transmission structure risk management

Osmose has worked extensively with utilities to conceive and successfully implement below-grade transmission structure foundation assessment and mitigation programs.  Below, Senior Director Len Martin answers a few questions that highlight some of the topics we discuss most often with customers.  Len provides an interesting perspective on these topics, given that prior to joining Osmose he spent 11 years of his career working for a large mid-Atlantic investor-owned utility.

Electric transmission providers across the United States are undergoing dramatic changes and challenges in many facets of their business. While the upheaval in the industry has at times been significant, one area remains largely unchanged from years prior, in spite of emerging, persuasive evidence to employ a different course of action.

Specifically, many transmission companies still adhere to a traditional approach of inspecting overhead lines, steel towers and poles solely with aerial and foot patrols. While effective in their own right in identifying certain types of overhead issues, these inspection tactics unfortunately fail to detect transmission structure foundation degradation occurring below-ground, the presence of which represents a significant and growing risk.

Based upon the serious foundation issues uncovered while conducting thousands of below-grade inspections for customers across the United States, Osmose firmly believes transmission entities need to supplement traditional overhead inspection activities by adopting foundation assessment and mitigation programs that will vastly improve the health of existing structures, thereby reducing the risk of eventual, catastrophic failures. 

What are some common misconceptions you hear when discussing transmission structure foundation inspection and mitigation concepts with customers?

Probably the most frequent misconception is that steel and concrete "lasts forever." Unfortunately, this just isn't the case.

Environmental factors such as soil acidity, as well as freezing and thawing cycles, among others, are tremendously damaging to steel and concrete foundations over time. We have seen firsthand the evidence of substantial foundation issues present in various transmission systems throughout the US.  Additionally, the many years' worth of empirical inspection data collected and analyzed we've collected fully supports this position.

Another misconception we encounter is the belief that conventional "foot patrols" or helicopter inspections of overhead facilities are sufficient to fully evaluate the integrity of a transmission structure. While these types of maintenance activities unquestionably add value by identifying certain deficiencies, cracked or damaged insulators for example, we believe that they do not go far enough in and of themselves. Why?  Because, structurally speaking, we know that a tower or pole is susceptible to corrosion and physical degradation from groundline down to approximately 24'' below, where moisture, oxygen and other factors work together over time in a destructive manner to ultimately compromise the integrity of the structure. A foot patrol or other visual assessment that fails to observe conditions below groundline will miss most foundation deficiencies, increasing the risk of an eventual failure.

Lastly, some utilities we speak with tend to be in a state of denial, thinking that transmission foundation problems don't exist on their system. Even when shown pictures of severe foundation problems uncovered at geographically adjacent utilities, it is not uncommon to hear a rebuttal of "well, that isn't OUR system."

However, upon further discussion and perhaps a site visit to a sister utility to view the evidence first-hand, clients usually take the step of commissioning a small, investigative project to see if these problems do in fact reside on some of their towers or poles. Unfortunately, far more often than not, we find very similar issues present on their system.

From a broader, industry-wide perspective, where do most utilities stand with inspection and mitigation programs?

In July 2015, Osmose surveyed the transmission utility industry regarding foundation assessment and mitigation programs, among several other topics.  The purpose of the survey was to obtain feedback on current system maintenance practices, with particular emphasis on steel structures. Included were questions about program funding and plans for system investments, types of inspection programs, the use of various inspection technologies, and concerns with potential future NERC compliance issues. The complete survey report can be found here.

The survey confirmed, not surprisingly, that the majority of utilities conduct an overhead inspection of transmission lines annually, primarily using ground-based and/or flying inspections.  Further, while approximately 80% of respondents reported concerns about the below-grade condition of their structures or foundations, only 20% are currently including a below-grade inspection as part of their current maintenance practices.  We also learned that the majority of respondents do not currently use capital funding for any portion of their transmission inspection and rehabilitation programs.  These responses underscore the fact that utilities recognize the value of routinely inspecting transmission system assets, and most see a definitive need to implement structural foundation assessment programs.  Additionally, many would benefit from capitalizing this investment.

When a customer wants to initiate a transmission foundation assessment and mitigation program, what approach do you generally recommend?

First, we will facilitate a collaborative workshop with the customer to achieve a mutual understanding of the key factors involved in this type of program and any unique characteristics of the customer's transmission plant that may impact the effort. There is quite a bit of knowledge sharing during the workshop, which ultimately helps set the stage properly for both the customer and Osmose as we move forward together.

After the workshop has been completed, we develop a pilot assessment project, or "proof-of-concept." Osmose has found that implementing a pilot project substantially eases the transition to a future full-scale program, as it establishes and galvanizes processes on a small-scale first, before moving to a broader roll-out. It's also very important to lay-out program goals, metrics and expected outcomes up front that ensure pilot objectives are fully achieved.

To support the pilot project, the customer will typically select a handful of transmission lines that may be concerning to them for some reason. For example, a good starting point may be lines with particularly old towers or poles. Another area of focus could be structures manufactured with a type of material known to exhibit troublesome characteristics, such as certain vintages of Corten steel.  

As an aside, Osmose strongly recommends assessing an entire line during the pilot project, from end to end, because our experience indicates foundation issues tend to occur randomly. This randomness is generally a product of environmental variability. Skipping around from structure to structure can result in drawing misleading conclusions about the health of the entire population, system wide.   

Once the pilot sample has been obtained, Osmose initiates the physical assessment process. We collect both structural and environmental data, which provides insight into the pole or tower foundation condition, as well as the attributes of the surrounding soil. We then aggregate the collected data and arrive at a foundation health rating score.

The health rating score facilitates prioritization of future mitigating steps to improve the structure, when necessary. For instance, if the extent of corrosion we identify on a direct-embedded steel tower leg is not too severe, we may simply apply a protective coating to extend the useful life of that leg and move on. If the corrosion is more severe, however, Osmose may bolster the leg by engineering and installing a rehabilitation solution that substantially extends overall tower life, while serving as an extremely safe, efficient, low-impact and cost-effective alternative to wholesale tower replacement.

If you could identify one major barrier many customers experience when attempting to implement programs, what would it be and how do you suggest they overcome it?

Without question the most common, major barrier to starting a program like this, and for that matter many other infrastructure improvement programs, is the utility's lack of available funding to support it. O&M dollars, in particular, tend to be quite scarce and usually reserved for well-established, "traditional" infrastructure programs that are firmly entrenched in the transmission maintenance budgets of our customers. Therefore, to obtain sufficient funding, any new program must compete against those initiatives already present within a utility's existing maintenance portfolio.

Several options exist for our clients to overcome this investment hurdle. As discussed earlier, embarking on a relatively low-cost pilot program is a great starting point because it will typically vividly illustrate the "burning platform" and need to take action, while not requiring a significant outlay of money to achieve results. Specifically, high-quality images captured by inspectors during the pilot project that clearly show tower legs eroded by corrosion, or concrete foundations literally falling apart, have served as a very compelling catalyst for change with many of our customers.

These pictures, coupled with the health ratings, fully reflect the stark realization of the issues present, and tend to float the program to top of the "must do" list in transmission maintenance portfolios from a risk management perspective alone. When this occurs, funding tends to becomes less of a concern, relatively speaking, as the priority of other, less urgent maintenance needs are lowered accordingly, freeing-up budget dollars for the new program.

We should mention that a pilot project also adds value by establishing real-world data to feed a business case justifying a new program, as well as providing input into future program budgets. So in essence the pilot program functions as a very effective enabler of funding, either through the aforementioned prioritization process, or by facilitating a sound business case.

Another option to pursue should O&M funding, specifically, be scarce is to capitalize the investment. In fact, Osmose has worked with several customers to successfully achieve this outcome. Without getting into too much detail, the activities being performed essentially extend transmission asset useful life via either application of protective steel or concrete coating systems, or by rehabilitating compromised steel and concrete foundations. The list of utilities capitalizing these programs continues to grow, and we are currently engaged in various stages of discussion on this important topic with many utilities across the country.

Finally, customers may capitalize these foundation assessment and mitigation activities as part of typical line-by-line upgrade, re-conductoring and "circuit hardening" projects. Osmose actually recommends as a best-practice assessing below-grade foundation conditions prior to undertaking any kind of line upgrade or revitalization project that may increase the loading on existing structures. Failure to sufficiently examine the health of foundations upon which additional load will be borne could result in severe, unanticipated overloading situations, greatly increasing the risk of future structural failure. Should the utility's overall line upgrade project be deemed a capital program, it stands to reason that associated pre-engineering, structural assessment and rehabilitation work may follow suit from an accounting perspective.

What actions should a utility take if it wants to further investigate this type of program?

The first step is to simply contact Osmose to initiate a conversation. There is no cost do so, nor obligation of any kind. We will gladly share our industry perspective to help our customers improve their understanding of transmission structure foundation issues and remediation options.

Should the client desire a small-scale pilot project to investigate foundation condition on their system, the lead-time between an initial discussion with us and obtaining an actual baseline assessment in the field is brief. Additionally, the investment required to perform the pilot work itself is minimal, particularly in exchange for the value and insight it ultimately provides the client in return.

If you'd like to learn more, please contact Len Martin. Len is a Senior Director at Osmose with expertise in electric T&D infrastructure maintenance and rejuvenation, asset portfolio management, reliability optimization, regulatory compliance, rate case design and Smart Grid strategies. Len currently specializes in consulting with utility clients who wish to overcome complex business challenges, particularly improving electric delivery system performance, resiliency and regulatory standing while achieving risk management and financial objectives.  Len can be reached via email at [email protected]