Deicing operations and practices Deicing at the gates. Storm sewer design. Parallel system routes storm and glycol water. Glycol storage before discharging to a POTW. Glycol capture by GRV’s 45-48%.
Environmental Concerns 1994 - SPDES permit 30 mg/L BOD5 and 500 mg/L glycol limit Frequent permit exceeded 1995 - Vacuum sweeping 3/1998 - The Citizen Alliance Group targets NYSDEC 4/1998 NYSDEC issues Order on Consent - Comply by 2/99
Over the next 4 years… ~$13.1 million spent deicing controls, storage and treatment Permit limits still exceeded Neighbor complaints Town prohibits discharge
Concerns Point source limit applying to a non-point source operation – Permit modification It’s not working –treat everything or reduce use? Large volumes – how do you treat this cost effectively? How do you pay for this?
Alternatives considered Dedicated sewer line to POTW Anaerobic/aerobic onsite treatment Membrane bioreactors Recycling Infratek systems Reed bed subsurface wetland Centralized deicing recycling
Subsurface engineered wetland Advantage – Lowest 20 year combined capital and operating cost Effective treatment for stormwater Totally Green process Disadvantage – Space constraints Public acceptance (Will it work?)
Go for it! 2005 - RFP for a Treatability Study and Conceptual design 2006 - Awarded to Jacques Whitford/NAWE/Urban Treatability study showing >95% reduction in BOD 2007- Design phase completed
GARRET A. MEAL, P.E., URBAN ENGINEERING Stormwater Management Impacts
URBAN ENGINEERS Buffalo Engineering firm with 10 offices 475 staff along the East Coast Extensive airport and civil transportation experience NY and local environmental permitting experience
Stormwater Management Strategies Divert upstream areas directly to wetlands, where possible Utilize wetlands for storm detention Utilize glycol infrastructure year round Design additional pumping capacity Evaluate emergency overflows Surface storage of severe storms
Treatment Objectives Provide treatment of contained deicing fluid Design system for integration into airfield Integrate system into existing stormwater management
Why Wetlands? Subsurface flow constructed wetlands do not pose a bird-aircraft strike hazard (BASH) More stable than mechanical treatment systems Biggest challenge is oxygen transfer into subsurface flow beds!
Conclusions System operation scales to glycol usage In this case, the design had to handle variable flows and concentrations from at gate deicing The design provides flexible operations Winter = glycol treatment Summer = storm storage
Lessons Learned Communicate early and often Never forget your key mission Every airport is different Design with flexibility in mind Listen to your stormwater engineer