25 October 2004
Filtering and Treatment of Pollutants. Runoff is directed across vegetated
areas and through porous media to provide significant reductions in the
concentration of sediments and pollutants in the water.
Groundwater Recharge. Infiltration is expedited to enhance groundwater
recharge rates and help sustain base flows in nearby streams.
LID Design Approach. The LID approach to site design seeks to maintain or
restore the hydrologic impacts of site development using a combination of runoff
management strategies, site design techniques, and distributed source controls (IMPs).
LID design requires that site plans address the overall natural resource and compliance
issues within the watershed. The long-term success of this approach requires an
understanding of the maintenance requirements and life-cycle effectiveness of the LID
practices and the development of an appropriate maintenance and pollution prevention
plan for the facility.
While the influence of each of the components of the design process varies
from site to site, a general process has been developed to ensure that all of these
components are considered. Although the preference in LID design is to reduce the
hydrologic impacts on the site and to retain naturally effective hydrologic features, it is
recognized that significant impacts may occur because of the nature of DoD activities.
When compensating features are required, LID emphasizes the use of integrated site
features that control runoff as close as possible to the source, rather than transporting
pollutants and attempting to mitigate for lost functions elsewhere. Figure 5-3 illustrates
the general flow of the design process.
Figure 5-3. LID Design Process
Minimize Development Impacts
Maintain Watershed Timing
This approach is often an iterative process that requires several attempts to
balance all of the design components in the most economical and environmentally
effective way. Described below are the individual design components.
5-4.2.1 Conservation of Natural Areas. LID is a stormwater management strategy
that addresses the overall regulatory and resource protection goals of a site in a
watershed context. Because development typically occurs incrementally, this approach
will allow for adjustments or modifications to site design strategies and techniques to