The Big Four: SUE Levels of Assurance
Subsurface utility engineering (SUE) provides information
and reliability defined by four quality levels:
Quality Level D: This is the most basic level for
utility locations generated solely from existing
utility records or verbal recollections;
both typically are unreliable sources.
The data provides an overall "feel"
for the congestion of utilities
but is often highly limited
in comprehensiveness and
accuracy. This level is useful
primarily for project planning and
route selection.
Quality Level C: This commonly used
level of information involves surveying visible
utility facilities (e.g., manholes, valve boxes, etc.)
and correlating this information with existing utility
records. Often this information determines that many
underground utilities were omitted or erroneously plotted.
Its usefulness is primarily for rural projects where utilities
are scarce or not expensive to repair or relocate.
Quality Level B: Surface geophysical methods such as
electromagnetic locating or ground penetrating radar
are used to “designate” the existence and horizontal
position of all utilities. Information obtained is surveyed
to project control. This level addresses problems caused
by inaccurate utility records, abandoned or unrecorded
facilities, and lost references. Information can be used for
preliminary engineering such as locating storm drainage
systems, footers, foundations, and other design features to
avoid conflicts with existing utilities. Slight adjustments in
design can produce substantial cost savings by eliminating
utility relocations.
Quality Level A: This highest level, known as "locating,"
is the highest level of accuracy available. It involves the
full use of SUE services, providing information for the
precise plan and profile mapping of underground utilities
through the nondestructive exposure of underground
utilities through vacuum excavation. This level provides the
type, size, condition, material, and other characteristics of
underground features.
Source: Federal Highway Administration
Colors are Key for Awareness
The next time you walk on a sidewalk or near a construction zone, you may notice spray paint on the ground. Ever
wonder what the colors, codes, and numbers mean? SUE technicians and surveyors use a color-coding system to mark
underground utilities in accordance with the American Public Works Association Uniform Color Code:
White Proposed excavation
Pink Temporary survey markings
Red Electric power lines, cables, conduits, and lighting cables
Yellow Gas, oil, steam, petroleum, or gaseous materials
Orange Communications, cable TV, alarm or signal lines, cables or conduits
Blue Potable water
Purple Reclaimed water, irrigation, and slurry lines
Green Sewers, drainage facilities, or other drain lines
Source: American Public Works Association
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