PH C5: Ecological HPD: Protect Wetlands + Avoid Slopes + Adverse Geology – Above Green

(1-24 points)

INTENT

Protect, buffer, enhance and restore areas designated as wetlands, shorelines, and bodies of water by providing natural buffer zones, vegetation and soil protection zones. Avoid development in adverse geologic formations and safeguard aquifers to reduce natural hazards risk and preserve high quality groundwater resources. Protect steep slopes and hillsides from inappropriate and unsuitable development in order to avoid exposures and risks from erosion and landslides, and other natural hazards.

STRUCTURE + COMMUNITY REQUIREMENTS

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PH Action 5.1: Protect Wetlands and Surface Water (4-18 points)

Establish a vegetation and soil protection zone (VSPZ) for an area within 100 feet of any wetland areas, shoreline, or bodies of water or within setback distances from wetlands prescribed in state or local laws and/or regulations, whichever is more stringent.

Enhanced Level

Buffer > 100 feet or within setback distances from wetlands prescribed in state or local laws and/or regulations, whichever is more stringent.

Superior Level

Buffer > 200 feet or within setback distances from wetlands prescribed in state or local laws and/or regulations, whichever is more stringent.

Conserving Level

Buffer > 300 feet or waterbody or within setback distances from wetlands prescribed in state or local laws and/or regulations, whichever is more stringent.

AND/OR

Restorative Level

Aquatic and wetland restoration: In addition to points awarded for buffering, project may earn points for restoring previously degraded buffer zones to a natural state as part of establishing the VSPZ. Restoration must include stabilization of stream channel or shoreline (bulkheads are not an acceptable stabilization measure for this objective), and revegetation with native plant communities.

Stream channel restoration must include a geomorphic analysis of the reach and the planning for dynamical stable stream banks, based on channel dynamics and sediment transport.

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AND/OR

PH Action 5.2 Avoid Adverse Geology (1-3 points)

Comprehensive delineation: Prior to project siting, the owner and the project team identify and delineate any faults, low-lying coastline and karst areas in and around the project site. Identification and delineation includes location, distribution, characteristics and groundwater hydrogeology, including flow and quality.

Enhanced Level (1 point)

Sound risk management: Develop plans and designs to reduce the risk of damage due to ground motion, tsunami flooding and collapse of karst areas and associated aquifer damage, or from the hazards of these areas, e.g., subsidence, sinkholes, flooding. Design operation procedures for the constructed works are designed to prevent damage and contamination. Establish programs for monitoring.

Refer to “Designing for Tsunamis: Seven Principles for Planning and Designing for Tsunami Hazards” by NOAA, USGS et. al. March 2001 edition

Superior Level (2 points)

Protection and risk management: Define the adverse geological areas and associate aquifers based on extensive geotechnical and hydrogeologic assessments. Define, designate, and avoid hazard areas. Create, and implement runoff controls, spill prevention, and cleanup plans.

Conserving Level (3 points)

Total avoidance: The owner and the project team site the project in a safe area that has no adverse geologic features and no negative effects on aquifers.

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PH Action 5.3 Avoid Unsuitable Development on Steep Slopes (1-3 points)

Identify relative landslide, subsidence and liquefaction risk, and critical slopes risk that may indicate unstable soil. Refer to state and local data1 to determine whether the project is located in a high-risk landslide area and whether there is land on or uphill of the building site with a slope exceeding 15% (6.75°).

Reference:

For general use only, not for site-specific information: USGS map, “Landslide Overview Map of the Conterminous United States”
- For additional guidance, refer to the most recent works by the American Society of Civil Engineers and the U.S. Geological Survey on slope stability and steepness

Superior Level

Optimal project siting: Work with local officials, property owners and other stakeholders to select and acquire a project site that is sufficiently suited for the project purpose. Seek to minimize siting on hillsides or steep slopes. Work to locate and acquire the best location that minimizes the possibility of excessive erosion and landslides.
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Landslide-Specific design measures

Demonstrate that any steep-slope (≥ 15% or 6.75⁰) soils and underlying geology on the building site and uphill from the building site have been investigated through a signed report from a geotechnical engineer.

Either provide a signed letter from a geotechnical engineer showing that landslides pose minimal landslide risk or a letter from professional engineer indicating that mitigation strategies for the project result in minimal landslide risk.