Success Dam

Challenges

Success Dam is an earthen embankment dam about 145 feet tall and 3,400 feet long, and is located in Tulare County, California.  The dam stores about 80,000 acre-feet of water and is used for flood control, recreation, and irrigation supply.  Dam safety concerns related to seepage and seismic stability were previously identified by others.  To address these items, the U.S. Army Corps of Engineers – Sacramento District (USACE-SPK) designed a new dam downstream of the existing dam.

The new dam foundation consists of intensely weathered and decomposed igneous and metamorphic rocks on the abutments and over 250 feet of Alluvium in the valley bottom, which will significantly complicate seepage cutoff below the new dam.

Solution

RJH was retained by USACE-SPK to perform geotechnical investigations and analyses to evaluate seepage cutoff options below the proposed new embankment alignment.  Early in the investigation, RJH identified issues with interpretation of existing data and recommended modifications to the investigation plan to focus the data collection in locations where critical features, including excessive depth to bedrock, were located.  Subsurface explorations included advancing 13 boreholes about 1,100 feet using sonic techniques and about 1,300 feet using rock coring techniques to classify materials and evaluate the permeability and groutability of the bedrock.  As part of the investigation, water pressure testing of new and existing borehole explorations was performed to estimate hydraulic conductivity, and optical/acoustic televiewer surveys were conducted to log and analyze fractures and other discontinuities in the bedrock.

RJH evaluated the collected data and prepared a 35 Percent Design Report that included evaluation of the geology and recommendations for the type and location of appropriate grouting and seepage cutoff technologies to develop a seepage barrier for the new embankment.