PLSO The Oregon Surveyor Sept/Oct 2020

Professional Land Surveyors of Oregon |  www.plso.org 21 Featured Article ends of a straight pipe and you draw a line in the middle. This is very common when connecting storm systems. It’s like the grown up version of dot-to-dot! Just draw a line from the catch basin to the pipe in the manhole. Ground-penetrating radar can be used to find the location of structures under - neath the surface. This method is very useful when being used on a medium that is of uniform material. This does very well for finding pipes and wires em - bedded in concrete walls or slabs. When there are layers of mixed soil types, it is more difficult to find clear results. This is also a very expensive method of locating. Probably the most odd and interesting method of locating is the use of dous- ing rods. They are also called witching or divining rods. This is usually done with some bent copper wire, although I have used bent marking flags in a pinch. Like electronic locating, this is all about using magnetic fields. In this case however, a person uses the rods to show a break in the connection of their magnetic field with the earth’s magnetic field. Because all people are different, not everyone has the same experience when trying this. Some people don’t find anything. Some people only find water-containing pipes. An ODOT worker told me that he could only find lines that were 10 inches in diameter or larger. While I know that it works, there is definitely an art to it. I only use this method when nothing else will work. The rods will react to a num- ber of things under the ground, without differentiating between one type of line and another. In the same way that ametal detector will make a beep for a chain link fence, a property pin, or a buried horse shoe, the rods just say there is something there. I do believe this is still the best way to locate a septic drain field. I have also used this method for locating concrete and PVC water lines and to find the edge of a concrete utility tunnel. For years I have had people ask me if my equipment was a metal detector. An old man would walk by and ask if I had found any gold. He would laugh at his clever comment, not knowing he was the third one to make the same joke that day. It wasn’t until I started my own com- pany that I even thought about getting a metal detector. I really only use it to find buried manholes, valve covers, and water meter boxes. It may get more use by my 13-year-old son who found a Hot Wheels car in the front yard. He dug up a horseshoe and some old cinches on a farm property. We also found less than a dollar in change at my in-laws’ house. Metal detectors may have significant use for surveyors finding property pins, but they are hardly used by utility locators over the age of 13. What Do I Need to Expect? Using a private locator can be very handy in many occasions. Whether plac- ing an easement or planning a building expansion, there are times when know- ing the location of lines is critical. While I may solve a number of problems, don’t be shocked if a locator uncovers more problems. Many times some- one has accused me of “putting” some line right in their way. I didn’t actually put the water line in their foundation plan, but some of the planning had to be changed. Sometimes it has been a buried fuel tank and sometimes it is a damaged line, but there are multiple times that I revealed some unexpected and expensive issues. I think of myself in many ways as a professional problem solver, but occasionally I am just the problem exposer. I also wish that every locator and every locate was perfect. Sadly, Superman has kept his X-ray vision to himself. It is reasonable to expect quality and professionalism, but locators are not all-knowing and all-seeing. There are things that are missed from time to time. There are also things that we may not be able to find out. I can hook to a trac - er wire and find its location, but I may not know the pipe size of a line. There have been multiple times when I found the location of a line, but was unsure of what it was. It is normal for signals to bleed off onto other conductive facili - ties, which has resulted in confusion for that once. Who would have thought that connecting to a street light would put a signal on the irrigation control wire? I hope this little peek into the world of a locator has been helpful, or at least interesting. Again, I want to express my appreciation to the surveyors with whom I have had the privilege to work. I look forward to seeing you all in the field.  x These are some treasures found by my sons and nephews at their grandparents’ house. Metal detecting has few applications for finding actual utilities.