Date of this Version
Bridge deck runoff is often discharged to water bodies. There are fewer studies focused solely on bridge deck runoff quality. Only one prior study assessed the impacts of bridge deck runoff on receiving waters in Nebraska; however, their conclusions were based on samples collected during a persistent drought. The objective of this research was to evaluate the quality of bridge deck runoff and to determine if contaminant occurrence can be related to traffic during the antecedent dry period (ADP).
Time-weighted composite samples of bridge runoff and hourly traffic data were collected in this study. Only total suspended solids (TSS) and hexane extractable material (HEM) had the highest concentrations during the first rainfall event of the year. Average concentrations of TDS, TSS, chloride, iron, and lead measured in this study were higher than those found in other studies. For lead and iron, it was difficult to observe a direct relationship between concentration and ADP, or concentration and daily traffic. However, there was a stronger correlation (R2 = 0.3716) between traffic during ADP and the concentration of zinc. This difference may be explained in the sources of these metals in runoff. The only source of zinc in bridge deck runoff is vehicle wear, but the sources of iron include the materials and structure of the bridge in addition to vehicle materials. Therefore, to improve the correlation for iron and lead, it is necessary to consider other variables such as bridge design and bridge materials, or other non-bridge related sources.
Adviser: Shannon Bartelt-Hunt