Low Impact Development Tour

Transcription

1 Low Impact Development Tour

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3 Low Impact Development The Great Lakes contain 20 percent of the world s surface freshwater, supply drinking water to 42 million people, and play a critical role in the region s economy. However, development and watershed alteration have resulted in the degradation of our water resources, including decreased water quality from non-point source pollutants (nutrients, oils, and metals) washed off of developed land, altered stream flows, bank erosion, and increased water temperature. This booklet addresses the effects of urbanization on watershed and the subsequent restoration of watersheds through the implementation of Low Impact Development (LID) techniques. LID, also known as conservation site design or green infrastructure, is a process of sustainable development that conserves and protects natural resources. LID manages rainwater where it falls by integrating natural systems and best management practices (BMPs) into the site. By having less water run off the land, non-point source pollution is reduced, watersheds are protected, and water quality is improved. LID is especially important in urban and urbanizing areas where it is crucial to promote water conservation, protect our waterways, and enhance green space.

4 What s Happening to the Rouge River? Land use within the Rouge River watershed has greatly changed over the last 200 years. Houses, stores, and factories have replaced meadows and woodlands. Paved roads and parking lots now cover the land to accommodate millions of automobiles. Rain now quickly moves to the river through runoff and concrete pipes. This conversion of natural land that soaked up water to impermeable surfaces that shed water causes significant water pollution and excessive flooding. Stormwater runoff includes pollutants such as excess nutrients, heavy metals, sediment, pathogens, and bacteria. Low impact development helps to manage stormwater runoff by providing opportunities for rainfall to soak into the ground, creating a healthier ecosystem in which to live, work, and play. LIVINGSTON COUNTY OAKLAND COUNTY HIGHLAND TWP. WATERFORD TWP. WHITE LAKE TWP. MILFORD COMMERCE TWP. MILFORD TWP. LYON TWP. OAKLAND COUNTY WASHTENAW COUNTY SALEM TWP. SUPERIOR TWP. YPSILANTI YPSILANTI TWP. WASHTENAW COUNTY WAYNE COUNTY WIXOM NOVI NORTHVILLE NORTHVILLE TWP. PLYMOUTH TWP. VAN BUREN TWP. WEST BLOOMFIELD TWP. FARMINGTON HILLS FARMINGTON LIVONIA WAYNE ROMULUS INKSTER PONTIAC ROCHESTER ROCHESTER HILLS TROY BLOOMFIELD TWP. BIRMINGHAM CLAWSON BEVERLY HILLS FRANKLIN ROYAL OAK BERKLEY SOUTHFIELD REDFORD TWP. OAKLAND COUNTY WAYNE COUNTY OAK PARK FERNDALE DETROIT DEARBORN WESTLAND GARDEN HEIGHTS CANTON TWP. CITY DEARBORN LTU OAKLAND COUNTY MACOMB COUNTY ALLEN PARK RIVER ROUGE ECORSE LINCOLN PARK TAYLOR SOUTHGATE WYANDOTTE 4

5 Prairie Grass and Wildflowers: More than a Pretty View Native wildflowers and grasses are hardy plants that evolved to our climate. Their roots penetrate deep, breaking up clay and compacted soil and making the soil more like a sponge, ready to soak up rainfall. The deep, penetrating root masses of native plants reduce erosion, increase soil fertility, and improve water quality by filtering stormwater pollutants. Native plants also do not require supplemental water and fertilization. Finally, by establishing no mow zones of native plants we can reduce carbon emissions from mowers and save money and energy. A streamside planting of native trees, shrubs, and perennials can slow and filter runoff water, removing pollutants that would have reached the natural waterway. With a reduction in the speed and volume of stormwater runoff, bank erosion is also lessened, resulting in clearer water in the stream Kentucky Lead Plant Blue Grass Amophora Poa Pratensis canescens Missouri Goldenrod Solidago missouriensis Indian Grass Sorghastrum nutans Compass Plant Silphium laciniatum Porcupine Grass Stipa spartea Heath Aster Aster ericoides Prairie Big Blue Cord Grass Stem Spartina Andropogon pectinata geradii Pale Purple Coneflower Echinacea pallida Pairie Dropseed Sporobolus heterolepsis Side Oats Gramma Bouteloua curtipendula False Boneset Kuhnia eupatoroides Switch Grass Panicum virgatum White Wild Indigo Baptisia leucantha Little Blue Stem Andropogon scoparius Rosin Weed Silphium perfoliatum Purple Prairie June Grass Clover Koeleria petalostemum cristata purpureum Cylindric Blazing Star Liatris Buchloe Grass Buchloe dactyloides cylindracea 5

6 Tour Map

7 Rain Gardens - These gardens were planted in 2007 as part of a Rouge River Project research and outreach project. Both gardens were retrofit around existing catch basins, with optional underdrains and stone reservoirs included. The only difference between the two gardens is the composition of the planting soil. The addition of topsoil and clay in one of the gardens slowed down the infiltration rate; using more compost in the other increased the volume of water that can be stored. Bioswale - This bioswale was completed in 2005 as part of the A. Alfred Taubman Student Services Center landscaping. It is 3 feet deep and consists of native grasses and shrubs in engineered soils designed to filter water runoff. The bioswale was designed to handle a 10-year storm event before overflowing into existing stormwater systems. Rain Garden - This rain garden was constructed in June 2011 as part of a student project. It consists of five native plant species carefully selected for this site s conditions. The garden also includes dry river rock beds to facilitate the flow of stormwater into the garden. Stormwater Harvesting - The Taubman Center s vegetated roof retains approximately 70 percent of annual precipitation, with the remainder draining into a 12,000-gallon underground cistern. The cistern recycles the grey water into the Taubman Center to flush toilets. Vegetated Roof - The Taubman Center s 10,000-square-foot Hydrotech Garden Roof includes a 4 granular soil that supports 9 different species of sedum ground cover. The roof has been monitored since 2007 and has proven effective in water management and energy savings. Porous Pavers - This outdoor dining patio was constructed in 2009 with Uni-Lock Eco- Stone pavers. The porous pavers allow water to infiltrate the engineered 6-inch stone layer below, designed to hold stormwater, allowing it to infiltrate the native soil layer below with zero runoff. Riparian Buffer Zone - Lawrence Tech planted two acres of riparian grow zones in 2009 as part of a Rouge River Project Grant. This area is the smaller of the two zones and is vegetated with more than 20 species of native plants and grasses to protect a small tributary of the Rouge River flowing through campus. This buffer zone plays a key role in improving water quality by filtering pavement runoff. 7

8 1 Rain Gardens Rain gardens, or bioretention cells, are shallow depressions planted with native vegetation to capture and treat stormwater runoff from rooftops, streets, parking lots, and lawns. Water that collects in the rain gardens and infiltrates the ground is diverted from city sewers and purified of pollutants and excess nutrients by the plants and soil. The rain gardens at this location were planted in 2007 as part of a research and outreach project. Both gardens were retrofit around existing catch basins, with stone reservoirs and underdrains included, as commonly found in engineered bioretention cells. The only difference between the two gardens is the composition of the planting soil. The addition of topsoil and clay in one of the gardens slowed down the infiltration rate and caused deeper ponding. Using more compost in the other garden increased the volume of water that could be stored in the pore space. Benefits Controls rainfall runoff and promotes infiltration Versatile can be installed in residential, commercial, and educational locations Works well with other stormwater systems Provides habitat for insects, such as butterflies and pollinators, and promotes biodiversity Attractive when maintained Native Plants Overflow Planting Mix Existing Soil Stone Reservoir Underdrain 8

9 Rain gardens vary in size and planting mix depth but are typically designed to capture and treat 1 of rainfall with larger rainfall events overflowing into a drain or swale. Ponding depths typically vary from 6 to 18 and the rain garden will dry in 24 to 48 hours after a rainfall. They do require careful selection of plants and routine maintenance, such as edging and weeding, to preserve a garden-like appearance. There are good homeowner design guides available from the Southeast Oakland County Water Authority (SOCWA) and Rain Gardens for West Michigan. How can you help? Establish rain gardens on low areas of your property to soak up runoff from your roof, driveway, and lawn. Plant rain gardens with wildflowers and native plants to help rainwater slowly filter into the ground. Rain gardens improve wildlife habitat by providing food and shelter for birds, butterflies, and insects. Public Works Building engineered rain garden. Macomb County, MI. Roadside rain garden. Lathrup Village, MI. Common Rain Garden Plants Bee Balm Purple Coneflower Blue Flag Iris Swamp Milkweed Common Bone Set 9

10 2 Bioswale Gently sloping vegetated drainage areas designed to slow, infiltrate, and filter stormwater runoff, bioswales function like rain gardens. They are typically located near parking lots or roads where pollutants, such as oil and gas, are washed away during rains. The bioswale that encircles the Lawrence Tech campus quadrangle is 3 feet deep and planted with long-rooted native grasses and shrubs in engineered soils designed to retain and filter water runoff. This bioswale was designed to handle the rain associated with a 10-year storm event before overflowing into existing stormwater pipes. Benefits Controls rainfall runoff and promotes infiltration Versatile can be installed in industrial, commercial, and educational locations Can replace curbs and gutters along roadways with significant cost savings LTU Quadrangle Bioswale Native Plants Existing Soil Planting Mix Stone Reservoir Underdrain 10

11 Bioswales can be flexible in width and depth. They need to have gentle slopes to avoid erosion and can include stone check dams to slow water down and improve infiltration. They are typically designed to capture and treat between 1 and 2.5 of rain while conveying larger storm events. Bioswales do require careful selection and establishment of plants and routine maintenance to preserve an attractive garden appearance. Roadside bioswale with native plants. Drainage swale carrying roof runoff. Parking lot bioswale with native grasses. 11

12 3 Rain Garden Rain gardens, or bioretention cells, are shallow depressions planted with native vegetation to capture and treat stormwater runoff from rooftops, streets, parking lots, and lawns. Water that collects in the rain gardens and infiltrates the ground is diverted from city sewers and purified of pollutants and excess nutrients by the plants and soil. Unlike other rain gardens on campus, this garden does not have an underdain or stone reservoir; in this way, it is similar to a private homeowner garden. This rain garden consists of native plant species carefully selected for this site s conditions. In addition, the dry river rock beds facilitate the flow of rainwater into the garden and limits erosion from the large volume of water flowing into the garden. Rock channels are convenient for transporting water into rain gardens and bioswales. This rain garden was constructed as part of an undergraduate student project. Benefits Controls rainfall runoff and promotes infiltration Versatile can be installed in residential, commercial, and educational locations Works well with other stormwater systems Provides habitat for insects, such as butterflies and pollinators, and promotes biodiversity Attractive when maintained Native Plants Rock Bed Planting Mix Existing Soil 12

13 Rain gardens vary in size and planting mix depth but are typically sized to capture and treat 1 of rainfall with larger rainfall events overflowing onto a portion of the yard or onto adjacent paved surfaces. Most homeowner rain gardens have ponding depths of less than 6 and dry in less than 24 or 48 hours. They do require careful selection of plants and routine maintenance, such as edging and weeding, to preserve a garden-like appearance. Rain gardens with Ours to Protect Rouge River Watershed sign. Lathrup Village, MI. Common Rain Garden Plants Great Blue Lobelia Black-eyed Susan Cardinal Flower Mountain Mint Spiderwort 13

14 4 Stormwater Harvesting Stormwater harvesting is the process of capturing stormwater in cisterns, tanks, rain barrels, or underground storage chambers for use in irrigation or grey-water applications, such as toilet flushing or laundry. Grey water is defined as water that is not good for drinking but can be recycled for internal use. The A. Alfred Taubman Student Services Center s 12,000-gallon cistern, which collects rainwater not absorbed by the building s vegetated roof, is buried underground. The stored rainwater is used in the Taubman Center to flush toilets. Benefits Controls rainfall runoff and provides supplemental water supply Versatile can be installed in residential, commercial, and educational locations Reduces the use of drinking water for non-consumption purposes Saves money A homeowner variation of this technique is the use of rain barrels connected to gutter downspouts for garden irrigation. Downspout The Taubman Center s 12,000-gallon cistern during installation Rainwater Overflow Spigot Hose 14

15 Most stormwater harvesting systems are effective at capturing smaller rainfall events (between 1/2 and 2 ) with overflow during larger storms. To optimize harvesting systems, the captured rain must be used before the next large rainfall event. Finally, supplemental sources of water might be needed in times of drought. How can you help? Install a rain barrel to collect and store rainwater to reduce runoff to the river. Use the harvested rainwater for your houseplants and outdoor landscaping, which grow better on rainwater than chlorinated drinking water. Or you can redirect runoff from downspouts to planted areas where water can seep into the ground naturally. More water on the landscape means less watering, which will reduce your water bill and save you money. Homeowner rain barrel. Elevated rainwater storage tanks. 15

16 5 Vegetated Roof Vegetated roofs, commonly known as green roofs, are partially or completely covered with living plants that absorb rainwater, create habitats for wildlife, and help lower urban air temperatures. The thickness of the soil layer and planting materials depends on the type of vegetated roof. Extensive green roofs are thinner and primarily designed for stormwater management and insulation. Intensive green roofs have much thicker layers of soil and larger plants because they are designed for human accessibility hence the more intense maintenance requirements. Benefits Captures 100% of the rain in smaller storms Provides insulation and reduces energy consumption Increases the lifespan of the roof Reduces air temperatures Creates habitats for insects and birds Significant financial savings over the life of the roof Can provide recreational opportunities such as running tracks or parks. The A. Alfred Taubman Student Services Center s 10,000-square-foot extensive green roof is about 9 thick and supports 9 species of sedum groundcovers. It is expected to last about 40 years, more than twice the lifespan of traditional roofs. The Taubman Center s Vegetated Roof Vegetation Substrate Soil Drainage Layer Moisture Mat Insulation Root Barrier Roof Deck 16

17 Intensive vegetated roofs utilize a wide variety of plant species that may include trees and shrubs, require deeper substrate layers (usually greater than 6 ), are generally limited to flat roofs, require intense maintenance, and are often park-like areas accessible to the general public. These roofs are significantly heavier than other types of green roofs (40 to 150 pounds per square foot). Extensive vegetated roofs are limited to herbs, grasses, mosses, and drought-tolerant succulents, such as sedum; can be sustained in a shallow substrate layer (less than 4 ); require minimal maintenance once established; and are generally not designed for access by the public. Extensive roofs are well suited to rooftops with little load bearing capacity, since they weigh between 10 and 40 pounds per square foot, and sites not meant to be used as roof gardens. Private green roofs exist but they are less common. Intensive vegetated roof on apartment building. Extensive vegetated roof on parking structure. Sedum Varieties Homeowner vegetated roof. Crystal Lake, MI. 17

18 6 Porous Pavement System A porous pavement system consists of a permeable surface with a storage reservoir built below to capture stormwater and let it soak slowly into the earth. The permeable top surface can consist of porous asphalt or concrete, connected concrete paver blocks, or reinforced turf. The storage reservoir can be a bed of stones or a pre-manufactured water storage unit. These systems have been shown effective in cold weather climates for pedestrian paths, parking lots, and alleys. Benefits Controls rainfall runoff and promotes infiltration Provides pavement application and meets stormwater design requirements The Hossack dining patio was constructed with connected concrete paver blocks. The porous pavers allow water to infiltrate the engineered 6 layer of stone below with no runoff into storm sewers. Hossack dining patio Concrete Paver Blocks Bedding Sand Stone Reservoir 18 Porous concrete.

19 The key to porous pavement is to provide water storage and structural stability in the stone underlayer. These systems tend to require more maintenance than traditional pavement but have been shown to perform well in cold weather environments. City Hall paver block parking stalls. Farmington Hills, MI. Porous asphalt municipal parking lot. Southfield, MI. Private concrete driveway. How can you help? Eliminate paved surfaces when possible. Use gravel or wood chips to slow stormwater runoff as it moves over the land. Consider brick or concrete pavers instead of traditional concrete to increase infiltration and reduce runoff. Permeable flexible pavement made from recycled tires. 19

20 7 Riparian Buffer Zone Riparian buffer zones are areas of land between low, wet areas, such as streams and lakes, and higher, dry areas of land, such as farms and cities. With development, many buffer zones have been stripped of their native plants and trees. Naturalizing these areas restores them, improving drainage and water quality and reducing the need to irrigate and fertilize. It has the added benefit of creating habitats for wildlife and promoting biodiversity, especially among insects. Other examples of naturalized areas include no-mow lawns, native prairies, and constructed wetlands. This riparian grow zone is vegetated with more than 20 species of native plants and grasses to protect a small creek of the Rouge River watershed flowing through campus. It improves water quality by filtering runoff from adjacent pavement areas. Benefits Controls runoff and promotes groundwater recharge through infiltration Creates new wildlife habitats and encourages biodiversity Helps prevent streambank erosion Improves water quality in adjacent streams Cost-effective alternative to lawns Low long-term maintenance requirements LTU grow zone Sidewalk Native Prairie Plants Groundwater Stream 20

21 Natural areas and grow zones can be improved by conducting periodic controlled burns. Controlled burns give native plants a competitive edge over invasive species because they evolved by being subjected to periodic wild fires. How can you help? Replace traditional turf grass with deep-rooted native plants where possible. Deeper roots allow more water to infiltrate the ground and can extract water from deeper reserves during times of drought, conserving water and saving you money. Controlled burn of LTU grow zone. Front yard native landscaping. Northern, MI. Native flower beds at Kresge Foundation headquarters. Troy, MI. Common Grow Zone Plants Big Bluestem Grass Swamp Milkweed Switch Grass Yellow Coneflower Purple Coneflower 21

22 Local Low Impact Development Resources State of Michigan LID Manual (Southeast Michigan Council of Governments) Lawrence Technological University Great Lakes Stormwater Management Institute Rain Gardens for West Michigan Southeast Oakland County Water Authority Healthy Lawns and Gardens Rain Gardens in Washtenaw County Alliance of Downriver Watersheds National Low Impact Development Resources Low Impact Development Center LID Center Urban Design Tools US Environmental Protection Agency LID Center for Watershed Protection Stormwater Management Stormwater Management Resource Center State of Minnesota Stormwater Manual (Minnesota Pollution Control Agency) stormwater-management/minnesota-s-stormwater-manual.html Seattle Public Utilities Green Stormwater Infrastructure GreenStormwaterInfrastructure/index.htm

23 The mission of Lawrence Technological University s Great Lakes Stormwater Management Institute is to effect positive environmental change in the Great Lakes region through research, education, and the practical application of low impact development and stormwater management techniques. Donald Carpenter, PhD, PE, LEED AP, Lawrence Tech professor and director of the Great Lakes Stormwater Management Institute, is a nationally recognized leader in low impact development and stormwater management. He routinely provides professional lectures and workshops on innovative stormwater treatment designs and their role in low impact development implementation and fulfillment of LEED Sustainable Sites Credits. He serves on various regional and national committees that promote low impact development and improved water quality. 23

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