WATER WORKS OF ST. LOUIS

WATER WORKS OF ST. LOUIS

[Concluded.]

THERE are six settling basins built in pairs. Each basin is 670 feet long and 400 feet wide, and has a capacity of 22,000,000 gallons. The sides and ends are heavy masonry walls backed with clay puddle and earth embankments. The bottoms of basins are lined with sixteen inches of puddle and covered with six inches of concrete in seven-foot squares, the spaces between the squares being filled with asphaltum to take up the expansion The basins slope to a cleaning ditch running east and west through the centre, which drains to a two-foot by three-foot mud gate in the east wall of the basin and leads to the sewer. There are six filling and drawing chambers, with hydraulic lifts for the gates. When all the basins are in operation, four are settling, one filling, and one drawing. Settling is continued in the basins until sufficient mud has been accumulated to justify cleaning them ; then the mud gate is opened and the slush is allowed to run through a twenty four-inch sewer to the river. A stream of water is then turned into the basin by means of a syphon from an adjoining basin, and men shovel the mud down into the cleaning ditch-the mud being carried to the sewer by means of the water. T he water from the settling basins is as clear as can be obtained by twenty-four to thirty hours’ settling. The drawing conduit carries the water along the east side of the basins through an open chamber (where screens catch any floating matter which falls into the basins) into the conduit, which from this point to Baden is eleven feet wide and nine feet high. The conduit is built of brick backed with concrete. When carrying 100,000,000 gallons, the velocity of flow is about one and one-half miles per hour, or two feet per second. T he fall is six inches to the mile, or one in 10.000. T he conduit passes over three bridges in its entire route. The bridge foundations are all carried down to bed rock. The bridges are provided with overflow wires and waste gates. 1 here is a gate chamber at Baden, where the conduit section changes from eleven feet by nine feet to nine feet by eight and one-half feet, and a branch leads off to 11. S. station No. 3. T wo gates cover the openings of both conduits.