LEED ® 2012 Rainwater Management

Michele Adams, P.E. LEED® AP, Principal, Meliora DesignSteve Benz, P.E. LEED® AP OLIN, Partner, Dir. Green Infrastructure

Members of U.S. Green Building Council SS TAG and “SWM” Team

Test

What is the LEED System?

LEADERSHIP inENERGY andENVIRONMENTALDESIGN

A leading-edge system for certifyingDESIGN, CONSTRUCTION, & OPERATIONSof the greenest buildings in the world

Scores are tallied for different aspects of efficiency and design in appropriate categories.

For instance, LEED assesses in detail:

1. Sustainable Sites (SS)2. Water Efficiency (WE)3. Energy & Atmosphere (EA)4. Materials & Resources (MR) 5. Indoor

Environmental Quality (IEQ)6. Innovation &

Design Process

Test

Levels of LEED Ratings

Green Buildings worldwide are certified with a voluntary,consensus-based rating system.USGBC has four levels of LEED.

LEED is an evolving process….® is an Evolving System

• LEED v1.0 launched 1998• LEED for New Construction (NC) v2.0, v2.1, v2.2, and v3.0 (2009)• LEED Standards Developed for:

– Core and Shell – Schools– Homes– Neighborhood Development– Commercial Interiors– Existing Buildings: Operation and Maintenance (EBOM)

• Next: LEED 2012

Sustainable Sites Credits (14 points)

Prereq Water Use Reduction1 Water Efficient Landscaping 2 Innovative Wastewater 3 Water Use Reduction (30%- 40%)

Water Efficiency Credits (10 points)

Prereq Construction Pollution Prevention1 Site Selection2 Development Density & Community Connectivity3 Brownfield

4.1 – 4.2 Alternative Transportation5.1 – 5.2 Habitat and Open Space6.1 – 6.2 Stormwater7.1 – 7.2 Heat Island

8 Light Pollution

Current LEED Stormwater Credits 6.1 and 6.2

• Intent– Limit disturbance of natural hydrology – Reduce pollution, eliminate contaminants– Reduce runoff volume

• Peak discharge rate and quantity cannot exceed predevelopment (1- and 2-year 24-hour design storms)

• Remove 80% total suspended solids (TSS)

Few projects achieve quantity control

LEED Shortcomings and the Sustainable Sites Initiative (SITES)

• What if there is no building?• Not comprehensive• Can still do “unsustainable” things

SITES: First national system for sustainable landscapes– ASLA, Lady Bird Johnson, U.S.

Botanic Garden– “Ecosystem Services” concept

LEED Sustainable SitesContinuous Improvement Priorities

Three – Raise the bar of existing SS credits

TIME

IMPA

CT

SUSTAINABLE

PRESENT FUTURE

REGENERATIVE

UNSUSTAINABLE

Green buildings

Conventional buildings

LEED for 2012What is a truly Sustainable Project?

• “Less” Bad?• Environmentally Neutral – no harm?• Regenerative – can a project heal the environment?

Stormwater is a byproduct, butRainwater is a resource.

10

Section 438 of the Energy Independence and Security Act (Dec 2009)

… (Option 1) prevent offsite discharge of the precipitation from all rainfall events less than or equal to the 95th percentile rainfall event.

Design, construct, and maintain stormwater management practices that….. practices that…

… (Option 2) preserve the pre-development runoff conditions following construction.

Retain the 95th

Percentile Rainfall Event

Site-Specific Hydrologic Analysis

OR

EPA’s Direction

OR

Two important observations:

Volume: In SE PA, 96% of the annual rainfall volume from storms 3

inches or less

Frequency: Most of the time, it rains 1 inch or less

Annual Percentage of Volume from Storms

95th Percentile for Select U.S. Cities

Philadelphia 95th Percentile: 1.6”(2-year net increase woods to impervious 2.05” C soils)

Source: Iowa Stormwater Management Manual

Ecological Impact Zone

Rainfall Frequency Spectrum

groundwater rechargepollutant load reduction

control of channel erosion producing events

channel erosion controloverbank control

flood control

Rainwater Partitioning

Precipitation

Green-water

Blue-water (groundwater, rivers, aquifers, lakes, wetlands, and

impoundments)

Transpiration

(productive component in biomass creation)

Evapotranspiration

(non-productive)

Soil Abstraction (moisture in the unsaturated

zone)

Ponding(surface storage)

Source: Stockholm International Water Institute

How Can We Quantify Performance?

• Manage volume for 95th percentile event– Small Storm Hydrology and LID

• Safely convey large events– Rainfall record and continuous simulation

Small Storm Hydrology

Google “Bob Pitt”Click on “Publications”

“Small Storm Hydrology and Why it is Important for the Design of Stormwater Control Practices” Robert Pitt, P.E., Ph.D., DEE Department of Civil and Environmental Engineering The University of Alabama

Design by Land Use and Rainfall Amount

Volume of Runoff = P x Rv x Area

Model My WatershedStroud Water Research Center

A Educational Water Balance Application

usingSmall Storms Hydrology Modeling

Dr. Susan Gill, Stroud Water Research CenterT. Perlman, R. Cheetham, AzaveaMichele Adams, PE, LEED AP, Meliora DesignSteve Benz, PE, LEED AP (BD+C)

LEED 2012 Rainwater Credit

• Intent– Restore and maintain natural hydrology and water

balance– Based on historic Ecosystems of the region– Reduce runoff volume

• Manage on-site runoff using Low Impact Development (LID)– 95th Percentile 2 points– 95th Percentile & maintain Pre-Columbian Levels OR– 98th Percentile 3 points

LEED ® 2012 Rainwater Management

LEED 2012 Update:

www.usgbc.org

Model My Watershed (Stroud Water Research Center):

www.Wiwkiwatershed.org

Contacts:

Dr. Susan Gill, Director of Education, sgill@stroudcenter.orgMichele Adams, P.E. LEED® AP Meliora Design michelea@melioradesign.netSteve Benz, P.E. LEED® AP OLIN sbenz@theolinstudio.com