Serving professionals in engineering, environmental, and groundwater geology
since 1957


Date: Tuesday, October 12, 2004
Location: Steven’s Steak House, 5332 Stevens Place, Commerce, California
Time: 6:00 p.m.-Social Hour; 7:00 p.m.-Dinner; 7:45 p.m.-Presentation

Cost: $25 per person with reservations, $30 at the door, $12 for students with a valid Student ID
Reservations: Call (949) 253-5924 ex 564, or email Brian Villalobos,
By noon, Monday, October 11, 2004

SPEAKER: Benjamin T. Benumof, Ph.D., Esq.
TOPIC: The Foreseeability of "Unforeseen” Geologic Conditions


Despite the growing sophistication of construction contracts, “unforeseen” or “differing” site conditions disputes continue to occur.

These disputes, which often result in substantial damages awards, arise when large volumes of unanticipated rock, soil, groundwater, or other adverse subsurface conditions are encountered during the “dirt” moving stages of construction, and the parties are in disagreement over who is responsible for the additional costs associated with the unforeseen conditions.

Although contractors typically initiate litigation over “unforeseen” or “differing” site conditions (“DSC”) against owners (and not geotechnical professionals) pursuant to principles of contract law (i.e., DSC lawsuits are typically based on express representations of expected subsurface geologic conditions provided to the contractor by the owner that differ materially from the conditions actually encountered), owners unable to successfully defend DSC lawsuits often seek indemnity from engineering geologists and geotechnical engineers under principles of tort and contract law. More specifically, owners seeking indemnity from engineering geologists and geotechnical engineers frequently contend that the geotechnical professional, in his/her investigation of subsurface geologic conditions and preparation of the project geotechnical report, fell below established professional standards of care (i.e., was negligent) and is therefore partially or wholly responsible for the owner’s losses.

Given that the risk of encountering unforeseen or differing geologic conditions diminishes greatly as the quantity and quality of subsurface geotechnical investigation increases, it is vital that engineering geologists and geotechnical engineers understand the importance of providing a complete and thorough subsurface investigation that is designed for the subject project site, reflects expected geological and environmental soil and subsoil conditions, and accounts for potential regional geologic variability.

The purpose of this presentation is to provide engineering geologists and geotechnical engineers with such an understanding by: (a) summarizing the basic areas of contention in DSC litigation (i.e., from a contractor’s, owner’s and geotechnical professional’s point of view); (b) carefully analyzing the legal rules governing DSC disputes and indemnity claims brought by owners against geotechnical professionals; (c) examining the various methods of contractually allocating risk and how each method affects the importance of the project geotechnical investigation and the manner in which the geotechnical professional/contractor conducts its site investigation; and (d) summarizing three heavily litigated, multi-million dollar DSC lawsuits, including: (i) a dispute arising from the failure of extensive silty-sand deposits during the excavation and construction of a large-diameter tunnel; (ii) a dispute arising from the collapse of a large excavated trench and the improper characterization of joint geometry; and (iii) a dispute initiated by a drilling contractor after having encountered substantially harder rock than represented by the owner.


Dr. Benumof is currently an independent consulting geologist working out of San Diego as well as an associate with a law firm based in Irvine. He received his B.S. in Geological Sciences from the University of California, Santa Barbara, his Ph.D. in Engineering Geology from the University of California, Santa Cruz and his J.D. from the School of Law at the University of San Diego.

Dr. Benumof has received many honors and awards in both his geologic pursuits and his practice of law. Dr. Benumof has published legal papers and geologic reports in addition to numerous maps. Most of his work has focused on coastal geologic hazards in southern California, however Dr. Benumof has also been involved with the mapping of lava flows in Hawaii for geohazard analysis.