Subsurface Utility Engineering - What Is It?

Since the mid 1980's, highway engineers in the United States have experienced difficulty in gathering accurate underground electric public service information. In fact, several states have hired engineering consultants to determine the validity of the subsurface information that has been gathered and is required for planning throughout an entire highway project. This involves identification of the precise horizontal location of all the underground utilities, which includes underground septic tank systems and wells. Basically, this type of engineering practice is called Subsurface Utility Engineering (S.U.E.).

Definition

According to the American Society of Civil Engineers (ASCE), S.U.E. is a practical engineering process that manages the risks related to the gathering of precise information, mapping, and characterizing of subsurface utilities at an early stage of project development. This process uses conventional methods of research, site surveys, and applied sciences such as geophysical surveys and excavating done by non-destructive vacuum systems to obtain the most exact information possible.

Scope of S.U.E. Practices

In developing Federal Land Highway projects, Subsurface Utility Engineering performs several tasks that constitute the first part of the engineering process.

• Owner Identification- It is necessary to identify electric public service owners who are affected by a highway project. This is followed by having one-on-one meetings with these owners to inform them about the particular project.


• Owner Management- It is fundamental to provide pertinent information to utility owners during the planning phase. Such information should be reviewed, examined and plotted on a composite drawing or demonstrated in a three-dimensional view of the underground electric public service before being shown to the affected owners.


• Identify Underground Features- It is advantageous to use the latest surface geophysical techniques to assign or trace certain underground utility features.


• Inspect and Draft Information- It is important to conduct field inspections to determine ground surface utility systems. All the data gathered should be plotted on the client's plan sheets.


• Resolve Incongruities- It is essential to resolve any discrepancies if all the collected information consisting of existing records, ground surveys, geophysical techniques, and underground surveys do not agree.


• Develop a Conflict Matrix- This involves analyzing and comparing all the conflicting information to the proposed development plans.


• Meet to Plan a Resolution- It is fundamental to meet with the utility companies to address all the identified conflicts and formulate possible solutions.


• Provide a Detailed Overview- It is critical to depict the enhanced information using three-dimensional views of the underground utilities and present it to the client. Discussing and explaining designs to the client will hopefully ensure that they understand the project and can provide any suggestions to resolve any conflicts.

To sum up, the scope of Subsurface Utility Engineering is to: locate and assess above-ground and subsurface utilities; utilize geophysical techniques; depict all information in computer-aided drafting; analyze and resolve any conflicting information; meet with the utility companies to solve the conflicts; and meet with the project owner to present all vital information before initiating the project.

Quality Levels of the S.U.E. Process

There are four quality levels (QL) of information utilized by subsurface utility engineering. They are considered by the degree of risk or the information needed to design the highway project. Basically, highway plans require accurate utility information to avoid erroneous plotting or omission errors before the client finalizes the project. The quality levels range from A to D with A as the highest and D as the lowest rating level. QL-A is only necessary if there are conflicts that need to be resolved in the utility's path. Lower levels are applicable if few or no conflict is being encountered.

To describe it another way: QL-D is the primary information gathered from existing records or during a verbal interview; QL-C is the information collected from the above-ground inspection; QL-B is the information gathered using surface geophysical techniques; and QL-A is the highest level of available information collected through the use of various utility engineering services.

Subsurface Utility Engineering is not a form of technology but a process being followed to gather comprehensive information. It is an engineering practice that aims to furnish accurate, reliable, and quality levels of information, creating a final draft before proceeding with a project. The new applied science that is involved in this branch of engineering is the use of surface geophysical techniques and non-destructive techniques using vacuum truck systems to help in the process. S.U.E. is indeed a very helpful process that greatly aids in the construction of our nation's highways!