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Levee Engineer Technical Letter

The draft Engineer Technical Letter (ETL) 1110-2-570 provides a consolidated document of Corps procedures for levee/floodwall systems certification determinations in support of the National Flood Insurance Program as administered by the Federal Emergency Management Agency. The Engineer Technical Letter will be used to respond to requests for local sponsor levee systems certifications.

  • The Engineer Technical Letter is consistent with 44 CFR 65.10 while updating methods and references to current Corps practices and criteria.
  • The Federal Emergency Management Agency fully participated on the Engineer Technical Letter Project Delivery Team and will be part of the Independent Technical Review.
  • The Corps and the Federal Emergency Management Agency (FEMA) agree that the local sponsor seeking recognition of the levee system for National Flood Insurance Program purposes is responsible for providing certification documentation.  The Corps will continue to certify levees it operates and maintains.  For all other levees within the Corps program, funding must be provided by the local sponsor.
  • The Engineer Technical Letter will undergo peer review prior to final publication.

Policy Highlights

  • Systems Approach - NO PARTIAL CERTIFICATIONS - A levee system includes all components that are interconnected and necessary to insure flood and storm damage reduction for the associated floodplain – levee/floodwall sections, closure structures, pumping stations, culverts, interior drainage works, and system operation and maintenance. No certification of individual components of the system is allowed.
  • Professional Engineer Signatory – Certifications will be signed by the District Levee Safety Officer (LSO) or an equivalent registered professional engineer competent in the areas of design, construction, operation, inspection, and evaluation of levee systems.
  • Risk-informed methodologies for analyzing the full suite of engineering and operational elements of a levee system or dam are under development for Corps dam and levee safety assessments.  Methodologies are expected to be adapted to levee certification determinations and made part of this Engineer Technical Letter as they mature.
  • Maximum period of validity for Corps certification will be 10 years and consistent with the cycle of inspection and assessment provisions. Certification may be reviewed any time before the maximum period of validity.
  • The Corps will examine and report all elements of residual risk and public safety by providing a statement regarding project exceedance; as methods mature, this could eventually include loss-of-life.
  • In 1997 the Corps issued guidance to incorporate risk and uncertainty (R&U) to determine levee height for certification in lieu of the Federal Emergency Management Agency’s fixed three feet of freeboard.  The draft Engineer Technical Letter uses the R&U’s 90-95% certainty level of the base flood elevation (BFE) while maintaining the concept of a two foot minimum freeboard above the mean value (50%) of the base flood elevation.  The Corps will use the higher of these two values to determine levee height. 
  • Emergency operations and flood warning plan required for systems that are under evaluation.
  • Looks toward resiliency for wave overtopping as way forward for coastal and large lake environments.