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Elements of Successful Subsurface Utility Engineering


Subsurface Utility Engineering is a complex data compilation and Geophysics process that can only add value and minimize risk if implemented correctly. When a SUE program is uncoordinated and strays from prescribed standards, the process can open project stakeholders up to further risk and liability. Furthermore, bad practices and a lack of qualifications can prevent the accurate detection of underground utilities. Here are a few key factors that are required in order to ensure a successful SUE program:

Having a clear understanding of SUE

A clear understanding of SUE on behalf of project owners is necessary to accurately define the scope of work required, estimate costs and set expectations around deliverables.  SUE is far more than a form of locating buried utilities. On the contrary, it blends civil engineering, subsurface geophysical surveying and mapping, vacuum excavation and utility asset management technologies.

An authentic SUE Program is one that adheres to the four quality levels outlined by the ASCE Standard, and to be effective, these levels must be carried out in order, by experienced professionals that leverage the right technology.
Once collected, data should be presented in CAD format or a GIS-compatible map. A utility conflict matrix should also be created that evaluates and compares collected utility information with project plans. This allows the project engineer to identify conflicts and propose solutions. 

Taking an integrated approach

In order for a SUE project to succeed, it must be integrated and systematic so the project engineer can narrow down the geographic region where higher quality information is required, and then take full ownership over this judgment call.

When tasks within the process are outsourced or a client attempts to accomplish certain steps on their own, (such as gathering existing utility records), the margin for error increases as does the potential for liability.  In order to produce a true composite data set during a SUE investigation each quality level defined under ASCE 38-02 must be compared and correlated. 

Some steps to ensuring an integrated approach include:
  • Hold a preconstruction meeting as early as possible. Invite each and every project stakeholder to discuss and document project plans and expectations.
  • Coordinate early and often with utility owners as to their anticipated involvement in the project.
  • Consistently maintain open communication and keep everyone informed of design or timetable changes throughout the life of the project that might affect the work area and the subsurface utilities that lie beneath it.
  • Where possible, trust a single team of trained professionals to carry out each step of the SUE program. Avoid service providers that outsource steps in the process such as the GPS data capture, as this may affect the value of the final deliverable.
     

Using the right technology

More and more underground utilities are being made out of durable PVC materials rather than the more traditional cast iron piping and ductile iron. These non-conductive, “non-toneable” assets are not always traceable through commonly used utility detection methods, and utility owners don’t always perform the necessary steps to enable their detection such as effectively installing tracer wires.

As such, an effective SUE program generally leverages a wide intersection of technology and techniques including inductive electromagnetic instruments, Ground Penetrating Radar (GPR), GPS and vacuum excavation.  This is key because there is no single technology that can locate utilities effectively for all site conditions where utility composition and depth varies.

Today, electromagnetic induction and GPR are the primary methods of finding buried utility assets, and the effectiveness of these tools is directly related to the training and experience of the field technician. As locating is a highly interpretive skill, years of experience are generally required to develop the expertise needed to identify utilities in varying conditions. When selecting a SUE provider, it is important to choose an organization that can bring a wide range of geophysical tools onsite rather than basic induction equipment only.

Leveraging diverse expertise

As a multifaceted discipline, SUE requires solid project management, sound judgment, and sharp analysis skills capable of interpreting data from a variety of sources, identifying utility conflicts and planning relocation where necessary.

Moreover, a SUE provider must be familiar with a range of geophysical techniques so they’re able to select the appropriate geophysical methods for the project at hand. Without the ability to select the right tools, additional surveys may be required which can cause major project delays.

This is especially true of high profile projects such as a highway rehabilitation which might contain extensive underground utility congestion consisting of underground gas, water, telecommunications and electrical utilities.  If any of these utilities are missed due to the wrong equipment or a lack of expertise, the main objective of the SUE program, which is to mitigate risk, will not be fulfilled.