Phase 1: Preliminary Environmental Investigation of Heavy Metals in Highway Runoff

Heavy metals in highway runoff continue to be a national concern for most transportation agencies
including the Washington State Department of Transportation (WSDOT). In this project, a
comprehensive critical review of the literature and data associated with heavy metals in stormwater
runoff from highway settings was conducted to assist WSDOT in better understanding the indicators
associated with elevated concentrations in response to suggestions that locations for dissolved metals
treatment BMPs are to be determined based solely on Average Annual Daily Traffic.

Results found that multiple regression models have been used to predict contaminant concentrations
with some success, however there are still considerable uncertainties related to the predictions due to
the complexity and variability of highway settings. Furthermore, studies indicate that multiple linear
regression models are only applicable in the geographic region and range of conditions represented by
the original data set. Regional data necessary to populate and substantiate such a model for the State of
Washington do not currently exist. As such, additional runoff quality and ancillary information across a
variety of Washington highway AADT settings would be needed to improve the reliability associated
with locating BMPs for treating metals contamination. In discussing these uncertainties with WSDOT
and the department of Ecology, it was determined that a multiple regression model was not feasible.

Publication Date: 
Tuesday, November 21, 2006
Publication Number: 
WA-RD 661.1
Last modified: 
12/19/2018 - 11:01
Authors: 
Michael E. Barber, Michelle G. Brown, Katie M. Lingenfelder, David R. Yonge
Originator: 
Washington State Transportation Center (TRAC-WSU). Washington State University. Department of Civil and Environmental Engineering.
Number of Pages: 
44
Subject: 
Annual average daily traffic, Contaminants, Heavy metals, Highways, Pollution control, Quality of specific environments, Runoff, Statistical analysis.