Identifying and Evaluating Levee Improvement Alternatives – The City of West Sacramento Michael J. Vecchio, P.E. Watershed Planning and Design Sacramento, CA PRESENTED AT: Association of State Flood Plain Manager’s Conference 20 May 2010

Purpose and Scope Analyze problems and opportunities associated with existing levee system and its upgrade Define levee system upgrade alternatives Evaluate alternatives with respect to technical adequacy, environmental and community impact, and construction costs Recommend upgrade alternatives for all currently deficient levee reaches

Levee Deficiencies Evaluated Geometry Freeboard Stability (static and rapid drawdown) Seepage (through- and underseepage) Erosion Seismic Vulnerability Vegetation*

Data Sources West Sacramento Levee System Problem Identification and Alternatives Analysis Volume 1: Geotechnical Problem Identification (Kleinfelder, 9/21/2007) Phase 1 Geotechnical Evaluation Report, West Sacramento (URS, 11/2007) West Sacramento Levee System: Problem Identification Report; Erosion Assessment and Treatment Alternatives (NHC, February, 2008) West Sacramento Levee Evaluation Project: Draft Problem Identification Report (HDR, 4/28/2008)

Planning Objectives Improve level of flood protection City Ordinance 07-11: 200-yr Flood Protection Certification under 44 CFR and Accredited by FEMA Flood protection objectives are primary Recreation and restoration objectives are secondary

Alternative Plans Single Deficiency Mitigation Measures Levee Deficiency Groups Combinations of Mitigation Measures Mitigation Alternatives Selection Criteria Mitigation Alternative Evaluation

Single Deficiency Mitigation Measures MeasureFreeboardThrough - SeepageUnderseepageSlope StabilityErosionExcess Vegetation In-Place Levee RaiseYesNo YesNo Adjacent Levee RaiseYes NoYes No FloodwallYesNo Cutoff WallNoYes No Jet GroutingNoYes No Sheet Pile WallsNoYes No Seepage BermNo YesNo Stability BermNoYesNoYesNo Relief WellsNo YesNo Slope FlatteningNoYesNoYesNo Interior DrainNoYesNoYesNo Setback LeveeYes NoYes Vegetation RemovalNo Yes

Deficiency Groups

Combinations of Mitigation Measures

Evaluating Alternatives System Continuity Community Impact Environmental Impact Operation and Maintenance Costs Construction Cost

Mitigation Alternative Evaluation Criteria: system continuity, community impact, environmental impact, operation and maintenance cost, construction cost Qualitative Evaluation – ‘negative’, ‘average’, ‘positive’ Scoring – Negative = -1 – Average = 0 – Positive = 1

Sacramento Bypass (1.2 miles) Deficiencies Corrective Measures Construction Cost Opinion Through- and Underseepage, Stability and Geometry Cutoff Wall, Slope Flattening $9.4 million

Deficiencies Corrective Measures Construction Cost Opinion Through- and Underseepage, Stability, Geometry, Freeboard Cutoff Wall, Slope Flattening, Levee Raise $77.7 million SACRAMENTO RIVER WEST NORTH (5.8 MILES)

Deficiencies Corrective Measures Construction Cost Opinion Freeboard, Geometry Floodwall$37.7 million PORT NORTH (4.9 MILES)

Deficiencies Corrective Measures Construction Cost Opinion Geometry, Stability, Through- and Underseepage Stability Berm, Cutoff Wall, Slope Flattening $51.5 million YOLO BYPASS (3.7 MILES)

Deficiencies Corrective Measures Construction Cost Opinion Through- and Underseepage, Erosion and Freeboard Cutoff Wall, Levee Raise, Rip Rap $144.8 million DEEP WATER SHIP CHANNEL WEST (18.9 MILES)

Deficiencies Corrective Measures Construction Cost Opinion Through- and Underseepage, Stability, Erosion and Geometry Cutoff Wall, Slope Flattening, Rip Rap $ 6.1 million DEEP WATER SHIP CHANNEL EAST (2.7 MILES)

Deficiencies Corrective Measures Construction Cost Opinion Underseepage, Freeboard and Geometry Cutoff Wall, Levee Raise, Slope Flattening, $9.1 million PORT SOUTH (3.6 MILES)

Deficiencies Corrective Measures Construction Cost Opinion Stability, Erosion, Underseepage, Freeboard and Geometry Cutoff Wall, Setback Levee, Levee Raise, Slope Flattening, $111.6 million SACRAMENTO RIVER WEST SOUTH ( 6.3 MILES)

Deficiencies Corrective Measures Construction Cost Opinion Stability, Erosion, Through- Underseepage, Freeboard and Geometry Cutoff Wall, Levee Raise, Slope Flattening, $11.7 million SOUTH CROSS (1.2 MILES)

WEST SACRAMENTO LEVEE SYSTEM IMPROVEMENT CONSTRUCTION COST OPINION REACH CONSTRUCTION COST OPINION (MILLIONS) Sacramento Bypass$9.4 Sacramento River West North$77.7 Port North$37.7 Yolo Bypass$51.5 Deep Water Ship Channel West$144.8 Deep Water Ship Channel East$6.1 Port South$9.1 Sacramento River West South$111.6 South Cross$11.7 TOTAL$459.6