A part of the billboard construction process – whether the sign has wooden poles or metal ones – is to dig a hole in the earth that meets the required engineering standards to hold the sign up. And digging a hole often 15’ deep in an area that rarely has seen excavation can often yield unusual results, such as hitting water and giant rocks. In this episode of the Billboard Mastery podcast we’re going to discuss what happens when you hit the unexpected, and how to mitigate the cost and make the right decision.
Episode 9: Drilling And Hitting Things That Are Not Oil (But Sometimes Are) Transcript
In the popular TV show from the '60s of Beverly Hillbillies, you had Jed Clampett go out in the Missouri Ozarks hunting for food, hits the ground with his rifle bullet and out gushes oil. And in many ways, we as billboard builders, owners, and operators who do a lot of digging, sometimes we're like Jed Clampett. We're drilling holes in the gravel. We're not really sure what's going to come out of it.
This is Frank Rolfe for the Billboard Mastery Podcast. We're talking about drilling and hitting things. Now, often when you drill a hole for a billboard based on the kind of billboard, whether it's a metal, monopole, steel, I-beam, wooden telephone pole, you drill at different depths, but you do always pretty much drill. Now, you don't always hit the same stuff. If I drill a pole six feet in the earth, I have a less likelihood of hitting something and if unless I drill a 15 foot or 20 foot like you do with the monopole sign. But nevertheless, even if I drill just a foot or so, you can sometimes hit things.
So I thought we'd go over the kind of things that you hit, what the workarounds are and some of the insider secrets and tricks you can have in doing that. So one of the first things you'll find when you drill holes in the earth that you can hit our utilities because lo and behold, there was that water line or that sewer line there, and you drill down and you hit it. And how do you get away from that? Well, that's easy. You always do a utility line locate before you ever even think about drilling into the ground. You'd be crazy to do it otherwise. There are utilities out there that if you strike that utility, it would wipe you out.
Fiber optic cable is the number one example of that. Hitting fiber optic cable, the bill to repair the cable and the lost income to the cable company can be a million dollars. I don't think that's survivable. So again, do a line locate. Every state has typically a one-source line locate number. You call that, tell them where it is. It doesn't cost you anything. And they come out and mark all the utilities and they'll put all clear where you were going to dig. That's how you get away from hitting utilities.
Now, another common thing you'll hit when you're out digging, although it doesn't happen every time. In fact, very rarely, but you'll hit water. Not the kind of water that comes through the water line from the city, but the kind of water that's inherent in the ground everywhere. Underground aquifers, high water tables. You'd be shocked at places where you drill and find water. So what happens when you hit water? Well, number one, you don't normally get gushing water. As you're drilling the hole and you pull out the drill bit, what you're going to see is the sides of the hole, they're starting to seep water out. And as you proceed farther down, there's more water coming out of the sides. Now you're getting water in the bottom of the hole.
So what do you do? Well, one option is you can do is call the casing the hole. That's where you take a piece of pipe and as you drill down, you insert the pipe in as it goes. So at the end of the movie, what you have in that hole, if it's 15 feet deep is a hole that's reinforced by a 15 foot deep piece of pipe. That stops the water from coming in the side.
But here's another way you can do it. You can do what's called a bell hole foundation. Now what's a bell hole foundation? Well, a bell hole foundation is you just let the water keep coming in the sides of the hole. And as you do it, the sides of the whole collapse. And they collapse first and foremost, down at the bottom, because as you get deeper, that's where there's more water pressure. Now, what people will then do is they'll go ahead after a drill down 15 feet or 10 feet or whatever the engineering says for you to do. Once you get on down there with the bell hole, so now it's caving in at the bottom. You go ahead and put the pipe in it. And then you pour in virtually dry concrete. To do this you have to use something called custom crete.
It's a truck that basically is not like your typical concrete truck, where the concrete comes already ready mixed with the water, rotating over and over again. But it's a different kind of truck. The concrete is stationary because what you have in the truck is basically just concrete powder and stone and all the ingredients of concrete, but they don't mix the water until it gets to the job site. The guy is then able to determine how much water to put in it on the truck. And if you have a lot of water in the hole, they won't put in any. He'll just pour the raw concrete mix into the hole. As it hits the bottom of the hole, it mixes with the water. And that's how you make the concrete.
Now what's the downside to a bell hole foundation? Well one, you have a very, very large amount of concrete in the hole because it's not like the original model where you're just pouring concrete in between the sides of the column or telephone pole or I-beam that you're putting in and the hole. Now you're also filling in that giant cave down there at the bottom. So one thing is you'll have extra concrete use. That's true. And if you ever had to pull the foundation out, it'd be nearly impossible. Because instead of pulling out a cylindrical tube out of the ground, which could be done by a crane, now you'd have to pull this amorphous triangular object out of the ground. It would be nearly impossible to do.
And if you, for any reason ever had to do it in your lease. If it said in the event of development, you have to remove the sign and the foundation, well that would be [inaudible 00:05:54] probably your ability to pay for it. You'd have to go through the backhoe and basically dig the thing out. It would be an absolute nightmare. The good news of the bell hole foundation is it's extremely strong. There's no way that sign will ever put tip over in a windstorm because moving that foundation in the earth at that magnitude of the size of the foundation, it isn't going to go anywhere.
Another thing you sometimes hit when you dig is rock. Now, I've probably hit more rock than I've hit water. And rock is a trickier thing. When you hit rock, you don't really know how deep you have to go to get out of that rock. And rock can be very expensive. It can also be very slow. Now the regular drill bit, that drills into the earth when it hits rock, it can't go any further. It's done. That's the end of the movie. So what you then have to do is you pull out that drill bit and you put on instead of very small drill bit that gives it more pounds per square foot of torque and pressure.
And then that little drill bit goes down and it starts drilling and perforating that rock with lots of little holes. And as you weaken the holes, then you could go back in with the bigger drill bit and then drill into it. It takes a long time. It's also very, very expensive. When you hit a rock, a boulder, whatever it may be, probably the best thing you can do is one of two things. You could see if the engineer would tell you that you can go with a different foundation. Perhaps something that's larger and wider in girth, but not quite as deep. But more commonly what you're going to do, is you're just going to move the hole over and see if you can find a spot that doesn't hit the big old boulder.
Now, this is easy enough to do if you're in a farm field, but what if you're not in a farm field? What if in fact you are in a developed property and you're supposed to be in one certain spot? The good news from my experience has been those boulders, those underground rocks you hit, they're normally not that big. You can sometimes just move the drill bit over three or four feet and you get clear of it. You may have to experiment. You may have to drill down several times till you find the area where there's no stone underneath. But that's typically a better course of action than trying to actually drill through the stone because it takes so long and it is so very expensive.
Now, this is one reason why when you do that lease with the property owner, you want to leave the exact location of the sign a little loose because you're not sure when you really go to drill that foundation if there's going to be something there to stop you from it. And if you have to the very inch where the foundation is in your lease and you had to move the sign over three feet, you'd be in violation of your lease. You'd have to go out to the property owner to get that renegotiated again as far as having them initial where the new location is. That's why you typically want to put just this amorphous rectangle roughly around where the foundation will be. You're doing that to protect yourself, because if you cut it too tight, you can get in real trouble.
Have I ever hit oil like Jed Clampett? Yes. I did once in a billboard out in East, Texas. I drilled a hole and I didn't hit water and I didn't hit a rock. I hit gasoline. Didn't hit a gasoline pipe. This area had so much gasoline leaking from underground storage tanks from truck stops and everything else that the ground was permeated with gasoline. I didn't have a playbook of what you do when it's permeated with gasoline. So we just drilled our hole, put the sine column in and poured it in the concrete. Sign is still there to this day. I don't really know what you're supposed to do when you hit things like that.
However, if you had a question you could always call the state or somebody and ask. Property owner would probably not be very happy with you because there may be some environmental issue with that. That's really not what billboard companies get involved in is the environment or remediating environmental pollution. But again, you never know what you're going to hit when you drill that hole.
Have I ever found an interesting artifact or item? Nope, never have. I always thought I would. I always thought maybe someday the drill bit would come up and it would bring up, I don't know, a hat from the civil war. Maybe an old coin or something interesting, but nah, never happened. Probably because you normally build billboard foundations in more rural areas where there really wasn't anything historically going on. But at least it does keep you interested to see what comes out of that hall. It also keeps you interested, always making sure you don't hit anything that really is important. This is Frank Rolfe for the Billboard Mastery Podcast. Hope you enjoyed this. Talk to you again soon.