Subsurface Utility Engineering (SUE) is a combination of techniques used for locating and mapping
subsurface utilities that reduces the risks associated with constructing near underground utilities.
SUE techniques include record searches, site reconnaissance, geophysical surveys, and vacuum
excavation (a drilling technique using high pressure air to remove soil without harming subsurface
structures), all combined with land surveying, and GIS to produce a final map depicting locations
of identified utilities. SUE can provide horizontal and vertical locations of buried utilities
with a vertical accuracy set to 15mm to the top of the utility.
SUE BENEFITS
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Utility Location by Ground
Penetrating Radar: Quality Level B |
SUE benefits development and redevelopment projects in the following ways:
- Unexpected conflicts with utilities are reduced. The location of utilities can be
determined and shown on construction plans.
- Unnecessary utility relocations are avoided. Utility information is available
to designers early in the project such that potential conflicts can be avoided at
the design stage.
- Safety is enhanced. Excavation or grading work can be shifted away from existing
utilities, thus reducing the possibility of utility damage, personal injury, property
damage, and releases of product into the environment.
SUE Quality Levels
The use of quality levels in the SUE process allows engineers to prepare plans with a
specified level of accuracy and comprehensiveness. The four quality levels from lowest
to highest accuracy are:
Quality Level D - Compiling information from utility records.
Quality Level C - Verifying records by mapping observable utility features.
Quality Level B - Conducting geophysical surveying to further verify locations
of known utilities and identify potential unknown utilities.
Quality Level A - Performing vacuum excavation at critical points to determine
the horizontal and vertical position of underground utilities. The locations of utilities
are then surveyed and mapped for use in construction planning and design.
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This drawing represents a typical
example of an SUE map that a client would receive. This map indicates the locations
of various utilities. The client can then use the information provided to better
determine how to proceed with the project. |
SUE Tools
Geotechnology uses the newest technologies for identifying buried utilities. Geotechnology is very
experienced at using Ground Penetrating Radar (GPR) to produce three-dimensional maps of buried
utilities (Quality Level B). Other geophysical methods used for locating buried utilities include RF,
electromagnetics and metal detectors. The firm has five geophysicists that have performed studies
for clients in government and private industry, including an award-winning project for the U.S.
Army Corps of Engineers.
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3-D GPR Survey Plot
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3-D GPR Survey
Geotechnology's air-vacuum excavation system (Quality Level A) uses both pressurized air and
vacuum to excavate potholes for subsurface access. High pressure air cuts the soil, but does
not damage utility lines. The vacuum excavation method allows an operator to safely excavate
potholes with minimal risk to personnel and underground structures. The vacuum excavation system
can be used in a multitude of applications where there is a need to excavate a relatively small
diameter excavation to shallow depths. In addition, work can be performed up to 200 feet away
from the vacuum unit, so difficult access or interior locations are not a problem.
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MoDOT Safe and Sound Bridge Program
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MoDOT Safe and Sound Bridge Program
Geotechnology was contracted by MoDOT to prepare Utility Plans at 226 bridge locations as part of
MoDOT's Safe and Sound Bridge Improvement Program. The bridges are located on state highways and
roads across 20 counties in northwest Missouri. At each bridge location, Geotechnology performed
Subsurface Utility Engineering (SUE) at Quality Level B. Field teams determined the existence of
each utility and then designated the approximate horizontal location of each utility using
geophysical methods. The utility designations were then surveyed and a utility map was prepared
based on the surveyed data. MoDOT required that the final deliverable, all 226 maps, be submitted
only 70 days from Notice to Proceed.
The six, two-person crews developed efficient methods of locating at bridge sites using hand-held
GPS units and identified the locations of known and unknown utilities using an RD-400/4000 radio
detection meter and an EM31 terrain conductivity meter. Each crew prepared site sketches that
depicted the relative locations of each identified underground or aboveground utility. Field work
was complete in 12 days.
Each geophysics crew was followed by a survey crew from one of three survey companies contracted
to Geotechnology to prepare final utility drawings for this effort: EDSI, Inc., Midland Surveying
Services, Inc., and Schultz Engineering, Inc.
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Vacuum Excavation System: Quality Level A
Typical Air Knife Hole: Quality Level A
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