TABLE OF CONTENTS Brian C. Roberts
National Corrugated Steel Pipe Association
Washington, DC
Subsurface stormwater management systems are increasing in popularity as a means of achieving the urban drainage objectives. This widespread use has resulted from a combination of high land values and limited above ground space in urban environments. Liability issues associated with surface systems have also lead to increased use of underground facilities. Subsurface facilities may also be incorporated into existing developments where flooding problems due to sewer surcharging are occurring. These retrofit systems can also be designed to provide water quality enhancement. Each proposed development should be carefully examined in order to determine which method of storm water detention or combination of methods could be best applied. Subsurface systems may be categorized under three classifications: 1) detention, 2) infiltration, 3) filtration, or any combination of these three. Infiltration and filtration systems are designed as water quality measures.
Corrugated steel pipe (CSP) detention structures have been used predominantly to control the quantitative aspects of stormwater management. Large pipes are installed underground, often beneath parking lots, where above ground use can be maintained. The quantitative design follows basic hydraulic procedures as described in detail in other chapters of this book. An inflow hydrograph is developed, and based on an allowable release rate, the required storage volume is estimated. Various pipe lengths and diameters are chosen to meet this storage volume. Once the release structure has been sized based on the allowable release rate, the inflow hydrograph is...
