SUBSURFACE UTILITY ENGINEERING (SUE)

There is no “silver bullet” to detect all the underground utilities below the ground. This is possible only through Subsurface Utility Engineering (SUE) which incorporates several detection methodologies like GPR, electromagnetic pipe/cable locators, metal detectors, acoustic pipe tracers, etc.. The ASCE Standard 38-02 denotes a system for classifying the quality of existing subsurface utility data, in accordance with four quality levels which are: QL-D, QL-C, QL-B, & QL-A.

QUALITY LEVEL D:

The quality level D is the most basic level of utility locations using information that relies on a combination of the existing plans, other available existing records, and cursory site inspections. When SUE is shown as of quality Level D, it should always be treated as an indication or sign of the potential presence of utilities only, and should NOT be used for the design.

QUALITY LEVEL C:

The quality level C Information is collected through correlating the survey of certain visible utility surface features like hydrants or marker plates and acquired plans to “draw” a string that shows the approximate position of services. This method usually does not show multiple banks of cables.

QUALITY LEVEL B:

The quality level B Information is collected through the designation of the horizontal and vertical location of underground utilities with the use of different geophysical tools like ground-penetrating radar (GPR), metal detectors, electromagnetic pipe/cable locators, acoustic pipe tracers, and so on. It addresses certain problems caused by inaccurate utility records, lost references and abandoned or unrecorded facilities. The right selection and application of surface geophysical methods to achieve QL-B data are critical. Information derived from QL-B can enable the accomplishment of preliminary engineering goals. Decisions on the location of storm drainage systems, foundations, footers and other design features can be made in order to successfully avoid conflicts with the existing utilities.

Additionally, Slight adjustments in the design can result in substantial cost savings by eliminating the utility relocation.

QUALITY LEVEL A:

The quality level A is the highest possible level of quality and accuracy. It is obtained by exposing the underground utility. It gives information on the precise plan and profile mapping of underground utilities (usually at a certain point directly from the site through trial holes. It also supplies information about the type, size, material, condition and other characteristics of the underground utilities.