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Smart Growth / Smart Energy Toolkit Low Impact Development * Effective Site Design * Natural Stormwater Management Practices Low Impact Development LID Smart Growth / Smart Energy Toolkit ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development The Problem The Solution Conventional Development Smart Development Less land clearing and grading costs Reduced infrastructure costs Protection of regional water quality Reduced stormwater runoff Loss of natural land or open space Depleted drinking water supply Reduced quantity and quality of water resources Increased infrastructure costs & maintenance ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development “Conventional” Planning & Design • Style of suburban development over the past 50 years • Generally involves larger lots • Clearing and grading of significant portions of a site • Wider streets and larger cul-de-sacs • Enclosed drainage systems for stormwater conveyance • Large detention ponds ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development Site Design Planning Process #1 AVOID IMPACTS – Preserve Natural Features and Use Conservation Design Techniques #2 REDUCE IMPACTS – Reduce Impervious Cover #3 MANAGE IMPACTS – Utilize Natural Features and Natural Low- Impact Techniques to Manage Stormwater ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development LID Site Design • Conservation of natural hydrology, trees, and vegetation • Minimized impervious surfaces • Dispersal of stormwater runoff • Conservation of stream & wetland buffers • Ecological landscaping ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development Site Design Practices • Reduce storm pipes, curbs and gutters • Preserve sensitive soils • Cluster buildings and reduce building footprints • Reduce road widths • Minimize grading • Limit lot disturbance • Reduce impervious surfaces ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development Source: R. Claytor Source: City of Portland, OR Source: CWP Better Site Design on Roadways and Driveways • Narrower streets • Alternative cul-de-sacs • Shared driveways ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development Source R. Droll West Farms Mall, W. Hartford, CT Better Parking Lot Design • Incorporate green strips and buffers • Create multiple small lots • Reduce requirements near transit • Allow shared parking • Require compact spaces • Set parking maximums • Alternative permeable pavers in overflow areas ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development LID Stormwater Techniques • Rain Barrels and Cisterns / Water Re-use • Stormwater Planters, Tree Planting • Permeable Paving • Open Channels • Bioretention • Stormwater Wetlands • Green Rooftop Systems • Vegetative Buffers • Infiltration ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development Rain Barrels and Cisterns Runoff Reduction & Water Conservation • Downspouts directed to tanks or barrels • 50 –10,000 gallons • Excess diverted to drywell or rain garden • Landscaping, car washing, other non- potable uses ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development Dry Well Infiltration of Roof Runoff Disconnection of Rooftop Runoff to Vegetated Swale Source: CWP ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development Copyright 2000, Center for Watershed Protection Permeable Pavement ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development Permeable Pavement @ Work ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development Vegetated Swales Conveyance, Treatment, Infiltration • Roadside swales (“country drainage”) for lower density and small-scale projects • For small parking lots • Mild side slopes and flat longitudinal slopes • Provides area for snow storage & snowmelt treatment ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development Source: LID Center Source: Larry Gavin Source: City of Portland, OR Bioretention Applications • Parking lot islands • Median strips • Residential lots • Office parks ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development Bioretention Applications • Urban retrofits • High-density areas ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development Source: City of Portland, OR Source: City of Portland, OR Vegetated Filter Strips Pretreatment and Attenuation • Mild vegetated slopes • Adjacent to small parking lots and roadways • Another opportunity for snow storage ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development Green Roofs • Stormwater Runoff absorption/collection • Reduced flooding of and damage to urban streets • Interior heating and cooling benefits of 10 degrees or more • Air purification • Recreational amenity • Improved aesthetics • Extended roof life, estimated at 40 years World Trade Center, Boston ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development Stormwater Planters • Vegetative uptake of stormwater pollutants • Pretreatment for suspended solids before they reach water-treatment facilities • Aesthetically pleasing • Reduction of peak discharge rate ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development Environmental and Community • Protects unique or fragile habitats • Reduces the pollution impacts of stormwater runoff • Promotes aquifer recharge • Provides opportunities to link wildlife habitats • Conservation values are part of the planning process • Can further goals of open space and community development plans The planning process inherently protects natural resources and promotes recharge to underlying aquifers. LID BENEFITS ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development Better Site Design will— • Identify and preserve natural features • Maintain natural hydrology • Help respect abutter’s properties • Retain property values • Augment groundwater supplies • Maintain high water quality • Provide new green space as a amenity Local Authorities ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development • Green strips in parking lots provide shade, serve stormwater collection and treatment needs, and reduce the need for large detention basins • Reduction in overall parking area reduces runoff volumes • Shared parking allows for more retail tax revenue • Enhanced aesthetics can increase retail traffic and sales revenue Local Authorities ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development • Infiltration replenishes groundwater supplies, increases aquifer recharge, and maintains base flows to streams and wetlands • Less runoff and sediment going into public drainage systems = lower maintenance costs, more overall capacity, and a longer lifespan for drainage systems • Reduced frequency and severity of Combined Sewer Overflow (CSO) events improves water quality and public health Local Authorities ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development The permitting structure encourages smart growth and facilitates a process that is clear, easy to understand, and cost-effective to developers. LID BENEFITS For Developer and Realtor • Streamlines the plan review process, reduces time and costs • Adds valuable amenities that can enhance marketing and sale prices • Decreases site development costs by designing with the terrain ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development Developer and Realtor • Low Impact Development practices can cost less than conventional drainage techniques • LID can reduce the size and number of detention facilities and the size and cost of drainage infrastructure • Systems designed to mimic nature can enhance aesthetics and property home values • Surface vegetative systems are more visible, thereby facilitating routine maintenance and requiring less maintenance than underground practices ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development Genzyme Corp. Headquarters Cambridge • Green roof • Recycled roof runoff for “make up” water for cooling system • Moisture sensors in green areas to minimize irrigation needs ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development Olmsted Green, Boston • Significantly improve existing physical site conditions • Increase the infiltration of rainfall into soils and groundwater • Reduce surface flooding • Protect and enhance wetlands on the property • Preserve existing mature specimen trees ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development LID methods will include— • Tree preservation • Soil amendents to improve vegetative growth and erosion control • Vegetated swales and rain gardens • Subsurface infiltration • Permeable pavers and pavements • Stormwater System Operations & Management Plan Olmsted Green, Boston ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development * Small clusters * Natural features retained * Minimum impervious surfaces * Narrow roads Pinehills, Plymouth ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development * Narrow roads * “Country drainage” * Shared driveways * Houses sited with natural terrain * Vegetation retained ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development LID Model Bylaw • Provides incentive for conservation site planning • “Stormwater Credits” reduce the size and number of conventional practices • Requirement to treat stormwater • Expands upon Massachusetts Stormwater Policy by including all land areas (beyond Wetland Protection Act jurisdiction) ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development Links for More Information • The Low Impact Development Center www.lowimpactdevelopment.org • ECONorthwest applies economic analysis to better understand the benefits of low-impact developments including a presentation by Ed MacMullan www.econw.com/casestudies/casestudy?study=low-impact- development • Rooftops to Rivers: Green Strategies for Controlling Stormwater and Combined Sewers Overflows www.nrdc.org/water/pollution/rooftops/contents.asp • Low Impact Development, Buzzard’s Bay National Estuary Program www.buzzardsbay.org/lid.htm • The University of New Hampshire Stormwater Center www.unh.edu/erg/cstev/ • Greenscapes www.nsrwa.org/greenscapes/default.asp ---PAGE BREAK--- Smart Growth / Smart Energy Toolkit Low Impact Development Links for More Information • Low Impact Development Center: Urban Design Tools www.lid-stormwater.net/ • Massachusetts Low Impact Development Toolkit, developed by the Metropolitan Area Planning Council (MAPC) www.mapc.org/LID.html • Green Roofs for Healthy Cities www.greenroofs.net/index.php • Heat Island Effect – Trees and Vegetation www.epa.gov/hiri/strategies/vegetation.html • Building Better II: A Guide to America's Best New Development Projects