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USGBC
Excerpted from LEED 2009 for Neighborhood Development
SLL Credit 6: Steep slope protection
Intent
To minimize erosion to protect habitat and reduce stress on natural water systems by preserving steep slopes in a natural, vegetated state.
Requirements
FOR ALL PROJECTS
All options apply to existing natural or constructed slopes. Portions of project sites with slopes up to 20 feet in elevation, measured from toe (a distinct break between a 40% slope and lesser slopes) to top, that are more than 30 feet in any direction from another slope greater than 15% are exempt from the requirements, although more restrictive local regulations may apply.
OPTION 1. No Disturbance of Slopes Over 15%
Locate on a site that has no existing slopes greater than 15%, or avoid disturbing portions of the site that have existing slopes greater than 15%.
OR
OPTION 2. Previously Developed Sites with Slopes Over 15%
On portions of previously developed sites with existing slopes greater than 15%, restore the slope area with native plants or noninvasive adapted plants according to Table 1.
Table 1. Required restoration area of slope
Slope Restoration > 40% 100% 26% to 40% 60% 15% to 25% 40%
In addition, develop ; development agreements; or other binding documents that will protect the specified steep slope areas in perpetuity. Comply with the requirements of Option 3 on any slope over 15% that has not been previously developed.
OR
OPTION 3. Sites Other than Previously Developed Sites with Slopes Over 15%
On sites that are not previously developed sites, protect existing slopes over 15% as follows:
- Do not disturb slopes greater than 40% and do not disturb portions of the project site within 50 feet horizontally of the top of the slope and 75 feet horizontally from the toe of the slopeWhere there is a distinct break between a 40% slope and lesser slopes..
- Limit development to no more than 40% of slopes between 25% and 40% and to no more than 60% of slopes between 15% and 25%.
- Locate development such that the percentage of the development footprintThe development footprint is the total area of the building footprint and area affected by development or by project site activity. Hardscape, access roads, parking lots, nonbuilding facilities, and the building itself are all included in the development footprint. that is on existing slopes less than 15% is greater than the percentage of buildable landThe portion of the site where construction can occur. When used in density calculations, the calculation for buildable land excludes: public streets and other public rights of way, and land excluded from development by law or other prerequisites of LEED for Neighborhood Development. that has existing slopes less than 15%.
- Develop CC&R, development agreements, or other binding documents that will protect steep slopes in perpetuity.
Potential Technologies & Strategies
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8 Comments
buidable land
Hi,
Is the definition of buildable landThe portion of the site where construction can occur. When used in density calculations, the calculation for buildable land excludes: public streets and other public rights of way, and land excluded from development by law or other prerequisites of LEED for Neighborhood Development. under LEED-ND identical to the following statement quoted from http://www.ci.blaine.mn.us/index2col.cfm?id=901246?
"The space remaining on a lot after the minimum setback, drainage provisions, ponding, compensatory storage, soils, open space and other site constraint requirements of this ordinance have been met."
No. Under LEED-ND, "an applicant may exclude additional land not exceeding 15% of the buildable landThe portion of the site where construction can occur. When used in density calculations, the calculation for buildable land excludes: public streets and other public rights of way, and land excluded from development by law or other prerequisites of LEED for Neighborhood Development. base defined, provided that the land is protected from residential and nonresidential construction by easement, deed restriction, or other enforceable legal instrument."
http://new.usgbc.org/glossary/term/4287
For reference, here's the full LEED-ND definition of Buildable LandThe portion of the site where construction can occur. When used in density calculations, the calculation for buildable land excludes: public streets and other public rights of way, and land excluded from development by law or other prerequisites of LEED for Neighborhood Development.: "the portion of the site where construction can occur, including land voluntarily set aside and not constructed upon. When used in density calculations, buildable land excludes public rights-of-way and land excluded from development by codified law or LEED for Neighborhood Development prerequisites. An applicant may exclude additional land not exceeding 15% of the buildable land base defined above, provided the following conditions are present:
c. The land is protected from residential and nonresidential construction by easement, deed restriction, or other enforceable legal instrument.
AND
d. Either 25% or more of the boundary of each contiguous parcel proposed for exclusion borders a water body or areas outside the project boundary that are protected by codified law; or ownership of, or management authority over, the exclusion area is transferred to a public entity."
Eliot
Abril and Eliot,
Thank you for the information.
Is it correct to say that building-to-land ratio and buildable landThe portion of the site where construction can occur. When used in density calculations, the calculation for buildable land excludes: public streets and other public rights of way, and land excluded from development by law or other prerequisites of LEED for Neighborhood Development. are the same before the exclusions?
In Japan, the building-to-land ratio may change depending on the fire-proofing of the building in certain areas. Would it be wise to count the worst number (smaller buildable land) in this case?
Thanks in advance.
Noriko, the definition of "buildable landThe portion of the site where construction can occur. When used in density calculations, the calculation for buildable land excludes: public streets and other public rights of way, and land excluded from development by law or other prerequisites of LEED for Neighborhood Development." is given earlier in this string. The term "building-to-land ratio" isn't used in ND, but maybe you mean "floor area ratioFloor Area Ratio (FAR) is the measure of the density of non-residential land use. It is the total non-residential building floor area divided by the total buildable land area available for non-residential uses. For example, on a site with 10,000 square feet of buildable land area, an FAR of 1.0 would be 10,000 square feet of built building floor area. On the same site, an FAR of 1.5 would be 15,000 square feet of built floor area; an FAR of 2.0 would be 20,000 built square feet and an FAR of 0.5 would be 5,000 built square feet.," which is non-residential building floor area divided by non-residential building land area. Can you clarify your question in relation to SLLc6?
Eliot
Hi Eliot,
Thank you for the additional information. This question is not specifically related to SLLc6. Sorry for posting it here.
We were interpreting the definition of "buildable landThe portion of the site where construction can occur. When used in density calculations, the calculation for buildable land excludes: public streets and other public rights of way, and land excluded from development by law or other prerequisites of LEED for Neighborhood Development." as applied to all single sites inside the neighborhood and not the the whole ND project as a site. If my understanding is correct now, the "buildable land" is not affected by the regional regulations that define the maximum built area of each single site.
The "floor area ratioFloor Area Ratio (FAR) is the measure of the density of non-residential land use. It is the total non-residential building floor area divided by the total buildable land area available for non-residential uses. For example, on a site with 10,000 square feet of buildable land area, an FAR of 1.0 would be 10,000 square feet of built building floor area. On the same site, an FAR of 1.5 would be 15,000 square feet of built floor area; an FAR of 2.0 would be 20,000 built square feet and an FAR of 0.5 would be 5,000 built square feet." term is used in Japan as well (for both residential and non-residential uses).
You're correct, Noriko. The 'buildable landThe portion of the site where construction can occur. When used in density calculations, the calculation for buildable land excludes: public streets and other public rights of way, and land excluded from development by law or other prerequisites of LEED for Neighborhood Development.' calculation is done for the entire project site, not individual building sites within the project.
Eliot
Thank you very much!
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