. Water & sewage works . per cent andthe filters removed 7 per cent, the totalbacterial efficiency of the system thusbeing over 99 per cent. The typhoid fever death rate of thecity follows this improvement, the rate of18 per 100,000 population of 1912 being18 per cent, less than the rate in 1911,with a total decrease of nearly 70 percent, from the average of the four yearspreceding the installation of the filter. The first of the illustrations showsa view of the sedimentation andcoagulating basins, taken from theelevated tank which serves as a pressureregulator on the distribution system andis
. Water & sewage works . per cent andthe filters removed 7 per cent, the totalbacterial efficiency of the system thusbeing over 99 per cent. The typhoid fever death rate of thecity follows this improvement, the rate of18 per 100,000 population of 1912 being18 per cent, less than the rate in 1911,with a total decrease of nearly 70 percent, from the average of the four yearspreceding the installation of the filter. The first of the illustrations showsa view of the sedimentation andcoagulating basins, taken from theelevated tank which serves as a pressureregulator on the distribution system andis located near the Crescent Hill pumpingstation, filter house and clear water reser-voir. The coagulating basins are in theforeground, the nearer one being abouthalf the area of the one adjacent andwith half the length of flow. Beyond isthe Crescent Hill reservoir, the nearerdivision being full of water and thefarther division being emptied for clean-ing. The cost of filtration for 1912 averaged 518 MUNICIPAL ENGINEERING. T NTERIOR vieio of the covered filtered?^ water basins. $ per million gallons. The monthlyaverage cost varied from $ in Octoberto $ in April. The -coagulant usedcost nearly half of the whole expense offiltration for the year, and in each of thefirst three months of the year reachednearly or quite 60 per cent, of the totalexpense for the month. The water usedfor washing the filters cost only per cent of the total filtration ex-pense. The wash water used per cent, of the amount filtered forthe year. The filters are now operatedalmost up to their full capacity and plansare ready for the addition of twelvefilter units, each 23 by 47 feet, which willdouble the size of the plant, filling thehalf of the building provided for thisextension in the original plans. Thesefilters will be gravity mechanical filtersof the same type as those in use, but theunits are more numerous and smaller insize so that a unit out of commission forcleaning
Size: 1953px × 1279px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectsewerage, bookyear191
