Underground Locating

Underground Locating

What is acoustic locating? According to Wikipedia: “Acoustic location is the use of sound to determine the distance and direction of its source or reflector. Location can be done actively or passively, and can take place in gases (such as the atmosphere), liquids (such as water), and in solids (such as in the earth).” Most people are familiar with SONAR, at least from the movies. There are many scenes with people in submarines listening to the “pings” and waiting to see if the enemy detects them.

Most are also familiar with bats using echolocation to help them find flying insects in the air and navigate at night.

Bat echolocation

Bat echo location is similar to our approach to finding and mapping underground infrastructure.

We use active acoustic technologies in a similar way to find things in the earth. Using frequencies audible to humans, we craft special sound waves and send them into the ground. Using very sensitive microphones we listen to all the sound in the ground. We can detect reflections of the specially crafted waves we sent out, so we know the sounds we generated reflected off something. Using Digital Signal Processing and some sophisticated mathematics, we can estimate the depth of whatever it was that reflected the sound. Since we are looking for reflected sound, it doesn’t usually matter what the underground features are made of. Because of the frequencies we use, we don’t care much about the type of surface (asphalt, concrete, dirt, or sod). Different soil types (clay, etc.) and the moisture content of the soils don’t make any difference to us. We produce great results for things up to 30 feet deep.

If you need to dig a hole or drill and sink something in the ground, maybe all you need to know is if there is something where you need to work. Frequently you need to know more about all the human-made things under the surface. Most of those things are linear, such as pipelines, or relatively large, like underground chambers. By performing acoustic surveys at a number of points, we can stitch together the findings from all the acoustic survey points to determine if there is something underground that seems to be a pipeline or some other human-made structure. We can’t see it, so we don’t know exactly what it might be, but we can determine if there are things you might want to know about, and approximately where they are, under the surface. This is a totally non-invasive and non-destructive process, so there is no concern about damaging anything on the surface or underneath it.

If you need to find something underground, give us a call!