scope:

The intent of these standard guidelines is to present design guidance for urban stormwater systems. It updates ASCE/EWRI 45-05 Standard Guidelines for the Design of Urban Stormwater Systems with material developed within the past eight years. The collection, management, and conveyance of urban surface waters are within the purview of these standard guidelines for applications such as airports, roads, and other transportation systems; and industrial, commercial, residential, and recreation areas. This document is intended for guidance during the design phase.

These standard guidelines do not address applications, such as agricultural drainage, landfills, and injection systems. Combined Sewer Overflows (CSOs) also are not addressed, because they are environmentally unacceptable as a new standard of practice in the United States.

Both SI units and customary units are used throughout the guidelines for the narrative, figures, and tables. The formulas are written in dual units or written separately to show the use of either SI units or customary units.