CITY OF SEATTLE: UPDATE OF THE ECA CODE "KNOWN LANDSLIDE AREAS" GEOSPATIAL LAYER

Environmentally Critical Areas (ECA) Code was established to govern locations within Seattle that either provide critical environmental function or represent challenges for development due to underlying geologic or natural conditions. The goal of the City of Seattle ECA regulations is to protect these areas, in addition to public safety, while contemporaneously allowing reasonable development as Seattle continues to expand. This can be challenging in historically problematic neighborhoods where geologic conditions have caused extensive landsliding.

The City of Seattle has recently undertaken the task of updating the “Known Landslide Areas” geographic information systems (GIS) layer, which includes areas that have experienced active sliding during human history. This layer currently consists of polygons and points generated from historical files preserved by both the Department of Transportation and Department of Construction and Inspections. Additionally, Shannon and Wilson Inc. was consulted to update the database in 2000. As a result, many of the current geodatabase features can be sourced from this engineering firm. However, many updates are needed in order to improve the utility of this geodatabase for current professionals.

There are several goals of the 2017 update: fixing any topologic errors, ensuring the accuracy of current geodatabase features by reviewing the historical files, and to convert these files into an electronic format that can be directly accessed online. When complete, this update will allow critical information to be accessed and allow more efficient implementation by developers and Seattle employees. Additionally, the geodatabase will provide the information necessary for current ECA protocol.