In-Place Weathering of Late-Stage Volcanic Materials at Ka Loko Dam, Hawaii

Friday, April 15, 2016 – 12:00 – 01:30 pm, 3310 Yeh Center

David_Groholski

David R. Groholski, PhD, PE
Senior Engineer, Civil Engineering

Ka Loko Dam, in Kauai, Hawaii, failed suddenly and catastrophically on March 14, 2006.  The resulting broad “U”-shaped breach was marked by three distinct topographic benches.  The lowest bench was founded on a greasy, waxy, gel-like material produced by in-place weathering of late-stage volcanic materials.  Gravel-size pieces in the hydraulic fill of the embankment derived from these materials were also weathered in place.  Engineers and geologists generally assume that the strength, stiffness, and durability of bedrock, earth, and embankment materials will not vary over the operating life of a hydraulic fill dam.  However, bedrock materials can progressively weather into soil constituents over “geologic time.”  In the case of Ka Loko, late-stage volcanic materials substantially weathered in-place over approximately 115 years.  Prolonged exposure to seepage of anoxic water completely weathered the bedrock to saprolite, including weak, sensitive, fine, spherical halloysite clay.

Please view the flyer and bio attached for further details: 16-03-22 – David Groholski