Geophysical Assessment of Foundation Conditions: Right Abutment Mill Creek Dam
Abstract
Results of a comprehensive, integrated geophysical investigation of the right abutment area of Mill Creek Dam near Walla Walla, Washington, are presented. The dam site has experienced anomalous seepage since the first reservoir filling in 1941, despite remedial measures, including a concrete cutoff wall completed in 1983. Self potential surveys and other geotechnical investigations conducted in 1984 concluded that the major anomalous seepage paths were through the right abutment area. Sinkholes and cracks in the reservoir floor and right abutment and the presence of fine in drain discharges indicate that silt, which forms the floor of the reservoir and the abutments, is being piped through the foundations of the dam. A potential is also considered to exist for piping of dam materials into the foundation. The geophysical investigations and a concurrent drilling program were designed to detect anomalous conditions, e.g. cavities and low density zones, in the dam and dam foundation in the right abutment area. Keywords: Geophysics; Microgravity; Radar; Resistivity; Seepage; Seismic reflection.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1989
- Accession Number
- ADA213188
Entities
People
- Donald E. Yule
- Dwain K. Butler
- Jose L. Liopis
- Michael K. Sharp