GEOSTRATA, 2015, May/June, 20-29.
By Hai (Thomas) Lin, EIT, S.M.ASCE, Suguang (Sean) Xiao, EIT, S.M.ASCE, and Hanna Moussa Jabbour, S.M.ASCE
George Tamaro is a leading authority and an innovator in the field of foundation engineering and slurry wall construction, as evidenced by his contributions over the past 50 years. Tamaro’s background in civil engineering began at Manhattan College, where he earned his B.S. in civil engineering in 1959. He then earned an M.S. in civil engineering from Lehigh University in 1961, and an M.S. in architecture from Columbia University in 1969.
His professional career path began at the Port Authority of New York and New Jersey (Port Authority) in 1961, where he served as a staff engineer. After 11 years, Tamaro joined ICOS Corporation of America, eventually earning a promotion to vice president and chief engineer. In 1980, he began consulting at Mueser Rutledge Consulting Engineers (MRCE). By the time he retired in 2006, he was a senior partner at MRCE. He continues to serve as a consultant to the firm. He has had a unique career working as an owner, a contractor, and a consulting engineer.
The World Trade Center site and the adjoining area at lower Manhattan have been the focus of Tamaro’s five-decade career in design and construction. In 1963, the Port Authority sent him to Italy to study reinforced concrete design with the well-known architect/engineer Pier Luigi Nervi. This is where he was first introduced to the slurry wall construction technique. In 1967, as resident engineer, he oversaw construction of the World Trade Center slurry walls. Tamaro joined ICOS Corporation of America in 1971 and worked worldwide on the design and construction of slurry walls, slurry trenches, and other earth retaining structures. Upon joining MRCE in 1980, his work focused on the World Financial Center, located just across the street from the World Trade Center.
After the terrorist attack of September 11, 2001, the original, 1967 slurry walls of the World Trade Center, known as the “bathtub,” were in jeopardy. Engineers were seriously concerned that the slurry wall “bathtub” could give way and water would pour into the basement and rush through the Port Authority Trans-Hudson (PATH) rail system. Tamaro was one of the members of a task force organized by the City of New York to stabilize the underground structures, assemble a construction team to clear the debris, and to re-support the “bathtub.” Upon completion of the recovery assignment, he worked on construction of the Freedom Tower and the reconstruction of World Trade Center 7. Tamaro has also worked worldwide on the design and construction of tunnels, dams, and the foundations of major buildings such as the MesseTurm in Frankfurt, the Torre Mayor in Mexico City, the Friedrichstadt Passagen and Sony project in Berlin, as well as many others.
Tamaro holds several patents in slurry wall construction in the U.S. and Canada. He has drawn from his wide range of design and construction experiences to prepare book chapters, conference papers, and technical journals. In addition, he is an active participant in the following professional organizations: ASCE, the Geo-Institute, The Moles, The Beavers, the ASCE Structural Engineering Institute, Deep Foundations Institute, the Council on Tall Buildings and the Urban Habitat, Tau Beta Pi engineering honor society, and Chi Epsilon civil engineering honor society.
Throughout his career at MRCE, Tamaro was a mentor to young staff and was always concerned with the development of young engineers within the firm. He has given back to engineering schools such as Manhattan College, Lehigh University, and Columbia University by guest lecturing, serving as an adjunct professor, and also serving on the Board of Advisors for various engineering programs.
In recognition of his contributions to civil engineering, Tamaro has received numerous honors and awards. ASCE awarded him the Martin S. Kapp Foundation Engineering Award, the Homer Gage Balcolm Award, the Edmund Friedman Professional Recognition Award, OPAL (Outstanding Projects and Leadership Award) Lifetime Award, the Fritz Medal, and the Ernest E. Howard Award. He also received the DFI Distinguished Service Award, The Moles Member Award, the Ralph B. Peck Medal from ASCE’s Geo-Institute, the Golden Beaver Award, the Lynn S. Beedle Distinguished Engineering Award from Lehigh University, the National Society of Professional Engineers Award, Leader of Industry Award from the Concrete Industry Board, an Outstanding Civilian Service Medal from the U.S. Department of the Army, and was nominated for the ENR Man of the Year Award.
Q: What first interested you in civil engineering?
The father of a high school friend was an architect, and I became interested in that field when I saw the work he did. Also, I was always interested in construction and spent a lot of time with my father working on repairs and alterations to our home. However, I could not afford tuition for architectural studies at local universities. Economics directed me to civil engineering at Manhattan College, which was the best decision that I could ever have made.
Q: Who has played a critical role in your career development?
The first person was Professor Lynn Beedle, my thesis advisor at Lehigh University. I welcomed his insights into the research that I was doing and his guidance and criticism of my reports and conclusions. The second was Professor Mario Salvadori, my thesis advisor at Columbia University. Dr. Salvadori was a true renaissance man who seemed to know everything about everything. I remember his painstaking review of my thesis; he said he would continue to critique it until I got it right. The third person was Dr. James P. Gould, my former partner at Mueser Rutledge Consulting Engineers. Jim’s clarity of thought and insightful vision — and his ability to lay out a simple solution to a very complicated problem — always amazed me. All three men had the highest intellect and moral character and encouraged me to work to my limits. All three became very good friends. Whatever I have achieved in my career I attribute to their teaching, patience, guidance, and friendship. I will always have a fond remembrance of them.
Q: Some say there’s a gap in understanding between the practice of structural and geotechnical engineering. What do you recommend to bridge this gap?
In my opinion, as part of their development as professionals, geotechnical engineers should be required to work on structural projects, while structural engineers should be required to work on geotechnical projects. Structures in and on the ground will interact with the soil; engineers should do likewise! Both engineering specialties have to be collaborative — it is important that each party understand how the other thinks and functions. The structural engineer is dealing with materials such as steel and concrete, which have small variability; he expects precision. Meanwhile, the geotechnical engineer is dealing with soils that have a wide range of properties and variability.
Q: How do you deal with large soil variability during design?
When studying a site, I try to identify the worst and best case scenarios. I try to not identify the worst soil condition, match it with the worst loading condition, and then superimpose an exaggerated safety factor to account for these extremes. Instead, I attempt to focus on identifying the worst uniform condition I can expect, how much cushion will be needed beyond that, and then how much safety factor will be required going even further. The safety factor in a design should be a function of how well you know the soils and structure.
Q: How did you get involved with slurry wall construction, and how did it impact your future career?
This goes back to meeting Pier Luigi Nervi, whom I mentioned earlier. Nervi was the architect/engineer for the innovative, reinforced concrete roof used at the George Washington Bridge Bus Station in New York City, where I started my engineering career. At that time, the Port Authority established a fellowship program that permitted employees to accumulate professional development through outside study. I applied for the fellowship and was selected to study reinforced concrete design and construction for a year in Rome under Nervi’s tutelage. While in Rome, the Port Authority’s chief engineer asked me to visit and comment on two slurry wall projects that were being considered as perimeter walls for the World Trade Center basement. I wrote a report about my observations and became an immediate “expert” on the subject, never realizing the effect of that experience on my career. Back in New York, I was assigned to help in evaluating ICOS and other slurry wall contractors bidding on the work. ICOS submitted the low bid for the work and was selected to construct the slurry wall. Initially, ICOS had an extraordinary amount of difficulty working in the New York City geology and construction environment. I was assigned to the project in the hope that my exposure to slurry wall work, my Italian language skills, and my experience in Italy would help move the project along. ICOS completed the project on time, and I became a slurry wall “expert.”
Q: What does a consultant company do?
MRCE designs and oversees construction of complicated underground and marine projects. We assist in the planning of projects, conduct field investigations, make recommendations for foundation design and construction, design the foundations or structures, assist in contracting for the work, inspect the work, and provide instrumentation of the structure and/or the ground works. MRCE does not own or construct the project. We also provide forensic and consulting services to clients encountering technical, cost, and contracting difficulties on projects. My prime retirement activity is dispute resolution and investigating distress and failures.
Q: You’ve done quite a lot of business internationally. What are the challenges of this type of work?
Being a first-generation American helps. I learned Italian as a child, then German, and lastly English. I was practically tri-lingual, but I’ve lost the German through non-use. I have no hesitancy going anywhere overseas to work. I am usually there because somebody thinks I have something to offer. My client might be an American developer who would prefer to work with me rather than with a local engineer. I can serve as an intermediary between the local engineers and the client. Or I could be hired to provide contract documents using U.S. technology and codes. My secret in working successfully overseas is do not think or act as if you are superior to the locals. The locals have a lot of knowledge to bring to the table, and you should be in a collaborative mode at all times.
Q: Back in the 60s, how did you solve engineering problems without using computers or finite element modeling?
In the 60s, we did not have sophisticated computational tools. We had to think our way through to the solution of the problem. We were forced to think about the solution before we went to pen and paper. The main computational tool at that time was the slide rule. I believe the slide rule is appropriately accurate for geotechnical engineering calculations, considering the wide variety of soil properties and soil strata found at most sites. Three significant digits are sufficiently precise for geotechnical work.
Q: Do you think engineers nowadays depend too much on technology?
One of the problems with young engineers is that they sit at the computer before they know what the answer should be. It’s like driving before you know how to operate an automobile, which is dangerous. An engineer should be sensitive to the difference between accuracy and precision. You can be very precise in a calculation, but be absolutely wrong because you started with the wrong input. Precision and accuracy are two very different things. We need to seek accuracy, not precision. Computer output implies an accuracy which may be ill-founded.
Q: What advice do you have for young geotechnical engineers?
What I learned from Nervi was to trust your judgment. When designing, question yourself. Does the answer you get make sense? Are the proportions reasonable? Is there any redundancy in your design? Are there any other loads or geometries that are more critical than those you have identified? Lastly, keep the calculations simple so that they can be checked quickly and efficiently. Also, spend time in the field to develop a sense of what things should look like. What effect will your project have on adjacent sites? Understand the limits of machinery and labor. You need to know the tools that are going to be used and what can be done practically. Talk to the site staff. You can learn a lot if you keep an open mind. Also, you need to make sure what you are doing is constructible. I have seen people put things on paper that cannot be built.
Q: Is it possible to be both a good engineer and manager?
Yes, the two are not mutually exclusive; you do not have to be one or the other. It’s okay to be both — you just have to be yourself, and you will be successful. However, it is essential that an engineer become as technically skilled as possible in his formative years before considering branching into management. It is impossible to manage engineers if you do not have commensurate skills and knowledge and earn the respect of your technical staff. I prefer a staff of engineers who lack management skills, but provide the right answer, to a staff of engineers who have great management skills, but give me the wrong answer! My goal has always been to hire and advance the most technically skilled engineers I can find, and then work with them to develop the necessary management skills.
Q: What was the most notable accomplishment made by geotechnical engineers over the last 50 years?
I do not think there is any single accomplishment that stands out for recognition. Calculation tools such as finite element analysis programs permit us to study complex structures and soil condition and study the effect of parameter variations, but judgment must be exercised to assure that the results pass the logic test. Remember, the output is only as good as the model and the input! The availability of sophisticated instrumentation now permits us to measure the performance of our design against expectation. Thus, permitting us to be less conservative on future designs. The major advancements in geotechnical engineering have come from the constructors and their engineers, who, in response to competitive pressures, are constantly developing new tools and technologies. For example, the development of slurry wall technology has been an important advancement initiated by contractors. Slurry wall technology permits geotechnical construction to depths and dimensions that could not have been achieved previously. There are so many other technologies, such as tie-back anchors, reinforced earth, and geotextiles, which permit us to execute projects that were inconceivable 50 years ago.
Q: What do you see as the future of urban geotechnical engineering, such as in New York City?
In urban areas, the first soil strata you encounter is soil laid down by man, usually in an uncontrolled manner. It is usually fill consisting of soil removed from other sites, construction debris, and potentially contaminated waste. You have to come up with a judgment as to the material properties, which can be highly variable. You need to have some flexibility in your thinking. At one building site in Manhattan, there were footings cast on rock at one end, and 150-ft-long piles at the other end. Adequate site investigation and local experience is essential to a successful urban geotechnical engineering practice. It’s essential to develop as thorough an understanding of the site ground conditions as possible, as well as an understanding of prior use of the site. The unexpected should be expected when working in complex urban environments. Utilities, both non-functioning and active — as well as abandoned structures — can have major impact on the success and cost of a project. Sometimes understanding of the reviewing authorities’ concerns is more important than the knowledge of ground conditions! Finally, knowing the capability of the local contractors is important, as well as staying abreast of state-of-the art equipment and techniques.