A password will be e-mailed to you.

Rendered view of the complexity of subsurface utilities. Image: Emerson Melin


Updating the nation’s hidden infrastructure.

By Aaron Hopkins with Maraliese Beveridge

It’s no secret that infrastructure across the United States has reached a point of no return. Every building material we use — concrete, steel, rubber, wood, asphalt — all have expiration dates. Even with the most vigilant maintenance programs, eventual repair or replacement is inevitable. That doesn’t even account for expansion, new technology, or improvements in materials. On the other hand, new, redevelopment, or roadway expansion projects all rely on the associated utilities. While above ground infrastructure has the advantage of exposure to visual inspection, what about down under?

Subsurface utilities are in a class by themselves. They weave intricate pathways of water, electric, sewer, gas, drainage, and communication lines in, around, and connecting to the more familiar above ground counterparts — but to the naked eye, they are invisible. This alone makes them as hard to find as it does to maintain, which has always been problematic. Due to anything from inadequate data and incomplete as-builts to misinterpretations or unanticipated changes in geologic conditions, subsurface utilities can complicate projects and cause major delays, putting a strain on budgets. But there are solutions!

My name is SUE

A vacuum excavation unit is used to expose buried utilities to collect Quality Level A data. Photo: Dustin Spillman

Subsurface Utility Engineering (SUE) is an engineering practice providing the most effective means of verifying and mapping the location of existing underground utilities available. When used to its fullest potential, this powerful verification process has become a critical part of both the design and decision-making processes for new and existing infrastructure projects. This includes any project affected by subsurface utilities: roadway and transportation, airports, government, commercial, and residential developments.

SUE employs a coordinated approach to obtaining subsurface data, first by collecting data from all available sources, then using a combination of data tools such as survey and electromagnetic utility-locating devices including ground penetrating radar (GPR), and pipe and cable locators. Geographic Information Systems (GIS), designed to manage ongoing asset life cycle (identification, maintenance, replacement data, etc.) through a web-based program, can also be integrated into the mix. These tools combined enable the SUE team, comprised of licensed specialists including geodesists, surveyors, and civil engineers, to provide clients with a data-driven model that provides the most complete information available.

From a planning standpoint, having the most complete knowledge of existing utilities facilitates project design, serving as a base map for the project approach as well as damage control and accident prevention. Not knowing costs money, shuts down crews, wastes materials, and creates change orders that may turn a standard installation into an unnecessarily over-customized design.

Aside from the core utilities, there are also drainage systems, retaining walls, underground storage tanks, bridge foundations, sign/traffic signal foundations, and any other buried obstructions that may have been abandoned or forgotten. SUE can be used to detect these for repair or removal. Vertical clearance is a consideration as well since many utilities are placed atop one another and need to have a required buffer between them. Thorough investigation in advance drives the decision-making process and can determine whether a roadway should be redesigned, if the utilities need to be moved, or both.

Purdue study

Although many studies have been done on project cost savings when implementing SUE, within and out of the United States, the general consensus of designers in the U.S. seems to support the Purdue University study (www.fhwa.dot.gov/programadmin/pus.cfm). Commissioned by the Federal Highway Administration in 2000, the Purdue University Department of Building Construction Management performed a study that analyzed “the effectiveness of subsurface utility engineering (SUE) as a means of reducing costs and delays on highway projects.” Four states — Virginia, North Carolina, Ohio, and Texas — were selected to participate, each controlled with a checklist that defined 21 areas for potential project savings. This included anything from unforeseen utility conflicts and delays due to relocations, change orders, conflict redesign, and contractor productivity to working relationships between the client and utility.

The study concluded that:

  • only three of 71 projects studied had a negative return on investment;
  • one individual project had a $206 to $1 return on investment;
  • SUE should be used in a systemic manner on virtually every project; and
  • for every dollar spent on SUE, the potential minimum saved is $4.62.

Ultimately, the cost savings reflected from this study are “a minimum quantifiable savings. The true project savings are likely to be significantly higher than this study can prove.”

Early utility coordination

Quality Level B data collection with GPR to designate underground utilities. Photo: Dustin Spillman

When integrating the SUE process, two key elements stand out: being proactive with early utility coordination and exercising a standardized approach to ensure the quality level of data collection.

“Early utility coordination should automatically be part of the subsurface investigation process,” said (John) Robert Memory, CPM, regional utility senior project manager for Maser Consulting PA. “The design team should partner with utility coordinators as early in the SUE process as possible to ensure they are both part of the project buy-in. You should look at performing Level B horizontal locations and collectively, as a team, decipher where Level A is needed for design utility avoidance.”

As former North Carolina Department of Transportation state utility agent, Memory has more than 30 years of expertise with utility coordination and emphasizes that projects involving subsurface utilities should employ the 4-C approach. When talking “utilities” to the experts, you will always hear the phrase, “Communication, Cooperation, Coordination, and Commitment.”

“To successfully work with any utility company, effective listening is a critical part of the communication process. Just as important is cooperation, especially where costs are concerned,” Memory said. “Executing proper cautionary steps for public safety is paramount when dealing with utilities. Ultimately, who’s paying for the relocation of the utilities shouldn’t be a factor.”

While the user usually bears the expense, communicating with utility companies is essential. For example, you’d never know if a utility already had a relocation plan near your project site that could be beneficial to both parties. Especially when hydraulics, right-of-way and easement limitations, conflict analysis and resolution, and redesign costs all come into play for both parties when relocating utilities (temporary and permanent) within a corridor. This is why Memory encourages SUE and utility coordination to be a combined discipline, working together for better coordination of the way in which subsurface space is managed throughout the entire course of the project.

While the 811utility location service is a good place to begin, it is generally implemented as only one of the many initial sources used during the initial document and record investigation phase. 811 employs a basic location identification service designed more for their utility operations, maintenance, and damage prevention at the schematic level. In contrast, the SUE team provides design-grade engineering data (spatial and attributes) for transportation, oil and gas, airport, industrial and military facility, marine port, and rail projects.

ASCE on your side

American Society of Civil Engineers (ASCE) 38-02 standards define four quality levels within the SUE process as Standard for Collection and Depiction of Existing Subsurface Utility Data. According to ASCE, this guideline presents “a credible system for classifying the quality of utility location information that is placed in design plans. When subsurface utilities are discovered during the construction phase, the costs of conflict resolution and the potential for catastrophic damages are at their highest. That is why the collection and systematic depiction of reliable data for existing subsurface utilities is critical if engineers are to make informed decisions and support risk management protocols regarding a project’s impact on these utilities.”

It’s important to remember that SUE is a process. Data collection for SUE is defined by the ASCE’s four quality levels of accuracy for performing the process.

Level D: Involves document research and gathering of utility records from all available sources. This includes permitting and utility company records, as-builts, field notes, and interviews of staff who may have been involved during installation and can provide information from memory and verbal recollection.

Level C: Everything in Level D combined with topographic feature surveys, and location of hydrants and other above ground appurtenances relative to the underground facilities. Depending on the scope of the project, this is where creating a GIS dataset for asset management could be beneficial.

Level B: This stage no longer continues to combine information.  It’s the level during which electromagnetic tools are implemented to designate utilities and identify areas of conflict by combining their signals from which above ground mark-outs are created.

Level A: This is the minimally invasive level where the utilities are physically exposed. Using a vacuum excavation unit to remove earth and debris enables operators to confirm the utility, its horizontal and vertical position, condition assessment, and collect descriptive size and material type.

Once collected, this data will be surveyed and sent from the field as line drawings to the office and transferred into CAD, or the client’s preferred software application, where this linework is transformed into a 2D or 3D model that can be analyzed and referenced into the design.

Adhering to this methodical standard is the most effective means for safe identification of subsurface utilities and their environment. While saving clients time and cost is certainly key, responsible utility management also enhances safety as it reduces the risk of loss of life during the course of construction activities.

In addition, it provides a control to the client for the project environment. Site information within each level is progressively taken into consideration to ultimately produce a viable model of the underground infrastructure that can be used to make data-driven decisions on how to move forward in customizing existing utilities to fit the project. According to one source at the ASCE, on average about 30 percent more buried infrastructure is found by following ASCE 38-02 methods than is shown on available utility records at the Level D quality level.

Dreaded as-built

Quality Level A test hole confirms utility depth, size, and material and reduces the risk of damage to existing infrastructure. Photo: Dustin Spillman

If the ASCE 38-02 is the best practice standard during the SUE process, the subsurface as-built should be the cherry atop the cake — yet it rarely ever is! But why is the as-built so elusive?

“When we’re performing SUE for our clients, which includes anything from highway authorities to utility company projects, we take exhaustive measures to map utilities underground. But during the process, which can take years for larger projects, there are a combination of new installations while other utilities get moved, replaced, or adjusted along the way,” said Mark Pitchford, regional director, Survey/Geospatial, Southeastern U.S., for Maser Consulting. “Changes never seem to fully make their way back to an as-built. Once you’ve completed all this work, that’s the time to re-map it with final placement and add in the GIS component if at all possible and you’d be golden.”

A proponent of the true as-built, Pitchford estimated it would only cost an additional two to five percent of the original design fee to produce. Other government agencies making improvements, even a municipal sidewalk project, would benefit from this data coordination, which eventually would have to transfer into savings with the cost of permitting, new installations, or modifications for starters.

Future big data, storage, and sharing

In the United States, the ASCE 38-02 standard is the premier guideline for investigating and depicting existing utility infrastructure. ASCE also believes a complementary standard for producing a common “as-built” data set is essential for safeguarding public and commercial infrastructure, protecting the public, and making optimal use of public right-of-way. Accordingly, the ASCE Construction Institute and Utility Engineering Surveying Institute have been sponsoring a multidiscipline, technical committee which, after five years of effort, has developed and is about to publish a non-mandatory, consensus Standard Guideline for Recording and Exchanging Utility Infrastructure Data. This is a straightforward 3D digital standard for mapping and documenting newly installed or freshly exposed utility infrastructure lying both below grade and at or above the surface. This “as-built” standard interleaves with ASCE 38 for documenting quality Level A observations.

Example of field sketch merged with surveyed field data and CAD design file. Photo: Dustin Spillman

“ASCE 38-02 provides excellent guidelines for investigating existing buried installations to treat and remedy a widespread and persistent symptom. Our new ‘as-built’ standard addresses the cause of this symptom by providing guidelines to document new utility infrastructure in an accurate and consistent manner at the time of installation,” said Philip J. Meis, P.E., M.ASCE, president of Utility Mapping Services, Inc. and committee chair of the ASCE Standard Guideline for Recording and Exchanging Utility Infrastructure Data. “Our effort stems from ASCE 38-02 as well as The Canadian Standards Association CSA S250-11, championed by the utility industry in Canada, but goes further by providing a standard framework for documenting infrastructure spatial, geometric, and feature attribution characteristics in a clear-cut manner such that the utility features can be reproduced in a virtual 3D-rendered model. This will unleash a plethora of emerging 3D digital technologies such as augmented reality viewing, 3D computer-aided design, building information modeling (BIM), civil integrated management (CIM), clash detection and conflict analytics, and machine guidance construction technologies which expedite excavation, facilitate damage prevention, and reduce project risk. The bottom line is with this standard we can develop more sophisticated designs and construction approaches which compress project schedules, reduce costs, improve utilization of public right-of-way, mitigate public and commerce disruption, and safeguard and better serve the public.”

Going forward, application of this standard will ensure that accurate and consistent information about the location and nature of new underground utility infrastructure is captured at the time of installation and available for future project development.

Conclusion

Every project for which the design team gathers and handles subsurface utility data responsibly is one project nearer to closing the gap of obscurity. In fact, this is a key factor in the future viability of land development through data-driven decision-making processes. The power of a reliable as-built plan depicting an underground utility field is our best legacy. So, now that new standards are beginning to emerge, the responsibility of storing and using this data once the project has been completed and how it is eventually applied to integrated city management remains to be seen. Who will be steward of this broad collection of subsurface management information? Until we can harness Superman’s power of X-ray vision and do this all in one fell swoop, we will have to rely on the experience and best practices employed by professionals in the field and the integrity of the data collected.


Aaron Hopkins is a geographic discipline leader for Subsurface Utility Engineering (SUE) for Maser Consulting P.A. (www.maserconsulting.com) currently overseeing SUE operations throughout the state of Florida. With more than 17 years of experience in the construction and consulting industries, he specializes in the underground utilities construction industry with extensive experience working for and with local governments, utility owners, and other regulatory agencies. Hopkins’ responsibilities include fostering client relationships; preparing estimates; contract negotiation; project execution and analysis; implementing and maintaining corporate safety program standards; and training and educating employees in the office and field.
Maraliese Beveridge is the senior technical writer and public relations specialist for Maser Consulting P.A., a multidiscipline engineering firm with a network of offices nationwide. With more than 25 years of experience in journalism, she is a nationally published writer within the engineering industry. Her expertise is focused on transforming complex technical ideas into comprehensible articles on trending subjects.

X