6PPDQ Screening Model: Model Documentation and Output King County, Washington

Tire-derived pollutants, such as 6PPD(N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine) and its oxidation product 6PPD-quinone (6PPDQ), are conveyed through roadway runoff to streams, causing urban runoff mortality syndrome (URMS) in coho salmon and adverse effects to other salmonids and aquatic organisms. There are hundreds of stormwater outfalls within 100 feet of coho bearing streams in King County, Washington. King County roads vary in their potential to generate tire-derived toxic chemicals, and King County is looking to develop a method to prioritize the placement of stormwater treatment facilities. This report documents the development and application of a 6PPD-quinone (6PPDQ) Screening Model (Screening Model). The Screening Model is an expert-knowledge-based spatial model that classifies roadways by the relative expected amount of 6PPDQ delivery to the stormwater drainage network, using available spatial data for model inputs. To support development of a Screening Model that meets the specific needs of King County roads and stormwater planners, the project team identified a specific set of model specifications that served as guiding principles throughout its development. The model was developed with local and regional subject matter experts in stormwater pollution, road runoff, tire wear, and spatial data analysis and modeling.

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6PPDQ Screening Model: Model Documentation and Output King County, WA