DEICING MONITORING SYSTEMS ASSESSED
Airport Cooperative Research Program (ACRP) Report 72
BY MARK R. ERVIN
Deicing is a crucial part of airport winter operations and comes
with its own set of environmental and regulatory concerns.
Left untreated or uncaptured, chemicals from the deicing
process can mix with stormwater runoff and affect surrounding
ecosystems and water bodies. Various environmental
problems can result, including contamination of groundwater,
surface water or municipal water sources; and breeding of
excess bacteria, which remove oxygen from water, potentially
harming local aquatic populations.
Recognizing these problems, the Environmental Protection
Agency (EPA) imposed stormwater regulations, and airports
across the country began searching for practices to comply
with stricter regulations. The compliance process exposed
the need for a comprehensive tool to help airports find
methods that best fit their unique characteristics and
requirements and that most effectively address complex
From that need, ACRP Report 72: A Guidebook for Selecting
Methods to Monitor Airport and Aircraft Deicing Materials was
developed. ACRP contracted with design and engineering firm
Gresham, Smith and Partners (GS&P) to research and develop
the guide. More a tool than a verdict, the report arms airport
staffs with the information necessary to find and implement
methods best suited to their individual needs.
Parameters covered in the guidebook include:
•;Glycols (including surrogates such as BOD5, COD, TOC)
•;Total Suspended Solids (TSS)
GS&P and partner Terra Hydr Inc. researched current
practices and emerging trends within the aviation industry
and consulted with leading companies in other industries that
monitor similar water or wastewater streams, such as the
pharmaceuticals industry, the brewery industry, and the food
While the complete guidebook offers the most thorough
analysis, the following broad set of best practices can be
KNOW YOUR “DRIVERS”
When selecting appropriate monitoring systems, airports
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should consider the parameters they want to monitor, broadly
determined by one of three monitoring “drivers”:
Regulatory — compliance with stormwater permits, broadly
controlled by the Federal Water Pollution Control Act and
the National Pollutant Discharge Elimination System permit
Process control — directing stormwater to specific places
within deicer management systems; and
Tracking and accounting — quantifying the characteristics of
stormwater, generally for billing purposes.
After identifying primary drivers, airports can track the required
parameters. For example, environmental permits might require
airports to track applied deicer fluid captured in stormwater
runoff systems, or to monitor dissolved oxygen content or pH
levels of stormwater.
ON-SITE VERSUS OFF-SITE MONITORING
Monitoring practices fall into two categories: off-site
monitoring, where samples are taken to remote laboratories for
analysis, and on-site monitoring, where samples are analyzed
at the airport. Each brings advantages and disadvantages.
Off-site monitoring methods extensively analyze a small
number of samples, generally producing consistent, high-quality results. Most laboratories use methods that have
been vetted and approved by the EPA. As a trade-off, off-site
monitoring takes longer and can incur higher labor costs.
Additionally, it can be difficult to capture the variability of
stormwater characteristics, given the limited number of
samples and delay in analysis.
On-site monitoring methods allow for more frequent samples
and less delay. On-site monitoring can be performed with
handheld monitors at the sample site, test kits in on-site
laboratories, or with permanently mounted online devices that
automatically collect data. In terms of quality and regulatory
value, on-site methods generally have fewer quality assurance/
quality control checks and may be more variable; some
methods have been approved by regulatory agencies, but
many have not.
Airports should weigh these advantages and disadvantages
with their particular needs to determine between off-site
monitoring, on-site monitoring, or some combination thereof.
MONITORING METHOD EVALUATION
The guidebook presents an organized methodology to screen
and compare potential monitoring methods for stormwater
parameters. Data on 47 monitoring methods are presented
in fact sheets for easy reference. A screening procedure and