Flood and Stormwater Mitigation
Using Green Infrastructure
Kari Mackenbach,
Green Initiatives Practice Leader,
URS
Christine Worley, URS
Incorporate Green Infrastructure
•What is Green Infrastructure?
•How does it relate to stormwater
and flood management?
•What are the site selection criteria?
•What are costs and operation and
maintenance concerns?
Green Infrastructure
• Natural and managed green areas in both
urban and rural settings,
• Strategic connection of open green areas,
• Treating rainwater as a resource and not as
trash to be discarded as quickly as possible,
• Transforming “grey” infrastructure to green
through restoration of watersheds to slow
and store water, and
• Providing multiple benefits for people.
What Else Can Green
Infrastructure Do?
• Help communities come closer to
attaining their requirements (CWA, MS4,
NPDES, CSO, Chesapeake Bay TMDL, etc.)
• Enhance public perception (sustainable
cities)
• Leverage State and Federal program
dollars (brownfield redevelopment)
• Opportunity to “marry” two forms of
public work effort (street, sidewalks,
stormwater management)
Even your home has a big impact on stormwater runoff
House
Driveway
Stormdrain
Street
+ “Green Concrete” Compacted Lawn
8,390 s.f. “impervious” x 1” rain
(if infiltrates first ¼” of rain)
= 3,880 gallons of runoff
1,500 s.f. house (& patio) x 1” rain
= 925 gallons of runoff
In a 1” rainfall
Potential Runoff:
5,422 gallons
1,000 s.f. driveway x 1” rain
= 617 gallons of runoff
2,500 s.f. “impervious” x 1” rain
Stormdrain
= 1,542 gallons of runoff
Street
Where can rain soak in?
Q - How Do We Protect Our
Streams?
A - Manage How Stormwater Runs Off the Landscape
Photo: Rusty Schmidt
Distributing Stormwater Controls
Close to Runoff Sources
Distributed
Stormwater Features
Regional
Traditional Techniques
Green Roof Applications
Pervious Infrastructure
Rain Gardens & Bio-Infiltration Devices
Green Infrastructure in Your Backyard!
Local Challenges
Local Opportunities
CONSTRUCTING GREEN SOLUTIONS ON
EVERY STREET
RESIDENTAL RETROFIT VISUAL
RESIDENTIAL RETROFIT
RAINGARDEN
RESIDENTIAL RETROFITPERVIOUS PAVERS
Green infrastructure does not replace
gray infrastructure.
Can reduce the capital costs and
O & M costs of gray technology.
$
$
http://www.coxconcrete.com/products/rcp/index.html
$
The Green Behind the “Green”
Green Infrastructure
Type
Installation
Costs
Operation and
Maintenance
Life Cycle
Costs
Rain Gardens
$5-7 sq. ft.
$12-15 sq. ft.
minimal
Annual Mulching and
Weeding $0.50-2 sq. ft
Pervious Pavement
$20-35 sq. ft.
minimal
Fewer repairs, longer
overall lifespan, yearly
vacuuming/ pressure
washing $0.15 sq. ft
Green Roof Applications
$30 sq. ft.
$12-15 sq. ft.
great to
minimal
Conventional roof 1520 yrs, green is double
or triple that life cycle,
watering needed until
established.
Rain Barrels
$35-75
great
No maintenance,
reduce water bills
Constructed Wetlands
$6-20 sq. ft.
minimal
Replace pretreatment
components 3-5 yrs,
weed invasive plants
$200-500 yr
RIGHT-SIZING STRATEGY
Downspout Disconnection
Infiltration Trenches & Dry
Wells
High Cost
Effectiveness
Bio-infiltration Swales
Rain Gardens
Pervious
Pavers
Green
Roofs
Lower Cost
Effectiveness
Burnsville, MN
Paired Study of Residential Street
Runoff Control
Diagram courtesy of the City of Burnsville, MN from
their Burnsville Stormwater Retrofit Study
17 Rain Gardens Installed
Burnsville, MN
Diagram courtesy of the City of Burnsville, MN from their
Burnsville Stormwater Retrofit Study
5.3 acres treated and 7.5 acres controlled
Average treated lot < .5 acres
Average total rain gardens < 1 acre
Neighborhood Application
Burnsville, MN
Residential
Neighborhood
AFTER
Rain Garden Retrofits
Long-Term Monitoring
BEFORE
Photos Courtesy of Rice Creek Watershed District
Burnsville, MN
Blue: Control
Red: With Rain
Gardens
Diagram courtesy of the City of
Burnsville, MN from their Burnsville
Stormwater Retrofit Study
Site Specific/Neighborhood
Application
•Create a “First of its Kind”
•Municipal scale rain garden
•Educate the public
•Design model for rain gardens
•Balances security and openness
•Low impact/low maintenance
•Use innovative design measures
FEMA Supported, FEMA Funded.
Regional Applications
Large Cities Initiatives
Opportunities, Incentives & Regulatory
Kansas City, MO
• Educating the public about
water quality, sewer and
stormwater concerns
• Promoting green solutions
• Encouraging funding for
required sewer and
stormwater improvements
Montgomery County, MD
RainScapes Program
•Provides rebate
rewards to property
owners for LID
practices
http://www.montgomerycountymd.gov
LOUISVILLE, KY.
OVERVIEW
•
•
•
Flood Protection
Wastewater
Treatment
Stormwater
Management
EVALUATION OF
GREEN VS. GRAY
 Develop Case Study Template
 Cost per Gallon
 Gallons Removed
 Long-term Trends
 Standardize Design Criteria and O&M
 Standardize Green Modeling Parameters
 Target Pilot CSO Basins for Right-Sizing
CLEAN, GREEN, GROWING COMMUNITY
GREEN TOOLS
COLLABORATION ON GREEN
FIRST CRADA COMMUNITY
• 3 Year Effort-potential for up to 10 years
• EPA’s involvement in Green Infrastructure
validation process
• Establish gallons removed compared to
gray
• Evaluate and establish long term trends
• Standardize Design Criteria/O&M
• Standardize Modeling Parameters
• Other Ancillary Benefits
• Partner with University of Louisville
US EPA ORD PARTNER
• Monitoring Lead
• GMP Selection QA/QC
MONITORING IN LOUISVILLE
CSO 130 RESULTS
Existing AAOV
Existing # OF / YR
0.84 MGD
9
Option
Gray Cost
Green
Cost
Total Cost
POST
AAOV
POST #
OF / YR
Gray Only
$1,077,000
$0
$1,077,000 0.67
MG
Green Only
(Option 1 –
GMPs 0, 10,
11, 13, 21)
$0
$129,000 $129,000
0.44
MG
7
Green Only
(Option 2 –
GMPs 0, 10,
11, 12,13,
14, 17,19,
21 )
$0
$342,000 $342,000
*Pendi
ng
Final
Model
Run
*Pending
Final
Model
Run
8
Wrap UP
Green Infrastructure can:
• Be implemented on a site,
neighborhood, or regional level
• Help manage flooding and stormwater
• Protect our streams
• Be cost effective
• Provide multiple benefits
• Help communities meet environmental
requirements
• Improve public perception
Questions?
Kari Mackenbach – Kari.Mackenbach@URS.com
Christine Worley – Christine.Worley@URS.com