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Sea-Tac Airport's Stormwater Program

Clean water is a priority for businesses and citizens in Seattle and surrounding communities. The importance of water quality encompasses agriculture, commerce, tourism, recreation, and wildlife, all key drivers of the regional economy. Water quality is influenced by stormwater runoff and management. Sea-Tac Airport is responsible for 1,600 aces of drainage area that flows directly into three local streams and the Puget Sound.   
Contamination of surface water can occur as a result of the storage, use, handling, and disposal of fuel and hazardous products on airport property. Because a substantial amount of the airport property is impervious, rain that falls onto runways, ramp areas, and buildings on the site runs off through drainage ditches and culverts and into the stormwater collection system. Aircraft fueling, equipment cleaning, oil and fuel spills, and maintenance activities are among the activities that can contaminate stormwater and runoff into surrounding streams if appropriate measures are not taken to prevent it. Sea-Tac’s network of stormwater collection piping, retention ponds, stormwater best management practices, and wastewater treatment facilities, effectively manage the risk to local waterways as demonstrated through the airport’s water quality monitoring program.
Learn More About Stormwater Management at Sea-Tac International Airport 
Stormwater runoff from the Airport drains to three local streams Miller Creek, Des Moines Creek and Gilliam Creek as well as directly to Puget Sound. In order to protect these aquatic resources, the airport has implemented numerous Best Management Practices (BMPs) to remove pollutants, reduce flooding and prevent spills from discharging into the environment. 
Airport stormwater runoff is collected into two conveyance systems: Industrial Waste System (IWS) or Stormwater Drainage System (SDS) depending upon the activities that occur within each area.  The IWS collects and treats stormwater from areas where aircraft or vehicle maintenance activities occur such as aircraft fueling and deicing. The SDS collects, detains and treats stormwater from the remaining portions of the airport including runways, expressways, the airport terminal and service road areas.
As part of the recently completed Master Plan improvements, the airport stormwater management systems have been completely retrofitted and upgraded to meet the most stringent environmental standards.  Through these improvements runoff containing high concentrations of deicing fluids are captured and treated before being discharge to Puget Sound. Metals and other pollutants harmful to salmon and other aquatic organisms have been reduced to safe levels before entering local streams.  Stormwater discharges from the airport are well below permit limits with low variability in comparison to other airports and industrial stormwater. 
The airport evaluates and as needed implements new stormwater BMPs as part of its ongoing stormwater adaptive management program and Stormwater Pollution Prevention Plan (SWPPP) implementation.   The adaptive management program takes a proactive approach and evaluates water quality monitoring results to determine if additional BMPs are necessary to prevent permit limit exceedances.  If additional BMPs are needed, the program first evaluates if low impact development (LID) stormwater BMPs are feasible to meet permit limits followed by evaluation of traditional grey stormwater infrastructure.   LID BMPs are evaluated on a project by project basis due to FAA restrictions related to compaction requirements and wildlife attractants, along with restrictions associated with industrial activities and structural limitations associated with infiltration within embankment areas.
The airport’s comprehensive Stormwater Pollution Prevention Plan includes a description of source control and treatment BMPs used at the airport.
How is Stormwater at the Airport Regulated?
The Washington State Department of Ecology (Ecology) regulates the discharge of stormwater runoff from industrial facilities through the issuance of a National Pollution Discharge Elimination System (NPDES) permits. Ecology has a number of permit types it can use to best manage facilities. For complicated facilities such as the airport, Ecology often chooses to issue individual NPDES permits tailored to specific conditions at the site. The airport has been operating under an individual NPDES permit since the mid-1990s. The permit is renewed approximately every five years and has grown to be one of the more comprehensive ones issued by the state. The NPDES Permit Fact Sheet contains NPDES permit histirical information for STIA’s NPDES Permit.
The current permit is broken up into three different Parts:
Part I- Industrial Wastewater System Runoff
Part II-Stormwater Drainage System Runoff
Part III-Construction Stormwater Runoff

Airport Stormwater Reports

Regular monitoring of all stormwater runoff generated at the airport is a critical component of our program. These testing requirements are the cornerstone of one of the most comprehensive National Pollution Discharge Elimination System (NPDES) permits issued by the Washington State Department of Ecology for an industrial facility. In addition to testing and reporting, the permit requires airport stormwater quality to meet stringent effluent limits established to protect aquatic resources in our local streams as well as Puget Sound. 

The NPDES permit under wich the airport operates requires the submittal of monthly and/or quarterly Discharge Monitoring Reports that compare stormwater runoff quality against effluent limitation concentrations, and annual reports that summarize each year’s monitoring results as well as improvements to our treatment programs.

In addition to these performance reports, the airport regularly maintains a comprehensive Stormwater Pollution Prevention Plan. Download the PDFs below.    

Construction Stormwater Reports

 2015 Construction Reports

January 2015construction_2015_01.pdfconstruction_2015_01
February 2015construction_2015_02.pdfconstruction_2015_02
March 2015construction_2015_03.pdfconstruction_2015_03
April 2015construction_2015_04.pdfconstruction_2015_04
May 2015construction_2015_05.pdfconstruction_2015_05
June 2015construction_2015_06.pdfconstruction_2015_06
July 2017construction_2015_07.pdfconstruction_2015_07
August 2015construction_2015_08.pdfconstruction_2015_08
September 2015construction_2015_09.pdfconstruction_2015_09
October 2015construction_2015_10.pdfconstruction_2015_10
November 2015construction_2015_11.pdfconstruction_2015_11
December 2015construction_2015_12.pdfconstruction_2015_12

 2014 Construction Reports

January 2014construction_2014_01
February 2014construction_2014_02
March 2014construction_2014_03
April 2014construction_2014_04
May 2014construction_2014_05
June 2014construction_2014_06
July 2014construction_2014_07
August 2014construction_2014_08
September 2014construction_2014_09
October 2014construction_2014_10
November 2014construction_2014_11
December 2014construction_2014_12

 2013 Construction Reports

January 2013construction_2013_01
February 2013construction_2013_02
March 2013construction_2013_03
April 2013construction_2013_04
May 2013construction_2013_05
June 2013construction_2013_06
July 2013construction_2013_07
August 2013construction_2013_08
September 2013construction_2013_09
October 2013construction_2013_10
November 2013construction_2013_11
December 2013construction_2013_12

 2012 Construction Reports

January 2012construction01-2012
February 2012construction02_2012
March 2012construction03_2012
April 2012construction04_2012
May 2012construction05_2012
June 2012construction_2012_06
July 2012construction_2012_07
August 2012construction_2012_08
September 2012construction_2012_09
October 2012construction_2012_10
November 2012construction_2012_11
December 2012construction_2012_12

 2011 Construction Reports

January 2011construction1-11
February 2011construction2-11
March 2011construction3-11
April 2011construction4-11
May 2011construction5-11
June 2011construction6-11
June 2011construction7-11
August 2011construction08-2011
September 2011construction09-2011
October 2011construction10-2011
November 2011construction11-2011
December 2011construction12-2011
Industrial Wastewater Reports

 2015 Monthly Industrial Wastewater Reports

January 2015industrial_2015_01.pdf
February 2015industrial_2015_02.pdf
March 2015industrial_2015_03.pdf
April 2015industrial_2015_04.pdf
May 2015industrial_2015_05.pdf
June 2015industrial_2015_06.pdf
July 2015industrial_2015_07.pdf
August 2015industrial_2015_08.pdf
September 2015industrial_2015_09.pdf
October 2015industrial_2015_10.pdf
November 2015industrial_2015_11.pdf
December 2015industrial_2015_12.pdf

 2015 Quarterly Industrial Wastewater Reports

1st Quarter 2015industrial_2015_Q1.pdf
2nd Quarter 2015industrial_2015_Q2.pdf
3rd Quarter 2015industrial_2015_Q3.pdf
4th Q 2015industrial_2015_Q4.pdf

 2014 Monthly Industrial Wastewater Reports

January 2014industrial_2014_01.pdf
February 2014industrial_2014_02.pdf
March 2014industrial_2014_03.pdf
April 2014industrial_2014_04.pdf
May 2014industrial_2014_05.pdf
June 2014industrial_2014_06.pdf
July 2014industrial_2014_07.pdf
August 2014industrial_2014_08.pdf
September 2014industrial_2014_09.pdf
October 2014industrial_2014_10.pdf
November 2014industrial_2014_11.pdf
December 2014industrial_2014_12.pdf

 2014 Quarterly Inudstrial Wastewater Reports

3rd Quarter 2014industrial_2014_Q3.pdf
4th Quarter 2014industrial_2014_Q4.pdf

 2013 Monthly Industrial Wastewater Reports

January 2013industrial_2013_01.pdf
February 2013industrial_2013_02.pdf
March 2013industrial_2013_03.pdf
April 2013industrial_2013_04.pdf
May 2013industrial_2013_05.pdf
June 2013industrial_2013_06.pdf
July 2013industrial_2013_07.pdf
August 2013industrial_2013_08.pdf
September 2013industrial_2013_09.pdf
October 2013industrial_2013_10.pdf
November 2013industrial_2013_11.pdf
December 2013industrial_2013_12.pdf

 2013 Quarterly Industrial Wastewater Reports

1st Quarter 2013industrial_2013_Q1.pdf
2nd Quarter 2013industrial_2013_Q2.pdf
3rd Quarter 2013industrial_2013_Q3.pdf
4th Quarter 2013industrial_2013_Q4.pdf
Sanitary Reports Non-Construction Stormwater Annual Reports