A Benders decomposition model for sewer rehabilitation planning for infiltration and inflow planning

Infiltration and inflow (I/1) to a wastewater treatment plant can contribute significantly to the quantity and cost of domestic wastewater treatment. A known pipe or manhole defect can be repaired in a number of ways. Leaking pipes, for example, can be chemically grouted, lined, or burst/lined or excavated and repaired/replaced. Each repair option for eliminating the infiltration or inflow has a unique cost and efficiency. A general Benders decomposition model was developed to optimize the repair and replacement strategy for a sewer network. The model determines the least cost solution by minimizing the combined wastewater treatment and repair costs. The results of a detailed analysis of an existing sewer are presented.