Puget Soundkeeper and Washington Environmental Council created this decision tool to determine which projects to include in the Local Stormwater Pollution Controls report. The decision tool provides examples of projects that appear to meet Structural Stormwater Control (SSC) Type descriptions from the 2019 Phase I Permit, Appendix 12 (based on the SWMMWW (the “Manual”) where appropriate), and projects that do not. This tool does not replace Appendix 12 from the Permit.

This tool is intended to assist the Department of Ecology and municipal staff in understanding why reviewers did or did not include specific projects in the final SSC project lists. 

This list is not comprehensive. This list does not constitute legal advice nor should it be relied upon to determine compliance. Certain projects may constitute multiple SSC types which may not be reflected here. A project may not qualify as one type but could qualify under another type. This Decision Tool does not consider the 2019-2024 Phase I Permit SSC point system.

Type 1: New Flow Control Facilities

YesNo
Approved detention BMPs from Manual following design criteriaNew outlet for lake or pond to maintain water level during storms
Detention ponds, detention facilitiesReplace undersized and/or failing drain line with a larger line to drain a shallow depression
Retention ponds, retention facilitiesNew pipe to solve flooding by diverting flow to a lake
Bioretention if infiltrates
Vaults
Infiltration
Sediment ponds, sediment facilities
Installation of pervious pavement

Type 2: New Runoff Treatment Facilities

YesNo
Runoff treatment facilities that meet Manual or equivalent manual design criteria or the Highway Runoff Manual, or have a GULD designation through TAPE Maintenance activities
Bioretention, bioretention systemsOptions analysis or feasibility analysis between treatment system types
Biofiltration swales, water quality swales, bioswalesPretreatment 
Filter vaults or water quality vaults or vault treatment systemsAlum treatment
StormFilters, stormwater filter systems, filter cartridge treatment facilities or systems, synthetic media filtersDescriptions that need additional detail in order to qualify and thus, on their own, do not qualify:
Treatment unit
Water quality facility or pond or runoff and flow control facility
Water volume and flow quality BMP
Stormwater wetlands
Landscape infiltration via underdrains
Oil/water separators
Wet ponds, wet pools
Installation of pervious pavement

Type 3: New LID BMPs

YesNo
Bioretention and bioinfiltration systems or facilities that meet design criteria, including swales and bioswalesDescriptions that need additional detail in order to qualify and thus, on their own, do not qualify:
Rain garden
Water volume & quality BMP
Silva cells and similar devices functionally equivalent to bioretention if they contain an 18” thick layer of qualifying bioretention soil mix (as defined by the Western Washington Stormwater Management Manual). Detention vaults: will be type 1 only unless infiltrate, as LID BMPs must infiltrate
Installation or conversion to pervious pavement 
Dispersion
Infiltration

Type 4: Retrofit of Existing Facilities

YesNo
Install improved pump intake and controls at flow control facility that decreases peak flows or duration Bioretention, storm filters, treatment devices, or installing other new facilities or systems 
Retrofit of stormwater wetland, detention pond, detention facility, detention vault, wet pond, or other stormwater facilityDam removal
Wetland enhancementBerm along park wetland
Water quality vault retrofitUpgrading storm sewer pipe to larger pipes
Channel and ravine stabilizationDescriptions that need additional detail in order to qualify and thus, on their own, do not qualify:
Replace pump and aged manhole with new pump and wet vault
Access road construction
Alley paving project
Replacement of conveyance pipe to regional flow control facility
LID retrofit
Retrofit of slope drains
Wet pond addition
Berm at overflow of infiltration pond
Increase pond volume and add pre-settling cell
Combine and improve undersized facility

Type 5: Property Acquisition

YesNo
Requires a permanent designation on the land to protect it from future development. Should be noted in deed.Property acquisition of land on the river side of a levee to protect those properties from flooding
Acquisition of property, priority habitat, riparian habitat, or forest landProperty acquisition to protect nearshore salmon habitat
Acquisition for wetlandsAcquisitions without sufficient reference to how the property will be maintained or used in the future
Open space expansion
Acquisition, demolition, then planting
Property acquisition of land on the land side of a levee to permanently protect that land from development
Purchase of property to perform floodplain restoration or reconnection
Purchase and remove homes to allow riparian habitat in channel migration area

Type 6: Maintenance Over $25K

YesNo
Maintenance of wet ponds, drywells, settling ponds etc. to improve treatment or performanceBerm at overflow of infiltration pond
Removal of material from facilitiesModify the inlets to a lake to enhance pollutant removal by repairing an existing grass-lined channel and vault
Control sediment loaded overflowCapital improvement project remediation to provide additional overflow protection at an existing regional stormwater flow control facility

Type 7: Restoration of Riparian Buffer

YesNo
Restoration of riparian forest or riparian vegetationWetland buffer
Stream bufferRiparian restoration program
Riparian plantings to improve stream tempsRemove bulkhead and restore shoreline processes
Dam remediation
Increase channel complexity and enhance riparian vegetation
Descriptions that need additional detail in order to qualify and thus, on their own, do not qualify:
Creating acres of off-channel habitat, then revegetating
Enhancing topography, hydrology and riparian/wetland vegetation
Removing sediment from stream channel to improve drainage, then revegetating to mitigate impacts
Revegetating shoreline of estuary/lagoon
Vegetation enhancement/ enhancing vegetation

Type 8: Restoration of Forest Cover

YesNo
Forest restoration
Woodland restoration

Type 9: Floodplain Reconnection

YesNo
Remove structure to restore floodplainEstuary or creek enhancement
Floodplain restorationFeasibility analysis for actions to reduce flood risk
Setback or remove entire leveeRepair levee or revetment
Improve floodplain connection, conveyance or capacityRebuild levee in a structurally stable manner and increase local flood conveyance capacity within reach. Includes: reconstruct levee toe, install large woody debris, excavate a mid-slope bench and toe buttress revegetated with live willow layers and native riparian trees and shrubs, and stabilize the upper bank
Purchase of property to perform floodplain restorationAdd woody debris and structure in creek and surrounding wetlands to improve floodplain reconnection and riparian function
Descriptions that need additional detail in order to qualify and thus, on their own, do not qualify:
Constructing a setback berm along the perimeter of a wetland and acquiring private properties to provide protection from inundation of flood waters

Type 10: Removal of Impervious Surfaces

YesNo
Removal of fill and impervious area
Asphalt removal, construction of medians with planted trees
Buy and remove a repeatedly flooded home along creek. Impervious surface removed and replaced with riparian plantings

Type 11: Other

YesNo
Enhanced street sweeping (high efficiency) in applicable MS4 service areaDecommissioning UIC wells
Filter vault maintenance
WQ facility plans
Descriptions that need additional detail in order to qualify and thus, on their own, do not qualify:
Line cleaning
Cleaning and inspecting existing stormwater mains

Should you have any questions regarding our decision-making, please contact Mindy Roberts at Mindy@wecprotects.org or Alyssa Barton at Alyssa@pugetsoundkeeper.org.