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United States Department of Agriculture
Natural Resources Conservation Service

2118 W. Park Court, Champaign, IL 61821
Phone: 217/353-6600 Fax: 217/353-6676 Website:

DATE: May 7, 2013

SUBJECT:  ENG – National Engineering Handbook (NEH), Part 650, Engineering Field Handbook (EFH)

Purpose:  To announce an update to the Illinois supplement for Chapter 6, Aluminum Toe Wall Drop Structures and Double Wingwall Drop Spillways and their companion standard drawings

Expiration Date:  Upon receipt

Explanation: The quantity tables in the IL EFH Chapter 6 supplement for the Aluminum Toe Wall Drop Structures and the Aluminum Double Wingwall Drop Spillways have been updated. Minor updates to create consistent rounding procedures were made to all tables, and additional standard structure sizes were included. Reinforcing steel marks 4 and 5 were removed from the Double Wingwall Drop Spillway table. A consistent value for freeboard was also added to the Double Wingwall Drop Spillway and the capacities of each standard size were updated accordingly.

Updates to IL-ENG-117 include the addition of geotextile around the drainfill and riprap, and other minor changes such as rewording from “emergency spillway” to “auxiliary spillway.”

Updates to IL-ENG-123 include removing the reinforcing steel in the concrete cutoff trench under the wingwalls (Marks 4 and 5).

The Illinois NRCS Engineering website will be updated with these changes at

Filing Instructions:

Holders of hardcopy Engineering Field Handbook binders should:

  1. Archive IL EFH Supplement IL6-14.1 to IL6-14.35.
  2. Print out the attached supplement ILEFH Chapter 6 supplement pages IL6-14(1) to IL6-14(38) on green paper and file in the EFH Chapter 6 directly after the EFH page of the same number.
  3. Print out the attached table of contents and file at the beginning of the EFH, replacing the existing table of contents.

Holders of hardcopy Illinois Engineering Drawing binders should:

  1. Print copies of the revised drawings, which will temporarily be available on SharePoint until 5-24-2013:
  2. Replace existing copies of IL-ENG-117 and IL-ENG-123 with the newly revised drawings.

Questions regarding this submittal should be directed to the Area Engineer.

Ivan Dozier
State Conservationist

DIST: Partner


This attachment requires  Adobe Acrobat Reader to view: 
EFHNotice63.pdf  [PDF, 122kb]

Supplement Index
SupIndex_5-13.pdf [PDF, 22kb]

Category Index
CatIndex_5-13.pdf [PDF, 34kb]

Numerical Index
NumIndex_5-13.pdf [PDF, 112kb]

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