Utility Location

The Method

Most line locating equipment operates through principles of electromagnetics (EM), designed to detect underground utilities constructed of electrically conductive materials. An active signal is applied to the underground utility by means of a radio frequency (RF) transmitter and then traced with a receiver. With direct coupling, an RF signal is applied to a cable or pipe where there is access to a contact point. With no access to the utility, the indirect mode is used. A transmitter is placed or walked along the ground surface above the conductor and the signal is induced through earth onto the pipe or cable. For non-conductive pipes and conduits, a plumber's snake can be inserted into the line and a signal induced along its length. If electromagnetic methods will not detect a particular utility, ground penetrating radar (GPR) can be employed to image the subsurface feature.

Equipment Used

Pipe and Cable Locators
Ditch Witch Electronics Subsite 950 R/T
3M Dynatel 2200 series cable locator
Fisher TW-6 pipe and cable locator / metal detector

Ground Penetrating Radar Units
Sensors & Software Noggin SmartCart (250, 500 and 1000 MHz)
Sensors & Software Conquest 1000 MHz
MALÅ Geoscience 250 MHz
GSSI StructureScan Mini HR 2,600 MHz
GSSI UtilityScan DF 300/800 MHz

Field Procedures

NAEVA Geophysics' approach to utility location begins with a highly experienced and motivated crew equipped with a variety of state-of-the-art utility location instruments. Our personnel, without exception, are all geophysicists and geologists with a strong understanding of geophysical principles and how they are effectively applied to utility location. Utility location is an exacting science. When a complete and accurate utility mark-out is desired, NAEVA Geophysics provides geophysical consultants, not service technicians.

APWA Code

Data Processing and Presentation

Utility location equipment is designed for direct detection and recognition of targets, real-time in the field. The surface traces of underground utilities are marked directly on the ground as they are identified, using the color code established by the American Public Works Association. Field sketches are made and later digitized using our CAD facilities, showing all detected underground utilities as they relate to permanent above ground facilities.

Applications

  • Mapping the surface trace of buried utilities
    • Electric
    • Natural Gas
    • Telephone
    • Fuel
    • Water
    • Sewer
  • Providing mark-outs where subsurface utilites are an issue
    • Generate or update subsurface utility maps for future planned development
    • Clear drilling location for subsurface interferences
    • Identify utilities for avoidance during excavation
    • Map utility pathways that may be related to contaminant migration
    • Accurately mark-out utilities scheduled for repair or replacement
Markout

Complexity of markouts range from single USTs to the streets of Manhattan