DEICING / ANTI-ICING FLUIDS STORMWATER RUNOFF TREATMENT IN TRIGG LAKE AT DFW AIRPORT
Abstract:Airline tenants at Dallas/Fort Worth International Airport (DFW Airport) use deicing/anti-icing chemicals, as may be needed, to maintain wintertime operations. DFW Airport has implemented best management practices for pollution prevention measures relating to deicing/anti-icing activities. The DFW Airport currently operates nine Designated Source Isolation Deicing Pads. Even though the deicing/anti-icing operations are performed on the Designated Source Isolation Deicing Pads and the deicing fluids are collected for treatment and disposal, as the planes leave the deicing pads, deicing/anti-icing fluids drip from the planes onto the runways, taxiways, and ramp areas. In addition, as planes take off, anti-icing fluids remaining on the aircraft surfaces shear off onto departure runways. During winter storm events, these deicing/anti-icing fluids are flushed off the taxiways and runways, commingled with the stormwater. Stormwater containing deicing/anti-icing fluids can discharge through outfalls into Trigg Lake, an irrigation reservoir, located in the southwestern part of the DFW Airport property.
The discharge of deicing fluids to Trigg Lake with stormwater has been and continues to be a concern to DFW Airport. Elevated levels of deicing/anti-icing fluids (primarily spent ethylene glycol) in Trigg Lake create potential concern for the fish communities. The primary impact on Trigg Lake fish communities is the exertion of the Biochemical Oxygen Demand (BOD), instead of toxicity, of the discharged ethylene glycol. Oxygen deprivation resulting from the biodegradation of elevated ethylene glycol BOD levels causes stress on the fish communities.
The duration of exposure is particularly relevant at Trigg Lake due to the pulsed or spike impacts of deicing/anti-icing fluids that occur after storm events. The short environmental persistence of the deicing fluids causes exposure regimes that are highly variable.
Due to concerns regarding deicing/anti-icing fluids discharged to Trigg Lake during wintertime inclement weather conditions, especially freezing precipitation events, a process definition of the condition of Trigg Lake was performed. Samples were collected to define the important water chemistry relative to both the biology of Trigg Lake and biodegradation of glycol in Trigg Lake. Aquatic toxicity tests and Trigg Lake ethylene glycol biodegradation simulation studies were also performed using Type 1 and Type 4 deicing fluids. Concept engineering analyses were performed for process definition of the engineered solutions for adequate treatment of glycol, oxygen dissolution, and mixing requirements in Trigg Lake. Both the oxygen demand and oxygen transfer or dissolution requirements into Trigg Lake were defined under projected operating conditions (glycol releases).
A concept design was developed from the Trigg Lake simulation studies and implemented at the beginning of the 2001-2002 deicing season. Brush rotor aeration equipment was installed in Trigg Lake. The water quality standard (3.0 mg/L dissolved oxygen) was maintained throughout the 2001- 2002 deicing season. No notices of violation were received from any regulatory agency for glycol discharges into Trigg Lake during the 2001-2002 deicing season. Lake monitoring data for the 2001- 2002 deicing season is presented along with the study program methodology, test results, conclusions, and concept engineering design recommendations.
Document Type: Research Article
Publication date: January 1, 2003
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