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LEED BD+C: Core and Shell | v3 - LEED 2009

Rainwater management

SSpc16 | Possible 1 point

Intent

Pilot Credit Closed

This pilot credit is closed to new registrations

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.

Requirements

* This credit language is drawn from the LEED v4 draft. Where other point totals are noted, this pilot credit is worth 1 point in total. *

Option 1. Percentile of rainfall events
Path 1. 95th percentile (2 points except Healthcare, 1 point Healthcare)

In a manner best replicating natural site hydrology processes, manage on site the runoff from the developed site for the 95th percentile of regional or local rainfall events using low-impact development (LID) and green infrastructure.

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 95th percentile amount.

OR
Path 2. 98th percentile (3 points except Healthcare, 2 points Healthcare)

Achieve Path 1 but for the 98th percentile of regional or local rainfall events, using LID and green infrastructure.

OR
Path 3. Zero lot line projects only – 85th Percentile (3 points except Healthcare, 2 points Healthcare))

The following requirement applies to zero lot line projects in urban areas with a minimum density of 1.5 FAR. In a manner best replicating natural site hydrology processes, manage on site the runoff from the developed site for the 85th percentile of regional or local rainfall events, using LID and green infrastructure.

OR

Option 2. Natural land cover conditions (3 points except Healthcare, 2 points Healthcare)

Manage on site the annual increase in runoff volume from the natural land cover condition to the postdeveloped condition.

Path 1.

Achieve Option 1 and manage on site the annual increase in runoff volume from the natural land cover condition to the postdeveloped condition.

OR

Path 2.

Achieve Option 1 but for the 98th percentile of regional or local rainfall events, using LID and green infrastructure.

Zero lot line projects only (3 points)

The following requirement applies to zero lot line projects in urban areas with a minimum density of 1.5 FAR. In a manner best replicating natural site hydrology processes, manage on site the runoff from the developed site for the 85th percentile of regional or local rainfall events, using LID and green infrastructure.

Projects that are part of a multitenant complex only
The credit requirements may be met using a coordinated approach affecting the defined project site that is within the master plan boundary. Distributed techniques based on a watershed approach are then required.

Credit specific

Option 1:

  • Provide a narrative describing the proposed practices to be implemented on the project site and what qualifies these strategies as LID or green infrastructure techniques that best replicate natural site hydrology processes.
  • Provide any applicable specifications, drawings, and storage and infiltration calculations of the LID practices utilized on site.
  • Provide calculations showing the 95th percentile regional or local rainfall event amount and how the runoff is managed onsite by these practices.

Option 2 – Path 1:
In addition to the submittals listed in Option 1, provide any applicable specifications, drawings, and water balance calculations describing natural site hydrology and post-development partitioning of annual rainfall volumes. Natural site hydrology conditions can be determined using a combination of pre-settlement vegetation maps and soil maps. Where detailed pre-settlement vegetation maps do not exist, typical land cover for the project’s EPA Level IV Ecoregion can be used.

Option 2 – Path 2:
Provide all submittals listed in Option 1 for the 98th percentile regional or local rainfall event.

Zero Lot Line Projects:

  • Provide all submittals listed above, but for the 85th percentile threshold.
  • Provide density calculations or density information from the municipality in which the project is located.

Retail NC Projects:

  • Provide all submittals listed above.
  • Provide a narrative describing the distributed techniques and watershed approach, if used.
Additional questions:
  1. The goal is to replicate the natural hydrology and water balance of the site. What obstacles make this difficult? Obstacles may or may not be specific to the proposed credit requirements.
  2. What climate data source is most applicable for your area?
Changes:
  • 1/15/2013: update with SSc4 from LEED v4 draft

    • BD+C: wording changes, the Stormwater Calculator methodology was removed
    • EBOM: Revised requirements to allow for rwm practices currently in place on the EBOM project, and to make the credit more performance-based
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