TABLE OF CONTENTS John N. Paine
BIG, Incorporated
Newport News, Virginia
A. Osman Akan
Department of Civil and Environmental Engineering
Old Dominion University
Norfolk, Virginia
Urban development results in increased runoff volumes and flowrates, which may cause frequent flooding and severe stream erosion downstream. Many communities use flow retardation structures to limit adverse downstream effects of urban storm runoff. These structures can also partially settle out the particulate pollution contained in the storm runoff.
Various types of flow retardation measures include detention basins, retention basins, roof top storage, infiltration basins, and dry wells. Detention basins are small impoundments of water with a capacity of normally 10 acre-ft or less. Retention basins are usually larger, and they release stored water at a slower rate mostly through controlled outlets. Infiltration basins are used to allow the stored water to percolate into the ground. Dry wells are small trenches excavated in porous soil and backfilled with rock. Although different flow retardation measures may be used under different circumstances, detention basins are probably most common. A detention pond can be created by damming a channel or by excavating a pond into the existing ground. Often, ponds are constructed by a combination of cut and fill. Figure 7.1 is a schematic diagram of a typical detention basin.
This chapter first presents a brief review of hydrology and hydraulics for detention systems. Then various methods are summarized for preliminary sizing of detention basins, extended detention basins,...
