On February 1st Seattle Public Utilities (SPU) released a Draft Geotechnical Report that analyzes the results of soil tests that were undertaken in October and December 2012 to identify potential sites where soils with “medium to high:” infiltration capacity likely exist in the [Ballard] basin.” The report describes geological conditions in the area and presents conclusions regarding depth to hydraulic restriction and potential infiltration areas. The report contains the draft soil boring logs .February 2013 Draft Geotechnical Report
SPU previously conducted soil tests in the Ballard Basin in 2009 and 2010 including deep soil boring tests, test pits and shallower hand-auger tests. These historical tests can be downloaded here. Historical Tests
The Ballard Stormwater Consortium will be meeting with Seattle Public Utilities to discuss the results of this report and proposed next steps on Tuesday February 5th from 4:30 p.m. to 6:00 p.m at the Ballard Public Library. SPU will inform the community of these results at a public meeting on Tuesday February 12th from 6:00-8:00 p.m. at the Sunset Hill Community Club.
To learn more about the types of soils in Seattle read Glacial Geology of the City of Seattle by William James Stark and Donal Ray Mullineaux (1950), available from the Seattle Public Library. My Summary Notes.