West Sacramento Area Flood Control Agency November 10

West Sacramento Area Flood Control Agency November 10, 2011 Update on Current Levee Construction Projects and on the Southport Sacramento River Levee Early Implementation Project

Program History and Milestones • Problem Identification Report completed for entire perimeter levee system (2008) • Alternatives Analysis Report completed for entire perimeter levee system (2009) • Construction of I-Street EIP (2008) • Construction of CHP Academy and Rivers EIP’s (2011) • Initiation of Southport EIP Project (2010)

Program History and Milestones (cont) • USACE Construction of Yolo Bypass Slip Repairs (2009, 2011, new south slip) • USACE Sacramento Bank Protection Project Setback Levee Improvement Project (2011/12) • USACE General Reevaluation Report initiated in 2009, estimated completion (2015)

Goals for Southport EIP • Summary of Project Goals and Criteria – Protect safety and public health of residents within the City while minimizing impacts to community as much as possible – Selected Southport EIP project based on repairing highest risk sites – Select least cost alternative that achieves public safety goals and complies w/Federal and State regulations

Federal and State Levee Design Criteria • Engineering design standards established by U. S. Army Corps of Engineers, Central Valley Flood Protection Board, and CA Department of Water Resources and include: – Freeboard – Erosion – Geotechnical Stability – Under-seepage – Vegetation – Geometry

State Cost-Share Formulas • State cost share ranges from 50% to 90% • Base state cost share is 50% • Objectives that increase state cost share: – Habitat, open-space and/or recreation from 5% to 20% – State facilities from 5% to 20% – Setback levee from 20% to 40% – Disadvantaged area up to 40% *State cost share is limited at 70% except for disadvantaged areas and setback levees which can achieve up to a 90% state cost share.

WSAFCA Role in EIPs • Select Early Implementation Projects that utilize available funds to improve the highest risk reaches of levee in advance of USACE construction • Provide local share of funds necessary for design and construction of projects to meet the 200 -year level of protection mandated by the State Plan of Flood Control • Design projects that provide the maximum reduction in flood risk for the local funds invested, while considering project impacts on the community and local landowners • Provide a forum for public information and engagement in the decision-making process

An “Inside Look” at a Levee

Typical Levee Deficiencies

Key Factors Limiting Use of In-Place Measures • Local conditions like soil layer thickness, type and depth can determine whether cutoff walls or relief wells will correct a seepage deficiency. • Cutoff wall depth depends on soil type over depth of wall and soil type at the bottom of the wall. • Large particles - like gravels, cobbles and boulders - can limit the cutoff wall depth due to alignment and mixing problems. • Sacramento District Corps of Engineers recently shut down a deep cutoff wall project for these reasons.

Relief Well with Confining Layer

Relief Well without Confining Layer

What Factors Can Require a Landward Shift of the Levee Template? • Steep waterside slope with evidence of erosion or potential for erosion • Rapid drawdown instability • Vegetation encroaching into Corps ‘vegetation free’ zone

Steep Slope with Erosion

Shifted Template

Rapid Drawdown Failure Plane Intruding into Levee Template

Template Shifted Outside of Failure Plane

Task Order No. 3 Scope and Status • Scope items include: Hydrologic and hydraulic analysis, geotechnical and groundwater investigations, civil engineering analysis, environmental documentation, and geomorphic investigations • Develop 15% design for two project alternatives with cost opinions • Complete Administrative Draft Environmental Impact Statement/Environmental Impact Report • WSAFCA staff and consultant team present Task Order No. 3 analysis at December board meeting.

Projected Milestone Overview • December 2011: Presentation of Task Order No. 3 Analysis • January 2012: – Presentation of 15% design with cost opinions and consideration of approval of Task Order No. 4 – Public Workshop on preferred alternative (January 26) • February 2012: WSAFCA Board selects preferred alternative and provides direction on 60% design • April 2012: – 60% design complete – Appraisal process initiated

Projected Milestone Overview (cont) • January 2013: Certify EIR – 100% design completed • March-August 2013: Federal and state regulatory approvals received • September 2013: WSAFCA Board consideration of approval of construction contract

Public Outreach Opportunities • Monthly JPA Meetings (2 nd Thursday of every month at 10: 30 a. m. ) • Public Meeting: January 26, 2012 (evening time TBD) • One-on-one meetings w/WSAFCA staff on request

Questions?