Date of Award

Summer 2002

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)


Civil and Environmental Engineering

First Advisor

Melching, Charles S.

Second Advisor

Zitomer, Daniel

Third Advisor

Novotny, Vladimir


Winter deicing activities at airports are necessary for safe travel. A negative consequence of this activity is that a large portion of the aircraft deicing and anti-icing fluids (ADAF) applied to the aircraft and runways runs off untreated into receiving streams, and 97% of primary commercial hub airports in the U.S. are located near environmentally sensitive areas such as wetlands, rivers, and lakes. The National Pollution Discharge Elimination System (NPDES) requires that airports obtain or are in the process of obtaining a permit to discharge this runoff. In some instances, the permit requires monitoring for aquatic toxicity. Airport runoff with glycol based ADAF is toxic to aquatic species, and the toxicity of many of the components of ADAF has been quantified. Additives, which typically make up less than 2% of ADAF, increase its toxicity by orders of magnitude. The data used to quantify the toxicity of ADAF have come from laboratory toxicity tests using diluted concentrations of samples taken during deicing events. Because they do not include environmental factors and interactions with the pollutant being analyzed, the lab toxicity results are limited in what they can determine. Laboratory toxicity tests have been shown to overestimate toxicity at times, and they have been shown to underestimate toxicity at other times. The research reported herein used an in-situ toxicity test with adult fathead minnows to assess the toxicity of an airport stormwater receiving stream. A control group was placed upstream (US) of any airport storm water outfalls, and a test group was placed 0.72 miles downstream (DS) of a major airport stormwater outfall. When available, laboratory toxicity results were compared to the in-situ results. It was determined that during the non-deicing season, the minnows experienced toxicity in the stream, but that they were able to survive for extended periods of time. Survival also resulted in the US location during the de-icing season when no snow cover was present, as the US minnows achieved l 00% survival during all seven tests. Conversely, the DS minnows that were exposed to deicer runoff experienced substantial mortality during six of the seven tests (60%-100%). Rainfall-runoff events were effective at inhibiting toxicity of ADAF applications during the deicing season when there was no snow cover on the ground, and the storm was not washing off old snow cover. When snow was present, it was observed that under the right conditions snow could provide a temporary buffer against toxic effects from large ADAF applications. The melt water from these snow covers was toxic, as it appeared to have a combined toxicity of ADAF and other pollutants in the snow. But the toxicity of the meltwater was not unique to the DS minnows, as the US minnows experienced toxicity as a result of chloride and other snowmelt pollutants. If a substantial rainfall runoff event occurred on a snowpack, after the first flush and while the discharge was high, meltwater and successive ADAF applications did not appear to present any toxic threat to the minnows. These in-situ results were complemented by the laboratory bioassays, as most of the results indicated similar toxic effects. Further analysis into the relation between lab and in-situ results is suggested.



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