Model Investigations of Pile Groups in Sand

An optimizing sewer design program that incorporates discrete dynamic programming optimization is described. This digital computer program determines the least cost combination of pipe sizes and depths for the specified sewer system and constraint set. A design and cost sensitivity analysis for an interceptor sewer is given to illustrate application of the optimizing design system. Cost sensitivity to the design constraints varies markedly from system to system, but for this interceptor it was found that the cost was very sensitive to minimum velocity, Manning n value, design flowrate, and minimum depth. It is estimated that optimization and sensitivity analyses would typically reduce sewer costs from 10 to 20% or more.