Exposing Common Myths About Utility Locator Services

Underground utility detection and inspection services play a critical role in damage prevention. However, there are many rumors or misconceptions about utility locating services that need to be exposed. Read this post to clear the common myths regarding utility detection and inspection services.

1. One Call (811) Will Mark All My Utilities.

One Call usually only locates the public portions of the underground utilities. Sometimes they mark electrical power, telecommunications, and natural gas lines from the street to your buildings, but usually won’t mark water, propane, yard lighting, irrigation, sanitary sewer, storm drain utilities, septic systems, utilities to outbuildings, etc.

2. Private Utility Locators Will Mark All My Utilities.

Although private utility locators will try to meet your needs to mark all relevant utilities, locating technologies including electromagnetic locates (EM), ground penetrating radar (GPR), video pipe inspections (VPI), amplified acoustical microphones for listening, electronic pulse transmitters (EPT), traceable insertion rods, etc. have limitations and there are no guarantees that all utilities can be located. You still need to proceed with caution while performing subsurface work.

3. I Just Ordered Utility Locate Services, Now I Can Sit Back and Relax Until They Arrive.

If your site is complex which is common for industrial and commercial sites, there is some tasks you should accomplish before the utility locators arrive on site. Mark the target work area with white paint, make sure there is minimal obstructions such as parked cars, piled construction materials, etc., check to see if there is access to the areas around the target work area. Sometimes there are locked utility rooms or fenced in utilities that are vital to gain access to for utility locating; and it might not be easy to get into them unless access is prearranged. Also, try to see whether you can get any utility records/maps, or if you want CNI Locates to collect any available utility maps. They could provide important clues which could make a difference between identifying and missing some utilities.

4. Utility Locates Are 100% Accurate.

Occasionally public locators will identify utilities based on utility records without actually locating them which may not be accurate and could lead to subsurface damages. Even with locating technologies used, locates can be inaccurate or incomplete due to bleed offs, signal attenuation, congested utility trenches, no access, non-conductible utilities, grounding, etc. Despite the high accuracy of locating technologies including ground penetrating radar and electromagnetic locates, they all have limitations, and the instruments readings are subject to the operators’ interpretation.

If you are performing a drilling project, try to stay away from marked lines as far as possible. In Oregon and Washington State, it’s required that you should be at least two feet away from both sides of a marked line. When possible, it’s suggested to keep your drilling location 3, 5, or even 10 feet away from a marked line. If you are doing excavation, keep in mind that there is a high probability that there could be parallel utilities next to a marked line. One marked line could indicate a single pipe/cable, or a group of parallel pipes/cables close to each other.

5. In My Proposed Work Area, There Are No Utilities Shown on My Utility Maps, So I Don’t Need to Have Underground Utility Locating Services Performed.

Past records are seldomly accurate or complete. In our experiences, unknown underground utilities are often detected while performing underground utility locating services. In fact, it is rare to find all existing utilities shown on utility maps that are provided.

6. Only Metallic Pipes, Cables, And Wires Can Be Detected, But Non-Metallic Utilities Like PVC Pipes, Fiber Optic Cables, Concrete Pipes Cannot Be Detected.

GPR cannot see everything, but it is useful to help find locations of non- metallic utilities and other subsurface elements in favorable subsurface conditions. If you have access, we can insert a traceable flex rod or push video camera with a sonde into a pipe or conduit so we can trace it with an electromagnetic receiver. Also, we can use electronic pulse transmitters (EPT) to send a pulse through plastic water lines that we can listen for with our subsurface microphones that amplify any subsurface noise. Along with other methods. 

7. Ground Penetrating Radar Can See All Underground Utilities.

GPR is extremely effective at locating subsurface utilities and other materials, however it does have certain limitations. While some of the GPR energy pulse is reflected to the antenna, energy also keeps traveling through the material until it either diminishes (attenuates) or the GPR control unit has closed its time window. The rate of signal attenuation varies widely and is dependent on the properties of the material through which the pulse is passing.

Materials with a high dielectric will slow the radar wave and it won’t be able to penetrate as far. Materials with high conductivity will attenuate the signal rapidly. Water saturation dramatically raises the dielectric of a material, making an area difficult to scan due to signal attenuation.

Metals are a complete reflector and don’t allow any amount of signal to pass through them. Materials beneath a metal sheet, fine metal mesh, pan decking, or any other metallic objects will not be visible.

8. Once a Utility Locating Service Is Performed, I Can Use Its Results for All My Future Subsurface projects. 

Underground utility locating is a dynamic process, there are a lot of variable factors involved affecting its outcome. For example, the soil condition varies with seasons and weather, and it could significantly affect the GPR performance. Also, utility locators may or may not have the full access to the site due to obstructions during the locating process. Other factors include accesses to nearby utility rooms, availability of utility records, and even clues from conversations with people familiar with the site. In addition, a utility mark out usually serves a particular purpose and the locates may not be suitable for other purposes. For example, a mark out for clearing a 2-feet deep trenching route may not be suitable for deeper excavation or soil boring activities. CNI Locates will not guarantee the longevity of facility markings due to activities on site that may destroy or otherwise alter any markings placed on the ground by CNI Locates.

9. No Marks Means No Existing Utilities

Even though utility locating services are highly effective, there are chances that there is a utility that wasn’t accessible, was non-conductible, was not visible with GPR, etc. Therefore, we advise that you hire a professional private utility locating company like CNI Locates to double check the area, especially if non-metallic utilities are present. The absence of marks does not confirm that there is no utility in the area; further, it can also mean that the utility is not located yet. Choose C-N-I Locates Ltd for an array of utility detection and inspection services from Aerial Drone Imagery, Design Survey Locating, Electrical Fault Detection, Ground Penetrating Radar, Leak Detection, Magnetic Detection, Metallic Line Detection, Non-Metallic Line Detection, Photogrammetry, Plastic Water Pipe Detection, Public and Private Utility Locates, Sewer Crawler Inspections, Structural & Concrete Imaging, Utility Mapping, Video Push Camera Inspections, and more from experienced technicians in all of Oregon and Washington State.