Drainage Improvements & Natural Treatment System

Gerald R. Ford International Airport Authority

The Natural Treatment System (NTS) technology uses detention, bacterial treatment, filtration, and natural aeration to transform nutrient-laden stormwater into clean water before discharging it into the Thornapple River.

Grand Rapids’ Gerald R. Ford International Airport (GFIA) is Michigan’s second largest air carrier airport, serving over 2.3 million passengers each year. In the winter, the airplanes get sprayed with a deicing solution for safety and compliance with Federal Aviation Administration standards. At GFIA, deicing fluids (propylene glycol) mixed with snowmelt would run off from the airfield before entering a nearby stream, known locally as Trout Creek.

Propylene glycol is an organic compound (a sugar) commonly used as a food additive and in personal hygiene products. It is biodegradable and does not “linger” in the environment. However, the deicer presents two challenges in a natural water system because it:

  • Competes with other organisms for dissolved oxygen as it degrades.
  • Provides a food source for algae, fungi, and other aquatic organisms, allowing them to multiply to nuisance levels under ideal conditions.

In Trout Creek, fast-growing aquatic organisms created a nuisance biofilm. This was a problem for residents living along Trout Creek. Their odor complaints prompted the Michigan Department of Environmental Quality (MDEQ) to include within GFIA’s 2010 National Pollutant Discharge Elimination System NPDES permit a requirement to remove the airport’s contribution to the nuisance biofilm by October 1, 2015. GFIA’s NPDES permit called for continued seasonal collection of deicing fluid, stormwater testing, and reporting.


ASCE Outstanding Civil Engineering Achievement Certificate of Merit, 2016


Call John Stroo, P.E. at 616-364-8491 Email at: jstroo@preinnewhof.com

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