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SUSTAINABILITY 28 airportbusiness February/March 2016 being used successfully at airports in Buffalo, Montreal, Toronto and Washington Dulles. The system is designed to create a favorable envi- ronment for bacteria and other micro-organisms to establish and consume the residual aircraft deicing fluids in the stormwater before it is dis - charged to the Thornapple River. The storm- water treatment system enhances the quality of the natural environment with an innovative design for collecting and treating propylene glycol, and managing stormwater. The green design uses gravity, vegetated beds and nat- ural organisms to treat the stormwater with essentially no power consumption or residual waste, reports Ecklund. The new treatment system will bypass the Trout Creek tributary and reroute runoff directly into the Thornapple River and will include a natural treatment system that consists of treat- ment cells that the runoff travels through before reaching the river. The vertical system includes a top layer of dry vegetation, followed by two layers of sand, and then by two layers of gravel. "We wanted to change the ultimate end run- off point from this small tributary to the larger river," says Ryks. "It's better for the stormwater to be going into the river which has a much greater volume of water than the smaller tribu- tary. That was the real issue — the runoff was going into a smaller water source, and the way glycol is dissolved it was using up the oxygen in the water. When you put it into a much larger water source, that's not going to happen." That being said, not much of the glycol run- off should make it to the river after treatment. "The basin will act as a sediment trap and also act as a trash removal facility," Ecklund says."The flow will leave the basin, and the basin is designed to control the flow into the first set of cells. The flow will go through the first set of cells and receive treatment. It will then be discharged into the second set of cells where that treatment process will be duplicat- ed. It will then go into a third stage of treat- ment, which is basically a riprap channel, to add some oxygen into the flow, which is import - ant to improve quality." Ecklund said the bacteria that feed on glycol would use the material as a food source during this process. "The natural bacteria in the soil will break down the glycol into a carbon food source," he says. The wastewater glycol treatment system is 100 feet lower than the airport, adds Ecklund, who notes this is important because the water is brought to it through gravity eliminating the need for a pumping system. Part of the project also included adding a pipeline at the apron areas to ensure that all commercial aircraft deicing runoff flowed directly toward the treatment system. "Previous to that some of it was flowing in one direction and some of it was flowing in another direc- tion," Ryks says. PROJECT DEEMED A SUCCESS Though this is the first winter the system has been in place — and it's been a particularly mild winter thus far, Ecklund says the system is exceeding expectations. Eventually the airport hoped the treatment facility would effectively remove up to 80 per- cent of the glycol in stormwater runoff. Ecklund explains they expected the system wouldn't work at that capacity immediately and would require a few tweaks before it did. However, after just one winter event, testing showed the system was already removing 75 percent. "We were extremely happy with the results and expect to attain higher than 80 percent removal with some fine-tuning," Ecklund says. Before 2000, an estimated 65 percent of the glycol used at the airport made it to the tributary. Once the airport began vacuuming up and recycling glycol, that amount dropped 36 percent. Now that the project is complete, less than 7 percent will make it to the river. "It may even be lower than that with the system performing as well as it is," says Ryks. GFIA's stormwater management will ensure the stormwater reaching the Thornapple River will be well within the state of Michigan's water quality protection standards, and pro- vide significant improvement in the Thornapple River. "We commend the airport on their actions to better the quality of storm water discharged from their facility, and complet- ing such a large challenging project on time," says William Creal, Michigan DEQ Director of Water Resources Division. "This was a diffi- cult situation that Kent County showed quality leadership on, and took action to put a positive solution in place. We look forward to working with the airport and observing the treatment system in action." Detention basin and natural treatment cells in the background