IN: Green Infrastructure and Low Impact Development
Green Infrastructure and Low ImpactDevelopment in Northwest IndianaConservation Design Forum | Northwestern Indiana Regional Planning CommissionUSEPA | Northwest Indiana MS4 Community Partnership
Two out of every threepeople in the world will befacing water shortages by2025…global conflict willinevitably result… United Nations
Low Impact Development is a planning approach that • concentrates site development on areas least sensitive to disturbance • uses distributed, on-site stormwater best management practices (BMPs) to emulate natural hydrology, reduce runoff, and improve water quality. • BMPs can be simple, nonstructural, low-tech, and low cost (e.g., vegetation), more complex when necessary • helps address: wet weather flows, Combined Sewer Overflows, National Pollutant Discharge Elimination System permits, Total Maximum Daily Load permits, and Nonpoint Source Pollution Program goals. • can be applied to almost any element of the developed landscape—buildings, yards, driveways, roads, walkways, open
What kinds of strategies are used? • Conserving open space and protecting streams, wetlands, and wet soils • Reducing the use (and cost) of pipes, detention ponds, curbs and gutters, mass site clearing and grading, and paving • Reducing and disconnecting impervious surfaces (roads, sidewalks, rooftops) • Preserving and using the natural topography and drainage features of the landscape, as well as some engineered systems, to manage stormwater, such as…
Examples of stormwater BMPs • Natural landscape systems • Green roofs • Bioswales and rain gardens • Permeable paving • Rain barrels and cisterns • Naturalized retention
Low Impact Development Benefits Cost Implications • Preserves and • Reduces regulatory integrates open space burden (mitigation, stormwater mgt) • Creates / preserves naturalized drainage • Reduces site grading systems and infrastructure costs • Improves aesthetic • Reduces engineering views costs • Protects water quality • Increases approval time / cost • Minimizes changes to the natural hydrologic cycle (less flooding) • Increases property value
Create Conditions to Support Low Impact Development • Establish local commitment and support • Policies, funding, incentives, practices, standards, rules, codes and regulations must point in the same direction to create the right conditions for implementation • Stormwater management, drainage and detention • Natural area protection and management • Landscaping • Parking and transportation • Zoning and subdivision standards • Block and lot dimensions and setbacks • Street and sidewalk dimensions •Development density, lot yield, and ‘bulk’
How are these practices integrated into development? Site Design
Site Design “First Principles”• Identify and protect natural features and open space early• Use site topography and natural drainage patterns to guide site layout and stormwater management• Use the natural landscape and engineered, naturalized drainage and detention BMPs to filter and infiltrate stormwater on site• Reduce the impervious area of development• Allow flexibility in lot size, street, block, and lot layout• Calculate site yield based on developable space— the total site area minus floodplains, wetlands, waterways, steep slopes, natural areas…• Concentrate built areas in a range of lot sizes and orientations to create views, privacy, and amenities for each home
Site BoundaryWetlandsFloodplainSoilsVegetation Step 1: Identify sensitive areas
Wetlands, floodplain, remnant woodlands No limitations Hydric soils Site access TopographyStep 2: Identify development and restricted areas
Moderate-Density ResidentialConventional (90 lots) Conservation (90 lots)• Wide roads • Narrower streets• No public open space • Integrated, naturalized stormwater• Storm sewers that discharge into system turf or rip-rap-lined detention basins • Public trails and open space • Views of naturalized open space
Native Landscaping Naturalized Detention Bioswale Vegetated Swale/ Rain Garden • Combined infrastructure & landscape cost 10% to 15% less than conventional template. • 50% less detention required.
Moderate Density ResidentialConventional $3,350,000 ($37,600/lot) / Conservation $2,880,000 ($32,400/lot)$1,000,000 $900,000 $800,000 $700,000 $600,000 Conventional $500,000 Conservation $400,000 $300,000 $200,000 $100,000 $- 1. Site 2. Stormwater 3. Sanitary 4. Water 5. Site 6. Landscape Design Preparation1 Management Sewer Distribution Paving and Development Contingency2 Sidewalks
Commercial/Industrial/Multi-Family Green roof garden for second floor units Green roof garden for second floor units• Typical strip mall • “Main Street” retail setting• Two “big box” retail • “Big box” retail incorporates establishments green roof• Isolated outlet shops • Second floor mixed-use areas• Parking, landscaping, and • Parking areas feature detention according to code permeable paving, bioswales, and naturalized landscaping
Bioswale Naturalized DetentionGreen Roof Porous Pavement • Similar combined infrastructure and landscaping cost as conventional template. • Significant potential for additional commercial space. • 40% less detention required.
Vegetated Naturalized Detention SwaleRain Garden Native Landscaping • Combined infrastructure and landscape cost 5% to 10% less than the conventional template. • 70% less detention required.
Rural Residential Conventional $1,570,000 ($71,000/lot) / Conservation $1,470,000 ($67,000/lot) $700,000 $600,000 $500,000 $400,000 Conventional Conservation $300,000 $200,000 $100,000 $- ks y n t n t m er en en nc io tio iu w al at em m ge Se m u w ar rib op e de tin ag ep Pr ry st l ve Si n an ta Di Pr d Co De d ni n rM er an la te Sa n et at e Si g te g ap si W W 3. in wa 1. De sc v d 4. Pa m e nd ct or La ru St te st Si 6. 2. n Co 5.
Low Impact DevelopmentA Comparison of Two Different Land Plans in Arkansas Projected Results From Total Development Total Site Conventional Plan Sustainable Plan Lot Yield 358 375 Linear Feet Street 21,770 21,125 Linear Feet Collector Street 7,360 0 Linear Feet Drainage Pipe 10,098 6,733 Drainage Structures 103 79 Inlets/Boxes/Headwalls Estimated Total Cost $4,620,600 $3,942,100 Estimated Cost per Lot $12,907 $10,512Actual Results from First Phase of DevelopmentPhase 1 Conventional Plan Sustainable Plan (Engineers Estimate) (Actual Figures)Lot Yield 63 72Total Cost $1,028,544 $828,523Total Cost Per Lot $16,326 $11,507
Low Impact DevelopmentA Comparison of Two Different Land Plans in ArkansasEconomic and Other Benefits From Low Impact DevelopmentHigher Lot Yield 17 additional lotsHigher Lot Value $3,000 more per lot over competitionLower Cost Per Lot $4,800 less cost per lotEnhanced Marketability 80 percent of lots sold in first yearAdded Amenities 23.5 acres of green-space/parksRecognition National, state, and professional groupsTotal Economic Benefit More than $2,200,000 added to profit