Concrete is economical and is easily deteriorated. For any substantial reaction to occur, thorough mixing of components must take place. In sewage treatment, the microorganisms must be dispersed evenly through out the raw wastewater in order for BOD removal to occur. Municipal, regional, and contract work crews are responsible for line maintenance and cleaning out stopped lines. This requires a knowledge of pipes, flows, materials, cross connections, compaction, slope, and a concern for public health.
Stability is a measure of the support capacity of the soils, which contain water and sewer lines.
Usually, increased moisture lessens stability. Proper bedding of lines increases stability. Suspension velocity is the aggregation of particulate material in a two-step sequential process. A toxin is any of a variety of unstable, poisonous compounds produced by some microorganisms or organisms characterized by antigenicity in certain animals and having a high molecular weight and causing certain diseases of physical reactions. Flows can be traced by dyes and other materials contained in the water.