Proposed Plan for Ammonia‐Chlorine Treatment in Chicago

Abstract

To meet the lake pollution situation, Chicago is preparing to change the method of treating the water for the south side from chlorination at the three pumping stations to the use of ammonia and chlorine at the 68th Street and Dunne cribs. The principal reason for this new policy is because pollution of the lake in the vicinity of these cribs has increased to such an extent that the chlorination equipment at the pumping stations is taxed at times almost to capacity to provide sufficient chlorine for effective disinfection. The bacterial pollution of the southern end of Lake Michigan in the vicinity of these cribs increased from 1927 to 1930, as shown in figure 1. Since 1931 there has been a slight drop in bacterial pollution, due to the decline in industrial activities in the Calumet region, but the industrial waste pollution has in the last two years become a serious problem. The industrial wastes, principally those from the oil refineries, caused a prolonged period of offensive taste in Chicago water late in December, 1932 and in the early part of January, 1933. During some of these taste periods the water had the property of absorbing large quantities of chlorine, necessitating high chlorine dosages in order to obtain sufficient residual chlorine for effective disinfection. It is expected that pollution will increase to even a greater extent in a few years when a decree of the U. S. Supreme Court becomes effective which requires that diversion from Lake Michigan into the Drainage Canal be reduced from 6500 to 5000 c.f.s. on December 31, 1935 and to 1500 c.f.s. on December 31, 1938. When these reductions in diversion become effective frequent reversals of the Calumet and Chicago rivers may be expected, discharging pollution into the lake waters. At most of the Chicago pumping stations the water pumped into the distribution system reaches the first consumers only a few minutes