C4.4: Conserve Healthy Soils and Appropriate Vegetation

(4-6 points)

INTENT

Maintain existing ecosystem services and landscape performance, reduce resource use, and protect soil health by limiting the disturbance of existing appropriate plants and healthy soils.

REQUIREMENTS

• Conserve existing healthy soils and plants that are appropriate for site conditions, climate, and design intent in Vegetation and Soil Protection Zones (VSPZs) to equal at least:
  • 50 percent of the site’s existing vegetated area 4 points
  • 75 percent of the site’s existing vegetated area 5 points
  • 95 percent of the site’s existing vegetated area 6 points
• Ensure the section of the site assessment (see Pre-Design P2.2: Conduct a pre-design site assessment) is complete and describes and locates the healthy soils and appropriate plant species found on site.

Note: Limited restoration activities, including invasive species removal, are allowed within VSPZs (see Pre-Design P2.3: Designate and communicate Vegetation and Soil Protection Zones (VSPZs)).

RECOMMENDED STRATEGIES

• Locate construction activities, including storage of materials, vehicular access and parking, and placement of utilities, on areas of previously disturbed soils as identified in the site assessment (see Pre-Design P2.2: Conduct a pre-design site assessment).
• Limit grading to areas of previously disturbed soils.
• Establish clear construction boundaries to minimize disturbance to healthy soils and appropriate vegetation.
• Limit construction to a tight envelope around development, which will reduce the area of soil that needs to be restored in Construction P7.3: Restore soils disturbed during construction.
• Additional planting within the one foot (0.31 meter) radius per inch (2.54 centimeters) diameter at breast height (DBH) should be avoided. Planting here runs a high risk of damaging tree roots and soil chemistry and having other negative impacts due to excessive irrigation.
  • Planting should be limited to 25 percent of the area under the tree canopy or the area within a one foot (0.31 meter) radius per inch DBH and must be done in consultation with a certified arborist or other appropriately qualified professional.
• Protect the root zone of trees found on site:
  • Try to protect groups of trees rather than individual trees.
  • Design utility access away from the soil and roots of trees.
  • Reduce the need for utility trench work through strategic placement of utilities.
  • Where utility trench work is necessary, use air excavation to expose tree roots without damaging them (according to ANSI A300 Part 5).
  • If applicable, consider using directional boring technology (e.g., “mole,” “Ditch-Witch”).
  • For trees, ground-penetrating radar (GPR) or air excavation can be used to determine the location of tree roots.

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