Geotechnical Report - Overview

There are many issues to consider when you're trying to decide whether a project is viable. Some obvious ones like, will the project cost too much? Will it be useful for the clients? Will it fit into the context in a sort of reasonable way? Is there a population of people that either want to buy the apartment units, or go to that store, or whatever it happens to be? But there's also a series of very closely related to the site issues that are hugely important from a viability standpoint. And one of them is the soils conditions.

If you have a set of soils that are really poor soils for being able to take any loading, or you have very very high water tables, or some other kind of condition. It might well be the thing that says, You know you really can't do that building in this location. It's just going to be too expensive. The foundation systems are gonna be just too crazy. It doesn't make any sense to try to put that kind of building in this location.

Or, maybe it says, well, we've got two acres on this site, and the area that we thought we were gonna be building on, well, it turns out that's kind of a wet area, or it's poor soils that aren't going to be very useful from a foundation standpoint. And this other area, well that's actually much more likely, much sort of more reasonable soils for the kind of work that we want to do. So the soils report ends up becoming a very important early decision maker. It's one of those things you're going to go to right away, early on, to see is this project even viable in this location?

Or at least viable in the way that we're imagining it when we first started to approach the project? So it's a useful tool early on in the process. Now, interestingly, the soils report is actually something that the client is supposed to get. The owner of the site is the one who actually provides the soils report, and they're technically supposed to provide that at the very onset of the project.

So even before the architect is involved, the soils engineer should have been on the site, doing soil boring tests and getting all that information and putting together that soils report, so that the architect, right from the start, has that soils boring report, and they are able to sort of get going right away with that information. Now, it doesn't always work that way. Things are complicated. There's reasons why sometimes it doesn't show up for a little while, things like that. But, technically, that's how it's supposed to work. So the site information, like the survey and the soils boring reports, those should both be given to the architect right at the very beginning, so that you're not spinning your wheels designing a building that it really can't happen because the soils just aren't good enough for that site.

But the soils boring report will show up later as well. As the project starts moving along. As you kind of go from schematic design in towards design development and the engineers are getting involved more deeply.

And you're starting to think about how specifically the foundation systems are going to work. Or how the storm water systems are going to work. Does the site percolate well enough for how the storm protection needs to be. Will a pounds per square foot resistance of the soil at various heights make a difference in terms of which depth of foundation we're gonna go for. All of those sort of more nuanced decisions, which start happening a bit later, kind of the schematic design, design development, kind of moving into that range.

You'll reference back to this soils report. And then as you start getting into the CD sets, as you're moving closer and closer towards the finals, you're gonna use the soils reports again just to kind of check to make sure. And you're probably gonna have to include that soils report in some of the presentations of information to, for example, code officials to get a permit. Or to funders to make sure, the funders want to know that this is a viable project in this location, things like that. So, it shows up at various points along the way, but the key thing for understanding is that you also really wanna make sure that you look at it right away, right at the very beginning, in order to understand viability. Is this project viable?

So, let's take a look at an example soils report, and just sort of get a sense of the feel of how these things are done. They're very long and wordy, and frankly, there's about three parts that we really care about. And so a lot of it we can just sort of skip by.

It's important. They have to go through it, and the engineers may be interested. But for the most part, you're looking for what their recommendations are. And you're looking to see the actual boring reports to see the depths of where the different soils are. Cuz you're trying to make sort of final decisions. Like, should we put a basement in? Should we not put a basement in? Do we want to go down 12 feet to get to the better soil? Or is that gonna be more expensive and we'd be better off just going to four feet with the lesser soil, but have a slightly bigger foundation. Those kinds of questions, you're trying to decide, and so you use this as a tool to help you decide.

And when it comes down to it, all things soils, like these are the folks who are gonna tell you, you know if there's any question about soils, you're gonna go back to them. You're not gonna make your own decisions. You're gonna go back to this report and figure out, from the report, what they're recommending, to understand how you're gonna go forward. You wouldn't want to be making your own set of decisions about whether a certain kind of foundation makes sense on a certain kind of soil or not.

They bring a lot of expertise to the field, and they put it all together for this site, and they've packaged it in a way that you can use very simply and easily. If, for some reason, the things that they're recommending just don't fit with what you're trying to do, then that's a conversation to be had between the architects and the owners and the people who put together the soil boring report. Because you want to make sure that they are on board with any changes that you're making to the, sort of, assumption of how you're going to be working with the soils.

So, it may be obvious, but I'm gonna say it anyway. Clearly, if something goes wrong with your reading of the soils, and you put too heavy of a building onto too small of a foundation, and the building starts settling badly, and things start going wrong, that's a very big problem. That's a huge deal. So the insurance companies, if you go into litigation and things like that, the first thing when something like that happens, the first thing they're gonna wanna know is, well what did it say in the soil boring report?

They're gonna wanna take a look at it and find out what was said, what the soils engineers told you to do. And if you didn't follow that advise, then that's gonna be on you. If you did follow that advise, then it's not on you, it's on them, because that's their job, is to give you that information.

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