Vermont Business Magazine Demonstrating Vermont’s ongoing commitment to flood mitigation, pollution reduction and energy preservation, four Vermont State Agencies and Departments submitted reports to the governor Monday documenting their work to utilize and promote Green Stormwater Infrastructure (GSI). These reports build on Executive Order 06-12 issued by Governor Peter Shumlin in March 2012 that directed the Agency of Commerce and Community Development, Agency of Natural Resources, Agency of Transportation and the Department of Buildings and General Services to come together to form the Interagency Green Infrastructure Council.
Natural Resources Secretary Deborah Markowitz celebrated the submission of these reports, noting, “Vermont must increase utilization of green stormwater infrastructure if we are going to successfully reduce polluted runoff and increase flood resiliency; these reports show state government leading by example.” She continued, “Passage of the Vermont Clean Water Act has reinforced the need for state agencies to work closely together to tackle water pollution and related challenges.”
Vermont’s agencies provide a range of services from offering innovative technical, financial, and educational resources needed to implement green stormwater infrastructure in downtowns, new developments, and on backroads to incorporating state-of-the-art green stormwater practices into new construction and retrofits for state buildings, state parks, and wildlife access areas. These reports show that, by working together, Vermont is making important strides in deploying this innovative approach to managing polluted stormwater run-off.
Green Stormwater Infrastructure BMPs
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Rain gardens are typically surface depressions with native plantings and amended soils used to capture, slow, infiltrate, and treat runoff from impervious surfaces, including rooftops, streets, parking lots and driveways. There are several design modifications for this practice to get the desired result and are flexible in size and infiltration rates. Ultimately bio-retention practices are designed to pond to depths of 6-18 inches with a complete drawdown in 48 hours. |
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Using native plants to vegetate an area is an effective method of improving the quality and reducing the volume of site runoff. Native plants significantly change the soil medium by adding carbon, decreasing bulk density, and increasing infiltration rates. Native species are typically more tolerant and resistant to pest, drought, and other local conditions than non-native species. |
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Capture and reuse practices are designed to intercept and store runoff from impervious surfaces, such as rooftops, reducing volume and overall water quality impairment. The stormwater is contained and reused for irrigation but can also be used to supplement gray water usage. Typically rain barrels or cisterns are the vessels of choice for storing runoff for reuse. Underground cisterns can be designed to allow for seeping release into the substrate to recharge groundwater. |
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Pervious pavement (a term that includes pervious concrete, porous asphalt, permeable paver blocks and reinforced turf) is an infiltration BMP that combines stormwater infiltration, storage, and structural pavement consisting of a permeable surface underlain by a storage or infiltration reservoir. Pervious pavement is well suited for parking lots, walking paths, sidewalks, driveways, low speed-low volume lanes, plazas, and low vehicle weight streets. |
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A constructed wetland effectively removes sediments and many other common stormwater pollutants, and enhances the visual appeal of the landscape, providing tremendous capacity to reduce peak flow and runoff volume in general. A wetland utilizes a variety of biological, physical, and chemical processes for pollutant removal through uptake of pollutants by vegetation and microorganisms; and within the gravel sub-base and root matrices. |
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Infiltration planters can be referred to by several names - stormwater planters, flow-through planters, or contained planters are among the most popular. These, generally small, contained planting areas capture stormwater runoff and treat it through bioretention. |
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A Dry Well is a subsurface storage facility that temporarily stores and infiltrates stormwater runoff from the roofs of residential and small structures. Roof leaders connect directly into the Dry Well, which may be either an excavated pit filled with uniformly graded stone, wrapped in geotextile or a prefabricated storage chamber or pipe segment. Dry Wells discharge the stored runoff via infiltration into the surrounding soils. |
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Soil media restoration increases the water retention capacity of soil, reduces erosion, improves soil structure, immobilizes and degrades pollutants (depending on soil media makeup), supplies nutrients to plants, and provides organic matter. Soil restoration is also used to reestablish the soil’s long term capacity for infiltration and to enhance the vitality of the soil. |
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Vegetated roofs, or green roofs, are conventional rooftops that include a thin covering of vegetation allowing the roof to function more like a vegetated surface. The overall thickness of the vegetated roof may range greatly depending if it is an intensive (deep) or extensive (shallow) design, they typically contain multiple layers consisting of waterproofing, synthetic insulation, non-soil engineered growth media, fabrics, synthetic components and foliage. |
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Vermont has a long history of managing its forests for multiple uses - including timber, fuel wood, wildlife, habitat, and recreation. In addition to the 4.5 million acres of land that we traditionally viewed as forestland, another forest touches our lives everyday: our urban and community forest. Trees along streets, in parks and town greens, and on municipal forest lands are our community forests. These trees provide numerous environmental, social and economic benefits. |
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Infiltration trenches are shallow open channels lined with dense vegetation. Infiltration trenches can be used to treat runoff. The first flush from a storm event can be diverted to infiltration trenches. Infiltration systems are highly versatile and can be applied in small residential areas to extensive systems to address downtown, commercial, and industrial impervious surfaces such a parking lots, roads/sidewalks and rooftops. In urban environments the largest constraint is available open space. |
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Vegetated filter strips are a permanent, maintained strip of vegetation designed to slow runoff velocities and filter out sediment and other pollutants from stormwater. Filter strips require the presence of sheet flow across the strip, which can be achieved through the use of level spreaders. Frequently, filter strips are designed where runoff is directed from a parking lot into a stone trench, a grass strip, and a longer naturally vegetative strip. They provide good performance at a low cost, as well as providing aesthetics and habitat benefits. |
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Level spreaders evenly distribute runoff over a stabilized vegetative surface calming and decentralizing the erosive nature and velocity of concentrated stormwater flows. By slowing and spreading the flow, it allows for infiltration and improved water quality. Level spreaders can be used as the first practice in a working system of BMPs. |
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Vegetated swales are shallow open channels lined with dense vegetation designed to treat, attenuate, and convey excess runoff. Vegetated swales can replace curb or gutter systems and although they require more space, they manage runoff better. |
For more information download the Low Impact Development Guide for Residential and Small Sitesor visit our Additional Resources page.