Highway Stormwater Runoff Quality: Investigation of Improved Operational, Predictive and Treatment Approaches

Date

2017-05-09

Authors

Trenouth, William Robert

Journal Title

Journal ISSN

Volume Title

Publisher

University of Guelph

Abstract

Highway stormwater runoff from large, multi-lane highways is one of the leading causes of watercourse impairment worldwide. Road runoff frequently carries within it a substantial physicochemical pollutant burden which includes sediments, nutrients, petroleum hydrocarbons and heavy metals. In seasonally-cold climates, winter maintenance activities entail the use of road salts, which constitute an additional source of pollutant loading to the road surface. A multi-pronged approach was used to improve the state of practice surrounding highway design, management and the methodological application of treatment approaches. First, a simple road salt application optimization tool was developed in order to help highway maintenance managers utilize a sound, scientifically defensible methodology when making determinations related to the frequency, timing and rate of road salt application. Data from three sites was used to modify the temperature index (TI) model to include sinusoidal variance in the daily melt coefficient, in addition to considerations related to the surficial rerouting of snow as well as the melt point depression caused by salt’s interaction with snow and ice. The second avenue of investigation led to the development of artificial neural networks (ANNs) capable of predicting the runoff concentration statistical distribution parameters for common heavy metals (Cu, Zn, Cr, Pb) and total suspended solid (TSS) event mean concentrations (EMCs) within highway stormwater runoff. The third avenue of investigation focused on the assessment and testing of novel treatment media for the purpose of enhancing existing roadside ditches in environmentally sensitive areas (ESAs). Blast furnace (BF) slag, basic oxygenated furnace (BOF) slag, iron-enriched overburden (IRON) and wood chips (WC) were tested. The long-term removal of Cr, Co, Cu, Pb, Ni and Zn within repacked soil columns ranged from 46-98%. The fourth research effort focused on the development of a methodological framework for designing enhanced roadside ditch systems for application in ESAs. The feasibility of this framework is demonstrated through a field-scale pilot study, complemented by three years of real-time monitoring data. Three different types of impermeable liner – compacted clay (CC), high density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) – were tested for their ability to prevent stormwater egress from the facility.

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Keywords

Highway Runoff, Water Quality Prediction, Artificial Neural Networks, Temperature Index, Snow Hydrology, Snowmelt, Salt-induced Melt, Filtration, Heavy Metals, Soil Column

Citation