Tag: Aviation Engineering

3 Things to Consider When Designing for Stormwater on Airports

Stormwater that ponds or collects on airports can be considered a hazardous wildlife attractant and pose a significant risk to aircraft and the flying public. According to the Federal Aviation Administration, there were 17,228 wildlife strikes at 753 US airports in 2019. In a previous blog post by Senior Airport Engineer Wilbur Mathurin about protecting wildlife, he mentions the importance of proper drainage on an airport, calling the stormwater design “a delicate balance between aircraft safety and providing adequate infrastructure to manage stormwater runoff during a storm.”

There are of course, some challenges when it comes to finding the right balance. Stormwater design is not necessarily straightforward, and there are quite a few different goals and standards that need to be met. Below are three important airport stormwater design concepts that provide some insight into what is considered during design.

1. Elevation

For the safety of the moving aircraft, airfield pavement and airport turf areas are designed with minimal slopes, making most airports relatively flat. When the differences in elevation from inlet to outlet are minor and the slopes of any channels or pipes might be minimal it can make it difficult to move stormwater quickly off the pavement and away from the aircraft. Additionally, stormwater may need to be stored to reduce the peak flow, or treated, both of which could impact some of the elevation you need to outlet. Stormwater chambers and/or some treatment systems are located underground, so you need to make sure that it isn’t too deep that you can’t get the water out.   

Another potential limiting factor with underground storage may be possible contamination from nearby fueling operations or by the depth to groundwater and/or bedrock. Impermeable liners can be used, but this eliminates the possibility of infiltration to groundwater and requires an outlet to an appropriate discharge location or integration into a closed drainage system.

2. Above ground stormwater detention

It would be ideal to avoid any and all areas of stormwater detention, but as mentioned above, underground operations are not always feasible. If above-ground detention is used, it is important to make sure that the stormwater will drain as quickly as practicable so that it does not become an attractant for birds. When using detention in combination with a soil filter for treatment, state design standards typically require that the water drains in no less than 24 hours for proper filtration and no more than 48 hours to avoid prolonged detention.

When treating stormwater, multiple infiltration ponds may be needed to collect stormwater from multiple impermeable areas. Each soil filter or infiltration basin requires a certain amount of space to collect properly, store, and filter the required volume of stormwater runoff. In some areas of an airport such as adjacent to the runway or taxiway, a long soil filter design might be more feasible, but it can be challenging to find enough space for the proper size system near aprons and buildings.

3. Permitting

To safeguard water quality stormwater treatment is required is required for runoff from impervious areas including airport building rooftops and airfield pavement. In addition to federal standards, the permitting process is specific to each state, so permitting requirements and treatment design solutions vary by airport. Stormwater treatment design at airports can include infiltration ponds, soil filters, subsurface sand filters or underground storage chambers with filtration, open-lined channels to convey the stormwater to another location, or meadow buffers if they are available. Before permitting, it is essential to check the data you will need to submit with the design. This can include test pits, bedrock and groundwater depth, soil type, hydraulic conductivity of existing soils, etc. Information will need to be obtained relatively close to the area of the proposed stormwater treatment, so the design must be closely coordinated with the data collection process. It is ideal for permitting to happen before the design is complete to start the review process with the permitting agency.

As airport design engineers, we understand the direct correlation between aircraft safety and stormwater management. Proper stormwater drainage design considers each airport’s unique terrain, storage capacity and treatment standards.  I am available to discuss any of these elements may be impacting your airport’s stormwater management and how we can help improve your facility’s system.

What Makes it Military: A Note on Joint-Use & Shared-Use Airports

C-17 Featured Image

Hoyle Tanner aviation professionals have worked on hundreds of projects in New England and Florida. What we know about airports is that even though their components are similar, each has its own unique fleet mix, operations, management and facility needs. For example, climate will play a significant role in the design of a Florida versus New England airport. There are other differences between airports that most people don’t think about: how military operations work at airports, and what types of airports can even support those operations.

The Hoyle Tanner engineering team provided the design and construction management services for the 2020 Reconstruction of the Runway at Portsmouth International Airport at Pease, a shared use airport. Photo taken during the construction phase.

Defining Different Airports

There are three kinds of military airports, a) Military only, b) joint-use, and c) shared-use. Military only is meant for Department of Defense use only, and no civilian aircraft utilize the airfield. A joint-use airport is a military airport that arranges for civilian access to the airfield. There are 21 joint-use airports in the United States. A shared-use airport is owned by the US government and co-located with an airport specified under Federal Code of Regulations 139.1(a). At shared-use airports, portions of the airfields are shared by both parties.

How the Different Types Came to Be: The War Era

As of 2020, there were 65 shared-use airports across the nation. A few in New England include Portsmouth International Airport at Pease, Bangor International Airport, Burlington International Airport, Bradley International Airport, Westfield Barnes Regional Airport, and Quonset State Airport. Not surprisingly, many of these airports can trace their roots back to their military ownership during World War II. Through the Development of Landing Areas for National Defense (DLAND) appropriation, the Secretary of War and Commerce and the Secretary of the Navy enabled land acquisition to build 986 airports throughout the United States. Many of these airports still exist where you live, as after the war many were declared surplus, and transferred to municipalities for civilian use. Additionally, since 1977, Congress has periodically granted temporary authorities known as Base Realignment and Closure (BRAC) on five occasions. As a result, more than 350 military installations have been closed, some remaining as shared-use airports.

An example of a military taxiway design with additional FAA pavement and geometry shown in yellow cross hatched areas.

Design Standards

There are different design standards in terms of maintaining the infrastructure on these shared use airport facilities. For instance, the US Air Force has different geometric layout criteria for runways, taxiways and aprons, and safety-critical areas. Additionally, there are different pavement design methods and ways to determine the required runway length for both civilian and military aircraft. An example of a differing design standard is shown in the accompanying colored graphic. In terms of runway thickness, it is interesting to note that pavement strength at all types of airports is a function of underlying pavement materials, aircraft fleet mix, number of operations, aircraft weight, and gear configuration. Given all these variables, a runway’s pavement thickness is not always driven by the biggest and heaviest aircraft, and therefore not all military airfields require the longest or thickest runways. If you have flown into a joint-use or shared-use runway, you will note that the military has typically required some (if not all) of their runway to be made of concrete instead of asphalt; a difference in material choice driven by design standards, hot weather conditions, and in some cases, availability of one material over another.

Transitioning from One Type of Airport to Another

To help transition from a military base and airfield to a civilian airport, FAA administers a separate funding program called the Military Airports Program (MAP). This program assists new sponsors in converting former military airfields to public use to add system capacity and reduce congestion at existing airports experiencing significant delays. Both the Portsmouth International Airport at Pease and Brunswick Executive Airport have been recipients of MAP funding in recent past. Being in MAP affords an airport sponsor an additional stream of funding through FAA that can be used in addition to the traditional FAA funding avenues. In the cases of Portsmouth International Airport at Pease and Brunswick Executive Airports, this program has been very successful in replacing the lost jobs, businesses, and reduces the impact to the local economy that occurred when Pease Air Force Base and Brunswick Naval Air Station closed.

Air Force C-17 taking off at Burlington International Airport, with concrete apron construction in the foreground.

Experience all Around

Hoyle Tanner has developed a strong history of planning and designing projects at six current shared-use airports, one joint-use airport, two in the MAP program, and three former military airfields closed due to BRAC. If you want to learn more about the differences between joint-use and shared-use airports, please contact any of these experts within our company: Our subject matter expert for the MAP program is Suzanne Sheppard, PE, and for shared-use airports Nils Gonzalez, PE and Tim Audet, PE. We recognize the value of airports in our communities, especially when the military use and mission enhances the infrastructure, supporting airfield services and overall value of civilian use.

How Florida airports play a key role in emergency preparedness and response

General Aviation airports play a vital role in serving their local communities through disaster preparedness and response. Hurricanes pose the largest natural disaster threat to Florida communities. Airports are not immune from the devastating impacts a hurricane can cause to infrastructure, including hangars, essential navigation equipment, and other airfield facilities. Based on the important role an airport can play during and after a hurricane, the airport must have a sound emergency plan in place. This emergency plan should consider how the facility is used and will be used during these times.

There are countless historical examples of how General Aviation airports have helped respond to a disaster or crisis. In 2016, the Flagler Executive Airport became a “Point of Distribution” for food and water after Hurricane Matthew, a Category 3 storm, left two-thirds of residents without power.

A year later, during Hurricane Irma, Marion County Airport served as the location for the Duke Energy base camp, which housed 1,700 utility trucks and 3,700 employees. The open nature of airfields and large areas of asphalt and concrete paving make airports ideal staging areas for emergency response operations.

A more recent example of a municipality leveraging the airport as part of their resiliency planning is the Marathon International Airport located in the Florida Keys. In 2019, the County decided to build its Emergency Operations Center (EOC) at the airport. Being a barrier island poses unique challenges to emergency management operations; housing the EOC at the airport will allow aid to come into the County even if the single highway entering and exiting the keys becomes unusable due to flooding.

Besides natural disasters, airports are also valuable in other areas of emergency response planning. The COVID-19 pandemic has highlighted airports’ role in the containment of an infectious disease: Millions of people pass through airports each day, making airports a primary pathway for this contagion. During the pandemic, airports are being relied upon heavily to put emergency measures in place to reduce the risk of spreading the virus. The pandemic has accelerated the need for airports to find ways to leverage automation and touchless technology in their day-to-day operations. Providing appropriate response tools will help in containing the spread of the pandemic.

History has shown that airports play an essential role in assisting people in times of disaster by providing an avenue for the delivery and distribution of food, water, and medical supplies. Given the critical role in emergency management, airports should add elements of resiliency planning as part of any master planning process. Spending some time now assessing risks will allow the airport to rebound quickly from unexpected events and continue to meet their users’ demands. Hoyle Tanner works with airports to create or enhance infrastructure projects so that they are sustainable and maintainable for years to come. If you would like to find out more about some steps you can take to make your airport more resilient, contact me.

*featured photo image courtesy of Michael Grawe, Airport Manager, Marion County Airport

Employee Spotlight: Robby Moon

Employee Spotlight featured image of Robby Moon, Airport Engineer, and his brother

Robby Moon – Airport Engineer & Great Brother

1. What drew you to Hoyle Tanner?

My former supervisor had worked in aviation and hearing about what he did, drew me into the aviation field. One of my peers had recommended Hoyle Tanner because they had an aviation group.

2. What’s something invaluable you’ve learned here? (Please elaborate your answer)

I’ve learned a lot about engineering, so I can’t choose just one thing. But, for the lunch hour, I’ve learned that at the Gyro Spot on Elm Street, ordering the chicken burrito with sauce on the side because sauce in the burrito makes the tortilla soggy.

3. What’s your favorite time of year to work at Hoyle Tanner & why?

Summer is my favorite time of the year to work at Hoyle Tanner because that is when projects are under construction. I travel a lot and get to see a lot of really cool places during the construction season.

4. What’s the coolest thing you are working on, and why?

The coolest thing I am working on is finding the required soil filter area for Pittsfield Municipal Airport in Maine. Dealing with soil filters and drainage is something new for me.

5. What’s the best thing that’s happened to you so far this week?

I went to Disney World and met my brother and his family!

6. How many different states have you lived in?

Three states: New York, Maine and New Hampshire

7. If you could only eat one meal for the rest of your life what would it be?

The spicy chicken sandwich from Chick-fil-A

8. What kind of pet do you have and how did you choose to name it?

I currently do not have any pets, but I used to have a dog named Wolfie. I named him Wolfie because he looked like a wolf.

9. What is a fun or interesting fact about your hometown?

The Treaty of Portsmouth that ended the Russo-Japanese War of 1904-1905 was signed in Portsmouth, New Hampshire.

10. What are three things still left on your bucket list?

  1. See the Eiffel Tower
  2. Go to a Brad Paisley concert
  3. Own a house

11. Name three items you’d take with you to a desert island

  1. Fishing pole
  2. Lighter
  3. Knife

12. What characteristic do you admire most in others?


13. How old is the oldest item in your closet?

My dad’s AC/DC vinyl records that are about 35-years-old.

14. Words to live by? Favorite quote? Why?

“You miss 100% of the shots you don’t take.” – Wayne Gretzky. I find this quote inspiring because it shows that you can’t succeed unless you try.

15. What did you want to be when you were growing up?

I wanted to be a NBA player.

16. If you were to skydive from an airplane what would you think about on the way down?

I would probably be in too much shock to have any thoughts.