Stormwater Management: Curb Planters
Stormwater runoff is excess precipitation that flows into water bodies and local storm sewer systems and not into the ground largely due to the prevalance of hard surfaces, such as impervious concrete. Stormwater runoff collects pollutants, chemicals and debris as it flows over paved surfaces and into water bodies. It also causes erosion, decreases groundwater recharge and alters aquatic environments.
Curb planters are popular landscaping applications that reduce stormwater runoff. Planters come in different forms including contained boxes, flow-through and infiltration and can be planted with various species for an aestically pleasing landscape feature.
RATIONALE
According to the Portland Bureau of Environmental Services, natural drainage and native landscaping areas in residential developments can remove up to 80% of the suspended solids and heavy metals, and up to 70% of nutrients like phosphorous and nitrogen, from stormwater runoff. Increased plant and soil area on building sites and public sidewalks can greatly affect the amount of runoff in a given area. Less stormwater runoff reduces the impact on surrounding water bodies and minimizes erosion while increasing groundwater recharge. Because curb planters are landscaping methods that are inexpensive and easy to install, they are very practical stormwater runoff solutions.
Curb planters can also play a role in policy. Many cities have developed stormwater policies limiting the amount of impervious cover or requiring a reduction in stormwater runoff from each site.
EFFORT REQUIRED
Contained planters can be placed on any impervious surface and require little maintenance outside of watering and weeding. Because flow-through and infiltration planters can accommodate more plant diversity and allow stormwater to drain through pipes, they may be larger in size and require additional maintenance such as removing sediment and maintaining pipes. All planters also require regular maintenance to ensure adequate drainage.
BENEFITS
- Improved water quality in surrounding water bodies. Plants and soil systems naturally collect stormwater, and reductions in stormwater lessen the transfer of pollutants and chemicals into nearby water bodies.
- Shading from plants and trees. Planters containing taller plants and trees provide shading, reducing the heat island effect and potentially improving the efficiency of adjacent buildings.
- Aesthetic appeal. The utilization of planters is visually attractive and adds value to surrounding property.
- Increased biodiversity. Biodiversity is defined as the variation of life forms in a given ecosystem. Landscaping with different varieties of plants in planters adds complexity to the local ecosystem.
- Groundwater recharge. As water seeps into the soil it is stored underground and available for human use through well construction.
- Less interference with aquatic ecosystems. Stormwater runoff is often warmer than the water in streams, lakes, and rivers. The increase in temperature in these water bodies from runoff negatively impacts aquatic ecosystems. For example, studies show that temperature changes among sensitive fish species can cause increased feeding, disorientation, increased metabolism, reduced reproduction and possible mortality.
- Wildlife habitat. Planters, depending on their size and type, attract animals, organisms and insects.
- Flood prevention. Stormwater quantity reductions minimize the risk of flooding in nearby areas/
- Minimization of erosion. Stormwater quantity reductions minimize erosion in the nearby area and along the banks of water bodies.
RISKS
There are relatively no risks involved in the implementation of curb planters. However, improper installation could lead to safety or leakage problems.
ACTION AGENTS
Landscape architect, property owner, local government (if permit is required), horticulturist, plant nursery
COSTS
The use of curb planters requires a small financial investment for the actual planters as well as the plants, soil and drainage system (if needed). On a city scale, these costs may be lower than the cost of a new stormwater management facility.
A basic unit of nature that includes a community of biological organisms and their nonliving environment linked by biological, chemical, and physical processes.The variety of life in all forms, levels, and combinations, including ecosystem diversity, species diversity, and genetic diversity.Water from precipitation that flows over nonporous surfaces into sewer systems or receiving water bodies.Surface material that absorbs less than 50% and therefore promotes runoff of water instead of absorption into the subsurface.The absorption of heat by dark, non-reflective hardscapes (including pavement and buildings) and its radiation to surrounding areas. A problem in urban areas, the effect is exacerbated by vehicle exhaust, air-conditioners, and street equipment.
