Stormwater Run-Off and Management
For insight into stormwater runoff issues and management options, Landscape and Irrigation recently asked Jeff Speck, vice president of sales & marketing, Big River Industries about how landscape professionals can meet, and overcome, stormwater challenges.
L&I: What are the most prevalent stormwater challenges for landscape design / build and contractor professionals?
Speck: Environmental concerns surrounding the threat and conditions of stormwater involve a multi-billion-dollar concentration among industry professionals. Although there are many challenges caused by stormwater, three primary concerns include the volume and flow of run-off, harmful pollutants in corrupted water, and compacted soils with decreased exchanges of air and nutrients.
L&I: What are a few key purposes m stormwater management?
Speck: There are numerous reasons to conduct stormwater management at both existing and new sites. A few purposes Big River Industries finds particularly important involve the intent to:
* Limit the disruption and pollution of natural water flows by managing stormwater run-off.
* Limit the disruption of natural water flows by eliminating stormwater run-off, increasing on-site infiltration, and removing contaminants.
* Reduce heat islands (thermal gradient differences between developed and undeveloped areas) to minimize impact on microclimate and human / wildlife habitat.
* Limit or eliminate the use of potable water for landscape irrigation.
* Reduce generation of wastewater and potable water demand, while increasing the local aquifer recharge.
* Establish standards and best practices for controlling flooding, erosion, and the release of pollutants into surfaces and waterways.
Implementing these and other best practices can lead to the possibility of earned LEED credits.
L&I: What are a few important factors to consider when working to achieve low-impact land and landscape development?
Speck: Low-impact development is a means to deal with or control stormwater run-off with as little burden to the pre-development environment as possible. It involves land planning such as bioswales and infiltration systems, as well as engineered design in the forms of cisterns, biofiltration and permeable surfaces that help regulate and quell run-off. Low-impact technologies equate to a reduction of impervious cover with the use of permeable pavements and other similar surfaces. Though dissimilar to common compacted stones used under conventional surfaces, permeable technologies include layers of lightweight expanded clay aggregate sitting under the bearing surfaces. In keeping with Best Management Practices (BMPs), these permeable surfaces often have underground storage where retrofitted systems are installed to manage and treat stormwater flow.
L&I: What can happen to sites where the landscape's capability to absorb water is insufficient?
Speck: At sites where the landscape or soil has low ability to absorb stormwater, the ground acts as host to surface run-off, causing the flow of water over land. When soil is compacted by saturation and infiltration, the innate particles are pressed together, and pore spaces for water and air are greatly reduced. As the pore space is reduced, there is less movement of water and a marked amount of decreased air and nutrient exchange. With the combination of today's concentrated populations and construction, impervious surfaces and compacted soil can lead to stormwater run-off, extending to issues of flood control, erosion and even weed invasion.
L&I: What consists of a healthy soil profile that permits filtration and aeration, and why should this be addressed prior to site / landscape installations?
Speck: In general, a good soil profile is approximately 25 percent water, 25 percent air and 50 percent solid particles. …