DEPARTMENT OF THE ARMY
ETL 1110-1-185
U.S. Army Corps of Engineers
Washington, DC 20314-1000
CECW-EG
Technical Letter
No. 1110-1-185
1 February 1999
EXPIRES 31 December 2003
Engineering and Design
GUIDELINES ON GROUND IMPROVEMENT
FOR STRUCTURES AND FACILITIES
1. Purpose
The purpose of this Engineer Technical Letter (ETL) is to provide guidance on ground improvement for
USACE civil works and military programs projects. The enclosed document (Appendix A) contains an up-
to-date overview of ground improvement techniques and related considerations. It addresses general
evaluation of site and soil conditions, selection of improvement methods, preliminary cost estimating,
design, construction, and performance evaluation for ground improvement. This document should be used
as a resource during planning, design, and construction for new projects as well as a reference to guide
more detailed design efforts for modification of our aging inventory of existing projects, particularly
embankment dams. The use of such state-of-the-practice techniques is in keeping with good engineering
practice and provides better service to our customers in concert with the USACE Strategic Vision.
2. Applicability
This ETL applies to all USACE Commands having civil works and military programs responsibilities.
3. Distribution
Approved for public release, distribution is unlimited.
4. Background
Ground improvement, in the context of this guidance, is the modification of existing site
foundation soils or project earth structures to provide better performance under design and/or
operational loading conditions. Ground improvement techniques are used increasingly for new
projects to allow utilization of sites with poor subsurface conditions and to allow design and
construction of needed projects despite poor subsurface conditions which formerly would have
rendered the project economically unjustifiable or technically not feasible. More importantly, such
techniques are used to permit continued safe and efficient operation of existing projects
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