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Highway Runoff in Washington State: Model Validation and Statistical Analysis


Statewide sampling of highway runoff continued through 1980-81, and the resulting data has been aggregated with that from previous years to further investigate pollutant loadings. Results have validated the solids loading model previously proposed by Asplund (1980) for Western Washington Highways and tentatively extended the model to Eastern Washington. Loading of other pollutants can be predicted from total suspended solids loading using ratios derived from the data. These ratios may be taken as constants at any Washington State location for some pollutants or as linear functions of traffic for other contaminants. Comparison of runoff from a sulfur-extended asphalt pavement with runoff elsewhere indicates higher sulfate loads in the former case. A limited sampling program along an uncurbed highway section observed higher pollutant concentrations from these sections to curbed areas. Sampling of solids adhering to the undercarriage of automobiles produced widely varying results but suggested that vehicles traveling on rural or unpaved roads accumulate significant amounts of solids that can be released on highways. The final year of field sampling will concentrate on improving the loading models, especially for Eastern Washington application, and continuing the sulfur-extended asphalt study with a functional control site experiencing the same conditions. 

  • Date Published: January, 1982
  • Publication Number: WA-RD 39.12
  • Last Modified: November 2, 2007
  • Authors: Tai Wik David Chui, Brian W. Mar, Richard R. Horner.
  • Originator: University of Washington. Environmental Engineering and Science Program.
  • # of Pages: 48 p., 1,198 KB (PDF)
  • Subject: Asphalt pavements, Environmental impacts, Highways, Mathematical models, Pollutants, Runoff, Sampling, Statistical analysis, Sulfates, Suspended sediments, Toxicity, Water quality.
  • Keywords: Asphalt, asphalt pavement, concentrations, highway runoff, loads, models, pollutants, runoff, sampling, statistical analysis, sulfur, suspended solids, Washington (State)
  • Related Publications: Water Quality Impacts Associated with Leachates from Highway Woodwastes Embankments, (WA-RD 39.1).
    Effects of Velocity and Nutrient Alterations on Stream Primary Producers and Associated Organisms, (WA-RD 39.2).
    Highway Runoff Monitoring: The Initial Year, (WA-RD 39.3).
    Composite Sampling of Highway Runoff: Year 2, (WA-RD 39.4).
    Criteria and Requirements for Statewide Highway Runoff Monitoring Sites, (WA-RD 39.5).
    Characterization of Highway Runoff in Washington State, (WA-RD 39.6).
    Year 3 - Runoff Water Quality, August 1979 - August 1980, (WA-RD 39.7).
    Views of Risk and Highway Transportation of Hazardous Materials - A Case Study in Gasoline, (WA-RD 39.8).
    A Survey of Trace Organics in Highway Runoff in Seattle, Washington, (WA-RD 39.9).
    Transport Deposition and Control of Heavy Metals in Highway Runoff, (WA-RD 39.10).
    Effects of Seattle Area Highway Stormwater Runoff on Aquatic Biota, (WA-RD 39.11).
    Assessment of Pollutant Loadings and Concentrations in Highway Stormwater, (WA-RD 39.12.1).
    Year 4, Runoff Water Quality, August 1980-August 1981, (WA-RD 39.13).
    Guide for Water Quality Impact Assessment of Highway Operations and Maintenance, (WA-RD 39.14).
    Impacts of Channel Reconstruction in the Pilchuck River, (WA-RD 39.15).
    Summary -- Highway Runoff Water Quality Study, 1977-1982, (WA-RD 39.16). 

This abstract was last modified April 29, 2008