File:Annual report of the Metropolitan Water and Sewerage Board (1904) (14804693393).jpg

Identifier: annualreportofme31904mass (find matches)
Title: Annual report of the Metropolitan Water and Sewerage Board
Year: 1902 (1900s)
Authors: Massachusetts. Metropolitan Water and Sewerage Board
Subjects: Sewerage Water-supply
Publisher: Boston : Wright & Potter printing co.
Contributing Library: Boston Public Library
Digitizing Sponsor: Boston Public Library

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such a manner that the water willbe forced through all the holes at nearly equal velocities. The inner pool, into which the water will rise through the holesin its bottom, is 56 feet in diameter, and surrounded by a stone curb4 feet in height. The outer pool is concentric with the inner, and is150 feet in diameter, and its floor is at the same level as that of theinner pool. It is surrounded by a retaining wall 7 feet in height,except on the down-stream side, where there is a spillway 110 feetIons:, over which the water will flow to the river below the dam. This arrangement of discharge outlets, with the spillway andcoping of the inner pool above the level of the backwater from theLancaster Mills dam, makes it possible to obtain access to the con-duits and waste gates at any time by merely pumping out theconduits, without the use of stop-planks or bulkheads. The inner pool and the floor of the outer pool are constructedwholly of Portland cement concrete. Both floors are covered with a
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No. 57.) AND SEWERAGE BOARD. 97 granolithic surface 1 inch thick, composed of 1 part Portland cementand 11/2 parts of coarse sand, trowelled hard and smooth on top.The retaining wall around the outer pool is also built of Portlandcement concrete, but is faced with stone masonry with a face dress-ing of fine-pointed work. The spillway and the curved retainingwalls at its ends are of quarry-faced ashlar, backed with rubble-stonemasonry. The top surface of the crest stones of the spillway, whichare curved in profile, is fine-pointed. These crest stones are nearly6 feet long, and are all anchored to the concrete with %-inchanchors. During 1902 the waste conduits, some of the lower courses of thespillway and part of the pool were constructed ; so much of the poolbeing then built as would serve, in connection with a wooden flume,to convey the water discharged by the four 48-inch pipes throughthe dam to the river below the spillway. During the latter part ofMarch the wooden flume, which had

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