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Portland International Airport - Deicer Management System Enhancements

Innovative and self-reliant method serves as an example for deicing systems everywhere

...innovative ...very impressed with the complexity and overall impact to the environment.

The Port of Portland (Port) has stringent regulatory requirements for managing discharges of storm water impacted by deicing chemicals from the Portland International Airport (PDX) to local surface waters. Those requirements drove construction of an initial deicer management system in 2003 and subsequent implementation of significant enhancements to the that system in 2011. The enhancements will greatly improve the ability of the Port to achieve compliance with its regulatory permits and provide a significant increase in flexibility for responding to Portland’s highly variable weather and deicing conditions. GS&P has been a major contributor to implementation of the enhanced deicer management system, including leading development of the system concept during schematic design, providing high-end computer simulations using its GlyCASTTM deicer management software, and leading the design of an anaerobic fluidized bed reactor (AFBR) biological treatment system.

 

 

A deicer system was already in place at the airport. Why are the enhancements necessary?

Jon Prier: The need for enhancements to the PDX deicer management system was driven by the very limited ability of the Columbia Slough, which has historically received the airport’s storm water drainage, to assimilate deicer discharges. The Port’s limit for deicer load into the Slough is based on flow rates, so the higher the flow rate (in the Slough) the more they can discharge. The lower the flow rate, the less they can discharge. After the initial deicer management system was in place, the airport was able to collect additional data and perform more analyses of the expected range of flow rates in the Columbia Slough. They discovered that flows were sometimes lower than expected, and this led to some permit compliance issues.

What makes this site unique when compared with other airports?

Mark Ervin: Compared to other deicer management systems I’ve worked with, the enhanced PDX system offers more features and options for managing the wide variety of potential deicing circumstances that the airport might encounter. Getting all of the elements functioning together was a monumental task.

Tim Arendt: Portland experiences some of the most unique deicing conditions in the country. While the climate is fairly temperate and total aircraft deicer use is typically less than 100,000 gallons per year, the airport is subject to unpredictable and intense icing events that can result in very high deicer use in a short period of time.

The Port is also faced with a unique regulatory situation in that it faces limitations on what it can discharge to its three primary outlets for storm water — the Columbia Slough, the Columbia River, and the local municipal wastewater treatment facility. As Jon said, the Columbia Slough limitations are a significant driver with the NPDES permit governing discharges to the Slough being unique, complex, and under certain conditions, very restrictive. In addition, an outside agency has control over the flows through the Slough, which means there is not a significant relationship between the type of weather events and the flows in the Slough. Compared to other airports, the load of deicer that the local sewage treatment facility can expect is quite restrictive.

This combination of unpredictability, lack of airport control, and restrictive conditions for discharging deicer-impacted stormwater drove the need for a highly-controlled and monitored deicer management system. The core element of the enhanced system is a re-routing in winter of large volumes of stormwater currently destined for the Columbia Slough on the airport’s south side to the much larger Columbia River on the airport’s north side. This need to re-route large quantities of storm water from the south side to the north side of the airport in winter was a significant factor in the system cost.

So while none of the individual components of the PDX deicer management system are unique to Portland, it is the combination of different deicer management elements, and the means by which they are controlled that make this system stand out.

The GlyCASTTM model was used to create simulations for weather conditions at the airport. How does that work?

Devon Seal: Airports apply deicer in order to make the planes safe for departure, and we had to understand what future weather conditions might be and how much deicer might be applied in those future conditions. The GlyCASTTM model uses historic weather data, which includes hourly data on precipitation and temperature. We have information specific to the airport, including the airport drainage system, the size of the areas where the deicer is applied and whether it’s on the pavement or other areas. Using the airport’s future flight schedule projections allowed us to consider future deicer management needs.

Jon: We try to simulate all the processes that the deicer would go through, from when it’s applied to the airplane to when it gets to the storm sewers. This includes all the things associated with stormwater runoff, including runoff coefficients, losses due to different movements by the aircraft, and infiltration into the pavement. There are hundreds of inputs that we include in the model to define the hydraulic and hydrologic characteristics of the airport, as well as the geography of the airport and how that deicer and stormwater is going to move.

There was a significant amount of data that Portland provided to you for input into the model. Is this typical?

Jon: It is not typical to include the amount of data that we used at PDX. We found that the Port of Portland had greater amounts of data available due to the complexity of their permit and management system, and also due to their previously established data collection procedures. Because of the amount of information available, we were able to conduct more specific analyses than we would have been able to do at other airports.

Devon: The model really provided us with the opportunity to look at how their existing system was operating under a range of potential weather conditions, going back 20+ years. We simulated alternatives that we were considering during the schematics phase of the design and we could assess how the system would perform given different design elements. It really helped when we started looking at value engineering and different options. We could ask, “What would happen if they used a different chemical for deicing” or, “What would happen if they combined flow from these two pump stations?” Being able to do that without having to perform pilot scale studies, or just guess, provided us an advantage.

Were there any particular value engineering options proposed during design?

Tim: The project team placed a high priority on value engineering. The objective was to identify means by which costs could be reduced while still maintaining the functional integrity of the system and the ability to comply with regulatory requirements. The value engineering has been a collaborative effort among the Port, airlines, and design consultants. Over a hundred potential value engineering concepts were proposed and over 30 were implemented.

How will the enhanced collection and treatment system operate?

Devon: The existing system was primarily a collection system that discharged collected concentrate water to the local publicly owned treatment works and metered dilute water to the Columbia Slough according to the permit conditions. It included pump stations, a storage tank and storage basin. These components have been tied into the new system components via the computer monitoring and control systems. There will be additional pump stations to collect water from more areas around the airport, and overall storage capacity will also increase.

The other big enhancement is the treatment system, which GS&P developed and designed. The system, which allows the Port of Portland to be less reliant on the sanitary sewer system, uses a biological treatment process. They’ll be able to treat the run-off onsite and discharge the clean run-off either to the sanitary sewer or to the Columbia River.

Mark: The treatment process, which uses an anaerobic fluidized bed reactor (AFBR), is a biological treatment system that uses bacteria to break down the deicer chemicals into methane and carbon dioxide. The system needs to be kept at about 90 degrees Fahrenheit, must be fed nutrients and the pH needs to be near neutral. The methane produced as a by-product is then used as fuel in a boiler that maintains the necessary heat. The system is very efficient, removing about 98% of the deicer from the stormwater stream.

How will the new system be brought on line?

Tim: We’ve been coordinating with the Port and it’s commissioning team which is verifying that the constructed system “checks out” prior to startup. GS&P developed detailed standard operating procedures for startup and operation of the treatment plant, as well as plans for performance testing after startup. We will work alongside the system operators at the site throughout startup to provide guidance on operation actions, troubleshooting and assessment of performance.

Was anything learned from the Portland project that you will be able to use on other projects?

Jon: The amount of information available from the airport has helped us improve our understanding of deicer runoff at airports in general. We can take the information gathered and conclusions made at PDX and apply them to other airports that may have similar circumstances.

Tim: We were also able to refine our process for implementing a deicer management system from concept development through startup.

John Lengel: In fact, we are in the process of starting another deicing system design for the Rhode Island Airport Corporation in Providence and we are using some of the modeling and deicer treatment techniques learned in Portland.

Are there other airports looking at the Portland model as a guide?

Tim: The aviation industry as a whole likes to say that every situation is unique, and that’s very true when it comes to deicer management systems. Individual system needs are very much dependent upon local weather conditions, air traffic, permit conditions and airport infrastructure. That said, I think that there are definite elements from Portland that the industry can use as a source of ideas and reference.

What about the Portland project makes you the proudest?

Devon: I guess the part of the project that I’m most proud of is the part of the schematic design where we were able to look at many different options and provide the client information so they could make an informed decision and design the best system to meet their needs.

Tim: I would say one of the key roles we’ve provided on this project is being able to identify what the essential issues were as the project evolved and help lead the team through the resolution of those issues. There are a lot of complex components in this design based in part on projections of future airport activities. It is difficult to develop concepts for a system that works in the here and now, but is adaptable for future circumstances. I think GS&P played an important role to help ensure these complex issues were considered. Because of that, we were able to help guide a unique and critical project to a successful conclusion.

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Project Info

  • Client: Port of Portland through CDM
  • Location: Portland, OR, USA
  • Market: Aviation, Environmental Services, Sustainable Design
  • Services: Engineering, Civil Engineering, Construction Engineering and Inspection
  • Team:
    • Timothy P. Arendt, P.E. PRINCIPAL-IN-CHARGE
    • Devon E. Seal, P.E. PROJECT MANAGER
    • Mark R. Ervin, P.E. Project ENGINEER
    • Jonathan R. Prier, P.E. Project ENGINEER
    • Melanie Knecht, P.E. Project Coordinator
    • Thomas L. Dietrich, EI, LEED AP BD+C
    • Jim Hagerty., P.E
    • John A. Lengel Jr., P.E.
    • Diane Marable
    • Robert W. McGormley
    • Cheryl A. Shafer, P.E.
    • C.R. Weaver, EI
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