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Guideline S.4 Sustainable Vegetation Design

Intent

To restore natural areas and ensure the conservation of existing site features during planning and construction so the site can sustain its water, soil, and plant cover functions and promote biodiversity of both net and viable species populations.

Required Performance Criteria

Guidelines apply to all projects designated New Buildings and for all Major Renovations that include area of site disturbance that is greater than 3,000 square feet or area of imperviousness (footprint of building plus site impervious area) renovated that is greater than 2,000 square feet.

  1. On previously developed sites: maintain or improve natural site functions and biodiversity for 50% of site area (excluding building footprint) in accordance with existing conditions and surrounding site context.
  2. On all sites: A minimum of 75% of total vegetated area on the site must be native to the local area. In addition, a minimum of 75% of all trees and shrubs, by quantity, are to be native material. Native is defined as a plant which originates from within a 200-mile radius of the site without human intervention. Cultivars may be used if they do not appear on the Minnesota Native Plant Society or University of Minnesota Extension Service “Invasive” or “Species of Concern” lists. Exception: Do not remove existing, non-invasive vegetation solely in order to achieve this threshold.
  3. Maintain or supplement tree trunk area of site so that there is no net loss of tree trunk area (square inches) at diameter at breast height (dbh = 4.5 feet) (Reference: International Society of Arboriculture (ISA) measurement tree area ratio for translating dbh to caliper.) Pre-project tree trunk area may disregard existing trees less than 6 inches in diameter. Replaced tree trunk area may include trees of any diameter.
  4. If the site selected did not completely avoid (per Guideline S.1A) land of national, state, regional, or local natural resource and biological/ecological significance as identified in national, state, regional, or local natural resources inventories, assessments, and biological surveys and an associated 150-foot buffer zone, then for the portions of this site that include this type of land, create and implement a protection and maintenance plan that follows Minnesota County Biological Survey (CBS) guidelines and with CBS staff input before any site work is done.
  5. If the site selected did not completely avoid (per Guideline S.1C) land with elevation lower than 5 feet above the elevation of the 100-year flood as indicated by the local watershed district, watershed management organization, or joint powers organization and an associated 50-foot buffer zone, then for the portions of this site that include this type of land, create and implement a protection and maintenance plan that follows BWSR guidelines and with BWSR staff input before any site work is done.
  6. If the site selected did not completely avoid (per Guideline S.1D) land (including a 300-foot buffer zone) which provides habitat for any animal or plant species on the federal or state threatened or endangered list, and/or if the site provides habitat for any rare animals or plant species, using the Minnesota County Biological Survey (CBS), then create and implement a protection and maintenance plan that follows CBS guidelines and with CBS staff input before any site work is done.
  7. Determine if the vegetation on site includes invasive species using the Invasive Species County Weed Guideline. If the site does contain invasive species, create or implement a mitigation and maintenance plan as defined by the Minnesota Department of Agriculture.
  8. Promote pollinator health. Do not select neonicotinoid-applied plants. Include in specifications of site establishment, maintenance and operations the requirement of non-use of neonicotinoid pesticide products. Select plantings that are pollinator friendly as listed in the resources below.

Recommended Performance Criteria

  1. On previously developed sites: Maintain or improve natural site functions and biodiversity for 90% of site area in accordance with existing conditions and surrounding site context.

Implementation in the Design Process:

Select a site where the proposed building and infrastructure will have minimal disturbance on the existing vegetation and the supporting soil and hydrologic conditions that support it. Identify areas of vegetation or high quality areas for restoration that will be protected or restored during the design and construction process.

Through the design process, integrate techniques that minimize negative impacts on soil, water, and vegetation on the site and adjacent sites that are to be preserved or restored. Develop details and specifications that support the use of native plantings, maintain existing biodiversity, and promote enhancement of site conditions per the B3 Guidelines.

Hold a preconstruction meeting to identify requirements for protection/preservation of vegetation during and after the construction process. Monitor submittals for compliance with plans and details. Make bidders aware of specific responsibilities for integrating the onsite vegetation management with connections to vegetation on adjacent sites. Ensure that existing plants and trees indicated to remain are protected, and maintain or improve soil and water conditions to promote and improve vegetation growth.

Create an operation and maintenance manual to protect and maintain onsite vegetation. Document the existing conditions of the vegetation, the reason why it was preserved or enhanced, and its ability to function in its current capacity. Note what enhancements, and what enlargements or reductions in spatial area, would be needed to accommodate a different building type in the future.

Pollinator friendly planting list:

Select pollinator friendly planting from the list below for compliance with S.4H:

DNR Pollinator Best Management Practices and Habitat Restoration Guidelines: http://files.dnr.state.mn.us/natural_resources/npc/2014_draft_pollinator_bmp_guidelines.pdf

University of Minnesota Bee Lab “Plants for Minnesota Bees” https://beelab.umn.edu/help-bees/actions-help-bees/plant-bee-flowers

Calculations:

S.4C: 90% of the 30-year maturity-level area may be used if and only if the following two conditions are met:

  • Condition 1 – Minimum soil volume – 1,000 cubic feet per tree is provided for trees individually planted, or 600 cubic feet per tree for trees in shared soil. For structural soils this volume must be multiplied by a factor of 5.
  • Condition 2 – Minimum area of catchment sloped to tree soil – 1,000 square feet of impervious surface or 3,000 square feet of turf (or similar); this area can be prorated for partially impervious areas.

Design:

  • S.4A: Amount of non-building site area with natural site functions and biodiversity pre-project.
  • S.4B: Amount of non-building site area with native species pre-project.
  • S.4C: Amount of tree-trunk area and percent site area of tree canopy pre-project.
  • S.4D: Verification of implementation of protection plan (if Guideline S.1A is not met).
  • S.4E: Verification of implementation of protection plan (if Guideline S.1C is not met).
  • S.4F: Verification of implementation of protection plan (if Guideline S.1D is not met).
  • S.4G: Identification if invasive species are present onsite.
  • S.4H: Verification of selection of pollinator friendly plantings.
  • S.4I: Amount of non-building site area with natural site functions and biodiversity pre-project.

Final Design:

  • S.4A: Verification that the amount of site area with natural site functions and biodiversity pre- and post-project meets 50% threshold.
  • S.4B: Amount of non-building site area with native species pre and post-project meeting 75% threshold.
  • S.4C: Amount of tree-trunk area and percent site area of tree canopy pre and post-project demonstrating no loss in tree trunk area or canopy.
  • S.4D: Verification of implementation of protection plan (if Guideline S.1A is not met).
  • S.4E: Verification of implementation of protection plan (if Guideline S.1C is not met).
  • S.4F: Verification of implementation of protection plan (if Guideline S.1D is not met).
  • S.4G: Verification of implementation of mitigation plan if invasive species are present onsite.
  • S.4H: Verification of selection of pollinator friendly plantings.
  • S.4I: Amount of site area with natural site functions and biodiversity pre and post-project meeting 90% threshold.

Closeout:

  • S.4A: Verification of final construction site area with natural site functions and biodiversity pre- and post-project meeting 50% threshold and verification that the site contractor understands the requirements and intent of this guideline
  • S.4B: Verification of final construction non-building site area with native species pre- and post-project meeting 75% threshold and verification that the site contractor understands the requirements and intent of this guideline
  • S.4C: Verification of final construction tree-trunk area and percent site area of tree canopy pre- and post-project demonstrating no loss in tree trunk area or canopy and verification that the site contractor understands the requirements and intent of this guideline.
  • S.4D: Verification of implementation of protection plan (if Guideline S.1A is not met) and verification that the site contractor understands the intent of this guideline.
  • S.4E: Verification of implementation of protection plan (if Guideline S.1C is not met) and verification that the site contractor understands the intent of this guideline.
  • S.4F: Verification of implementation of protection plan (if Guideline S.1D is not met) and verification that the site contractor understands the intent of this guideline.
  • S.4G: Verification of implementation of mitigation plan if invasive species are present onsite and verification that the site contractor understands the intent of this guideline.
  • S.4H: Verification of planting of pollinator friendly plantings and verification that the site contractor understands the intent of this guideline.
  • S.4I: Verification of final construction site area with natural site functions and biodiversity meeting 90% threshold and verification that the site contractor understands the requirements and intent of this guideline.

USDA Electronic Field office Technical Guide (eFOTG): https://www.nrcs.usda.gov/resources/guides-and-instructions/field-office-technical-guides

Seeding Manual – Latest Edition, Mn/DOT Office of Environmental Services, Turf Establishment & Erosion Control Unit https://www.dot.state.mn.us/environment/erosion/vegetation.html

The Minnesota County Biological Survey: https://www.dnr.state.mn.us/eco/mbs/index.html

United States Dept. of Agriculture, Natural Resources Conservation Service, Engineering Field Handbook: https://directives.sc.egov.usda.gov/viewerFS.aspx?hid=21429

Xerces Society Pollinator Conservation: http://xerces.org/pollinator-conservation/

DNR Pollinator Best Management Practices and Habitat Restoration Guidelines: http://files.dnr.state.mn.us/natural_resources/npc/2014_draft_pollinator_bmp_guidelines.pdf

University of Minnesota Bee Lab “Plants for Minnesota Bees”: https://beelab.umn.edu/help-bees/actions-help-bees/plant-bee-flowers

Minnesota Department of Agriculture, Invasive Species: https://directives.sc.egov.usda.gov/viewerFS.aspx?hid=21429

International Society of Arboriculture: www.isa-arbor.com/publications/tree-ord/ordprt3d.aspx

Board of Water and Soil Resources: https://bwsr.state.mn.us/

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