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Low impact development

Our certified professional soil scientist staff’s understanding of how natural soils and groundwater systems interact make us uniquely capable of providing valuable information about when and how Low Impact Development (LID) technologies might best be applied on a site. PRS&W Inc. will apply our expert knowledge of soils, hydrology and plants to help select and apply appropriate LID technologies on your site.

LID technologies can and have been misapplied, but when used correctly, can result in great benefits to both the developer and the community.

Rain gardens
Rain gardens provide a sustainable approach to stormwater management. While continued population growth is inevitable, we can take our cues from nature on how to better manage onsite stormwater. Through the use of LID techniques, we can mimic the pre-development hydrology. Ever increasing stormwater runoff deteriorates water quality, increases erosion and sediment loads, degrades habitat, and decreases summer stream and river flows. While conventional systems have reduced runoff, they are often costly, unsightly and difficult to maintain.

LID techniques may eliminate the need for a large scale, traditional stormwater facility. For example, rain gardens use the existing native soil and existing and/or supplementary native vegetation in naturally occurring depressions to infiltrate stormwater runoff from a small surrounding area. As described in our rain garden brochure rain gardens decrease storm water runoff through interception, evaporation, and infiltration, resulting in decreased erosion and improved water quality. Beautiful as well as functional, a rain garden is an aesthetic addition to any landscape, providing a noise buffer, enhanced privacy, and urban wildlife habitat. Rain gardens are inexpensive and easy to install and don't require much maintenance once the plants are established.

Current development practices detrimentally alter the hydrologic function of native soils. Surface layers are cleared or highly compacted; soil biological activity is reduced; and deep-rooted vegetation, which fosters infiltration & aeration, is replaced by a shallow-rooted monoculture of seeded grass.

By using LID techniques such as retaining existing soil and vegetation, minimizing compaction during construction and using less invasive stormwater management techniques such as rain gardens at the onset of the design process, these problems may be avoided.


Native vegetation reduces stormwater runoff through interception and evaporation. Plant roots stabilize the soil, decrease erosion and absorb soil moisture. Roots also increase aeration of soil and create flow paths for infiltrating water. Plants physically attenuate flow of stormwater across the soil surface and filter out sediments. Through phytoremediation, plants immobilize metals and assimilate and break down organic pollutants, increasing overall water quality. Native vegetation encourages a healthy and balanced community of soil organisms that aid in decomposition and soil amelioration, and provides the highest habitat value for native wildlife. For all of these reasons, retention of existing vegetation at the onset of a development project along with increasing plantings of native plants at any stage during a development’s life span are crucial to hydrologic function.
Melinda Spencer,
Sep 29, 2010, 12:19 PM