Utility Locate Services
Comprehensive Subsurface Solution
- Optim is able to use five different locate methods including Conductive Mode, Inductive Mode, Passive Mode, Sonde Insertion, and Tracing Wire.
- Output Quality Level A Subsurface Utility Engineering(SUE) projects to aid in your subsurface utility needs.
Utility locating is performed based on a transmitter emitting an electromagnetic wave into a metallic utility and a receiver being tuned to detect a change in the wave. A magnetic field is created by the transmitter with the output frequency determining the distance the wave travels, the ability to identify a utility, and the depth of detection. The electromagnetic wave transmitted into the utility will leak away with distance as the impedance to the ground will be reduced.
Conductive Mode is the most common method of pipe and cable locating as the operator can directly connect to the targeted utility with the transmitter. Inductive Mode is applied when a utility can not be directly connected to, therefore the transmitter is placed above the utility and sends an electromagnetic wave through the utility. Passive Mode can detect utilities with no transmitter needed as low frequency radio energy is radiated to the operator’s receiver. Sonde Insertion is utilized when the utility can be accessed by a manhole and a radiating transmitter is thread through the utility to emit radio frequencies to the receiver. Tracing Wire is used when the utility is installed in the subsurface and contains a metallic wire that the locater can send an electromagnetic wave through by either Inductive or Conductive Mode.
- Ground Penetrating Radar(GPR) is a non-invasive method that uses electromagnetic waves in the microwave band (UHF/VHF frequencies) of the radio spectrum to detect subsurface materials.
- GPR is best utilized when the utility does not posess a tracer wire or can not be located using traditional locate equipment.
Ground Penetrating Radar(GPR) is utilized as one of Optim’s geophysical methods that uses radar pulses to image the subsurface. GPR is applicable in a variety of environments including rock, soil, water, pavement, and ice. Utilities can be located in the subsurface by an electromagnetic wave being transmitted from the GPR and reflected back.
The center frequency, the electrical conductivity of the material, and the radiated power will influence the depth range of the GPR. Depth of penetration will be decreased using a high frequency GPR or amplified electrical conductivity in the soil attenuating the electromagnetic waves. The general rule of thumb is a GPR with higher frequencies will have decreased depth of penetration but increased resolution, with a converse trade-off associated with a low frequency GPR.
As the GPR is moved perpendicular across the utility, a hyperbola will be formed therefore displaying the top of the utility. A hyperbola is formed due to the GPR being moved over a utility with the electromagnetic waves being reflected at an angle whereas being directly above the utility will display the peak amplitude. The operator will determine the top of the utility based on this peak amplitude of the uppermost positive wavelet. GPR is best utilized when the utility does not posess a tracer wire or can not be located using traditional locate equipment. For example, a given utility may be made with plastic or cement and not be able to be located with traditional electromagnetic detection systems.
Hyperbolas shown above indicate the top of a given utility. Utility Locators are able to use these hyperbolas to properly map the utility at a specific depth.
Optim can locate the following utilities:
- Telecommunication Line
- Water Lines
- Gas Line
- Sewer Line
- Storm Drain
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