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Sacramento District
REVISED ETL 1110-2-571 – Guidelines for Landscaping and Vegetation Management
Paige Caldwell, P.E. Emergency Manager
Sacramento District
• Overview– Policy revision process– Key points from the ETL guidance– Illustrations of acceptable vegetation
placement– Photos of potential vegetation impacts– Update on Corps research initiative
Sacramento District
Revision of EM 1110-2-301 – 2 phases
• Phase I: A necessary first step (completed April 2009)– Purpose: Clarify our existing guidelines, which are somewhat
ambiguous, and, in the process, identify unknowns that require further research
– Products: (1) an Engineering Technical Letter, and (2) a scope for required research
• Phase II: The real work (ongoing)– Purpose: Conduct research to establish both scientific and
engineering grounds to reaffirm and/or revise Corps vegetation guidelines, and to better accommodate ecological enhancements to Flood Damage Reduction (FDR) Systems.
– Product: final guidelines, published as an Engineering Manual (EM)
Sacramento District
• Key points from the newly revised ETL guidance:– Public safety is the number one priority of the USACE
Levee Safety Program.– This ETL does not establish new standards, but clarifies,
and supersedes, those formerly presented in EM 1110-2- 301 (Jan. 1, 2000).
– An Independent External Peer Review, conducted in 2008, and Independent Technical Review validated the ETL based upon existing and available engineering and scientific data.
– USACE is currently undertaking a two-year research program to enable reassessment of its engineering-based understanding of the public safety consequences of vegetation on FDR projects.
Sacramento District
• Key points (continued)– It is essential that FDRs retain structural integrity,
functionality, and safety; it is also necessary to be able to inspect, monitor, and flood-fight the projects.
– The local sponsor may request a variance from the standard vegetation guidelines as presented in the ETL.
– Fifteen feet, or to existing project easement, is the minimally accepted vegetation free zone (VFZ). To date, no research exists to justify a reduction to existing standards.
– The ETL discusses a limited range of conditions under which a variance to vegetation standards may be granted.
Sacramento District
• Key points (continued)– Any addition of landscape plantings to existing FDR
systems must comply with the project’s Operations and Maintenance manual. New plantings with an engineering evaluation may be approved on a case by case basis.
– Once new projects are completed, O&M manuals will be updated to reflect requirements for vegetation maintenance.
– Planned research is intended to compliment the ETL guidance.
– The use of suitable vegetation, such as shrub forms of willows, riverward of the vegetation-free zone is encouraged as an environmentally beneficial means to moderate erosion potential of water currents and wave action.
Sacramento District
Levee Section - Basic
Sacramento District
Levee Section – Basic, with floodwall on crown
Sacramento District
Levee Section – Basic, with Blanket Drain
Sacramento District
Levee Section – Basic, with Relief Well or Piezometer
Sacramento District
Levee Section – Basic, with Planting Berm
Sacramento District
Levee Section with Ordinary High Water Mark above the Riverside Toe
Sacramento District
Potentially Negative Impacts from Vegetation on Levees
Sacramento District
Potentially Negative Impacts from Vegetation on Levees
Sacramento District
Potentially Negative Impacts from Vegetation on Levees
Sacramento District
Potentially Negative Impacts from Vegetation on Levees
Sacramento District
Vegetation Research Objective:
• Develop a methodology (work plan) using nationwide research to study the effects of woody vegetation on levee integrity and stability;
• Identify failure modes where vegetation may accelerate failure;
• Select sites indicative of regional setting (varying climatic conditions, geographic and geologic influences, and soil type) to obtain a statistical acceptable database;
• Include root systems of different riparian woody vegetation species; however, noting that a given species does not always produce the same root morphology;
• Address the variation in soil properties and levee geometry.
Sacramento District
Research Approach:The research work plan is divided into the following sections based on mechanisms and processes influencing levee integrity and stability, and data analyses of the research:
• Field Assessment/Laboratory Analyses– Slope stability– Root characterization– Geophysical analyses (non-invasive)– Pull-out tests (invasive)– Overthrow– Seepage and piping– Overtopping erosion and riverside erosion– Geological/geotechnical characterization
• Case Histories• Engineering Assessment to Generate • Fragility Curves Risk Assessment/Probability Analyses
Sacramento District
• Future Activities of Research Initiative:– Secure field sites in Sacramento, New
Orleans, Seattle, Portland, and Albuquerque (Northeast site has not been identified)
– Begin testing at selected site in New Orleans– Conduct workshop to present initial findings
and adjust work plan, if needed (mid-June)– Present initial findings at the Infrastructure
Systems Conference (20-24 July 2009)
Sacramento District
Questions?The ETL is available at:
http://140.194.76.129/publications/eng-tech-ltrs/etl1110-2-571/toc.htm
