YOU PAY FOR A REASONABLE GEOTECHNICAL INVESTIGATION WHETHER YOU HAVE ONE OR NOT

That is one of my favorite expressions. I think that I made it up. If I didn’t, I wish I had.   The “saved” money almost always gets used elsewhere.  Either in the design or in the construction.

What am I talking about? Well, it’s pretty typical for a geotechnical engineer to carefully develop a site investigation plan, and to present that plan to the owner. The plan is carefully developed taking into account the site conditions, planned facilities, etc. The owner often discusses the need for the various investigation points and techniques. Sometimes (usually?) some activities of the site investigation are eliminated. It feels like an opening bid that gets negotiated down.

Sometimes (usually?) you have to hold your ground and explain why certain components of the site investigation are necessary. And then your client tells you why you don’t need all that, and honestly, sometimes we don’t really need all that. But, more often than not, we get surprised by something in the field, and we could use additional investigation work.

I recall a simple shallow foundation design assignment in Nevada. Expecting the normal valley-fill alluvium/colluvium, and being sympathetic to the client’s budgetary restrictions, I arranged for an excavator and I sent one of my engineers out to inspect the excavations. Naturally, I would have preferred to use a geotechnical drill rig. What my engineer found had confused him. He showed me a bag of the material that was obtained from the excavation. It was sand. Sand dune sand. Nope, we’re not building a structure on shallow foundations on a sand dune! We had obligingly saved the client money on the site investigation, but we were unable to design the foundations that they needed. They did not retain us for any additional work, and I often wonder if some poor outfit had designed the shallow foundations that the client wanted on those sand dune sands.

On another major project, a site investigation was completed for a major infrastructure installation. The client “negotiated” down the extent of our site investigation. We completed our work, which included developing the foundation recommendations. Much later, during the construction, we were asked to take part in the foundation approvals process (among other things). Several of the structures required the removal of several feel of surficial material, because it was collapsible. I entered one such excavation, and began examining it. The base of the excavation should have been on a dense alluvium unit. One half of the floor of the excavation did not look right to me. I asked for an excavator to poke a few holes here and there. There was a silt unit beneath half of the excavation. Having two dissimilar materials beneath a heavily loaded structure could have easily caused unacceptable settlement issues. Together with some of my other colleagues, we had to halt the construction work until the engineering could be solved. Did we miss something during the original site investigation? No. The client had re-arranged the facilities, which resulted in them being spread to the north, beyond the extents of the site investigation. The client thought that they were saving money by not allowing us to drill a couple more holes.

One last story. We were again asked to perform a site investigation for a foundation recommendation project. The loads would be fairly high, but the client ensured us that the natural ground would be very dense. We got talked into using an excavator rather that a drill rig, which we would have preferred. We had completed two or three excavations, and everything seemed pretty normal. And then we dug into a bread bag at a depth of about 20 feet. Natural material my Aunt Fannie! We informed the client that we would have to arrange for a drill rig. They agreed. Unfortunately, the finding of that site investigation indicated that we would either need to relocate the structure or design deep foundations. The client said “no thanks” to both of those options and they hired another firm to complete the work that we had started. The other firm did some additional drilling, and came up with the same recommendations. I’m pretty sure that they ended up going with the deep foundations. They sure didn’t save any money by insisting that we avoid using a drill rig.

I could go on and bore you with more stories like this, but hopefully you get the point. Try to not get placed into a situation where your site investigation is so limited that you don’t do the project justice.  And remember:  You pay for a reasonable site investigation whether you have one or not.