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Under state stormwater guidance, found in the current edition of the Washington State Department of Ecology Stormwater Management Manual for Western Washington (SWMMWW), there are instances when bioretention of stormwater and rain gardens are either NOT required, or not allowed. These include when professional geotechnical evaluations recommend against infiltration, or in areas of erosion or landslide hazard. Other requirements related to stormwater may still apply; consult the SWMMWW and your local government planning department.
Reference: SWMMWW, Volume 5, BMP T7.30: Bioretention Cells, Swales, and Planter Boxes. http://www.ecy.wa.gov/programs/wq/stormwater/manual.html
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The local government planning department where the property is located is a good place to start. To correctly identify and remedy drainage problems on properties located near or on steep slopes, you may need to contract with a geologist, an engineer and/or a construction contractor.
Permits may be needed for drainage work; consult with your local government planning department for help in identifying permit requirements.
Please refer to your local phone book or an Internet search for locating geotechnical consultants.
This varies, so contact your local government planning department to start.
The City of Mukilteo issues emergency permits, but the City of Everett does not.
Some local government planning departments may have cost-sharing; please call your local planning department.
Timeframes vary according to the permits and the local planning agency. Many local jurisdictions process permits within 120 days. Contact your local government planning department to determine permits and timeframes.
Washington State University Extension or your local garden club may have plants and volunteers to help identify appropriate plantings.
City of Seattle
Storms and Flooding in Seattle
Marine Resources Committee, Snohomish County
Information for Coastal Landowners
Washington State Department of Ecology
Surface Water and Groundwater on Coastal Bluffs
Slope Stabilization and Erosion Control Using Vegetation: A Manual of Practice for Coastal Bluffs
Vegetation Management: Guide for Puget Sound Bluff Property Owners
Puget Sound Landslides
Puget Sound Shorelines Slope Stability Maps (see ‘Map slope stability’)
Washington State Department of Natural Resources
Division of Geology and Earth Resources Geological Hazards
Washington State Military Department
Emergency Management Division
U.S. Geological Survey
Landslides Hazard Program
Not at this time. For stabilizing slopes, there may be insurance cost savings for homeowners. Local agencies may waive permit fees for low-income residents.
Local government agencies may have right of way permits or other permits associated with stormwater drainage connection. Contact your local government planning department.
If you are cutting or removing vegetation on a slope there may be a permit or other permission needed depending on the type, size, and location of the vegetation, as well as the height and inclination of the slope. Check with your local government planning department.
If you are planning on retaining stormwater on your property, a geotechnical report and drainage plan may be required to show that the site soils are suitable for stormwater retention. Consult your local government planning department.
Yes. In disposing of unwanted or excess surface water, landowners may be liable for their action or inaction that results in damage to neighboring properties. Landowners may be responsible for the following:
•Altering a watercourse or natural drainage way
•Collecting and discharging water onto their neighbors' land in quantities greater than, or in a manner different from, its natural flow, including, but not limited to:
•Exercising their rights in bad faith or failing to avoid unnecessary damage to others' property
For more information on drainage requirements, check with your local government planning department.
The original model developed by the United States Geological and Survey (USGS) used data from rain gauges installed at Sea-Tac Airport and in Tacoma and Everett. Sound Transit worked with the USGS to install additional rain gauges and monitoring devices along the north rail corridor, with a focus in Mukilteo. These monitoring devices now provide the interested agencies and railroads, as well as the general public, more accurate data on rainfall and soil conditions in the affected corridor. The USGS is in the process of updating their model in order to more accurately assess rainfall and soil conditions; a final report from the USGS is pending.
Several slope stabilization projects have been completed in the Everett and Mukilteo areas by WSDOT and BNSF. The work includes slope stabilization, slide containment walls, slide detection fences and drainage and erosion control improvements. The goal is to reduce slides in the historically slide-prone area, thus reducing passenger rail disruptions.
In addition, local jurisdictions are making improvements, such as the City of Everett’s Shore Avenue Stormwater Outfall Improvements project, completed in 2015.