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Geotechnical Review Checklists - P & S

John Poullain, P.E.


Course Outline

This two-hour online course discusses guidelines for reviewing geotechnical features of a project during the P&S development stage. This course covers data and specific information required for subsurface soil and water conditions for major and unusual geotechnical features.  It presents P&S review checklists, which target elements such as embankments and excavations, structural foundations and material sites. The student will gain an understanding of the types of subsurface investigations and the requirements for the minimum number of borings, spacing and depths of borings, samplings and testing for various types of projects and soils. 
Among the topics covered:

This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.

Learning Objective

At the conclusion of this course, the student will have reviewed the following topics:

Intended Audience

This course is intended for civil engineers and project engineers.

Benefit to Attendees

The student will become familiar with the geotechnical features of a project during the P&S development stage.

Course Introduction

The course covers geotechnical report checklists, which aid in reviewing geotechnical features during the preliminary and design stages of a project. Geotechnical review of the P&S must be thorough or cost overruns are risked, often because information was not complete or was omitted from the specs or plans.  The design of foundations for buildings, roadways, excavations, and embankments requires a complete understanding of soil strength; soil characteristics, problem soils and how soil behaves under imposed loads.

There are also software solutions for preparing geotechnical reports, which help reduce the time to generate reports, and at the same time a variety of related reports. Predesigned questions in template form are used to cover different types of projects, shallow and deep foundations, embankments, cuts and retaining walls. The computer software templates incorporate review questions similar to those of the course text.

From the initiation of a project, subsurface investigations progress through several phases from the concept to construction and to operation and maintenance. Initially the investigations are general and cover data gathering for subsurface conditions. As the project develops from the planning and concept phases to plans and specifications for construction the reports are more detailed for design and interpretation of subsurface conditions. It is important to follow established criteria and guidelines in order to select the appropriate drilling, sampling and testing methods.  

Planning for subsurface investigations can be broken into these steps:

a. Historical and Geological Studies.

Geological maps, topographical maps, aerial photographs, site histories and adjacent property developments are reviewed to gather data. Proposed construction features are studied for access and to plan investigations. Land use, problems areas, subsoil information; terrain conditions will indicate the necessary subsurface investigations.

b. Site Reconnaissance.

Existing surface features and topography of the site with the data gathered from prior historical and geological studies are compared. Telltale signs of problem areas, presence of soft terrain, wet areas, outcrops and changes in topography like cut or fill developments will be noted.

c. Subsurface Investigations Requirements.

Extent of investigations will depend on available subsurface data, geological data, groundwater variability, adjacent development and the proposed construction. Investigations progress from generalized and large areas to more specific and detailed studies. Conceptual or preliminary subsurface investigations require limited laboratory and sampling work and are used to prepare possible routes or structures layout for evaluation. More detailed subsurface investigations including borings, samplings and testing are performed in order to design for the selected route or structure location.

Boring logs are prepared from subsurface information encountered while drilling and sampling. Information is derived from measurements such as the energy required for drilling per foot of borehole, monitoring rock and soil debris, drilling mud and return water pumped from the borehole, sample recovery percentages and loss of drilling mud, to mention a few. It is very important to complete the logs in the field and not the laboratory and that the field observations and lab test results are differentiated to make clear the source of information. When more comprehensive information is desired, downhole logging may be performed.

Soil and rock samples must be handled and stored with care and should be inventoried, examined and tested as soon as they are received. If samples are stored for a long time the undisturbed samples should be protected against damage or changes in water content by maintaining at temperatures close to those required for the project. Rewaxing and relabeling may be required. Nevertheless the stored samples may undergo physical and chemical changes when stored too long no matter how carefully stored and resealed.

Course Content

The course is primarily based on pages 1 to 10 and 30 to 39 of the FHWA publication FHWA ED-88-053, “Checklist and Guidelines for Review of Geotechnical Reports and Preliminary P & S”, (2003 Revised Edition, 23 pages with index), PDF file. The course is also based on Chapter 11 of the US Dept of Transportation FHWA publication FHWA NHI-01-031, “Subsurface Investigation-Geotechnical Site Characterization”, (2001 Edition, 10 pages), PDF file.

"Subsurface Investigation-Geotechnical Site Characterization”, Chapter 11

“Checklist and Guidelines for Review of Geotechnical Reports and Preliminary P & S”

Please click on the above underlined hypertext to view, download or print the document for your study. Because of the large file size, we recommend that you first save the file to your computer by right clicking the mouse and choosing "Save Target As ...", and then open the file in Adobe Acrobat Reader. If you still experience any difficulty in downloading or opening this file, you may need to close some applications or reboot your computer to free up some memory.

Course Summary

This course should serve as a guide to review geotechnical features of P&S in the preliminary stages during project development. Minimum requirements for data and design reports for subsurface investigations are covered. The course provides the basics for selection of spacing of drilling, depths and number of borings needed to determine the condition of subgrade soil and rock formations. Guidelines for site investigation and sources of existing geological and historical data are presented. Review checklists are presented to ensure the data information is adequate and to avoid omission. Geotechnical features covered in the course include embankments, excavations, structure foundations, retaining structures and material sites.

Related Links

For additional technical information related to this subject, please refer to:

http://www.usace.army.mil/publications/eng-manuals/em1110-1-1804/chap3.pdf
Information and applications describing subsurface investigations, borings, map studies, remote sensing methods, geotechnical reports and field reconnaissance.

http://www.bakerhughes.com/inteq/evaluation/lwd/index.htm
Discusses logging during drilling in order to provide real time information by using various resistivities, nuclear and acoustic means to define the subsurface conditions.

http://www.ggsd.com
Lists over 50 software packages, shareware or commercial as noted, for soil boring logs and subsurface profiling.

http://epg.modot.com/index.php?title=320.1_Preliminary_Geotechnical_Report
Gives guidance and procedures for sampling, lab testing and reporting required for GTRs.

Quiz

Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDH Center or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered architect and/or professional engineer/surveyor. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.