25 October 2004
Provide small-scale distributed features and devices that help meet
regulatory and resource objectives.
Treat pollutant loads where they are generated, or prevent their
LID Devices. Reevaluate the site design once all of the appropriate site
design strategies are considered and proposed to determine whether the stormwater
management objectives have been met. Stormwater management controls, if required,
should be located as close as possible to the sources of potential impacts. The
management of water quality from pavement runoff, for example, should utilize devices
that are installed at the edge of the pavement. These types of controls are generally
small-scale (because the site planning strategies have created small-scale drainage
areas and runoff volumes) and can be designed to address very specific management
issues. The objective is to consider the potential of every part of the landscape,
building(s), and infrastructure to contribute to the site stormwater management goals.
When selecting LID devices, preference should be given to those that use natural
systems, processes, and materials. The following list briefly defines the LID devices (or
IMPs) described in this UFC.
BASIC LIST OF IMPs. Here is a basic list of IMPs that are available. More
detailed descriptions are presented in Chapter 8. Appendix B contains a list of
acronyms and abbreviations cited in the UFC.
Bioretention: Vegetated depressions that collect runoff and facilitate its infiltration into
Dry Wells: Gravel- or stone-filled pits that are located to catch water from roof
downspouts or paved areas.
Filter Strips: Bands of dense vegetation planted immediately downstream of a runoff
source designed to filter runoff before entering a receiving structure or water body.
Grassed Swales: Shallow channels lined with grass and used to convey and store
Infiltration Trenches: Trenches filled with porous media such as bioretention material,
sand, or aggregate that collect runoff and exfiltrate it into the ground.
Inlet Pollution Removal Devices: Small stormwater treatment systems that are installed
below grade at the edge of paved areas and trap or filter pollutants in runoff before it
enters the storm drain.
Permeable Pavement: Asphalt or concrete rendered porous by the aggregate structure.
Permeable Pavers: Manufactured paving stones containing spaces where water can
penetrate into the porous media placed underneath.