Most significant new constructions projects begin with a subsurface exploration. Part of the purpose of the subsurface exploration is to provide a basis for geotechnical engineering necessary to design the foundations, earthwork, pavement and utilities for the project. In addition, the subsurface exploration and geotechnical engineer’s interpretation of the conditions observed inform the construction contractor’s pricing and planning of below-grade work. Given the importance of geotechnical considerations to the cost and risk of a construction project, it should be apparent that adequate budget and scope need to be authorized to address these considerations. However, often the scope of services agreed to by the geotechnical firm and their client, be that the owner, another design professional or some other stakeholder, does not take advantage of opportunities to reduce construction cost and risk of below-ground work. So who should be responsible for determining the right geotechnical scope of services?
For a lot of projects, the scope is determined by another professional and issued to multiple geotechnical firms for pricing. The scope might be prepared by an architect or structural engineer for building projects or by a civil engineer for utility and highway projects. This approach is often problematic. While an architect or engineer would understand that geotechnical services are necessary, they are typically unfamiliar with sampling and testing methods and do not know how subsurface information is or should be used to determine parameters and recommendations for design and construct of the project. Therefore a scope prepared by another design professional will typically include quantities of borings and laboratory tests that are arbitrary or based on code requirements alone. Since the purpose of specifying quantities is to allow a comparison of proposals from different firms, this situation results in a firm being selected based on price rather than on the proposed scope or the quality of the engineering going into their reports. This creates an incentive to minimize the geotechnical engineering provided on these projects and results in higher costs or risks due to over-conservatism and omissions.
A better approach would be to have the geotechnical firm propose a scope and fee appropriate for the project based on the proposed construction and the firm’s knowledge of local geology and construction practice. However, the market for geotechnical services in certain areas are dominated by materials testing firms that approach their work as a commodity. Because these firms offer their services at low cost, they may use under-qualified field staff to observe drilling and sampling, over-rely on laboratory tests and provide little, if any, site-specific interpretation or analysis of the subsurface conditions in their reports. Another potential problem with the geotechnical firm providing their own scope is the fact that many geotechnical engineers are unfamiliar with or hostile to code provisions affecting their services. For example, most building codes require an evaluation of certain issues when deep foundations are to be used or if the Seismic Design Category is C or greater. These issues are not always addressed in the geotechnical report when required.
Perhaps there is a better way. In the past, foundation engineering was recognized as a distinct specialty concerned with all aspects of supporting a structure on soil and rock. The advent of soil mechanics in the early 20th century resulted in the empiricism and holistic practice of historical foundation engineering practice being deprecated. This results in what is fundamentally one engineering problem being split into two problems that interact at an artificial boundary, each of which is solved independently by parties who do not understand the other side of the problem.
The scope of geotechnical services should be determined on a project-specific basis by someone who understands both sides of the problem. A geotechnical subsurface exploration is not planned for a site; it is planned for a project that is to be built at that site. Since most sampling and testing methods are standardized, it may be unavoidable that a portion of the geotechnical scope is commoditized. However, interpretation of the subsurface conditions and selection and design of foundation systems requires relevant education, experience and professional judgment. These same qualifications are necessary for determining what geotechnical sampling, testing and analysis should be performed. There is still a role for the foundation engineer.
The information and statements in this document are for information purposes only and do not comprise the professional advice of the author or create a professional relationship between reader and author.