By Tom Delaney
Not that long ago, the traditional approach to stormwater management focused on directing the runoff, created by torrential downpours, from a site into the sewer system and eventually into a river basin. This practice often resulted in the erosion of stream beds and river banks, and has led to the contamination/poor health of numerous bodies of water throughout the country.
Today, we are much savvier about the impact this traditional approach has had on the quality of our water supply. So much so that local, state, and federal agencies have increased their attention and regulation of stormwater management. Many of the proposed solutions to address stormwater-related impacts involve integrating runoff reduction practices into the landscape. And, this is creating new income opportunities for landscape professionals in installing and maintaining green infrastructure.
Green infrastructure, the techniques used to implement low impact development (LID), uses vegetation and soil to manage rainwater where it falls. According to the Environmental Protection Agency (EPA), “LID employs principles such as preserving and recreating natural landscape features, minimizing effective imperviousness to create functional and appealing site drainage that treat stormwater as a resource rather than a waste product. There are many practices that have been used to adhere to these principles such as bio-retention facilities, rain gardens, vegetated rooftops, rain barrels, and permeable pavements. By implementing LID principles and practices, water can be managed in a way that reduces the impact of built areas, and promotes the natural movement of water within an ecosystem or watershed.”
These practices often employ strategically placed and constructed landscape areas that use soil, sand, stone, plants and mulch to store, absorb, infiltrate and transpire stormwater runoff. Stormwater regulations can be met by using products, such as porous pavers and structural soils, designed to promote infiltration. More and more, these practices are required elements in new development and redevelopment projects and, in some communities, are required to be retrofitted in existing sites.
Green infrastructure practices can improve stormwater management by:
Reducing stormwater volume. Runoff is captured or absorbed by the green infrastructure practice, thereby reducing the flow of stormwater to the storm sewer, reducing the occurrence of Combined Sewer Overflows (CSOs) where they exist, and reducing flooding in local waterways.
Reducing impervious cover. Surfaces that allow water to penetrate are “pervious” or “permeable,” while those that do not are “impervious.”
Decreasing and delaying peak discharge. Peak discharge is the highest rate of flow in a stream, which is influenced by the land cover in the surrounding watershed. In areas with high impervious cover, green infrastructure practices — in addition to decreasing runoff to streams — capture and absorb stormwater volume, slowly infiltrating water into the ground. This reduces peak volumes, thereby lessening the burden on the sewer system.
Preventing pollution. Many green infrastructure practices filter or remove stormwater pollutants, such as heavy metals, nutrients, sediment, and pathogens, which leads to improved water quality. In addition, green infrastructure often prevents pollution-carrying runoff from reaching the local waterway by absorbing and treating stormwater near its source.
Recharging groundwater. Green infrastructure techniques that absorb runoff — tree plantings, permeable pavement and pavers, vegetative swales and rain gardens — allow water to penetrate into the soil infrastructure. There is growing demand for this type of work, particularly associated with regulations to protect water from pesticides and fertilizers.
Local stormwater programs often provide homeowners and property managers with incentives to voluntarily install and maintain landscape features that also serve a stormwater role. Landscape companies should consider learning about the connection between the landscape and stormwater management industries with the idea of adding stormwater management expertise to their existing service offerings.
Tom Delaney, is director of government affairs at the Professional Landcare Network (PLANET). He can be reached via e-mail at TomDelaney@landcarenetwork.org.