ABSTRACT
All sewer systems and waste treatment plants are susceptible to corrosion caused by the action of microbes. One of the problems of sewer corrosion is that the problem lies underground and, as a result, is often “out of sight out of mind.” Corrosion rates increased as well, and the decision to save a relatively small amount of money by the unnamed agency left it with a legacy of susceptible pipes in the ground. Once the corrosion problem was recognized, early sanitary engineers tried a variety of protective measures. Concrete is a wonderful building material, resistant to many types of corrosion. But it is very susceptible to acid. Concrete below the water surface is unaffected because any produced acid is neutralized immediately by the natural alkalinity in the sewage. Concrete surfaces were lined with clay tiles or bricks. Mortar between the two brick layers was completely compromised, and pH levels were measured in the range of 1 to 3.
