Sherman Island / Mayberry Slough Setback Levee

The Mayberry Slough Setback Levee project entailed approximately 1.6 miles of levee improvements. The improvements included construction of a landside setback levee and waterside slope flattening. The design presented challenges due to significant slope stability and settlement issues related to the peat and soft clay soil underlying the site. Historically, these issues caused slope movement and levee cracking.

 Blackburn Consulting performed subsurface exploration (exploratory borings and down-hole vane shear testing), laboratory testing (permeability, consolidation and triaxial shear), and engineering analysis. We prepared a Geotechnical Report with recommendations for design and construction of the proposed setback levee. Our recommendations included proposed slope inclinations, fill placement sequencing, and waiting periods to mitigate detrimental pore pressure build-up and slope movement. BCI installed slope inclinometers and vibrating wire piezometers with data loggers to monitor slope movement and pore pressure build-up during construction. BCI downloaded and plotted piezometer data during construction to determine the magnitude of pore pressure build-up, rate of dissipation, and confirm/adjust fill placement rates.

Location Sacramento County, CA
Agency/Owner California Department of Water Resources
Timeframe 2008