THE PLANNING PROCESS FOR LID - Low Impact Development and Sustainable Stormwater Management - page 83

Figure 4-6 Porous pavement and infiltration system, Morris Arboretum, 1984.
As with all human-made materials, maintenance is a constant concern. Every
design must consider this element in developing a solution, and with stormwater
management it is a critical issue. Any method that removes sediment and other
pollutants from a turbid fluid flow like runoff must, of necessity, include the
maintenance of such systems in the implementation process.
Every design solution must also be practical and realistic, capable of fitting
into a wide variety of site settings. Selection of the method is the first step in
sustainable site design, but it must fit the site conditions. It must be a practical
method to apply, and local construction personnel must be capable of building
the design, following a carefully crafted specification.
The availability of required materials in the site location is important unless
other suitable materials can be substituted. In the following chapters we propose
methods that are universal in nature and materials that have been available at
a given site, but the creative design process should never be ignored, and each
designer must make use of his or her own skills to shape a solution.
Guideline 5: Calculate Runoff Volume Increase and
Water Quality Impacts
A concept design proposed for a given site is first evaluated to determine the
potential increase in runoff volume during a series of rainfall events, and then
that site plan is evaluated to determine if dimensions, layout, and development
needs can be modified to reduce the footprint of impervious surfaces. Other
“nonstructural” measures are also considered for the building program. Then the
modified site plan is evaluated to consider the type of structural materials that
are suitable for site conditions, based on analysis of soils, geology, landform,
and vegetation. Next, the potential pollutant production from the built site is