Our utility locating service uses a variety of methods and techniques for locating buried lines. Before deciding on a best approach for a project, key decisions have to be made based on information at hand. During the planning phase, information is gathered from a visual inspection of the job site and available mapping data.
Once this is complete the next step is to choose a method for the specific challenge. Spearhead uses several different electromagnetic locating techniques, as well as ground penetrating radar and acoustic detection, to identify the position of buried lines. We keep up with the latest developments in our industry and are experts at finding underground utilities -- an absolute must before any construction project or excavation begins.
The final step if required or requested is documentation of the locating service. Spearhead provides digital as built plans and GIS mapping data showing the located lines in an aerial map with color coded overlays.
Electromagnetic locators allow us to find conductive utilities such as phone, electric, and water lines. Our receivers pick up the metallic body below the ground, and then its position and orientation is marked on the surface per CGA and APWA standards.
This method uses a transmitter to apply a detectable signal to the buried line. A receiver detects this signal and provides information about the signal field, including the horizontal centerline of the field, intensity of the field, and estimated distance to the center of the signal.
Direct Connection: Allows a low frequency to be transmitted directly through the line. This method of utility locating is best for targeting a single utility in a congested area due to low levels of signal bleed off to other lines in the area.
Clamp Induction: The induction clamp (coupler) method produces a strong EM signal field within the clamp which is transferred to the conductor encircled by the coupler clamp. This method can be used without making metal-to-metal contact to the line. The clamp is ideally used for applying signals to live cables. A signal is transferred from clamp to cable without taking the cable out of service in a pedestal, manhole, electrical panel or junction box
Broadcast Induction: This method is an indirect way to induce a signal from the transmitter to a buried line. This technique is use to sweep an area for conductive lines that may not be evident during the initial inspection.
Ground Penetrating Radar
What is GPR utility locating? Ground penetrating radar, or GPR, is a method that uses radar pulses to image the subsurface and find buried utilities. It is ideal for finding nonconductive types of pipe, such as PVC pipes or septic tanks.
The way GPR works is that a radio signal is sent into the ground, after which the GPR reads the response of the signal and then shows an image of what’s below. UHF/VHF frequencies are the kind of signals directed into the ground, and the reflected signals from subsurface structures are collected and graphed.
When access is difficult or electrical current does not flow (i.e. there is a non-metallic element or a broken connection), or external noise makes electromagnetic detection impossible, GPR provides a valuable alternative. Some of the benefits of GPR utility locating are that it provides its own source of energy and detects both metallic and non-metallic objects, as well as detecting disturbed soil conditions and other buried structures.
The electrical conductivity of the ground, the transmitted frequency and the radiated power all affect the depth range of GPR. Higher frequencies do not penetrate as far as lower frequencies. However, higher frequencies may provide improved resolution. Thus, operating frequency is always a trade-off between resolution and penetration.
At Spearhead Locating, our utility locating professionals know how to make the best use of GPR and its capabilities for the locator. Our work conforms with CGA best practices and the APWA uniform color code.
We will work with your contractor to determine whether ground penetrating radar is the best fit for your utility locating needs. We work quickly, but as always, accuracy is our main goal! We want to be the ones to find the buried utilities in your property before you find them the hard way. Contact us today for more information or a free quote on our utility locating services!