Environmental Management


Seattle Tacoma International Airport (STIA) NPDES Compliance Monitoring, Port of Seattle, Seattle, WA

National Pollutant Discharge Elimination System (NPDES) compliance monitoring at Seattle Tacoma International Airport found highly elevated concentrations of zinc in one isolated stormwater basin at the airport. Source tracing up the storm drain system found that a high contribution of dissolved zinc was generated from a zinc-treated roof at a large air cargo building.

Rather than replace the roof, the airport tasked Cardno TEC with evaluating the effectiveness of various stormwater filter treatment media on removing pollutants, particularly metals, from the roof runoff.

Cardno TEC monitored and evaluated three filtration media for treating stormwater runoff from the rooftop and two filtration media for treating the overall stormwater subbasin. The roof runoff treatment study was conducted using a full-scale treatment system deployed in the field, while the subbasin runoff treatment study was conducted using scaled-treatment devices in a laboratory setting. Cardno TEC prepared the Quality Assurance Project Plans and designed, fabricated, and installed custom flow monitoring, field sampling, and laboratory testing equipment. Flow weighted composite inflow and outflow samples from multiple events and water compositions for each study were analyzed and reported. The results provided information for capital planning to treat the roof and for future stormwater treatment alternatives at the airport.

More about our ENVIRONMENTAL MANAGEMENT SERVICES >