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Low Impact Development Stormwater
Controls and Changing State and
Federal Regulations
Steven Roy, LEED® AP
Geosyntec Consultants, Inc.
Acton, MA
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Presentation Objectives
• Understanding of the new regulatory drivers for
innovative stormwater management including
Infiltration and groundwater recharge
• Energy Independence and Security Act Section 438
requirements, and Executive Order 13514
• Discuss examples of Low Impact Development (LID)
stormwater implementation including techniques
such as porous pavers, porous asphalt, bioretention,
raingardens, and dry wells
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www.epa.gov/owow/nps/lid/section438
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Impervious Surfaces Generate Stormwater Runoff
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Low Impact Development (LID)
An ecosystem-based approach to land development
and stormwater management
Mimic pre-development site hydrology
Low Impact Development Center
www.lowimpactdevelopment.org
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Conventional vs. LID Approach to Stormwater
• Conventional
 Collect
 Convey
 Discharge
• LID Approach
 Reduce volume
 Minimize impacts
 Distributed controls
 Treatment trains
 Infiltration
 Hybrid systems
 Mimic the
predevelopment
hydrology
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What are the Drivers for Innovative Stormwater
and Ground Water Recharge?
• Energy Independence and Security
Act of 2007 (EISA)- Federal Facilities
• LEED/Green Design
• State Stormwater Regulations
• New Municipal Separate Stormwater
System (MS4) Stormwater Permits
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New Terminology for Stormwater in
Permits and Regulations
• Mimic Pre-development Hydrology
• Retain onsite
• Maximize Infiltration
• Groundwater Recharge Requirements
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EISA Section 438
Text of Section 438:
“Storm water runoff requirements for federal
development projects. The sponsor of any
development or redevelopment project involving a
Federal facility with a footprint that exceeds 5,000
square feet shall use site planning, design,
construction, and maintenance strategies for the
property to maintain or restore, to the maximum
extent technically feasible, the predevelopment
hydrology of the property with regard to the
temperature, rate, volume, and duration of flow.”
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Maximum Extent Technically Feasible
(METF)
• Stormwater control practices that are effective in
reducing the volume of stormwater discharge must
be used.
• The Federal facility must use all known, available
and reasonable methods of stormwater retention
and/or reuse to prevent the off site discharge of
stormwater runoff consistent with the performance
standard.
• In cases when a facility seeks or claims an
exception, it is expected that there will be a serious
and documented attempt to comply.
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Performance Options
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 Option 1 : Control 95th Percentile Rainfall
Event
•Manage rainfall onsite
•Infiltrate, Evapotranspirate, Harvest and
Infiltrate, and Reuse Runoff
Note: The 95th percentile rainfall event is the
event whose precipitation total is greater than
or equal to 95 percent of all 24-hour storms on
an annual basis.
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95% Storm Event
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City
Atlanta, GA
Baltimore, MD
Boston, MA
95th Percentile Event
Rainfall Total (in)
1.8
1.6
1.5
City
Kansas City, MO
Knoxville, TN
Louisville, KY
95th Percentile Event
Rainfall Total (in)
1.7
1.5
1.5
Buffalo, NY
Burlington, VT
1.1
1.1
Minneapolis, MN
New York, NY
1.4
1.7
Charleston, WV
1.2
Salt Lake City, UT
0.8
Coeur D’Alene, ID
Cincinnati, OH
Columbus, OH
Concord, NH
Denver, CO
0.7
1.5
1.3
1.3
1.1
Phoenix, AZ
Portland, OR
Seattle, WA
Washington, DC
1
1
1.6
1.7
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Worst case cost
52,272 sq ft @
$15/sq ft =
$784,080
Plus site demo,
design, permits=
~$900k
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Performance Options
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• Option 2: Preserve predevelopment
hydrology (rate, volume, duration &
temperature)
 Conduct hydrologic and hydraulic analyses
 Quantify post-construction hydrographs for the following storm
sizes:
• 1, 2, 10 and 100 year 24 hour storm events
 Maintain pre-development hydrographs for these storm events
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Performance Options
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What if Options 1 and 2 are not technically
feasible?
• Conduct site evaluation and assessment
• If site conditions or other factors preclude
achievement of Options 1 or 2, i.e., neither is
technically feasible
• Agency/Department follows a process to employ
onsite practices to the METF
• Agency/Department documents stormwater design
based on METF and other factors
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Complying with EISA
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• Executive Order 13514, Federal Leadership
in Environmental, Energy, and Economic
Performance, Oct 5, 2009:
 Required EPA to Issue Guidance
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www.epa.gov/owow/nps/lid/section438
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DOD - EISA Implementation Policy
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•
•
New Proposed Federal and State Stormwater
Regulations
EPA Proposed new SW Rulemaking – Effective Nov 2012
 New stormwater controls for “newly developed and redeveloped sites”
 Recently completed “listening” sessions
 EPA sent out an ICR (Information Collection Rule) to developers, MS4
permit holders, and states
 Likely to require retrofits to existing sites
New – North Coastal Watersheds MS4 Permit - Massachusetts
 84 Communities and several state/federal and transportation agencies
 Requires compliance with new MA SW Management Standards for post
construction stormwater control
 Requires as-built plans for all new development to demonstrate
compliance
 Requires elimination of local barriers to green infrastructure
 Requires GW recharge and infiltration where feasible – first 1 Inch
 Requires an assessment of street design & parking lot guidelines and other
requirements that create impervious cover
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LID BMP Performance Metrics
(Ventura and Orange County, CA)
• Retain (infiltrate, harvest and use, or
evapotranspire) or biotreat the runoff
volume from the 85th percentile, 24hour storm event (“design capture
volume”) on-site to the Maximum
Extent Practicable (MEP)
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Effective Impervious Area Metric
(Ventura County, CA)
• Projects must reduce Effective Impervious Area
to less than 5% of the total project area
• Impervious surface are rendered “ineffective” if
water quality design storm runoff volume is fully
retained onsite
 85th percentile, 24-hour event
 80 percent capture volume
 0.75 inch storm event
• Any remaining surface discharges must be
treated
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Draft District of Columbia MS4 Permit
• Integrate green technology stormwater
management practices at the site and
neighborhood level through policies,
regulations, ordinances and incentive programs
• Mimic pre-development site hydrology through
use of on-site stormwater retention measures
(e.g., harvesting and using, infiltration and ET)
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Draft DC MS4 Permit
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• Performance standards:
 On-site retention of 1.2 in. (non-federal) or 1.7
in. (federal) from a 24- hour storm with a 72hour antecedent dry period
 Retention of the predevelopment runoff
volume of stormwater from a 24- hour storm
with a 72-hour antecedent dry period
• Maintenance of predevelopment hydrographs
•
(volume, rate and duration) for the 1-, 2-, 10- and
100-year 24-hour storm events.
Modeled predevelopment condition must be
meadow.
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MA Stormwater Standards
• the annual recharge from the post-development
site shall approximate the annual recharge from
pre-development conditions based on soil type.
• capture of at least the 1 inch (90th percentile) storm
event.
• The term “capture” includes practices that infiltrate,
evapotranspire, and/or harvest and reuse
rainwater. This means that 100 percent of the
volume of water from events less than or equal to
the 90th percentile event shall not be discharged.
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Pennsylvania Stormwater BMP
Manual – Volume Control
• At least the first one inch (1.0”) of runoff from new
impervious surfaces shall be permanently removed
from the runoff flow — i.e. it shall not be released
into the surface Waters of this Commonwealth.
Removal options include reuse, evaporation,
transpiration, and infiltration.
• Wherever possible, infiltration facilities should be
designed to accommodate infiltration of the entire
permanently removed runoff; however, in all cases
at least the first one-half inch (0.5”) of the
permanently removed runoff should be infiltrated.
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EPA Class V/Stormwater Memo-2008
•Infiltration Trenches
•Commercially
Manufactured Stormwater
Infiltration Devices
•Drywells, Seepage Pits,
Improved
Sinkholes
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Dry Wells and UIC Class V
States require registration – Is it happening?
Leaching catch basins in roadways- State and Local DOT’s?
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Sustainable Stormwater Management
• Low Impact Development Stormwater Designs
 Green roofs
 Trees and tree boxes
 Raingardens/bioretention/infiltration planters
 Vegetated swales
 Pocket wetlands
 Permeable pavements
 Reforestation/revegetation
 Site planning- protection of riparian
buffers/floodplains
 Rainwater harvesting/reuse (where allowed)
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Tree Box Filters/Roof Top Planters
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LID Design Feature
Planter Box Bioretention Cell
• Treat roof top drainage
• Reduce storm water volume
• Decrease peak discharge
• Provide high levels of pollutant
removal
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Porous Surfaces
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LID Design Feature
Porous Pavers
• Surface with "holes" which can be
filled with vegetation or aggregate
depending upon the need.
• Porous pavers provide the same
advantages as traditional concrete
pavers, including resistance to
heavy loads, flexibility of repair, low
maintenance, exceptional
durability, and high quality.
• Use infiltration to reduce
stormwater runoff that leaves
parking lots
• Increase stormwater storage
• Reduce thermal loading on surface
waters
• Reduce pollutants reaching surface
waters
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US Navy Monterey Post Graduate Naval Academy
Installed 30,000 Square Feet of Permeable Pavers
Photo Credit: Belgard Pavers
LID Opportunities
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Drivable Grass®
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FlexiPave™ – recycled rubber tires
and aggregate
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Porous Asphalt
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Porous Concrete
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Bioretention Cells
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LID Design Features
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Bioretention Cell
• Provide water quality treatment; remove suspended solids,
metals, nutrients
• Increase groundwater recharge through infiltration
• Reduce peak discharge rates
• Reduce total runoff volume
• Improve site landscaping
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100 ft Bioretention Cell in Parking Lot
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Leadership in Energy and
Environmental Design -LEED® and
Stormwater Management
 Green Building- GSA Has a “Zero
Environmental Footprint” Goal
 Green Infrastructure- Promoting LID and
Pre-Development Hydrology
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Summary – the New Stormwater
• Federal Requirements for Green Design and EISA Section
438 are mandating stormwater infiltration- Guidance
• Most requirements require capture and onsite infiltration of
between 1.0 -1.5+ inches of runoff from impervious surfaces
• New stormwater regulatory terminology
 Mimic the pre-development hydrology
 Retain onsite
 Infiltrate stormwater to the maximum extent practicable
(MEP)
 Federal Facilities -Maximum Extent Technically Feasible
(METF)
• UIC Class V Well registration may be requiredCompliance?
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Questions?
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