Subsurface Utility Engineering Division 

Subsurface Utility Engineering (SUE) is a branch of civil engineering dedicated to managing the risks of underground utilities (as defined by FHWA).  The use of Subsurface Utility Engineering allows for cost-effective decisions to be made during the planning, design, and/or construction phases of a project.  These cost effective decisions can include route selection, identifying/resolving facility conflicts, and/or construction sequencing.  These services are most effective when utilized during preliminary and/or final design of projects where potential facility conflicts can be identified and resolved prior to construction.

The American Society of Civil Engineers (ASCE) has established standards for this service as referenced in Standard Guidelines for the Collection and Depiction of Existing Subsurface Utility Data (ASCE 38-02).  Also, The United States Department of Transportation established the Common Ground Task Force to develop a guide for underground utility damage prevention best practices for use throughout the United States.  As a result of this task force the Common Ground Alliance was created as a nonprofit organization dedicated to shared responsibility in damage prevention and promotion of the damage prevention Best Practices identified in the Common Ground Study Report.  Both organizations have identified a classification system for the quality of data associated with existing underground utilities.

Designation, Location (test holes), and Data Management are the three major components of Subsurface Utility Engineering.  The Spectra Group, Inc. performs these services under the supervision of licensed Professional Engineers.  These services can be provided at various Quality Levels that allow the client to select the degree of accuracy of the existing underground utilities to fit the needs of their particular project. 

Designation

Designation is the indication, by surface marking, of the presence and approximate horizontal location of underground facilities utilizing specialized equipment and techniques.

Location (Testholes)

Location is the verification of the actual horizontal and vertical location of an underground facility.  The Location process utilized by The Spectra Group, Inc. consists of a compressed air/vacuum system to expose the desired facility via a test hole.  Once exposed, data is obtained which will be useful during the project’s design or construction to identify and resolve possible conflicts. Such data includes the precise horizontal and vertical location, size, and material type of the facility.  The use of a compressed air/vacuum system avoids damage to existing utilities and minimizes the surface disruption (normally 10 to 12 inches square).

Data Management 

Data Management is the process in which the information obtained on the existing underground utilities is presented/incorporated into the survey and/or design documents.

Quality Levels of Service

Subsurface Utility Engineering can be provided in various quality levels of service.  This allows the client to determine the degree of accuracy of existing underground facility information that fits the particular needs of the project.  These Quality Levels of Service are defined as follows: 

• Quality Level D 

Information comes solely from existing utility records.  It may provide an overall “feel” of the congestion of utilities, but it is often highly limited in terms of comprehensiveness and accuracy.  Its usefulness should be confined to project planning and route selection activities.

• Quality Level C

Involves surveying visible above ground facilities such as manholes, valve boxes, poles, pedestals, pad-mounted devices, etc., and correlating this information with facility records obtained in Level D.  When using this information, it is not unusual to find that many facilities have been omitted from records or erroneously plotted.  Its usefulness should be confined to locations where facilities are not prevalent or are not expensive to repair or relocate.

• Quality Level B

Involves the use of surface geophysical techniques to determine the existence and horizontal position of facilities.  This activity is called designating.  The indications of underground utilities are marked on the ground surface, surveyed, and depicted on base plans to develop a two-dimensional mapping representation of information obtained. This mapping may involve information obtained from Quality Level C or D.  This information is usually sufficient for excavation planning.  Decisions can be made on where to place structures of new facilities to avoid conflicts with existing facilities.  Slight adjustments in the design can produce substantial cost savings by eliminating facility relocations.

• Quality Level A 

Involves the use of non-destructive excavation devices at critical locations to determine the precise horizontal and vertical position of existing facilities, as well as the type, size, condition, material, and other characteristics.  This activity is called “locating”. When surveyed and mapped, precise plan and profile information is available for use in making final design decisions.  Additional information such as facility material, condition, size, soil contamination, and paving thickness also assists the designer and facility owner/operator in their decisions.