Landfill sediment and estuarine water samples were collected during low tide. This study aims to assess the transfer of chemical elements from contaminated sediments to the estuarine water from cycles of sediment leaching so as to evaluate the ecotoxicity of the leachates, and to analyze the solid phases crystallized from those leachates. This knowledge will help winter maintenance agencies apply salt and salt brines effectively for the best performance on winter roadways.Wastes from a former Portuguese steel plant were deposited between 19 on the riverbank of a tributary of the Tagus River creating a landfill connected to the river, posing a potential contamination risk to the Tagus estuary ecosystem. Project deliverables included the development of training materials (a fact sheet and a video) to help provide winter maintenance practitioners with a better understanding of the phase diagram for sodium chloride and how to apply it to yield the best results in roadway deicing. The goals of this project were to provide winter maintenance practitioners with a better understanding of the sodium chloride phase diagram and of how brines with salt concentrations higher or lower than the eutectic point of 23.3% will behave on the roadway. Practitioners are unclear as to whether spraying a supersaturated brine can cause roads to become more slippery under certain circumstances.
In brine solutions with salt concentrations beyond the eutectic point, salt precipitate and ice begin to form in the solution as the temperature drops. However, there has been some confusion regarding the portion of the diagram to the right of the eutectic point. The NaCl phase diagram shows a familiar process: salt depressing the freezing point of ice. Winter maintenance practitioners are primarily concerned with the portion of the phase diagram where ice is formed. The sodium chloride phase diagram is a visual representation of the behavior of NaCl solutions across a range of temperatures and salt concentrations.
By Greg Waidley on Januin Completed Projects Problem
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