Green Infrastructure

September 22, 2015

Overview

*The Problem (one of them, anyway)

*The Solution?

*Examples in Practice

Leapfrog Development

Consequences of Leapfrog Style Sprawl

• Loss of Natural Areas & Habitat Diversity (Ex: Wetlands)
• Fragmentation of Open Space & Isolation
• Degradation of Water Systems
• Loss of "Free" Natural Services (Ex: Flood control, filtration, carbon sinks)
• Significant Investment in Gray Infrastructure Solutions

Not quite designing with nature.

Gray Infrastructure

Highly engineered, man-made components of an infrastructure network

Green Infrastructure

Engineering approaching that protects, restores, or mimics natural networks

Green infrastructure is a new term, but not a new idea

• Evolved from cross-section of two earlier traditions:
  • The inclusion and linking of parks and green spaces for benefit of people (think Central Park)
  • The linking of natural areas to benefit biodiversity and habitat (think Yellowstone National Park)
• Rooted in land conservation ethic, but with urban twist
• In short: An interconnected network of green space that conserves natural ecosystem values and functions + provides associated benefits to human populations

Green Infrastructure takes many forms and functions at many scales

Green Infrastructure captures the benefits & value of ecological services 

http://urbanforestmap.org/map/#

What sort of ecological services? You ask. Good question.

• Stormwater Management
• Flood Control
• Pollution Filtration
• Reduction in Heat Island
• Reduce Air Pollution

But how? You ask. Well, that's another good question.

• Rainwater Harvesting

But how? You ask. Well, that's another good question.

• Bioswales

But how? You ask. Well, that's another good question.

• Green Roofs

But how? You ask. Well, that's another good question.

• Urban Tree Canopy

A system of hubs and links, cores and corridors

Hubs

Examples include local nature reserves, working lands, regional parks, community parks, and conservation areas

Links

Examples include landscaped pathways, conservation corridors, greenways, greenbelts, and eco-trail systems 

Tallahassee Greenways Program

http://www.leonpenny.org/?project=greenways-master-plan

Example: Miccosukee Greenway

https://www.talgov.com/Uploads/Public/Documents/planning/pdf/environ/gwmp-2015-update-02.pdf

Local example: Tallahassee's topography is conducive to flooding

Cascades Park

Superfund site

• Liability for environmental cleanup fell on city
• Paid for by penny sales tax

Munson Slough watershed heavily polluted over time as it received runoff and contaminants from most of Midtown & Downtown TLH

• 22 miles of former rail lines around Atlanta
• Redevelopment plans include series of interconnected green spaces, trails, and transit options
• Began in 1999 as Master Thesis from Georgia Tech urban planning student

Pollution Control via Low-Impact Development

September 24, 2015

Overview

*Low-Impact Development

*Suburban Example

*Urban Example

Pre-1970s

Structural Storm Water Management

Objective: Provide adequate stormwater drainage from developed land and attempt to control flood flows. Rise of Gray Infrastructure and "vacate water ASAP"

1970s - 1980s

Water Quality as Storm Water Management

Objective: Adequate drainage, but via management of floodplain development, erosion and sediment control, mitigate point source pollution, and detention facilities

1990s - 2000s

Low-Impact Storm Water Management

Objective: Adequate drainage by onsite mitigation of stormwater flows, infiltration, runoff treatment, protect/restore natural drainage channels with non-erosive velocities

2010 to Present

Sustainable Storm Water Management

Objective: Use watershed approach to integrate stormwater management, focus on water quality, stream/habitat restoration, and living community design that amenitizes SWM assets

In general, a shift toward less structural methods to stormwater management to low-impact development. 

But why worry about stormwater management?

Mitigate flood damage

Prevent groundwater contamination

Prevent pollution of surface waters

Stream restoration

Habitat protection

Better aesthetics, better design, more livable communities

A method worth investigating: 
Low-Impact Development

"An approach to land development that works with nature to manage stormwater as close to its source as possible." - EPA, 2013

Applicable to developing watersheds in urban, suburban, and rural settings. 

Low-Impact Development's Overarching Principles

• Source control approach: Manage upstream to protect down stream. Treat stormwater at site level.
• Micro-scale & distributed design features in contrast to large-scale & centralized SWM infrastructure (ex: series of on-site bioswales vs. single detention area with pipe to sewer)
• Emphasizes conservation to replicate pre-development hydrologic regime of watersheds through filtering, infiltration, storing, evaporating, and detaining runoff

Low-Impact Development's Implementation Practices

• Conservation and minimization: conserving natural conditions on site and minimizing imperviousness
• Landscaping: alter the terrain and vegetation cover to minimize runoff
• Storage: retain or detain rainwater to prevent or delay the generation of runoff
• Conveyance: convey runoff through the site while providing infiltration
• Infiltration: capture runoff and allow it to infiltrate into the soil

What if stormwater isn't just a nuisance to manage, but a resource to utilize?

Alachua County provides a number of examples: 

http://www.alachuacounty.us/Depts/epd/WaterResources/EducationalPrograms/Documents/Overview%20of%20Low%20Impact%20Development.pdf

Using LID, improve site design. Cluster development in smaller area of site to preserve native vegetation. Minimize impervious surfaces and prioritize tree canopy.

Suburban Example

Patridgeberry Subdivision, Massachusetts

Patridgeberry, MA

• 38 acre parcel deployed as cluster development
• .2 acre lots with 28 acres of woodland left in native state
• Reduced all setbacks, narrowed streets, and shortened driveways
• 20 homes share common septic, not site by site
• Rooftops drain to drywells and infiltrates ground

http://www.lid-stormwater.net/general_urban.htm

Urban Example

Florida Aquarium, Florida

11.5 acre primarily asphalt and concrete parking area. Runoff retrofits proposed via end-of-island bioretention cells, bioretention swales around perimeter, permeable paving, small storage pond 

Dealing with Perceptions

• Uncertainty regarding effectiveness; countered by studies and pilot projects
• Up front capital costs are greater than traditional SWM infrastructure; turns out not always true, especially when full lifecycle costs are considered (O&M + replacement over time) and spill over benefits are given a market value and calculated
• Difficult to quantify untraditional metrics; can be true, but many communities are leading the way with benefit calculators to measure property value, pollution costs, etc.