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Council News

Council calls for federal review of toxic sealant used at Boeing Field


Applied to runways, runoff finds its way into water system


The Metropolitan King County Council today called on the Federal Aviation Administration to study the agency’s standards regarding the use of coal tar-based sealants at airport facilities. Coal tar-based sealants have been identified as a significant source of a class of toxic, cancer-causing pollutants that have been found in urban surface waters.

“Because we know runoff from coal tar-based sealants harms the environment and is hazardous to human health, it is time for the FAA to review the requirement for their use at places like King County’s Boeing Field,” said Councilmember Larry Phillips, chair of the Council’s Transportation, Economy and Environment Committee and sponsor of the motion. “Getting serious about cleaning up our waterways means seeking non-toxic alternatives to sources of toxic contamination.”

“Washington is again leading the nation in environmental protections,” said Councilmember Joe McDermott, Chair of the King County Board of Health. “It is my hope the FAA will acknowledge the harm coal tar-based sealants have on our rivers, lakes and oceans and joins our efforts preventing further damage to our fragile ecosystem.”

“Washington State has become a national leader in reducing pollution from coal tar. It’s great to see King County taking the next critical step to help eliminate this toxic goo once and for all,” said Mo McBroom, Policy Director for Washington Environmental Council. “Every action to prevent contamination from flowing through our storm drains is critical to help restore Puget Sound to health.”

A waste product of the coking of coal, a process used in manufacturing steel, coal-tar sealants are used to seal outdoor surfaces such as asphalt against penetration of water, fuel or other liquids. The FAA mandates use of coal tar-based sealants under certain circumstances at airport facilities that it licenses, including King County International Airport (KCIA), better known as Boeing Field.

Sealants derived from coal tar have recently been identified as a major source of the distribution of a family of chemical compounds known as polycyclic aromatic hydrocarbons ("PAHs"), formed by the incomplete combustion of carbon-containing fuels like coal, wood, diesel, and others. The Environmental Protection Agency has classified seven PAH compounds, such as benz [a] anthracene, chrysene, and benzo [a] pyrene, as probable human carcinogens.

A recent study by the United States Geological Survey has also identified coal tar-based sealants as a major contributor to the increase in PAH deposition in urban lakes and reservoirs across the nation. Based on the mounting evidence of the environmental harm associated with these sealants, the 2011 Washington State Legislature approved a ban on the sale of coal tar sealants in Washington and on their use on driveways and parking areas in Washington. There is a legal uncertainty regarding the applicability a state ban if the use of the sealant is directed by federal standards at a federally-licensed facility operated by a county within the state.

Among the county agencies responsible for asphalt surfacing, only one, KCIA, reported using coal tar-based sealants. As an FAA licensed facility, which qualifies it for FAA funding, KCIA is required to comply with FAA standards. KCIA reported that the FAA mandates the use of coal tar-based tar sealants as a fuel-resistant sealer in areas such as refueling ramps and aprons. The last time it was used at the airport was 2007.

The motion adopted by the Council requests that the FAA review its standards for use of coal tar-based sealants at FAA-licensed airport facilities. It calls on the agency to consider the potential toxic impact of coal tar-based sealants, and asks for the FAA to consider alternatives to the use of coal tar-based sealants.

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