Turbid Water of the Ohio Made Pure at Cincinnati
Through the agency of a new waterworks plant that cost $12,000,000. Cincinnati has reduced its typhoid death rate from almost the highest to perhaps the lowest among the large cities of the United States. The city draws its water supply from the Ohio River, and before the new plant was installed a large portion of the diluted sewage of Cincinnati and the Kentucky suburbs was being pumped through the mains. The faster the city grew, the more sewage flowed into the stream, increasing the disease-producing properties of the water supplies, and causing an appalling increase in the typhoid death rate. During the three years from 1904 to 190o inclusive, there were 4,332 cases of typhoid fever and 6o4 deaths from the disease in the city. Immediately the filtration and purifying plant was opened, the mortlity rate dropped. In the three years from 1908 to 1910 inclusive the total cases of typhoid numbered 636, and the deaths 133, or less than one-fifth of the previous death rate. In 1906 the statistics showed that sixty-four persons out of every 100,000 of population were dying each year from typhoid. In 1910 the disease had been combatted so successfully that it carried off only 5.7 persons for every 100,000 of population. In other words, for every 17,543 only one died from typhoid. The new plant has not only proved a great life saver, but it has also proved a fine investment financially for the city. In three years it has saved $529,000 in operating expenses, and its entire cost is being paid out of the revenues of the water department without increasing the water rates and without requiring a dollar to be raised by taxation. The results attained by the establishment of the new $12,000,000 plant, the remarkable reduction in the death rate from typhoid and other intestinal diseases and the manner in which the new works are stving money for the city are reduced to tables in a report recently made by Carl Dehoney, secretary of the Cincinnati Commercial Association, as follows:
Actual saving in operating three years$ 529,119 Great attention has been devoted to the new waterworks plant by engineers from other municipalities, and it has been visited by experts from several foreign lands as well as from all quaters of the United States. The success of the filtration plant led the imperial engineer of Russia to make a trip to Cincinnati a few months ago to inspect the plant. The method by which the turbid water of the Ohio River is transformed into a supply that comes clear and sparkling from the faucet is interesting. The intake is near the Kentucky shore, opposite California, Ohio. The water, after passing through screens that intercept grass, leaves and other river debris, flows into a shaft well and passes through a seven-foot tunnel driven through solid rock beneath the river for a distance of 1,430 feet until it reaches the rising shaft in the engine-room at the pumping station. Inside the engine-room are four 30,000,000-gallon-capacity vertical triple-expansion pumping engines, each weighing 1,500 tons. About 46,000,000 gallons of water are pumped daily at this station. Artef leaving the river station the water passes to the settling reservoirs on the foothills. There are two of these reservoirs, with a total water area of about 43 acres and a storage capacity of 330,000,000 gallons of water at an elevation of 110 to 141 feet above city datum. About 60 per cent of the suspended clay in the water settles in these reservoirs, taking with it about 40 per cent of the organic matter in the water. In these reservoirs the mud and organic pollution are precipitated without use of chemicals, simply by letting the water remain quiet. After the water has been in the basins from two to four days, it is drawn off from the surface through floating tubes, and piped to the coagulation basins, where the coagulating chemicals are applied. The chemicals are sulphate of iron or copperas and lime. They clgt the finely divided sediment together and hy settlement produce further clarification. The water remains in these basins for several hours while chemical reactions and precipitation remove about 25 per cent more of the mud and 20 per cent more of the organic matter. Then it is ready for filtration through sand and gravel. The chemicals have coagulated the fine particles into larger ones, held together by a gelatinous agent caused by the decomposition of the sulphate of iron, and the filtration proceeds rapidly. The filter beds ictnovc the remaining of the clay, and 10 per cent more of the organic matter, and the water comes out clear and brilliant. The purification process removes the iron entirely from the water. The experts report that the entire process removes 90 per cent of the bacteria in the original river water, 50 per cent of it being taken out in the settling reservoirs, 40 per cent in the coagultion basins and 9 per cent in the filters. Every fifteen or twenty hours the filter beds are cleaned by flushing filtered water through the sand bed up from hclow. Drains take away the dirty wash water. During the washing process the sand is partially floated, and the grains clean themselves by being rubbed together when the filtered water rushes up through the bed. From the filler beds the water flows to a reservoir, whence it travels through a gravity tunnel to the main distributing pumping station in Eastern avenue, near Torrence road, a distance of more than four miles. The tunnel is driven through the solid rock at a depth of 160 feet below the surface, and it is brick lined. The pumping station contains three high service pumping engines, each of 12,000,000 gallons capacity, and three low service pumping engines each of 25,000,000 gallons capacity.