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.  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 utility locators, 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. EQUIPMENT To conduct a thorough and accurate subsurface utility mark-out, a variety of equipment types should be employed.  No single instrument can detect all types of underground utilities.  NAEVA Geophysics uses several different utility location instruments and GPR to provide a complete on-site utility mark-out. Pipe and Cable Locators:   -  DitchWitch 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 250, 500 and 1000 MHz Smart Carts -  Sensors & Software Conquest system

APPLICATIONS Mapping the surface trace of buried utilities: Electric Natural gas Telephone Fuel Water Sewer Providing mark-outs where subsurface utilities are an issue: Generate or update subsurface utilty 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   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.     A utilities mark-out prior to excavating or drilling should be the rule, not the exception.