scope:

Introduction 

In undeveloped areas, rainwater is intercepted by vegetation and held in natural depressions and can be absorbed directly into the ground on which it falls. When an area is developed, buildings and parking areas cover the natural absorption areas where the rain would normally be infiltrated back into the ground. These impervious structures alter the typical absorption pattern. As a result, when the rain is not allowed to penetrate the ground it begins to accumulate and can cause ponding or flooding or flow to another location. Some consequences of flooding are as follows:

(a) on roads: collisions, washouts, and traffic delays;

(b) with buildings: structural and property damage, sewer backups, foundation settlement, and devaluation of property values;

(c) environmental damage;

(d) utility service interruptions;

(e) creation of health hazards;

(f) clean-up costs and increased insurance costs; and

(g) personal inconvenience. 

Subsurface stormwater structures are used in the collection, detention, retention, and infiltration of stormwater runoff. Structures can have configurations that include, but are not limited to, beds or trenches of various sizes or shapes designed to fit on most sites and offset the impact of impervious structures that cover natural absorption areas.