Green Infrastructure: The goal of better site design is to reduce runoff volume and mitigate site impacts when decisions are being made about proposed layout of a development site. These techniques are known by many different names, such as low impact development (LID), design with nature, sustainable development, sustainable site design (for LEED certification) and conservation design.
Several researchers have employed redesign comparisons to demonstrate the benefits of better site design over a wide range of residential lot sizes and commercial applications. For example, Center for Watershed Protection (1998b) demonstrated that better site design techniques could reduce impervious cover and stormwater runoff by 7 to 70 percent, depending on site conditions. A redesign analysis for a medium density residential subdivision (shown in the figure to the right) suggested that better site design techniques could reduce impervious cover and annual runoff volume by 24 percent, cut phosphorus loadings by half, and increase site infiltration by 55 percent, compared to a traditional subdivision.
Each better site design technique provides environmental and economic benefits to both the developer and the community at large. When techniques are applied together at a development site, they can result in tangible savings for the developer in the form of
- reduced infrastructure costs (e.g., paving and piping);
- reduced clearing and grading costs during construction;
- smaller and less costly structural stormwater BMPs;
- faster sales and lease rates;
- easier compliance with wetland and other resource protection regulations; and
- more land available for building since fewer structural BMPs are needed
Cost savings really start to add up when many better site design techniques are applied together. Research indicates that infrastructure savings alone can range from 5 to 65 percent, depending on site conditions, lot size and the extent that better site design techniques are applied (Cappiella et al, 2005; Center for Watershed Protection, 1998b; Liptan and Brown, 1996; Dreher and Price, 1994; and Maurer, 1996. Better site design techniques continue to provide benefits to the community long after the developer has sold the lots. Some examples of these benefits include
- reduced operation and maintenance costs for roads and stormwater system;
- increased property values for homes and businesses;
- increased open space available for recreation;
- more pedestrian friendly neighborhoods;
- reduced annual cost for mowing;
- more pleasing and attractive landscaping;
- improved air quality (more forest cover); and
- less temperature fluctuation from paved surfaces