October 20, 2020
By: Eric Denslow
Some years ago, a received a call from a customer that works for a small town in northern Connecticut for some assistance in locating a pipe that he was struggling to find. On-site he showed me a gate valve in the street as the last known location and had a map indication from the gate the pipe crossed the street at an unknown angle and depth. They had previously attempted digging it up across the street at the suspected angle, but had no luck. When I initially connected to the valve, I could locate the pipe going away from the gate box but could not locate any signal crossing the street. I decided to go completely across the street to see if I could find where it turned again, and continued straight on the opposite side of the road. I was able to locate some weak signal some distance away that indicated I was on the pipe, but could not find a turning point to tell where it came from. I then proceeded to connect my transmitter to a valve down the street on the opposite side of the road in an attempt to follow the signal toward the unknown location, but again could not find any signal leading me across the street.
After a number of failed attempts with different grounding techniques and frequencies, I decided to start over from the beginning by connecting to the valve at the original gate box. During all of my failed attempts I’d been using the peak locating mode. The RD7100 and RD8100 models were still fairly new at the time, and I didn’t feel very comfortable using the guidance mode. My thought was if the peek antennas could not see the signal, how could the other antenna modes see it? But, since all of my other attempts had failed, I decided to try the guidance antenna mode. The signal strength indicator was very reading was very week, but I began to notice that the guidance arrows were giving an indication of something. As I swept left and right over the area, I observed that the arrows on the receiver display were in fact giving a fairly clear left / right indication that I was indeed tracing some signal across the street. The directional compass in the center of the screen struggled to give me a clear indication, but it was somewhat straight while I passed through the signal. I followed what the arrows showed me across the street, and was able to pick up some signal turning and then continuing down the opposite side of the road before it disappeared again rather quickly. I wasn’t positive if I had found it or not, but the customer was happy that I tried to solve their issue and that I gave them another place they could dig to attempt to fine the pipe.
A few weeks later I received another call from the customer to tell me that I had perfectly located it. It turned out the pipe crossed the street at about a 22-degree angle after the initial gate valve, and went down in depth to around 15 feet which would be one of the reasons that we struggled to locate it. I learned that the guidance mode in the Radiodetection equipment can sometime see things that the peak mode can’t.
In conclusion, I make a point when training customers for them to practice and get comfortable with all of the modes and features of the equipment. The mode someone is most comfortable using may work 99% of the time, but using every feature of your equipment could make the all difference for locating that other 1%.