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LEED v4.1
Healthcare
Sustainable Sites
Rainwater Management

LEED CREDIT

Healthcare-v4.1 SSc4: Rainwater management 1-2 points

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View the LEED v4 version of this credit »

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Michael DeVuono

PE, CPESC, LEED AP BD+C

Arcadis North America
Regional Stormwater Leader

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Requirements

Option 1. Percentile of Rainfall Events (1-3 points except Healthcare, 1-2 points Healthcare)
In a manner best replicating natural site hydrology processes, retain on site the runoff from the associated percentile of regional or local rainfall events. The percentile event volume must be retained (i.e. infiltrated, evapotranspirated, or collected and reused) using low-impact development (LID)/green infrastructure (GI) practices. GI and LID strategies can be either structural or non-structural. Points are awarded according to Table 1.

Table 1. Points for percentile of rainfall retained
All Projects Zero Lot Line Projects Points Points (Healthcare)
80th Percentile 70th Percentile 1 1
85th Percentile 75th Percentile 2 2
90th Percentile 80th Percentile 3 -
OR
Option 2. Natural land cover conditions (3 points except Healthcare, 2 points Healthcare)
Calculate the difference between the projected runoff volume under the proposed design conditions and the runoff volume under natural land cover conditions that existed prior to any disturbance. Retain (i.e. infiltrate, evapotranspirate, or collect and reuse) on site the increase in runoff volume using LID and GI practices. See all forum discussions about this credit »

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Addenda

4/9/2021Updated: 4/20/2021
Rating System Correction
Description of change:
Revise the below SS credit intents as follows:

SSp Construction Activity Pollution Prevention
"To reduce pollution from construction activities by controlling soil erosion, waterway sedimentation, and airborne dust that disproportionately impact frontline communities."

SSc Site Assessment
"To assess site conditions, environmental justice concerns, and cultural and social factors, before design to evaluate sustainable options and inform related decisions about site design."

SSc Rainwater Management
"To reduce runoff volume and improve water quality by replicating the natural hydrology and water balance of the site, based on historical conditions and undeveloped ecosystems in the region to avoid contributing to flooding downstream in frontline communities."

SSc Heat Island Reduction
"To minimize inequitable effects on microclimates and human, especially frontline communities, and wildlife habitats by reducing heat islands."

SSc Places of Respite
"To provide patients, all staff, and visitors with the health benefits of the natural environment by creating outdoor places of respite on the healthcare campus."

SSc Direct Exterior Access
"To provide patients, all staff, and visitors with the health benefits of the natural environment by creating outdoor places of respite on the healthcare campus."
Campus Applicable
No
Internationally Applicable:
No
11/9/2020Updated: 2/3/2021
Form Update
Description of change:
The following changes were made to the form:

1. Radio buttons at the top for projects to indicate whether they are using IP or SI units.
2. Options re-titled "Option 1. Percentile of rainfall events" and "Option 2. Natural landcover conditions"
3. Radio buttons under Option 1 re-titled: "All projects" and "Zero lot line projects".
4. Add descriptions under 3 uploads included under "All Projects"
5. The checkbox regarding coal tar sealants was removed as it is no longer a requirement 
6. The sidebar note underneath the LID narrative revised to say the following: "In contrast to LID, conventional management techniques include grey infrastructure devices and hard runoff conveyance systems, such as detention or retention ponds, pipes, culverts and vaults. Conventional grey infrastructure devices can be compliant if implemented as a component of LID/GI systems to meet the requirements of this credit."
7. Under Option 2. Natural landcover conditions, the following uploads were added: 
- Rainfall Events Calculator: Provide the completed Rainfall Events Calculator (found under the credit's "Resources" tab in the Credit Library) or equivalent documentation. 
- Natural Land Cover Documentation: Provide documents, such as natural land cover condition maps and/or calculations (rate and volume based on natural land cover), that demonstrate the natural annual runoff volume.
8. The "For projects that are part of a multitenant complex" section was removed.
9. Zero-Lot Line project > the sidebar note "FAR must be at least 1.5 to qualify for this path" was removed as it is no longer applicable.
Campus Applicable
No
Internationally Applicable:
No
11/9/2020Updated: 11/30/2020
Rating System Correction
Description of change:
1. Remove the first sentence, "Treat run-off from pollutant-generating impervious surfaces (i.e. vehicle pavement, service courts, trash enclosures) using low-impact development (LID) practice"
2. Insert "Option 1" before the header "Percentile of Rainfall Events".
3. In the first paragraph under the Option 1 header, remove: "(i.e. infiltrate, evapotranspirate, or collect and reuse)" Replace the language "developed site for, at minimum, the 80th percentile" with "associated percentile". After the first sentence in this paragraph, include "The percentile event volume must be retained (i.e. infiltrated, evapotranspirated, or collected and reused)".
4. Remove the coal tar sealant prohibition in the second paragraph under Option 1.
5. Remove the bulleted list of examples of acceptable LID techniques.
6. Remove the paragraph below the bulleted list, containing language permitting conventional grey infrastructure only in combination of LID approaches.
7. Remove the paragraph containing language referring to the EPA daily rainfall methodology.
8. Revise Table 1 to include zero lot line thresholds (70th, 75th, 80th percentile for 1, 2, and 3 points respectively; 1-2 points for Healthcare).
9. The entire "Zero Lot Line projects" section should be removed.
10. Add "OR" after Option 1 requirements.
11. Include "Option 2. Natural land cover conditions (3 points except Healthcare, 2 points Healthcare)" after "OR" with the following requirements: "Calculate the difference between the projected runoff volume under the proposed design conditions and the runoff volume under natural land cover conditions that existed prior to any disturbance. Retain (i.e. infiltrate, evapotranspirate, or collect and reuse) on site the increase in runoff volume using LID and GI practices."
Campus Applicable
No
Internationally Applicable:
No
11/9/2020Updated: 11/30/2020
Reference Guide Correction
Description of change:
1. Under the Behind the Intent section, in the first sentence, remove "to make this credit more achievable."

2. Under the Behind the Intent, revise the second paragraph to read "Thresholds" rather than "Requirements" for zero lot line projects. The following sentence should also be added to the end of the paragraph: "New exemplary performance thresholds for all projects have been added, including exemplary performance under Option 2. Natural landcover conditions which rewards projects for fostering resilience by designing for future precipitation conditions."

3. Remove the first bullet under Step-by-Step Guidance and the following bullets:
 Option 1, Step 2. Obtain Rainfall Data for Project Location: Use daily rainfall data and the methodology in the U.S. Environmental Protection Agency (EPA) Technical Guidance on Implementing the Stormwater Runoff Requirements for Federal Projects under Section 438 of the Energy Independence and Security Act to determine the percentile amount to be retained.
 Option 1, Step 2. Obtain Rainfall Data for Project Location: Once you've gathered the rainfall events data, any rainfall events less than or equal to 0.1 inches should be omitted.
 Option 1, Step 7. Conventional grey infrastructure devices and hard runoff conveyance systems, such as detention or retention ponds, pipes, culverts and vaults, can be compliant if used as a component of LID/GI systems to meet the requirements of this credit.

4. The following bullets should be included following the "Further Explanation" header:
 Examples of acceptable LID techniques include the following:
• planting rain gardens with native or adapted plant material (e.g. trees or shrubs);
• installing a vegetated roof;
• using permeable paving, consisting of porous above-ground materials (e.g., open pavers, engineered products), a base layer designed to drain water away from the building, and (often) a 6-inch-deep (150 millimeters) subbase; and
• installing permanent infiltration or collection features (e.g., vegetated swale, rain garden, rainwater cistern) that can retain the runoff from the associated percentile of regional or local rainfall events.
 Treatment of Runoff:
Projects teams should consider prioritizing infiltration of runoff from impervious surfaces considered to be a significant source of pollutants in rainwater runoff. Such surfaces include those which are subject to: vehicular use; industrial activities; or storage of erodible or leachable materials, wastes, or chemicals and which receive direct rainfall or the run-on of rainfall.

5. The following sentence should be included following Further Explanation>Green Infrastructure and Low-impact Development Strategies: "Employ LID and GI strategies that mimic the natural infiltration-based, groundwater-driven hydrology of the site."

6. The sentence under Further Explanation>Project Type Variations, zero lot line projects should be removed and replaced with the following: "Any setback area resulting from a planned below-grade space, such as an underground parking garage, does not void a project’s zero lot line status so long as the setback area is designed as pedestrian-oriented amenity space, such as outdoor seating."

7. An "Exemplary Performance" section should be included under "Referenced Standards". For Option 1, a table should be included indicating that EP for All Projects is 98th percentile and EP for zero lot line projects is 95th percentile. A second bullet should be included for Option 2. Natural landcover conditions, and the following EP language should be included underneath: "Retain on site an additional 20% in runoff volume to address future precipitation rates (1.2 * [difference in annual runoff volume from the natural landcover to the post-developed condition]) using LID and GI practices."

8. The v4.1 Definitions section should be revised to only include the following definition: " retain (rainwater) on site to capture and reserve a specified volume of rainfall to mimic natural hydrologic function. Retention is a function of rainwater management that includes strategies involving evapotranspiration, infiltration, and capture and reuse."
Campus Applicable
No
Internationally Applicable:
No
7/25/2019Updated: 11/6/2020
Reference Guide Correction
Description of change:
Update the definition of a zero lot line project to the following:
"a project whose building footprint, exclusive of any required setbacks or easements (such as rights-of-way), rests directly on, or nearly aligns with, the LEED project boundary on multiple sides and covers at least 90% of the total site area."
Campus Applicable
No
Internationally Applicable:
Yes
4/10/2020Updated: 4/17/2020
Form Update
Description of change:
Updated to fix cell reference in the Historical Data tab
Campus Applicable
No
Internationally Applicable:
No
11/8/2019Updated: 11/8/2019
Form Update
Description of change:
Rainfall Events calculator published
Campus Applicable
No
Internationally Applicable:
Yes
7/25/2019Updated: 7/29/2019
Rating System Correction
Description of change:
Edit all point values (except healthcare) to 1-3 points. Healthcare should be 1-2 points.
Campus Applicable
No
Internationally Applicable:
Yes
1/1/2019Updated: 6/26/2019
Rating System Correction
Description of change:
"Percentile of Rainfall Events" associated points are (1-3 points except Healthcare, 1-2 points Healthcare)
Campus Applicable
No
Internationally Applicable:
No
See all forum discussions about this credit »

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LEEDuser expert

Michael DeVuono

PE, CPESC, LEED AP BD+C

Arcadis North America
Regional Stormwater Leader

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© Copyright U.S. Green Building Council, Inc. All rights reserved.

Requirements

Option 1. Percentile of Rainfall Events (1-3 points except Healthcare, 1-2 points Healthcare)
In a manner best replicating natural site hydrology processes, retain on site the runoff from the associated percentile of regional or local rainfall events. The percentile event volume must be retained (i.e. infiltrated, evapotranspirated, or collected and reused) using low-impact development (LID)/green infrastructure (GI) practices. GI and LID strategies can be either structural or non-structural. Points are awarded according to Table 1.

Table 1. Points for percentile of rainfall retained
All Projects Zero Lot Line Projects Points Points (Healthcare)
80th Percentile 70th Percentile 1 1
85th Percentile 75th Percentile 2 2
90th Percentile 80th Percentile 3 -
OR
Option 2. Natural land cover conditions (3 points except Healthcare, 2 points Healthcare)
Calculate the difference between the projected runoff volume under the proposed design conditions and the runoff volume under natural land cover conditions that existed prior to any disturbance. Retain (i.e. infiltrate, evapotranspirate, or collect and reuse) on site the increase in runoff volume using LID and GI practices.

LEEDuser expert

Michael DeVuono

PE, CPESC, LEED AP BD+C

Arcadis North America
Regional Stormwater Leader

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