Developing Criteria for Design Event Selection

Abstract

Design flows for sewers have evolved from steady state, constant flows calculated from the number of fixtures connected to complex dynamic calculation based on storm conditions and expected, although often illicit, interconnections with the storm drainage system. This paper will examine the historical evolution of the theory behind defined design flow conditions through the selection of specific design storm conditions. A recommended decision flow chart for selecting design storm(s) conditions for sanitary sewer systems subject to rainfall derived infiltration inflow is presented. This paper also includes discussion of storm(s) conditions appropriate for evaluation of long term control plans and design of subsequent combined sewer improvements.

Wastewater Collection Systems

“…Huber and Luking (2007) described the development of a permanent flow metering system in Huntsville, Alabama. Procedures for selection of design storms including a decision flow chart were reviewed by Schultz and Nelson (2007). The development of accurate representations of infiltration and inflow under varying antecedent moisture conditions was presented by Vatter et al (2007).…”