By Louis Teran
The adoption of green building codes and initiatives across the nation, combined with an increasing amount of impervious surfaces, such as concrete or asphalt parking lots, trails, roads and more, has led to the emergence of stormwater management as an important environmental issue.
Changes to any landscape can increase the levels of stormwater runoff and create environmental hazards if the area is not equipped to deal with excess water. For example, as landscapes are altered for new construction and landscape remodeling, several changes occur: Trees and underbrush that once intercepted rainfall are replaced with the slick roofing of new homes or turned into parking lots, while the natural depressions of the landscape are converted into chemically treated lawns and paved surfaces.
Excess stormwater cannot be absorbed as it travels over rooftops, pavement and other impervious surfaces, picking up harmful pollutants including oil, grease, chemicals, metals and bacteria along the way. The stormwater travels until it reaches a larger body of water such as a pond, lake or storm drain, contaminating the water and resulting in changes to wildlife habitat, a reduction in fish populations, even increasing flooding and stream bank erosion.
As a result, many recent municipal regulations are calling for the retention of stormwater within a property or site in order to prevent pollutants from entering and clogging the area’s main drain line and discharging into larger bodies of water. Incorporating the latest technologies into new construction, updating traditional drainage solutions at existing buildings, and minimizing the number of impervious surfaces are just a few of the strategies encouraged and eventually implemented by many municipalities.
Stormwater regulations will only become more common and stringent down the road. Since the responsibility falls on the local government to determine the appropriate stormwater management guidelines for their municipality, contractors and landscape designers must be aware of the legislation occurring in their area and stay informed of any changes. Meanwhile, manufacturers are working to provide simple solutions to reduce stormwater runoff. By arming themselves with up-to-date information on stormwater management solutions, not only can contractors and landscape designers contribute to sustainable design, but they can increase customer satisfaction and, in turn, their bottom line.
Effective Stormwater Management Techniques
When implementing new construction and landscape remodeling projects, there are a number of ways to reduce stormwater runoff while meeting regulatory requirements for stormwater retention. Depending upon the application, these solutions can include subsurface drainage systems as well as permeable surfaces.
Subsurface Drainage Systems
The most effective way to manage stormwater pollution is to install a leaching system as part of a sustainable landscape. A drywell is a traditional leaching system created by a large hole beneath the landscape filled with rocks. The drywell is designed to collect excess water and gradually percolate or leach it into the adjacent soil. The rocks provide structural support and create voids into which water is collected. However, as the drywell ages, the rocks begin to shift, decreasing the amount of void space and compromising the structural support.
There are products on the market that offer contractors more reliable stormwater management solutions. For example, a manufactured drywell increases water retention capacity and is easy to install and less expensive than other stormwater solutions. One product, the Flo-Well from NDS Inc., features a large, durable plastic container with holes throughout the sidewalls. When buried in the ground, the plastic walls provide structural support and the large space within the container serves as a high-capacity void into which water can be collected and slowly leached through the holes on the sidewall into the soil. Flo-Well doesn’t require complicated piping systems that demand large sloped trenches throughout the landscape, resulting in less time and equipment for installation.
The installation of a French drain system is also an ideal solution for reducing stormwater runoff. French drains are essentially ditches filled with gravel that redirect surface and groundwater away from an area such as a building’s foundation. Traditional French drains have been modernized to offer more durable and efficient solutions. Manufactured French drain systems eliminate the need for gravel and instead use a perforated corrugated pipe surrounded with manufactured aggregate. The amount of aggregate is pre-calculated for the corresponding size pipe in order to help minimize design guesswork. Most importantly, manufactured French drain systems are light and flexible in order to significantly reduce the installation time and cost when compared to traditional French Drain systems.
Permeable Pavers
With green building initiatives and ordinances calling for less concrete and more permeable surfaces, grassroad and gravel pavers provide aesthetically pleasing solutions for constructing a solid foundation for high-traffic areas while also reducing stormwater runoff. In fact, grassroad and gravel pavers provide a more permeable surface than any hardscape by limiting the number of impervious areas, and creating a more permeable surface for water to be absorbed into the ground. However, there are additional and perhaps lesser-known benefits attached to grassroad and gravel pavers. For instance, they are built with a structural capacity that is capable of withstanding significant loads, such as fire trucks in a fire lane application. Grassroad and gravel pavers are also suitable for lighter applications that range from golf courses and school fields to overflow parking lots.
Grassroad pavers are constructed from a strong plastic base composed of a series of cells that connect to form a flexible grid system, providing less soil compaction to help increase drainage and eliminate standing water. Gravel pavers are composed of a similar design, yet with the addition of a permeable geotexile fabric attached to hold gravel in place and to prevent rutting and the migration of gravel particles over time. Gravel pavers now allow for installation on a clean or washed stone base (as opposed to the traditional installation on a sand and stone base) in order to allow stormwater to more easily percolate directly into the ground. In addition, many grassroad and gravel pavers can also be used to achieve LEED credits.
Overall, proper stormwater management requires that stormwater not be allowed to become harmful to the environment. The solutions above demonstrate how stormwater can effectively be given passageways to leach back into the subsoil of a property before it can convey pollutants into the municipality’s main drain line.
It is important for contractors and landscape designers to keep stormwater management in mind during project planning stages. As more regulations continue to go into effect, the need for reliable stormwater management solutions will remain an important issue. By providing customers with affordable, effective solutions, contractors can help them meet regulations and become more environmentally sustainable, as well as increase their company’s reputation and profitability. uwm
About the Author:
Louis Teran is product manager for drainage products at NDS, Inc, a provider of stormwater management, landscape irrigation and water management valves.
