Natural resources such as plants, rocks and soil beautify a bioretention area but also further reduce stormwater runoff. Davey's Jennifer Lennox interviewed Davey experts about the benefits of using natural materials to build bioretention areas, bioswales and rain gardens and ultimately save money and resources. Her story appeared in the July/August issue of Defense Communities (see pages 12 - 14).
Reduce stormwater runoff - and save money - by incorporating a bioretention area
By Jennifer Lennox, The Davey Tree Expert Company
An impound lot and the surrounding aging warehouses are transformed into a 71-acre park using ecologically friendly materials and a handful of employees. An unused portion of a parking lot is cordoned off and converted to a "green island" to reduce the flow and velocity of stormwater. A depression behind a housing development is installed with a "bioswale" to reduce and slow runoff during storms.
All of these are examples of a new design and ecological trend to build bioretention areas using natural resources - plants, rocks, soil and mulch - to reduce stormwater runoff and also make the area more beautiful.
Bioretention areas, bioswales and rain gardens might sound intimidating and high-tech, but they're not.
"All of those terms really mean you're using natural materials such as plants, soil, and rocks to help retain and clean the water running off your roofs, gutters, and parking lots," said Blane Pshigoda, The Davey Tree Expert Company's Division Manager of Government Projects.
Furthermore, Pshigoda said, the installation of these areas can be environmentally friendly because they use natural resources to reduce stormwater runoff. "They're really the next step in making your property more ecologically friendly," he said.
Adding a bioretention area not only has environmental benefits, but it may also have a financial benefit. Some state and municipal governments also believe in the viability and positive capabilities of these features, and are willing to give tax credits to organizations to implement them.
Catching the extra rain
Whether you're talking about bioswales or rain gardens, you're essentially talking about stormwater runoff management, said Shawn Fitzgerald, Davey's Commercial landscape expert. "Both of these have the goals of reducing erosion and pollution and slowing water down," Fitzgerald said. "They're just different techniques based on what's available."
Once they've established, rain gardens can require less maintenance than turf grass. "Rain gardens can capture runoff from impervious areas such as roofs and driveways," said Fitzgerald. "They also allow runoff to seep slowly into the ground and recharge the aquifer."
The plants, mulch, and soil in a rain garden combine the natural, physical, biological, and chemical processes to remove pollutants from runoff. The deep, dense roots of native plants help increase the filtration.
Bioswales are very similar to rain gardens; they simply also incorporate rocks and gravel into the mix. "Research has shown that water moves 10 times faster over hard surfaces than in a meadow," said Fitzgerald. "So bioswales can be great in areas where stormwater tends to rush quickly through, such as over hard surfaces or depressions in the ground," he said. "They're very effective and work like mini-stop signs. They stop the water, allowing the ground and plants to absorb the water multiple times before it reaches the storm drain."
If the site happens to be in an arid part of the country, rain gardens can still be used to collect and absorb water slowly into the ground. "In many areas of the southwest, they barely have any water all year round," said Fitzgerald. "But then they have torrential rains for a few days or weeks that completely erode the landscapes when they hit."
In these areas, rain gardens can be used to slow the erosion and water damage from the storms as the plant material acts as a natural barrier and absorbs some of the force.
Location, location, location
Key to the project's success, of course, is placing the bioretention area in a spot of maximum effectiveness. "Pick your spot carefully," said Fitzgerald. "Because we're talking mostly about stormwater runoff, pick a high-traffic area that will really feel the benefits of the project."
In particular, Fitzgerald suggested locating bioretention areas in parking lots (perhaps at a church or school area) that have a lot of car or bus traffic. "These are areas that already have a lot of 'rainbow runoff' from chemicals left by cars," he said. "Putting a bioswale or rain garden in these areas will give you the biggest bang for your buck."
Installing for success
When it comes to actually installing the bioretention area, be sure to call on the professionals. "To do this project right, you need to first evaluate the area, test the soils, and then do a simulated runoff test," said Fitzgerald. "You don't want to just plop down some plants and call the project done."
To ensure the project is completed correctly, Fitzgerald suggested choosing a licensed, certified contractor who has had experience with bioretention areas. "Go with an expert," he advised.
Even after the project is finished, Fitzgerald preached that frequent monitoring is key to its long-term success. "This is not a 'one-and-done' sort of project," he continued. "You have to check in on it occasionally to make sure that evreything is still functioning properly."
Finish the job
Once the job nears completion, Fitzgerald recommends taking time to celebrate the moment. "This is a big deal, and installing one of these areas means that you are taking the time to really care for your environment," he said.
"Plan a ceremony, get children involved, and invite reporters," he encouraged. "Tell your community about the project. Who knows - maybe you will inspire others to take on a similar project."
10 Steps to Green Your Property
Follow these straightforward and practical tips to achieve a more beautiful and sustainable landscape.
1. Proper Plant Selection--Using native plants and others that are ideal for your landscape conditions will save money and help the environment as they grow and thrive locally. They will also require less supplemental irrigation, pesticide treatment, and fertilizer than non-native plants.
2. Lawn Space--Consider converting high-maintenance turf areas that are nonessential to curb appeal to low-maintenance landscapes. Planting perennials, installing mulch, or establishing no-mow regions will save money and resources, including water and fertilizers.
3. Perennial Color Displays--Perennial plantings can offer the same visual impact as annual flower plantings with less cost and maintenance. The investment in perennial plantings often pays off in just a few seasons, and the flowers return every year - bigger and brighter. Perennials can also act as a personal nursery as you can divide them to beautify other areas throughout your property.
4. Proper Mulching--Using effective amounts of mulch can retain soil moisture and reduce irrigation amounts. Gravel as mulch lowers soil temperature, inhibits weeds, and requires less frequent replenishment.
5. Energy-Efficient Landscaping--Use of evergreen trees on the western and northwestern exposures of your property will cut down on exposure to winter's penetrating winds. Deciduous trees on southern and eastern exposures buffer summer's intense sunlight but allow winter rays to warm your home. According to the Environmental Protection Agency, a well-planned landscape can reduce cooling costs by up to 50 percent and heating expenses by up to 40 percent.
6. Soil Testing--Have soil pH tested so the most appropriate plants and turf are selected for your landscape. Soil rich in organic matter retains more moisture and nutrients and reduces compaction. Encourage soil organic matter buildup by using organic mulches, recycled leaves, and clippings.
7. Check the Irrigation System--Auditing your irrigation system is the first step in making sure you get the best return on the investment. An effective irrigation system can substantially reduce water use, and usage of drip irrigation in lieu of spray heads cuts down on the amount of water lost to runoff and evaporation.
8. Water Conservation--Low-flow water devices have been shown to save water and money. Rain gardens can slow the runoff of rainwater, help eliminate overload on stormwater systems, and reduce erosion.
9. Green Maintenance Practices--Where possible, revert to "old-school" methods of maintenance. For example, pruning shrubs instead of mechanical shearing is better for air quality and the plants themselves, and it allows the pruner to create a more natural shape. Also, recycling grass clippings, leaves, shearing, and other lawn debris will trim the expense for transporting materials to an off-site location.
10. Contact an Expert--Learn more about ways to make your property more environmentally friendly by contacting an expert such as Davey Tree.
What is a bioretention area? It's a categorical term that describes both rain gardens and bioswales.
What is a rain garden? A rain garden is a garden that catches stormwater runoff from any impervious surface. It slows the water to recharge the groundwater and allows the water-tolerant plants to absorb water and pollution.
What is a bioswale? A bioswale slows runoff by sending the water through native plantings and gravel and rock barriers to increase infiltration.