Diggin’ for Gold – Underground Infrastructure, Part 1
The Essentials Newsletter, Twenty-eighth Edition
No, this version of the newsletter is not to revisit the last one about the Olympics – although maybe digging for gold could be a new Olympic sport that would have its own reward with no need to fight about who won…Alas, the summer games are sadly over for another four years until they restart in our very own Los Angeles, where I may weigh in from on-site – we’ll see. Instead, this edition of The Essentials will “dig” into underground infrastructure (see what I did there?) to lay groundwork (see what I did again?) for our discussion about the policy issues impacting the use of natural gas.
Before I revisit natural gas infrastructure (discussed in the seventh edition of this newsletter), it’s important to understand the level of critical infrastructure operations occurring underground. I’ll also delve into a bit of comparing and contrasting about costs and benefits between subsurface infrastructure siting and aboveground siting to further contextualize our discussion.
According to a comprehensive report developed in 2013 by the National Research Council at the request of the National Science Foundation (Summary | Underground Engineering for Sustainable Urban Development | The National Academies Press):
More recently, important infrastructure has been placed underground because of proximity to services, to preserve surface space, provide climate or security isolation and containment, reduce construction and energy costs, improve traffic flow, and for various aesthetic benefits…Infrastructure systems can be placed beneath cities, under rivers, and even through mountains. Millions of people rely on these systems with little thought to the comfort and convenience provided…
How Deep and Wide
Categories of underground infrastructure can be thought of relative to how close to the surface they can be installed – near enough to the surface that they can be accessed easily for operation, maintenance, and replacement or buried deeper to ensure above-ground integrity and to avoid other near-surface risks. The near-the-surface type of infrastructure is often linear and is used to provide services directly to homes and businesses -- the smaller distribution gas pipelines, internet cables, and lower voltage electric lines. I was actually surprised at how close this infrastructure is to the surface. For example, according to softdig.com (emphasis added):
The depth of utility lines can vary depending on the type of utility you are talking about. For example, cable and telephone lines in a conduit are typically buried one foot or less underground. Typically, sewage lines, electrical lines, and telephone lines not in a conduit are buried approximately two feet underground. Finally, water pipes, electrical lines, and larger sewage pipes are typically buried three feet underground. All of these utilities can be vulnerable to being damaged if you dig without verifying their location.
In terms of oil and gas pipelines, the estimate of how many miles of these larger, longer, “wholesale” pipelines exist in the U.S. varies, but is around 2.5-3 million miles. Because some of this infrastructure was installed prior to modern computerized databases and tracking, the estimate is not entirely accurate. The depth of these pipelines, some of which are on the surface, but most of which are subsurface, also varies greatly. According to Chapman Engineering, “Rules governing the oil and gas pipeline industry call for at least 2.5 feet of ‘cover’ over the typical oil or gas pipeline.” But beyond that, pipelines must frequently be built underneath roads, rivers, and other structures such that their depth can often be much greater.
Combining these two big buckets of underground infrastructure – electric lines, small gas pipelines, telecom cables, sewer lines and water pipes going into homes and businesses (typically known as “distribution lines”) plus the larger oil and gas pipelines and electric transmission lines often traversing multiple states (usually known as “transmission” lines) – add up to over 20 million miles of these types of underground infrastructure. To summarize an article written in August 2020 by Benjamin Dierker of the Alliance for Innovation and Infrastructure, this 20-million-miles statistic is likely on the low side because comprehensive data has not been collected for over 20 years.
But what about other types of subterranean infrastructure like oil and gas wells, mines, foundations for bridges and buildings? For oil and gas, both onshore and offshore wells have been developed here in the U.S. and can range in subsurface depth from a few hundred feet to up to 30,000 feet, which is close to six miles below the surface – close to the cruising altitude of commercial airplanes.
As the U.S. Energy Information Administration (EIA) notes: “Advances in drilling and production technologies have increased U.S. oil production. In the past, a drilling rig drilled a single vertical well. Now, many directional or horizontal wells can be drilled from one location, or well pad, to access greater areas of oil- and natural gas-bearing rock.” I find this fascinating. We now have a web of shallow subsurface lines across our country, as discussed above, but underneath those, in three dimensions, we also have drilling wells in certain places where oil and gas reservoirs are abundant. EIA further notes that “Oil may flow to the earth's surface from natural pressure in the rock formation, or it may have to be forced out of the ground and up through a well. The type of geologic formation where the oil is located determines the technologies used to start the flow of oil and natural gas from the reservoir or resource-bearing rock into the wells.” According to Aera Energy, “A well’s primary components are the wellbore and casing. The wellbore is the hole that’s drilled into the earth to create the well. The casing consists of telescope-like layers of steel pipe placed inside the wellbore...”
Many of you may know that determining the foundation depth for buildings and other surface structures (like bridges) depends on the type of foundation (concrete being most common), the amount of loading on the foundation, the soil, and the water table. Generally, foundations aren’t very deep as compared to other buried infrastructure, but they often mirror the dimensions of the structure which they support, requiring significant digging and leveling. I thought this worth noting here because it highlights the interrelationship between surface and subsurface structures.
As I discussed in the eighth edition of this newsletter, mining might be the first critical infrastructure sector to be developed by humans, with the first known mines dating to Africa and Europe approximately 43,000 years ago. The Mponeng Gold Mine in South Africa gets the gold, both literally and figuratively, for the deepest mine in history at 2.5 miles down. It is still in operation today as are many of the deepest mines, all diggin’ for gold. Of course, mines vary in depth and width, depending on the minerals being mined, the location, and the subsurface rock and soil.
Other subsurface structures take up space out of our vision, such as missile silos, bunkers, underground storage tanks, etc., but I won’t go into additional detail about those at the risk of beating that poor dead horse. To sum up, a significant portion of our critical infrastructure resides below the surface in a multi-directional and multi-dimensional way.
The Pros and Cons
Like everything in life, there is a mix of both challenges and opportunities in deploying infrastructure underground versus aboveground. While such analysis must be done on a case-by-case basis, some overarching considerations can be applied. In my research, I found a great description of these pros and cons for utility distribution lines on a website called pointman.com.
Benefits
Aesthetics and visual impact: Underground utilities offer a significant advantage in terms of aesthetics and visual impact. Unlike above-ground utilities, underground utilities remain hidden from sight, preserving the natural beauty of urban and rural environments. This unobtrusive nature enhances the overall appearance of communities and contributes to a more visually pleasing environment for residents and visitors alike.
Durability and resilience: Buried underneath the ground, these utilities are protected from exposure to harsh weather conditions, vandalism, and accidental damage. Unlike above-ground infrastructure, which may be susceptible to damage from storms, high winds, and other environmental factors, subsurface utilities remain largely unaffected, ensuring the reliable delivery of essential services even during adverse conditions.
Safety: Underground utilities also promote safety for both wildlife and people. Above-ground utilities, such as power lines, pose hazards to birds and other wildlife, as well as to humans in the event of accidental contact. By burying utilities underground, these risks are minimized, creating safer environments for both wildlife and individuals.
Challenges
Installation and maintenance: Excavating the ground to lay pipes, cables, and other infrastructure can be a costly endeavor, requiring specialized equipment and skilled labor. Additionally, ongoing maintenance and repair activities can incur substantial expenses, contributing to the overall cost of underground utility infrastructure. [Side-note from author: some companies have developed innovative ways to enhance existing underground infrastructure to minimize some of these pain points – like a technology to increase the available space in existing conduits.]
Labor-intensive processes: The installation and maintenance of subsurface utilities often involve labor-intensive processes that require careful planning and execution. Excavation, trenching, and backfilling operations demand skilled labor and can be time-consuming, leading to potential delays in construction projects. Furthermore, the complexity of underground utility networks may require extensive coordination among various stakeholders, further adding to the labor-intensive nature of these processes.
Difficulty in repairs and maintenance: Unlike above-ground utilities, which are easily accessible for inspection, repairs, and maintenance, underground utilities present unique challenges in terms of accessibility. Locating and accessing underground infrastructure for repairs and maintenance can be challenging, requiring specialized equipment and expertise. As a result, addressing issues with subsurface utilities may require additional time and resources, potentially leading to service disruptions and delays.
For the deeper and wider deployments of the interstate linear infrastructure such as electric transmission lines and oil and gas pipelines, the costs and benefits are similar, but on a bigger scale. While that seems to state the obvious, let me explain. The complexity of siting and permitting these projects (noted above by pointman.com under “labor-intensive processes”) is a massive challenge that can involve multiple jurisdictions and environmental analyses (discussed in more detail in the twenty-fourth edition of this newsletter on permitting and siting). Maximizing the economic benefits and minimizing the environmental or geographic challenges may skew toward undergrounding in certain locations and remaining above ground in others.
No Comparison
To state the obvious again, some subsurface infrastructure cannot be moved to the surface – oil and natural gas deposits are mostly found below ground and the massive improvements in technology have enabled wells to reach depths previously unimagined. Mining operations are in the same situation, with subsurface mapping and robotic capabilities improving human safety and enabling more precise exploration to limit projects’ aboveground footprint, among other improvements. The irony is that the mined and drilled raw materials have enabled these technological improvements. For example, as discussed in the twelfth edition of this newsletter, petroleum-based products are essential to electro-chemical processes that enable the transiters that are foundational to computers and other digital processes such as geospatial mapping.
For these below-ground critical infrastructure sectors that must dig deep, they have been forced to “dig deep” in another way, as well, by deploying innovative technology, processes and people to access raw materials crucial to our daily lives.
In Part II of this newsletter, Diggin’ for (and Delivering) Natural Gas, I will turn to the policy implications surrounding natural gas. Those issues implicate a variety of critical infrastructure (CI) sectors, including the electric sector and the generation and delivery of power.