Ford Airport hires firm to design de-icing system
Neighbors complain of pollution; DEQ sets restrictions.
Gerald R. Ford International Airport is taking steps to remedy a storm-water runoff issue caused by its annual use of de-icing fluids.
With two years left before the airport must be in compliance with the Michigan Department of Environmental Quality’s directive to eliminate its contribution of propylene glycol to a neighboring river, known as Trout Creek by area residents, it has hired the engineering firm of Prein & Newhof to design a new de-icing disposal system. The airport must be in compliance by Oct. 1, 2015, in order to receive its next storm-water discharge permit.
Prein & Newhof signed a contract with the airport board for just over $1.1 million to design a system that will carry the runoff to the Thornapple River instead of Trout Creek.
“Right now, the majority of our storm water is discharged to the northeast, off of the airport,” said Thomas Ecklund, facilities management director for the airport. “We have a detention basin in that vicinity and we have a controlled outlet on the detention basin. So it goes out into this unnamed tributary and works its way through a neighborhood and enters the Thornapple River.
“As a result of our de-icing activity, there is a biofilm, like an algae growth, that has developed in this unnamed tributary. The permit that we have that was issued in 2010 requires us to eliminate our contribution to the biofilm. We recognize that the biofilm is probably there because of the de-icing fluid. We start de-icing typically in the fall and usually a month or so later the biofilm starts to develop. We stop de-icing and within four to six weeks the biofilm starts to break up and washes away.”
Glycol is a sugar-based substance that is eaten by naturally occurring bacteria in the tributary, which then develop into a biofilm. Residents have complained previously that its entry into Trout Creek has killed off fish and other creek wildlife, as well as emitting an unpleasant odor each spring as the biofilm dies off.
Erv Gambee, president of the Thornapple River Watershed Council, said that when the biofilm is created, the oxygen is starved out of the river, making it difficult for fish and other aquatic life to survive. In addition, he said the smell has become awful for residents in the area from the decay that occurs in the springtime.
As a result of neighbor complaints, the DEQ has made its elimination a requirement for the airport to receive its storm-water runoff permit in 2015.
“It is not a violation of water quality standards, in regards to chemical standards and water quality that the DEQ uses,” Ecklund said. “It is a physical presence and we agree that we have a responsibility to eliminate our contribution to it.”
Prein & Newhof has been hired to design a system that will carry the storm-water runoff directly to the Thornapple River, south of I-96.
“This is going to include some large-diameter pipe, because we have to go underneath some railroad tracks and M-6. Also it includes what we are calling some natural treatment systems,” Ecklund said.
The natural treatment systems will be engineered wetlands that will use layers of gravel, topsoil and vegetation to help absorb or eat the glycol so that once the runoff reaches the Thornapple River it will have decreased in quantity.
The main concern from residents is whether the airport’s plan will solve the problem or merely divert it to the Thornapple River and residents there.
Gambee agrees with the airport’s plan to create engineered wetlands, saying that would be the best option to help clear up the glycol, but also noted that Federal Aviation Administration standards do not allow for open-water sources near airports due to the risk posed by waterfowl. He said he is interested to see what the design firm comes up with in terms of its plans for an engineered subterranean system along the new route.
Ecklund said the airport is confident the new system, which has a total project cost of approximately $15 million, will provide enough opportunity for natural processes to decrease the glycol in the runoff before it reaches the Thornapple River so the problem is not re-created there.
“We are convinced that the quality of the discharge, when it gets to the Thornapple, will be significantly better than it is right now,” Ecklund said.
Currently, the airport reports using an average of 80,000 gallons of glycol per year, and about a third, or 27,000 gallons, reaches the tributary, according to Ecklund. He said that national studies have shown that about 30 percent to 40 percent of the glycol stays on the aircraft. Additionally, the airport has been collecting and recycling glycol for about a decade and that collection reaches 30 percent to 35 percent. Ecklund said that the percentage of glycol reaching the river is small when considering that it is joined by 325 million gallons of storm water.
Gambee’s calculations differ, however.
“My estimates are, if you look at their data, they apply somewhere around 130,000 to 150,000 gallons and they collect 30,000,” he said. “That means 100,000 gallons are going somewhere. My calculation is that most of it is going down Trout Creek and into the Thornapple.”
He also is concerned with the airport’s data collection during the past two years.
“I would have liked to have seen them have an independent study versus using the airport’s engineers,” Gambee said. “That is why I would like to see the numbers from the beginning of the cycle to the end of the cycle through Trout Creek, but again we are relying on them to take the data and that’s one of the data points they didn’t want to take.”
Gambee is hoping that the DEQ will come forth with an allowable limit of glycol for the discharge into the Thornapple River that the airport will have to comply with, and that will make pre-treatment a necessity.
“That’s what I am hoping, that the DEQ will put a low enough limit that they are going to have to pre-treat, and I’ve tried to plead with them … that they spend the money and come up with some kind of pre-treatment before it enters the Thornapple.”
Ecklund said that in previous discussions the DEQ has not been able to determine an allowable limit for glycol, and has even requested the airport suggest the number.
“This is a very new issue nationwide. So new that there really is no history out there, and there isn’t anything that we can go to that says if you get the glycol percentage down to this amount, the glycol will go away.”
In addition to the adopted plan, airport officials considered other solutions, including centralized de-icing pads, improving collection and recycling, and sending the runoff to a wastewater treatment plant. But according to the criteria the airport developed to evaluate its options, diverting the runoff to the Thornapple was viewed as the best choice.
Prein & Newhof is expected to complete the design for the new de-icing system by August 2013, and construction of the project is slated to begin that fall. Once in working order, the new route will be used during de-icing season, while the previous route will still be utilized to some degree during the rest of the year.