Green Infrastructure and Low Impact Development in Northwest Indiana Conservation Design Forum | Northwestern Indiana Regional Planning Commission USEPA | Northwest Indiana MS4 Community Partnership
Green Infrastructure and Low Impact Development in Northwest Indiana
Conservation Design Forum | Northwestern Indiana Regional Planning Commission
USEPA | Northwest Indiana MS4 Community Partnership
Two out of every three people in the world will be facing water shortages by 2025…global conflict will inevitably 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
• Preserves and integrates open space
• Creates / preserves naturalized drainage systems
• Improves aesthetic views
• Protects water quality
• Minimizes changes to the natural hydrologic cycle (less flooding)
• Increases property value
Cost Implications
• Reduces regulatory burden (mitigation, stormwater mgt)
• Reduces site grading and infrastructure costs
• Reduces engineering costs
• Increases approval time / cost
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
Step 2: Identify development and restricted areas
Wetlands, floodplain, remnant woodlands
Hydric soilsHydric soils Site accessSite access TopographyTopography
No limitationsNo limitations
Step 3: Develop site plan
Permeable paving and rain gardens
Green roofs Bioswales Level spreaders
Merry Lea Environmental Learning Center, Wolf Lake, IN
Native LandscapePavement BaseBioswalesRain GardensWater reuse
Conservation Design Templates
Moderate-Density Residential
Moderate-Density Residential
Conventional (90 lots)• Wide roads• No public open space• Storm sewers that discharge into
turf or rip-rap-lined detention basins
Conservation (90 lots)• Narrower streets• Integrated, naturalized stormwater
system• Public trails and open space• Views of naturalized open space
• Combined infrastructure & landscape cost 10% to 15% less than conventional template.
• 50% less detention required.
Native Landscaping
Bioswale
Naturalized Detention
Vegetated Swale/ Rain Garden
Moderate Density Residential
$-
$100,000
$200,000
$300,000
$400,000
$500,000
$600,000
$700,000
$800,000
$900,000
$1,000,000
1. SitePreparation1
2. StormwaterManagement
3. SanitarySewer
4. WaterDistribution
5. Site Paving andSidewalks
6. LandscapeDevelopment
DesignContingency2
ConventionalConservation
Conventional $3,350,000 ($37,600/lot) / Conservation $2,880,000 ($32,400/lot)
Commercial / Industrial / Multi-Family
Conservation Design Templates
Commercial/Industrial/Multi-Family
• Typical strip mall• Two “big box” retail
establishments • Isolated outlet shops• Parking, landscaping, and
detention according to code
• “Main Street” retail setting• “Big box” retail incorporates
green roof• Second floor mixed-use areas• Parking areas feature
permeable paving, bioswales, and naturalized landscaping
Green roof garden for
second floor units
Green roof garden for
second floor units
• Similar combined infrastructure and landscaping cost as conventional template.
• Significant potential for additional commercial space.
• 40% less detention required.
Bioswale
Green Roof
Naturalized Detention
Porous Pavement
Conservation Design Templates
Rural Residential
Rural Residential
Conventional (22 lots) • Cul-de-sac design• Storm sewers discharge into
detention basins
Conservation Design (22 lots)• Narrow lane streets• Naturalized stormwater detention• Naturalized landscaping• Walking and biking trails
• Combined infrastructure and landscape cost 5% to 10% less than the conventional template.
• 70% less detention required.
Vegetated Swale
Rain Garden
Naturalized Detention
Native Landscaping
Rural Residential
$-
$100,000
$200,000
$300,000
$400,000
$500,000
$600,000
$700,000
1. Site
Prep
aratio
n
2. Stor
mwater M
anag
emen
t3.
Sanita
ry Sew
er
Constr
ucted
Wetl
and P
remium
4. W
ater D
istrib
ution
5. Site
Pav
ing an
d Side
walks
6. La
ndsc
ape D
evelo
pmen
tDes
ign C
ontin
genc
y
ConventionalConservation
Conventional $1,570,000 ($71,000/lot) / Conservation $1,470,000 ($67,000/lot)
Low Impact Development A Comparison of Two Different Land Plans in Arkansas
$10,512$12,907Estimated Cost per Lot
$3,942,100$4,620,600Estimated Total Cost
79103Drainage Structures Inlets/Boxes/Headwalls
6,73310,098Linear Feet Drainage Pipe
07,360Linear Feet Collector Street
21,12521,770Linear Feet Street
375358Lot Yield
Sustainable PlanConventional PlanTotal SiteProjected Results From Total Development
$11,507$16,326Total Cost Per Lot
$828,523$1,028,544Total Cost
7263Lot Yield
Sustainable Plan(Actual Figures)
Conventional Plan(Engineer's Estimate)
Phase 1Actual Results from First Phase of Development
Low Impact Development A Comparison of Two Different Land Plans in Arkansas
More than $2,200,000 added to profitTotal Economic BenefitNational, state, and professional groupsRecognition23.5 acres of green-space/parksAdded Amenities80 percent of lots sold in first yearEnhanced Marketability$4,800 less cost per lotLower Cost Per Lot$3,000 more per lot over competitionHigher Lot Value17 additional lotsHigher Lot Yield
Economic and Other Benefits From Low Impact Development