Early Design Studies

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Investigations of the Sacramento River South levee began in 2007 with the first two preliminary design investigations as part of what were know as consultant Task Orders 1 and 2. These investigations were used to collect data about the levee and conduct engineering analysis to better understand the levee deficiencies and improvements necessary to meet current engineering criteria and risk-reduction. Preliminary studies identified several levee deficiencies including under seepage, erosion and geometry and stability issues.

The first component of the preliminary design investigations completed the interim preliminary design process for conceptual setback levee alignments. Potential hydraulic and environmental effects and geotechnical constraints, indicated at a general level of detail, the advantages and disadvantages associated with setback levee alignments.

The second component of completed the final preliminary design and included comparative analysis of the setback levee alternatives identified as feasible during interim preliminary design, strengthen-in-place and adjacent levee alternatives. Based on the findings, the Final Preliminary Design Report was developed. The report identified the three alternatives that warranted further evaluation in the next phase of work: an in-place levee, repair construction of an adjacent levee and construction of a setback levee.

Preliminary alternatives were developed in 2009 and the design process began in 2010.

A levee improvement 'measure' corrects one or more levee deficiencies. Examples include:

  • Seepage berms
  • Cutoff walls
  • Relief wells
  • Adjacent levees
  • Setback levees
  • Rip rap placement

An alternative is a combination of corrective measures. Site-specific conditions control what measures will work. Based on levee deficiencies present in the Southport Sacramento River Levee, the team studied several measures including

The team studied corrective measures to find out which ones would be technically feasible in each segment.

CMAs 1, 2 and 3 represent corrective measures that would work in the Southport conditions and solve the technical deficiencies.

Upon determining feasible corrective measures, preliminary design alternatives were refined and combined for levee and seepage remediation measures to create an alternative that provides the best balance of community risk-reduction and private property impact, based upon available information. This work was conducted as a part of consultant Task Order 3. To learn more, visit environmental studies and current design studies pages.

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