Date of this Version
Swadener, Lauren M. Evaluation of the Environmental Impacts of Bridge Deck Runoff. University of Nebraska, Lincoln, Nebraska, Master of Science.
Bridges are located in very close proximity to receiving waters, and regulatory agencies often require specific stormwater control measures for bridge deck runoff. While there is some information available on roadway runoff, few studies have focused on bridge deck runoff. Currently, there is no information available regarding the impacts of bridge deck runoff on receiving waters in Nebraska. Due to the cost, maintenance, and design issues associated with implementing structural controls for bridge deck runoff, it is important to develop a better understanding of the relationship between bridge deck runoff and potential impacts to receiving streams. The objectives of this research were to evaluate the quality of bridge deck runoff, to determine the effects of bridge deck runoff on surface water bodies in Nebraska by evaluating water and sediment chemistry, and to evaluate the effects of bridge deck runoff on aquatic life. Throughout the course of the project a variety of sampling and testing was conducted: in-stream dry weather sampling, sediment sampling, wet weather bridge runoff sampling, and preliminary toxicity testing. Statistical analysis of upstream and downstream in-stream samples showed that bridges did not impact the quality of the water body. Similar results were found from sediment samples as there was no definite increase in streambed sediment concentrations from downstream to upstream. The low amount of rain during the summer of 2012 with large antecedent dry periods (ADPs) between storms resulted in worse conditions for the bridge runoff samples. The concentrations of bridge runoff samples were difficult to compare to literature values because they were not measured as event mean concentrations (EMCs); however, none of the results exceeded EPA recommended values for surface water. Two runoff events were also used in a 48-hour 5 dilution series toxicity test with fathead minnows, and no negative effects were found. These preliminary results show that there were no apparent effects of bridges on water quality and aquatic life, but it is recommended that research continues to provide more supporting data.
Advisor: Shannon Bartelt-Hunt