The Filtration System at Springfield, Mo.
Springfield, Mo., has a population of about 50,000 and is located about 240 miles southwest of St. Louis. In 1910 the Springfield City Water Company placed a modern filter plant in operation. Owing to the topographical conditions, it is necessary at times to pump the water four times before it is delivered to the consumers. The supply is obtained from the Valley Springs reservoir, capacity 125,000,000 gallons; Fulbright Spring, Hitter Springs, Owen Spring, Williams Spring, and an emergency supply from the Sac River. The Valley Springs reservoir is located about three miles from the filter plant, on the opposite side of the mountain. When the water from this supply is being used, it is discharged into a natural cavity in the side of the mountain, and after flowing through a natural channel is collected on the other side of the mountain at Fulbright Spring, three miles distant. The filter plant is located about four miles from the city. Fig. 1 shows the filter building and coagulating basin, Springfield, Mo.
The water is pumped to the coagulation basins, which have a combined capacity of about 300,000 gallons. After which it flows to the filters by gravity. There are six rectangular filters with a total sand area of 2,088 square feet. Each sand area is 14 1/2 feet by 24 feet. The filter beds the composed of 9-inch graded gravel and 27-inch selected sand, the sand being obtained from Red Wing, Minn. The total weight of filter material in each filter is about 63 tons. The water passes these filters by gravity and is stored in a covered reservoir under the filters. The filters arc equipped with loss of head gauges, rate controllers and hand-operated valves. In Fig. 2 is shown the operating floor.
Filtered water is used in washing the filters, and the beds are agitated by air. The filters are washed every day, the average amount of water used for this purpose during the past two years being 3.07 per cent, of the water filtered. Sulphate of alumina is used as the coagulant, and calcium hypochlorite employed as the sterilizing agent. The chemicals are obtained from the Pennsylvania Salt Manufacturing Company, of Philadelphia, Pa., the sulphate of alumina containing over 17 1/2 per cent, aluminum oxide and the hypochlorite containing 33 per cent, available chlorine. Fig. 3 shows the coagulant storage tanks and hypochlorite mixing tanks.
There are four chemical storage tanks, the capacity of each being 1,400 gallons. The chemicals are applied to the water by gravity, porcelain orifice boxes being used to control the amount used. The citizens are greatly pleased with the quality of the water being supplied, the consumption increasing 22.4 per cent, during the past year. The water is examined every day, a laboratory being maintained at the plant for this purpose. The operating results prove the good quality of the water furnished, as will be seen by the following table:
TABLE SHOWING AVERAGE BACTERIA PER C. C., UNFILTERED, COAGULATED AND FILTERED WATERS.
Standard gelatin is used as the culture media.
TABLE SHOWING BACTERIAL EFFICIENCY OF PLANT.
The removal of B. Coli-communis is about the same as the removal of the general bacteria. TABLE SHOWING REMOVAL OF B. COLI-COMMUNIS.
TABLE SHOWING PERCENTAGE OF POSITIVE PRESUMPTIVE TESTS FOR B. COLI-COMMUNIS, 1 C. C. SAMPLES, UN FILTERED, COAGULATED AND FILTERED WATERS.
The amount of chemicals used to produce these results is very small.
TABI.F. SHOWING AVERAGE AMOUNTS OF SULPHATE OF ALUMINA AND CALCIUM HYPOCHLORITE USED, IN GRS. PER GALLON.
The average amount of sulphate of alumina used is equal to 75 pounds per 1,000,000 gallons of water, while the calcium hypochlorite is equal to 6.14 pounds per 1,060,060 gallons.
TABLE SHOWING AVERAGE TURBIDITY, COLOR, CHLORINE AND ALKALINITY, IN PARTS PER 1,000,000, UNFILTERED WATER.
The highest turbidity during the two past years was 150 parts per “1,000,000, while the color reached 25 parts per 1,000,000. The lowest alkalinity ever found was 142 parts per 1,000,000, so that there is no danger of any of the undecomposed chemicals being present in the filtered water. There has never been any typhoid fever traced to the water supply, either before the filters were installed or since. Springfield being a railroad center, and having a large college as well as a normal school, there is quite a transient population. Being the largest city in this section of the State, a large number of typhoid fever cases are brought to the local hospitals. The average typhoid fever death rate for the two years before the filter plant was placed in operation was 83.7 per 100,000 population, while the average rate for the two years since the plant was placed in operation has been 77.0 per 100,000 population. A large portion of the typhoid fever is due to importation, the milk supply and wells have also caused cases. There are 98.8 miles of mains in this system. The filter plant was installed and is operated under the direction of James M. Caird, chemist and bacteriologist, Troy, N. Y. The New York Continental Jewell Filtration Company, 15 Broad street, New York City, were the contractors.