PHOTOGRAPHS EXHIBITING THE STRUCTURAL FEATURES OF THE PRINCIPAL TYPES OF AQUEDUCT UPON WHICH THESE ESTIMATES OF COST ARE BASED. REPRESENTATIVE SECTION OF OPEN CHANNEL. Side Slopes, 1 vertical inch, 3 horizontal; Bed and Slopes Covered with Gravel. The open channel shown above is of substantially the same type and size proposed for conveying the water of the Ten Mile river from Pawling to Sodom Reservoir. Fig. 59. STANDARD SECTION OF "CUT AND COVER AQUEDUCT. Proposed in this report for additional supply of water to New York. These photographs are from the Wachusett Aqueduct, constructed in 1896-97 by The Massachusetts Metropolitan Water Board, which is of exactly the same dimensions as "Section Size A," Tables 45 to 47, used as a basis in estimating cost of certain aqueducts herein proposed. TABLE NO. 45. LEADING DIMENSIONS OF AQUEDUCT SECTIONS. Details provisional for purpose of estimate. The Sectional Drawings represent Section "B" to scale. Sections A and C are nearly proportional thereto. The differences in sizes are shown by table of leading dimensions below. All dimensions in feet unless stated otherwise. To fit certain conditions, the grade in the tunnel portion of the Wachusett Aqueduct was made lighter than that of the "Cut and Cover" portion; and then to compensate for the decreased velocity due to the decrease in grade, as well as for that due to the greater roughness, fair to be expected, in the brick lining of tunnels, the width in the clear of the lined section was made 8 inches greater, and the depth inside 4 inches greater than for the corresponding "Cut and Cover" Aqueduct, thereby making the tunnel section nearly equivalent in hydraulic capacity to "Cut and Cover" work on the same gradient. The same finished inside dimensions have been followed above in Section "A" as for the Wachusett Aque duct. For Sections "B" and "C" the dimensions of the finished inside of the lined arched tunnel are made the same as for the "Cut and Cover" Aqueduct, for convenience in comparing the hydra ulic factors. |