AWWA JAW10543

In 1982 the incidence of noncoliform colonies increased alarmingly in the standard membrane filter tests of samples from the Springfield, Illinois system. This signaled a potential problem with bacteria and was followed by coliform infestation in the water mains. Intensive measures were taken to control bacterial growth in the water treatment process and in the distribution system, with an ultimate goal of preventing the reseeding of the system by chlorine-resistant organisms. This paper discusses action taken to eliminate this problem, including: chlorine application to incoming raw water; use of iron coagulant; discontinuation of ammonia feed; addition of potassium permanganate to mixing basin; increased feed rate of lime; flushing of the distribution system for eight days; and sample monitoring. Includes 17 references, tables, figures.