A topographical survey is basically, it's a map showing the property
that's going to give you contour elevation.
So it's also elevation data, as well as your X and Y data
grading features that sort of thing.
And as well as the power poles are going to show up and the tree line
if you're doing a topographical survey, you're doing some sort of development
you're going to improve a property in some manner.
So you need to know where those easement are.
And how exactly are you taking these measurements? Is it measuring it from sea level up?
Correct. So it's mean sea level and there's multiple datums,
but the most current datum is NAVD 88.
So that's your mean sea level for North America
And what kind of tool are you using to do this?
A lot of it's GPS, we're also going to use a toll station,
which measures angles and distances because once you get into the foliage, GPS doesn't work anymore.
It's trigonometry and coordinate geometry
survey grade GPS
For our setup, we're going to use a base station, which fixes a point on the earth.
And then we use a radio signal
and we've got a row report
Using that radio signal, it gives us a correction factor in the base station
and it tells us the distance from where we told it it was when we started the base and where it says now.
That gives you a kind of pinky type accuracy, I guess is the best way to say
When I looked at like those nationwide topographic maps, how useful is that?
The nationwide maps or even like the countywide maps. They're good for getting just a rough idea.
You know, you can come up with a conceptual plan because you can say, okay, I can't pull the road
down that hill, it's two steep. But as far as designing, you need to be more accurate.
There's always going to be error in measurements. There's no way to eliminate it.
Most of the stuff you're going to be dealing with,
your verticals is probably going to be
Horizontal will be less than that.
I'm talking survey dimension.
So 100th of a foot, roughly it's a little bit smaller than an eighth of an inch.
It's within that amount... - It's very accurate. - Okay.
Is it Google Earth something that one can rely on to figure out the accuracy?
It's a good tool, but as far as creating a map that you could work off of, it's not good enough,
partly because you don't know where your property lines are in relation to those contours.
The other issue you run into with like lidar is you can hit the top of that marker over there.
And it wouldn't know the difference between that and the ground grade, which is now two feet lower.
It's not going to be as accurate as boots on the ground.
They won't pick up things like gas valves or gas markers.
But it's a good tool to start things with.
How many different points of measurement are there?
Usually what we'll do is if it's relatively flat, like out here, we're going to do about a 50-foot grid.
At every 50 foot we'll put a point. If you've got more hilly areas where you've got banks,
it's going to be much tighter than that because you have to hit the top of bank
in the bottom of bank. On this side, I probably have about a thousand points of data.
So how long does it take to do that kind of survey? - At least a day. - Really? - Oh yeah. Yeah.
I guess that makes sense. It's a lot of barrier to cover.
What affects the cost of this kind of survey?
Some of it's going to do with how much work the surveyor has done in the area.
Cause if I already have information, it's going to cost you less.
There's also have to do with the distance that you are away from
Yeah. So you'll have some drive time. On a job you're going to be there the whole day.
That's not such a big thing, if you're not two or three hours away.
It's also going to deal with, okay, there's a lot more trees here.
It's going to cost you more because I can't just GPS the whole thing.
Different types of measurement take different amounts of time.
Do you guys ever worked with like an unmanned lidar system, like a drone?
So we don't actually have a drone at our company. We have used other companies drones for
sites like a gravel pit where there's no trees,
everything's to the dirt and accuracy is not that important
They want a rough idea for volume.
Is that cost less?
It's quicker. I'm not entirely certain it's cheaper all the time. In some cases probably yes.
Other cases it may or may not be.
Why do people order these surveys? Is it because they're about to build something
and they want to make sure?
What's the reason why people do it?
It's always because you're going to design something. If you're going to build a building
or say, you're going to split out parcels and other reasons are when you're building,
you need to know where your storm water runoff is going. So you can put up silt fences.
Do people ever start building without getting a topo survey?
Oh, yeah. People start building without a permit sometimes.
So I don't know if that's a fair question. If it's a simple piece of property,
you don't need topographical survey. Say you've got an in-town lot and you want to build a house
The lot is flat, you know you just got to build up from the ground, raise it up
you don't necessarily need
But if you got a more difficult site where you're dealing with,
okay, am I going to be able to get a walkout here? Or is this hill too steep?
Where am I going to set the house? Is the driveway too steep?
Anytime you need to start designing, looking at what slopes are going to be.
What your elevations are at, any time you have to deal with a flood plain.
At what point are the elevations so steep that you can't build something on it? Is there such a thing?
Anything can be engineered. It's just a matter of how much you want to spend to build it.
What does a topo survey not telling you?
It can only tell you what we see on the ground. So if the underground utility guys
don't mark something, we're not going to be able to locate it. It's not going to tell you what's
been buried years ago unless somebody told you, okay, this is an area. There's an old barn here.
It tipped it over, buried it under the ground. And it's also not going to give you your environmental data.
Like if there's pollution in the water or in the soil.
So, no septic tanks, no underground gas tank, if it's not marked.
Correct. Sometimes you can tell where a septic tank is and the drain field, but not always.
If there's a wooly mammoth, you can't tell me that either.
No, no wooly mammoths.