Managing the residual chemicals from deicing operations at Portland International Airport (PDX) includes vexing challenges on two fronts: Portland's highly variable winter weather is unpredictable at best, and its local environmental regulations are predictably tough.
Project: Deicing Management System
Location: Portland (OR) Int’l Airport
Cost: $76.26 million
Budgeted Amount: $77 million
Funding: $46.71 million from passenger facility charge revenue; $17.7 million from Series 19 bonds; $7.6 million from Port of Portland; $4.25 million from state grant
Predicted Annual Operating Costs:
Design Consultants: CDM Smith; Gresham, Smith and Partners
Operational: Winter 2011-2012
Efficiency: Removes 99.5% of deicer
Storage Tanks: 3 million-gallon tank for
Full-time Operators: 3
Online Monitoring Instruments: 15
The airport's owner/operator, the Port of Portland, recently addressed both challenges with a new deicing management system that cost about $76 million. The system, now in its second season, features new flexibility to process and manage runoff according to varying concentrations of deicing fluid - an attribute that earned it high marks from airport officials during its first winter of operation.
The need to maintain stormwater discharge permits from the Oregon Department of Environmental Quality drove the initiative to upgrade the airport's previous system, which was less than 10 years old. In 2006, the agency mandated the Port to address its non-compliance.
The conditions of the permits are derived from years of study about the Columbia Slough, which until January 2010, was the only body of water that received stormwater runoff from PDX. As such, there is strong regulatory pressure and community advocacy to protect the integrity of the slough. Because the water flowing through the slough is controlled by a local agency for flood management purposes, the Port faces extra challenges in effectively managing the pollutant loadings allowed to enter it.
To resolve its unique challenges, the Port combined environmental research and technical expertise from airport engineering firms with input it elicited from PDX's carriers.
Each airline's environmental experts were involved in the planning process and invited to all design meetings, including remote sessions and workshops with consultants, explains Port of Portland Project Manager Susan Aha. Throughout the design process, the Port and airline project team discussed and questioned assumptions - particularly those that affected construction costs, Aha recalls.
The meteorological dataset to be used for the analysis was a prime example. The initial plan entailed using the entire 50 years of meteorological data available for PDX, but the airlines questioned this assumption and hired a climatologist to perform an independent assessment of the data. The analysis was persuasive, and the Port consequently used 22 years of meteorological data instead.
"We were very open and transparent with (the airlines)," recalls George Seaman, an engineering project manager for the Port of Portland.
It's important for airport executives to develop relationships with their airline colleagues and make collaboration enjoyable, notes Aha. Working with PDX's carriers so cohesively was a "huge success from a project standpoint," adds Seaman.
The benefit was revealed when Aha and the airlines' environmental representative joined forces to brief the Airport-Airline Affairs Committee about the project. It was extremely helpful having the airline representatives there, acknowledging that a new system was necessary and agreeing to the plan in lock step, recalls Aha. Such collaboration makes it much easier to convince the "money people," she adds.
Not So Fast
Forming the partnership, however, took time and trust. Aha says that the first mention of spending $70+ million on a new system was "not very palatable to the airlines" - especially since the Port had spent $36 million for a system that went into service at PDX in 2003. The news inspired the airlines to rigorously research the Port's claims about non-compliance, notes Aha. "They had to satisfy themselves, which they eventually did," she explains. Then, their focus turned to cost containment. Value-based engineering was key throughout the project design phase, and a process the airlines appreciated, she relates.
Obtaining feedback first and understanding what guidelines the body of water required made the approval process much easier, summarizes Aha.
Widespread community outreach was also an important factor, adds Seaman. Because the new system would create new outfall to the Columbia River, the team members braced themselves for controversy from environmental and neighborhood groups. Port and PDX officials consequently mounted a public education campaign, explaining the project to a dozen neighborhood groups, myriad environmental groups, Columbia River tribes and of variety governmental leaders. "That really enabled the job to go further very smoothly," says Seaman.
Teamwork was also essential, he notes: "Everyone focused on the project's success more than their individual success; and because of that, everyone was successful individually."
A New Approach
The Port hired two engineering firms to provide technical and environmental expertise for the project. CDM Smith and Gresham Smith and Partners (GS&P) worked together to develop a new and better way to manage deicer runoff. One of the main challenges the duo faced was designing a system to operate under a wide variety of circumstances. "There are times which would have very little flow with a high concentration of pollutants, and others with very high flow rates and lower concentration of pollutants, and all combinations in between," explains Tim Arendt, GS&P's principal-in-charge.
Engineers used GS&P's proprietary GlyCAST(tm) deicer management software to simulate responses for various weather conditions, which led to the design and inclusion of an anaerobic fluidized bed reactor biological treatment system. The computerized modeling system used 22 years of local hourly weather data to generate simulations for storage, pumping system, treatment systems, etc. The results provided insight about the most cost-effective ways to manage a wide variety of stormwater and deicing situations. This enhancement gives the airport flexibility, confidence in compliance and ensures the vitality of the water bodies it depends on, explains Arendt.
The nuts and bolts of the new system began with re-routing winter stormwater that would normally discharge to the Columbia Slough on the south side of PDX to the Columbia River located to its north. CDM Smith designed a processing component that controls flow through the three new pump stations, 6 miles of pipeline that connects them to each other, the treatment plant and new outfall at the Columbia River. Online meters give real-time biochemical oxygen demand readings of the stormwater pollutant concentration in any area where they are located, says Mark Ryan, CDM Smith project manager. From that, he explains, pump stations are programmed to either pump to a certain area, certain tank or the treatment plant.
"I think this is pretty cutting-edge as far as having this number of pump stations around the airport, synchronized and working on an intelligent network to make the best decision of where to convey the water and treat it, or release it," relates Ryan.
While individual parts of PDX's system are used at other facilities, it is the system as a whole and the multiple technologies working cohesively that make it unique, he explains.
Biology in Action
When Aha traveled to other airports to survey their deicing systems, one message came through loud and clear: Build in flexibility and options to facilitate response to a variety of conditions. So that's precisely what the design team did.
Three new storage tanks were built to segregate water based on its deicer concentration, explains Arendt. One 3 million-gallon tank holds concentrated stormwater and two 6.5-million gallon tanks handle more dilute water. After separation, the discharge is sent to the slough, river, sanitary sewer or on-site treatment plant. Having its own treatment facility greatly reduces PDX's dependence on the local sewer system, he adds.
The onsite anaerobic treatment plant uses live bacteria to break down the deicer chemicals into methane and carbon dioxide - a process that required some initial tweaking. The first batch of bacteria used to seed the system proved to be too weak, but the second, procured from a fruit processing plant, got the plant up and running with ease, recalls Aha.
Operational readings from last winter, the plant's first deicing season, indicate that the process removes fully 99.5% of the biochemical oxygen demand, reports Arendt. Because the system must be maintained at 90F, runoff is heated by the methane captured as a byproduct.
"We were lucky on two accounts," says Ryan of the airport's experience with the new deicing management system. "The weather was mild, and the staff worked through glitches. They rolled with it and made everything work. They are the big success story in all of this."
For Aha, the bottom line is clearcut: The new system allows the Port to "keep the doors open" at PDX. "Without it," she says, "we couldn't comply with our permits, and wouldn't be able to deice."
The flexibility of the new system, however, goes well beyond regulatory compliance. The system's real-time analyzers help operators, licensed in Level III Oregon wastewater treatment, make timely decisions based on changing weather conditions. The ability to respond to Portland's wide-ranging weather in real-time, notes Arendt, is what truly sets PDX's system apart from the crowd.