Case Study: Geologic Hazard Assessment

Client: City of Bainbridge Island Location: Bainbridge Island, WA Contact for geotechnical projects: John Peterson

Project Background & Challenges

The City of Bainbridge Islands needed to improve its understanding of geologically hazardous areas throughout the entire island for several reasons. One was to meet the requirements of the Growth Management Act; another was to update and improve its critical area delineations and codes. New geologic hazard information is particularly important in light of recent findings about seismicity in the Puget Sound region.

Solution

Aspect was selected to review the best available science (BAS) for geologic hazards and related development impacts. The review focused on areas with steep slopes, high erosion and fault hazards, and high potential for liquefaction. It involved analyzing new and relevant scientific information and then using this information to revise the geologic hazard maps and codes. To generate the critical area maps, we used GIS methods to assimilate new, high-resolution, LIDAR-generated topographic data with existing geologic maps. This process allowed us to predict areas of high hazard potential and to propose changes to the geologic hazard maps and codes, making them more accurate and useful to both planners and permit applicants.