Permit Requirements for Landslide-Prone Areas in the City of Seattle
AGENDA Landslide-Prone Areas Rob McIntosh, P.E., Senior Geotechnical Engineer Department of Planning and Development (DPD) Trees and Vegetation Seth Amrhein, Senior Environmental Analyst Department of Planning and Development (DPD)
Definition of Landslide-Prone Areas in the Environmentally Critical Areas (ECA) Ordinance Known landslide areas Potential landslide areas Steep slopes (at least 10 feet high and 40% or greater average slope) http://web1.seattle.gov/dpd/maps/dpdgis.aspx
Development Regulations for Landslide-Prone Areas in Seattle No grading/disturbance of steep slope areas is allowed. Limited exemptions include: Proposed development is located where existing development is located Proposed development is located on steep slope areas created by previous legal grading Proposed development is in an isolated steep slope less than 20 feet in height Proposed development is the minimum necessary to stabilize the slope See Client Assistance Memo (CAM) 327A. Permit required for any grading over 25 cubic yards
Development Regulations for Landslide-Prone Property in Seattle Permit required for all retaining walls Permit required for installation of drainage
Development Regulations for Landslide-Prone Property in Seattle Getting a Building Permit Visit the Applicant Services Center on the 20 th Floor of 700 5 th Ave, Seattle to get started Call 206-684-8850 to get more information or to schedule an intake appointment Pre-application site visit (PASV) Plan review and corrections Expedited permitting for some landslide repairs Special Inspections
Don t List Don t direct storm or other water onto a slope. Don t denude vegetation on slope without an approved revegetation plan. Don t cut into the toe (or bottom) of a slope. Don t remove tree stumps from slopes. Don t install a permanent irrigation system in landslideprone areas. Don t put fill or yard debris on a steep slope.
Tree and Vegetation Overview SMC 25.09.320 Removing, clearing, or any action detrimental to habitat, vegetation or trees is prohibited within the following areas: landslide-prone critical areas, steep slope buffers, riparian corridors, shoreline habitat, shoreline habitat buffers, wetlands and wetland buffers, except for
Tree and Vegetation Overview (Tip 331) Normal and Routine Maintenance* Area of Work File Plan with DPD DPD Routed Plan Review SEPA review required Plan Type Less than 750 sq. ft. None 750 sq. ft. or greater YES Maintenance plan * Normal and routine maintenance includes practices that are necessary to maintain existing pathways and landscaping, ensure the health of existing vegetation, or achieve limited pruning to allow windowing, reduce tree mass or redirect tree growth. Removal of trees and vegetation is not considered normal and routine maintenance.
Tree and Vegetation Overview (Tip 331) Approved as Part of an Issued Building or Grading Permit Area of Work DPD Routed Plan Review Less than 1500 sq ft SEPA review required Plan Type YES NO Restoration plan as part of plan set 1500 to less than 9000 sq ft 9000 sq ft or greater for SFR YES NO Restoration plan as part of plan set YES YES Restoration plan and SEPA checklist as part of plan set
Tree and Vegetation Overview (Tip 331) Vegetation Restoration Project-removing invasive plants and noxious weeds by hand Area of Work* File Plan with DPD Less than 1500 sq. ft.** 1500 sq. ft. or greater YES DPD Routed Plan Review SEPA review required Plan Type Restoration plan, ECA Restoration plan application YES YES Restoration plan, SEPA checklist, ECA Restoration plan application * Area Slope measured Stability and cumulatively Vegetative over Soil three Stabilization years. in the Puget Sound Region ** In landslide-prone areas, when disturbance exceeds 750 square feet, the plan shall be approved by a licensed geotechnical engineer or geologist.
Tree and Vegetation Overview (Tip 331) Hazard Trees Area of Work File Plan with DPD DPD Routed Plan Review SEPA review required Plan Type All YES Hazard Tree Application (see Tip 331B* for information and submittal requirements. *Hazard Tree Removal Application, Tree Risk Assessment report by Tree Risk Assessment Qualified Arborist, photos, site plan
Vegetation Restoration (Tip 331A) Provides general information about creating a revegetation plan. Geared toward homeowners. Vegetation restoration projects need to be designed to: promote maintenance or creation of a naturally functioning condition that prevents erosion, protects water quality, or provides diverse habitat
Vegetation Restoration (Tip 331A) WHAT IS VEGETATION RESTORATION? Vegetation restoration is the establishment of native vegetation, including the removal of non-native or invasive plants. Goal is to promote maintenance or creation of a naturally functioning condition that prevents erosion, protects water quality, or provide diverse habitat (SMC 25.09.320). Restoration should result in a densely vegetated area with a significant diversity of native trees, shrubs and groundcover
Vegetation Restoration (Tip 331A) Examples of allowed restoration include: re-establishment of a native ecosystem in human impacted areas such as paved surfaces, lawns or landscaped areas replacing non-native, noxious and/or invasive species such as English ivy, Himalayan blackberry, or reed canary grass, with native plantings
Vegetation Restoration (Tip 331A) Examples of allowed restoration include (continued): replacing previously topped trees with healthy native trees replacing monocultural stands of deciduous trees like big leaf maples and red alder with native conifers
Vegetation Restoration (Tip 331A) Examples:
Vegetation Restoration (Tip 331A) Examples (before and after maintenance):
Vegetation Restoration (Tip 331A) Examples (established revegetation):
Vegetation Restoration (Tip 331A) Examples (established revegetation):
Hazard Trees (Tip 331B) Large holding roots on Bigleaf maple Hazard trees must have a target (infrastructure or people).
Selective Removal & Thinning For View Corridors Tree removal is not permitted for views. Pruning is OK when done using best practices to maintain tree health; topping is prohibited. Removal only permitted if tree is hazardous or if necessary to promote maintenance or creation of a naturally functioning condition that prevents erosion, protects water quality, or provide diverse habitat.
Question & Answer