. Journal of the New England Water Works Association . 7 di materiali disponibili per l'im] nucleo ervioso della diga. Quei test dimostravano che il sottosuolo ami era del tutto soddisfacente e si trovavano in stretto accordo con una vasta serie di test eseguiti su suoli dalla MetropolitanWater Works del Massachusetts circa 25 anni fa, A seguito di quale top- 352 LA NUOVA FORNITURA DI ACQUA DELLA CITTÀ DI PROVIDENCE. Suolo è dipeso solo per impermeabilità nella costruzione delle dighe nord e sud del bacino idrico di Wachusett. Esperimenti weremade del tasso di percolazione attraverso grandi lattine

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. Journal of the New England Water Works Association . 7 of materialsavailable for the im] ervious core of the dam. Those tests demonstratedtop-soil ami subsoil to be entirely satisfactory and were in close agreemenlwith an extensive series of test- made upon top-soil by the MetropolitanWater Works of Massachusetts some 25 years ago, following which top- 352 THE NEW WATER SUPPLY OF THE CITY OF PROVIDENCE. soil was depended upon solely for watertightness in the construction ofthe north and south dikes of the Wachusett Reservoir. Experiments weremade of the rate of percolation through large cans and through small cans, the apparatus for each of which is shown on accompanying photographs.For the large can experiments, the apparatus consists essentially offour circular galvanized iron tanks each 2 ft. A in. in diameter and 5 ft.high, the sectional area being 1/10 000 of an acre. Near the bottom wasa sill-cock. On the side of the tank were three perforations spaced 18 in.vertically on centers, with which were connected on the inside perforated. pipes traversing the material under test in the tank and on the outsideglass gages. A waste vent was provided near the top of the tank. Thetanks were filled in the following manner: At the bottom was placed a5-in layer of pervious material graduating up from coarse gravel at thebottom to medium sand at the top. Directly on top of this was placedthe material to be tested. This material had a total depth, or thickness, of 3 ft. 8 in. and on top of this was placed a 1-in. layer of coarse sand. Thematerial to be tested was put into the tank in quantities such that withenergetic tamping it was consolidated into layers from 1| to 2 in. in thick-ness. Water was let into the tanks from the bottom by attaching to thesill-cock a piece of rubber garden hose connecting with a funnel suspendedso as to give a moderate head. As it appeared advisable this funnel wasraised until water appeared on the surface of the sand near the top of thetank. Wat

Parole chiave associate all'immagine

• bookcentury1900
• bookdecade1920
• bookidjournalofnew
• bookyear1922