Safety 1st Advancer Manual do Operador descarregar pdf (Página 22)

Environmental Remediation Drilling

Safety Guideline

Page 22 of 132

Limitations of GPR cont.

It is important to note the depth limitations of GPR when clearing horizontal or directional drilling

boreholes. Horizontal drilling technology is usually used at depths greater than 20 feet below the surface

which is beyond the detection limits for GPR. An option for clearing horizontally drilled boreholes is use of

a template and water jet to clear the horizontal run to the required depth. This is a relatively extreme option

and will only be justified in cases where utilities may be present.

2.6.2 - Pipe Tracing Transmitter and Receiver

A pipe and cable locator and tracer can be used to detect and trace metallic utilities, utility tracing wires, or

warning tapes. In pipe and cable tracing mode, the transmitter can be coupled by direct contact

(conductively) to exposed portions of a metallic pipe, cable, or wire; or by simple proximity (inductively) to

a subsurface metallic utility with known location and orientation. The transmitter remains stationary and

energizes or excites the metallic utility to be traced with a signal that can be traced at the ground surface

using the mobile receiver wand or probe.

Figure 2.2 - A Pipe Tracing Transmitter/Receiver Being Demonstrated in a Non-environmental

Remediation Work Area (Photo courtesy of Enviroscan, Inc.)

Limitations of Pipe Tracing Transmitter and Receiver

To use the transmitter in the most effective manner, all metallic pipes to be traced must be available for

connection directly to the transmitter. The inductive mode is not as effective. Also, the detection is limited

to metallic objects and is not useful for plastic, ceramic, or fiberglass utilities.

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