Add a new option below Case 2. "OR OPTION 2. Percentile Rainfall Events CASE 1. Non-Zero Lot Line Projects In a manner best replicating natural site hydrology1 processes, manage onsite2 the runoff from the developed site for the 95th percentile of regional or local rainfall events using Low Impact Development3 (LID) and green infrastructure4. Use daily rainfall data and the methodology in the United States Environmental Protection Agency's Technical Guidance on Implementing the Stormwater Runoff Requirements for Federal Projects under Section 438 of the Energy Independence and Security Act to determine the 95th percentile amount. OR CASE 2: Zero Lot Line Projects For zero lot line projects located in urban areas with a minimum density of 1.5 FAR (13,800 square meters per hectare net), in a manner best replicating natural site hydrology processes, manage onsite the runoff from the developed site for the 85th percentile of regional or local rainfall events using LID and green infrastructure."
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LEEDuser expert
Michael DeVuono
PE, CPESC, LEED AP BD+C
Arcadis North America
Regional Stormwater Leader
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Credit language
© Copyright U.S. Green Building Council, Inc. All rights reserved.
Requirements
Option 1. Design storms
Case 1. Sites with existing imperviousness 50% or less
Path 1
Implement a stormwater management plan that prevents the postdevelopment peak discharge rate and quantity from exceeding the predevelopment peak discharge rate and quantity for the 1- and 2-year 24-hour design storms. ORPath 2
Implement a stormwater management plan that protects receiving stream channels from excessive erosion. The stormwater management plan must include stream channel protection and quantity control strategies.Case 2. Sites with existing imperviousness greater than 50%
Implement a stormwater management plan that results in a 25% decrease in the volume of stormwater runoff from the 2-year 24-hour design storm.OR
Option 2. Percentile rainfall events
Case 1. Non-zero lot line projects
In a manner best replicating natural site hydrology1 processes, manage onsite2 the runoff from the developed site for the 95th percentile of regional or local rainfall events using Low Impact Development (LID)3 and green infrastructure4. Use daily rainfall data and the methodology in the United States Environmental Protection Agency’s Technical Guidance on Implementing the Stormwater Runoff Requirements for Federal Projects under Section 438 of the Energy Independence and Security Act to determine the 95th percentile amount. ORCASE 2: zero lot line projects
For zero lot line projects located in urban areas with a minimum density of 1.5 FAR (13,800 square meters per hectare net), in a manner best replicating natural site hydrology processes, manage onsite the runoff from the developed site for the 85th percentile of regional or local rainfall events using LID and green infrastructure.1Natural Site Hydrology is defined as the natural land cover function of water occurrence, distribution, movement, and balance.
2Manage Onsite refers to capturing and retaining the specified volume of rainfall to mimic natural hydrologic function. This includes, but is not limited to, strategies that manage volume through evapotranspiration, infiltration, or capture and reuse.
3Low Impact Development (LID) is defined as an approach to managing stormwater runoff that emphasizes on-site natural features to protect water quality by replicating the natural land cover hydrologic regime of watersheds and addressing runoff close to its source. Examples include better site design principles such as minimizing land disturbance, preserving vegetation, minimizing impervious cover, and design practices like rain gardens, vegetated swales and buffers, permeable pavement, rainwater harvesting, and soil amendments. These are engineered practices that may require specialized design assistance.
4Green Infrastructure is a soil and vegetation-based approach to wet weather management that is cost-effective, sustainable, and environmentally friendly. Green infrastructure management approaches and technologies infiltrate, evapotranspire, capture and reuse stormwater to maintain or restore natural hydrologies (US EPA).
Streamlined path available
Achievement of this credit can be documented via a LEED ND v2009 submittal. For more information check out this article.SITES-LEED Equivalency
This LEED credit (or a component of this credit) has been established as equivalent to a SITES v2 credit or component. For more information on using the equivalency as a substitution in your LEED or SITES project, see this article and guidance document.What does it cost?
Cost estimates for this credit
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Our tab contains overall cost guidance, notes on what “soft costs” to expect, and a strategy-by-strategy breakdown of what to consider and what it might cost, in percentage premiums, actual costs, or both.
This information is also available in a full PDF download in The Cost of LEED v4 report.
Learn more about The Cost of LEED v4 »Frequently asked questions
See all forum discussions about this credit »Addenda
10/1/2012 – Updated: 2/14/2015
Global ACP
Description of change:
Campus Applicable
No
Internationally Applicable:
Yes
10/1/2012 – Updated: 2/14/2015
Global ACP
Description of change:
Rename "Option 2" "Path 2"
Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011 – Updated: 2/14/2015
Reference Guide Correction
Description of change:
Revise the third equation box to:Qr = (800 cf / 259,200 sec) = (0.003 cfs or 1.35 gpm)
Campus Applicable
No
Internationally Applicable:
No
10/1/2012 – Updated: 2/14/2015
Global ACP
Description of change:
Add the following footnotes to SSc6.1: Natural Site Hydrology is defined as the natural land cover function of water occurrence, distribution, movement, and balance. 2 Manage Onsite refers to capturing and retaining the specified volume of rainfall to mimic natural hydrologic function. This includes, but is not limited to, strategies that manage volume through evapotranspiration, infiltration, or capture and reuse. 3 Low Impact Development (LID) is defined as an approach to managing stormwater runoff that emphasizes on-site natural features to protect water quality by replicating the natural land cover hydrologic regime of watersheds and addressing runoff close to its source. Examples include better site design principles such as minimizing land disturbance, preserving vegetation, minimizing impervious cover, and design practices like rain gardens, vegetated swales and buffers, permeable pavement, rainwater harvesting, and soil amendments. These are engineered practices that may require specialized design assistance. 4 Green Infrastructure is a soil and vegetation-based approach to wet weather management that is cost-effective, sustainable, and environmentally friendly. Green infrastructure management approaches and technologies infiltrate, evapotranspire, capture and reuse stormwater to maintain or restore natural hydrologies (US EPA).
Campus Applicable
No
Internationally Applicable:
Yes
10/1/2012 – Updated: 2/14/2015
Global ACP
Description of change:
Add a heading for "Option 1. Design Storms" before Case 1.
Campus Applicable
No
Internationally Applicable:
Yes
10/1/2012 – Updated: 2/14/2015
Global ACP
Description of change:
Rename "Option 1" "Path 1"
Campus Applicable
No
Internationally Applicable:
Yes
11/1/2011
LEED Interpretation
Inquiry:
How can a project earn exemplary performance for Stormwater Quantity and Quality?
Ruling:
The exemplary performance requirements for SSc6.1 Stormwater Quantity and SSc6.2 Stormwater Quality listed in the LEED Green Building Design & Construction Reference Guide call for (1) a comprehensive approach to capture and treat stormwater runoff and (2) demonstrated performance above and beyond the credit requirements. To expand and clarify what these two requirements refer to, the following additional guidance is provided.SSc6.1 Stormwater QuantityTo demonstrate a comprehensive approach and performance above and beyond the credit requirements, the stormwater management strategies must:1. Address runoff from the entire development footprint of the site using Low Impact Development (LID) practices. 2. Achieve the following stormwater quantity performance:a. Case 1, Option 1: Achieve a post-development peak discharge rate and quantity that is equivalent to those calculated for the natural land cover site conditions.b. Case 1, Option 2: No EP available for his compliance path.c. Case 2: Achieve a 50% reduction in the volume of runoff during the 2-year 24-hour design storm.LID is defined as an approach to managing stormwater runoff that emphasizes on-site natural features to protect water quality by replicating the natural hydrologic regime of watersheds and addressing runoff close to its source. Examples include better site design principles such as minimizing land disturbance, preserving vegetation, minimizing impervious cover, and design practices like rain gardens, vegetated swales and buffers, permeable pavement, and soil amendments. These are engineered practices that may require specialized design assistance.SSc6.2 Stormwater QualityTo demonstrate a comprehensive approach and performance above and beyond the credit requirements, the best management practices employed must be non-structural, conforming to LID practices as defined above, and should be designed to remove at least 80% of the average annual total suspended solids (TSS) from twice the rainfall volume required for the base credit (i.e, runoff generated from 1 inch of rain in an arid climate, 1.5 inches of rain in a semiarid climate, and 2 inches of rain in a humid climate).To document compliance with these requirements, a detailed narrative or stormwater management plan summary should be provided that describes the exemplary performance approach and includes calculations that clearly highlight compliance with the exemplary performance requirements. As the exemplary performance requirements for these two credits overlap considerably, only one SSc6 EP point is available to projects. Applicable internationally.
Campus Applicable
No
Internationally Applicable:
Yes
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© Copyright U.S. Green Building Council, Inc. All rights reserved.
Requirements
Option 1. Design storms
Case 1. Sites with existing imperviousness 50% or less
Path 1
Implement a stormwater management plan that prevents the postdevelopment peak discharge rate and quantity from exceeding the predevelopment peak discharge rate and quantity for the 1- and 2-year 24-hour design storms. ORPath 2
Implement a stormwater management plan that protects receiving stream channels from excessive erosion. The stormwater management plan must include stream channel protection and quantity control strategies.Case 2. Sites with existing imperviousness greater than 50%
Implement a stormwater management plan that results in a 25% decrease in the volume of stormwater runoff from the 2-year 24-hour design storm.OR
Option 2. Percentile rainfall events
Case 1. Non-zero lot line projects
In a manner best replicating natural site hydrology1 processes, manage onsite2 the runoff from the developed site for the 95th percentile of regional or local rainfall events using Low Impact Development (LID)3 and green infrastructure4. Use daily rainfall data and the methodology in the United States Environmental Protection Agency’s Technical Guidance on Implementing the Stormwater Runoff Requirements for Federal Projects under Section 438 of the Energy Independence and Security Act to determine the 95th percentile amount. ORCASE 2: zero lot line projects
For zero lot line projects located in urban areas with a minimum density of 1.5 FAR (13,800 square meters per hectare net), in a manner best replicating natural site hydrology processes, manage onsite the runoff from the developed site for the 85th percentile of regional or local rainfall events using LID and green infrastructure.1Natural Site Hydrology is defined as the natural land cover function of water occurrence, distribution, movement, and balance.
2Manage Onsite refers to capturing and retaining the specified volume of rainfall to mimic natural hydrologic function. This includes, but is not limited to, strategies that manage volume through evapotranspiration, infiltration, or capture and reuse.
3Low Impact Development (LID) is defined as an approach to managing stormwater runoff that emphasizes on-site natural features to protect water quality by replicating the natural land cover hydrologic regime of watersheds and addressing runoff close to its source. Examples include better site design principles such as minimizing land disturbance, preserving vegetation, minimizing impervious cover, and design practices like rain gardens, vegetated swales and buffers, permeable pavement, rainwater harvesting, and soil amendments. These are engineered practices that may require specialized design assistance.
4Green Infrastructure is a soil and vegetation-based approach to wet weather management that is cost-effective, sustainable, and environmentally friendly. Green infrastructure management approaches and technologies infiltrate, evapotranspire, capture and reuse stormwater to maintain or restore natural hydrologies (US EPA).
Streamlined path available
Achievement of this credit can be documented via a LEED ND v2009 submittal. For more information check out this article.SITES-LEED Equivalency
This LEED credit (or a component of this credit) has been established as equivalent to a SITES v2 credit or component. For more information on using the equivalency as a substitution in your LEED or SITES project, see this article and guidance document.LEEDuser expert
Michael DeVuono
PE, CPESC, LEED AP BD+C
Arcadis North America
Regional Stormwater Leader
