PHOENIX CITY AND ITS FILTER BED

PHOENIX CITY AND ITS FILTER BED

Part of the new waterworks system at Phoenix city. Ariz., consists of a submerged filter bed and gallery, the object of which is to clarify the water of Holland creek. The total area of the filter bed is 1,760 square feet; its depth, three feet over the gallery and nine and one-half round it. The gallery inside is seven by 100 feel wide by six feet high. Both filter bed and gallery are placed lengthwise with the creek, and for their accommodation the ground has been excavated sixteen by 110 feet by nine feet deep, the bottom grade of five per cent being down stream. The ground through which the excavation was made presented the following features: At the top were three feet of sand, under which lay two feet of soapstone which could easily be removed by ploughs and scrapers, after which came four and one-half feet of hard granite, which had to be blasted out. The granite thus excavated was built up dry to a height of six feet, two feet thick at bottom, battered to one foot and one-half at top. There were built into the wall at a height of five feet, plates two-inch by six-inch, on which were built into the walls two-inch by twelve-inch joists, twelve inches centre to centre. A two-inch by four-inch scantling roof is laid longitudinally over all, with half-inch spaces between each. Four inches of gravel are on the top of the roof and gravel to the same depth surrounds the walls of the gallery. A Deane triplex pump, with a capacity of 300 gallons per minute and a sixteen-horsepower Blakelee, gasolene engine pump the water to the reservoir from the gallery. The reservoir is 182 feet above the pump, and the latter is nineteen feet above the lower end of the suction.

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