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The purpose of this web manual is to provide highway engineers with a basic knowledge of geophysics and nondestructive test (NDT) methods for solving specific engineering problems during geotechnical investigation, construction, and maintenance of highways. The web manual is not intended to make engineers experts in the field of geophysics, but rather to provide them with tools that will assist them in the use of suitable geophysical and NDT techniques to evaluate problems for design, planning, construction, or remediation efforts.

The application of geophysical imaging and NDT methods has been increasing in site Characterization and geotechnical investigations during highway constructions because they offer accurate and timely information for design quality and performance. Detailed knowledge of unforeseen, highly variable subsurface ground conditions reduces project risk and costs associated with "change of conditions" claims, and improve construction and safety. In this web manual, the term NDT is used to refer to condition evaluation of engineered structures. Condition evaluation includes integrity assessment for defects and corrosion, and the determination of unknown geometry, such as unknown foundation depths or extent of foundations.

This web manual provides a broad range of practical methods, including almost all traditional geophysical methods. These have been adapted to provide solutions more specific to a variety of engineering problems pertaining to transportation. For example, conventional geophysical methods have been used to evaluate the physical properties of soil and rock, such as seismic methods which are used to calculate the depth to bedrock or locate underground voids. In the NDT applications, the same seismic methods have been adapted for condition evaluation with great success, producing a technique known as the Ultraseismic test method. In this method, the concrete structure itself is used instead of the earth for the transmission of the acoustic energy with reflection events coming from either the bottom of a structure, as in a bridge foundation, or a defect zone. Similarly, the ground penetrating radar (GPR) geophysical method, originally developed for high resolution imaging of the subsurface, is now used routinely in condition evaluation of pavements, concrete slabs, and walls. These types of NDT geophysical investigations are used in the transportation and infrastructure systems to evaluate new procedures for Quality Assurance (QA) and existing structures for forensic and Quality Control (QC) purposes. To this end, many state and federal Department of Transportations (DOT's) have added various NDT testing standard specifications to their construction codes and will continue to do so with continued deployment of geophysics and NDT in the construction projects.

This web manual is divided into two parts. The first part is problem oriented and provides a range of geophysical and NDT methods that can be used to solve a particular problem. The second part describes the geophysical techniques in greater detail.
The authors would like to express their appreciation to Mr. Khamis Y. Haramy, COTR of the Federal Highway Administration (FHWA), Central Federal Lands Highway Division (CFLHD), for guiding, directing, and providing valuable technical assistance and review during the preparation of the web manual. The authors would also like to thank the following individuals who provided a technical review of the web manual:
  • Roger Surdahl
  • Justin Henwood
  • Linden Snyder
  • Benjamin Rivers
  • Barry Berkovitz
  • Thomas Lefchik
  • Hamilton Duncan
  • Silas Nichols
The authors would like to thank the following senior reviewers for providing helpful technical comments and reviewing the web manual:
  • Gary Young, Geomedia Research and Development
  • Neil Anderson, Ph.D., School of Mines and Metallurgy, University of Missouri-Rolla
  • Erick Westman, Ph.D., Virginia Polytechnic University
The authors would like to thank the following individuals for contributing and providing information used for the development of this web manual:
  • Michael Klosterman, U.S. Army Corps of Engineers - HQ02
  • Greg Hempen, Ph.D., U.S. Army Corps of Engineers - St. Louis District
  • John Diehl, GeoVision, a division of Blackhawk GeoServices
  • Carl Rascoe, GeoVision, a division of Blackhawk GeoServices
  • Francisco Romero, GeoVision, a division of Blackhawk GeoServices
  • Gary Young, Geomedia Research and Development
  • Wayne Peeples, Ph.D., Geomedia Research and Development
  • Choon Park, Ph.D., Kansas Geological Survey
  • Michael Culig, Colog, a division of Layne Christensen
  • Nathan Davis, Colog, a division of Layne Christensen
The authors would like to thank the manufacturers and consulting companies for providing the copyrighted materials used in this web manual. Reference to these materials is included in the web manual. The authors would like to thank Mr. Manuel Montoya, Computer Services, and Messrs. Linden Snyder and Alex Stefanacci, CFLHD, for the web page design of this web manual.

Finally, the authors would like to thank Ms. Cecelia Slivick, Blackhawk GeoServices, and Ms. Jean Rau, NSA Geotechnical Services, for editing, word processing, and layout of the web manual, and Messrs. Herman Vialpando and James Vialpando, Blackhawk GeoServices, for drafting and art work.

This web document was republished in 2022 by GEI Consultants, Inc., and The Karol Company, with updates to figures, technical corrections, and the addition of the Thermal Integrity Profiling section. The editorial team included:
Mary Nodine – GEI Consultants
Helen Robinson - GEI Consultants
Bernhardt Hertlein – GEI Consultants
Karol Paltsios – The Karol Company
Thanks also to Robert Garfield of Hager Richter Geosciences for providing televiewer imagery for figures.

This report is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange. The United States Government assumes no liability for its contents or use thereof. The United States Government does not endorse products or manufacturers. Trademarks or manufacturers' names appear herein only because they are considered essential to the object of this web manual. The contents of this report reflect the views of the authors, who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official policy of the Department of Transportation. This report does not constitute a standard, specification, or regulation.

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Form DOT F 1700.7