhere are about 600 houses on the drainage area, and a resident population of from 2,000 to 2,500. The average rainfall is about 36.5 inches. It is expected that about thirty-five per cent, of the rainfall—from 30,000,000 to 40,000,000 gallons daily —can be collected and made available through the works now under construction. The location selected for the reservoir is about ten miles northwesterly from the city. Here the valley of the Tomhannock, for a distance of five miles, has an average fall of about eight feet per mile and an average width of three-quarters of a mile. At the point selected for the dam, the hills on either side of the valley approach each other, until only a narrow ravine lies between them. The hills surrounding this valley are of a shale or slatey formation, with only a thin covering of earth. I’he valley is covered with glacial drift a few feet in depth, with here and there a deposit of considerable magnitude. Bedrock is found below this glacial deposit, in the upper part of the valley of the same general character as in the hills around it. At a point about threequarters of a mile from the dam site, the bedrock drops off, and borings to the depth of about 150 feet failed to reach it. The material underneath the glacial deposit at the dam site and for a distance of three-quarters of a mile upstream from it consists of a thin layer of yellow clay, overlying an extremely hard and compact blue clay and gravel, extending to a depth of more than 150 feet, as shown by borings. The crest of the spillway is located at an elevawatershed above the dam site is 67.3 square miles, About one-eighth of this area is covered with woods. The surface is quite uneven, being of tion of 390, Troy city datum, at which elevation the reservoir has an area of 1,685 acres. The maximum depth of water near the dam will be fifty-five feet, and the average depth over the whole area. 22.4 feet. The total capacity of the reservoir is 12,310.000,000 gallons, of which ninety-five per cent, will be available for use. Of the area to be flooded, 250 acres were covered with woods and brush, the remainder being largely lands under cultivation. The trees and brush have all been cut and removed from the area. The farm buildings, of which there were seventeen sets, have all been removed, and 22,000 cubic yards of muck and decaying vegetable matter have been excavated from the area to be flooded. Several highways crossed the reservoir site, and it has, therefore, been necessary to construct about six miles of new highways to take the place of those to be discontinued. The alignment of these roads has been made to conform in a large measure to the contour of the ground, and the maximum grade allowed has been five per cent. The subgrade was shaped so as to have a crown of six inches, over which was spread a gravel surfacing nine inches thick at the crown and six inches at the shoulders, thus giving the finished surface a crown of nine of this rock is very irregular. Excavation was carried on through four shafts and the opening at the end towards the reservoir. Steam was used for drilling during the sinking of the shafts and the driving of a few feet of the tunnel each way from them; but the greater part of the work was done with compressed air. Only one line of pipe has been laid, although provision has been made in the tunnel for the second, when it shall be needed. This line, as constructed, consists of about seven miles of 33-in., riveted-steel pipe connecting with the old 30-in. cast iron forcemain at Twenty-first street, in the former village of Lansingburgh. ,’rom this point the old forcemain or pumping main is utilised to the lower Oakwood reservoir, from which the low-service supply of the city is taken. This pipe-line will have a carrying capacity of from 15,000,000 to 18,000,000 gallons daily. Automatic air-valves are placed at all summits, and blow-offs are located in all low points. Manholes are provided every 500 to 600 feet. There are also gates, with suitable brick gatehouses, on this line, so that sections of the pipe can be shut off when needed for repairs. The last of these gatehouses is in the street near the junction with the old force-main. This gatehouse being entirely underground, a manhole was built to one side for easy access to the chamber; otherwise it would have been necessary to dig up the street and remove the cover to reach the valves. The work on this system is now practically completed, with the exception of making the connection between the old forcemain and the new pipe-line. This was to be done about April 1. Storage of water in the new reservoir was begun on January 10, and it was expected that water will be taken from this source to the city about the middle of May.
THE LANSINGBURGH SYSTEM.
The former village of Lansingburgh was annexed to the city of Troy in 1900. At that time they had in the process of construction a masonry dam on the DcepkiU and a 12-in. pipe-line leading from it to the reservoirs located just easterly of the village. When the city came into possession of the work, Professor Raymond found that only part of the dam rested upon a rock foundation, while nearly one-half of the length rested upon piles. After careful examination of the location and conditions, he determined it would not be advisable to build the dam to its intended height, and, consequently, the upper twenty feet originally designed were never built. The accompanying views show this dam and reservoir. The reservoir is of small capacity, and serves only as a diverting point. The watershed tributary to this system includes about ten square miles of very hilly country, lying adjacent to the Tomhannock watershed on the west.
The cost of the different parts of the work to January }, 1906, is as follows;
Original works and extension of
mains . $1,326,932.51
Original Lansingburgh works . 250.855.66
Deepkill system, Lansingburgh supply 150,507.67 Preliminary investigations, Troy new
supply ;. 25,545.18
I ttgh-service extension . 42,490.12
Ouackenkill system . 215,230.83
Tomhannock system . 1,142,589.03
Preliminary work on filtration plant. 5,580.00
the high-service extension and the Quackenkill and Tomhannock systems were designed by and partially constructed under the direction of Professor ^William G. Raymond. M. Am. Soc. C. E., Con. Eng., now of the State University of Iowa. Since September, 1903, the work has been under the direction of E. I.. Grimes, M. Am. Soc. C. E., as chief engineer.