Protecting Aviation  Infrastructure: Are We Prepared? Part 1

Read Part 2 here

Upon landing after their long trans-Pacific flights, air crew members stationed at Travis Air Force Base, California, received a flurry of texts from their families. Their spouses back at home base were under a mandatory evacuation. A wildfire spanning five nearby counties had raged out of control and was directly threatening this vital military base.

As many of you experienced during your service, there are extra stresses on military families, but having to evacuate an entire base with raging flames rapidly approaching is an immense undertaking. Unfortunately, events like this are going to become more common, and the U.S. Department of Defense (DOD) is concerned about their effects on its family members and on critical infrastructure. That applies equally to critical public infrastructure and, in the case of the business aviation industry, to critical aviation infrastructure.

The American military operates from bases worldwide that endure a wide spectrum of climates. The bases extend from the Arctic to deserts, from coastlines to the mountains. An inventory conducted by the DOD of 79 priority installations found that 53 are facing problems with recurrent flooding due to the effects of climate change. That’s just the beginning of the long list. Drought is currently compromising 43 of these critical facilities and wildfire potential is threatening 36. The cacophony of other negative effects include increased icing, desertification, sandstorms and dust storms and thawing permafrost. The civil engineers charged with the maintenance of these facilities are rightfully concerned about these daunting challenges.

The extensive DOD report, “Report on Effects of a Changing Climate to the Department of Defense, January 2019,” can be found at https://media.defense.gov/2019/Jan/29/2002084200/-1/-1/1/CLIMATE-CHANGE…

Business aviation’s facilities are suffering from similar threats. Twice in recent years New Jersey’s Teterboro Airport looked more like a lake fit for recreational canoeing than the nation’s key business aviation hub. Footage captured by WPRI’s news helicopter shows the airport’s extensive flooding (https://www.youtube.com/watch?v=hNk1B2Y04eA)

When the remnants of Hurricane Ida slammed the New York tri-state area in September 2021, it delivered a knockout punch to the public infrastructure, leaving destruction much greater than predicted and feared. Let’s not forget that Ida’s landfall occurred far away in Louisiana. Even though the tri-state area didn’t take a direct hit from the eye of the hurricane, the remnants of this storm once again revealed the inadequacy of our public infrastructure to withstand the new normal.

Damage to Critical Airport Infrastructure

Rachel Burbidge of Eurocontrol has studied the effects of precipitation changes on airports. Heavy rain events are causing more frequent airport flooding due to the inability of drainage systems to cope with the sudden onslaught. Inundation of underground infrastructure by water threatens the loss of electrical power, sewer operation and water. Ground transport access to airports has been shut off due to flooding, leaving passengers and workers stranded at airports and incoming passengers and workers unable to get to the terminals. This will lead to delays, capacity reductions and cancellations, rerouting of flights and a consequent increase in fuel burn.

You probably haven’t given much thought to the importance of the soil composition underneath a runway nor how that would affect the safety and efficiency of flight operations. Heavy rain events have the potential to saturate soils adjacent to airport paved surfaces, causing much more than short-term flooding to the runway and nearby infrastructure. 

Variations in the composition of the underlying soils can cause uneven expansion, which in turn will lead to increased cracking of pavement surfaces. St. George Regional Airport (SGU) in Utah provides a prime example of this. Within a year of opening, airport operators noticed cracks running 4 ft. deep and 1 in. wide on the west shoulder of the runway. Geotechnical engineers bored holes in the ground to determine the cause of the cracks. The engineers discovered striations of “blue clay,” which is a sediment deposit dating back to the dinosaurs.

Underlying Clay Formations
During airport construction, the first layer of clay was removed and filled with backfill, then paved over with asphalt. This, however, exposed the underlying striated clay formations, which had never seen moisture before, to moisture from rainfall.

The city’s Public Works director, Cameron Cutler, computed that a single quarter-inch rain storm has the potential to dump over 200,000 gallons of water on the affected portion of the runway. Moisture has subsequently percolated underground into the various types of clay, all of which expand at different rates when they become wet. 

The expansion of the clay soils resulted in cracks and bumps. Over the next couple years, the cracks continued to absorb water, allowing even more runoff to the expanding clay below. Despite efforts to patch those cracks, cracking and heaving continued on other portions of the airport surfaces almost as fast as the patch work was completed. Extensive heaving and cracking on a major portion of the 9,300-ft. runway were causing control problems during ground rolls.

SGU Airport Manager Rich Stehmeier offered to drive FAA officials down the side of the runway in a pickup truck at 80 mph to illustrate how severe the bumps were becoming. “They bounced their heads on the ceiling of the truck,” Stehmeier recalled. This convinced the FAA that the problem needed to be permanently fixed as soon as possible.

After only eight years of operation, the runway and taxiway surfaces at the airport were deemed unsafe for flight operations. The airport closed to all flights on May 29, 2019 through Sept. 26 as crews tore out 7,000 ft. of runway and excavated down to depths of 17 ft. before refilling with soils that are less prone to moisture problems than the native “blue clay.” A total of 888,500 cu. yards of problematic soil was removed. The replacement soils included 5 ft. of a moisture-conditioned clay, which will act as a plug preventing any liquid from seeping into the soil beneath. 

Over 65,000 sq. yd. of an impermeable water membrane was placed adjacent to both sides of the runway. The membrane extends 165 ft. from the edge of the runway. Six-thousand linear feet of drainage pipe is being installed to drain any errant water away from the runway and surrounding soils.

The costs to repair this damage were jaw-dropping. Approximately 90% of the $26 million project was funded by the FAA, with about 10% of the cost being covered by the city of St. George through passenger fees. 

Multiple airlines halted operations. St. George is headquarters to SkyWest Airlines, one of the largest regional airlines in the U.S. The airport also served regional affiliates associated with United and American Airlines, as well as providing direct connections for Allegiant Air. Some SkyWest employees were given the option to commute north to Cedar City, Utah, where SkyWest opened an additional flight, but generally most of the airline employees were out of work during the project.

The FBO stopped operations as it was unable to sell fuel, the city lost a significant source of revenue and travelers were left to find alternate routes to the popular tourism region.

In Part 2, we discuss the effects of drought, sandstorms and dust storms on airports and aircraft.