Abstract Perhaps the most logical conclusion this study can offer is that more research is necessary. This report should be considered a preliminary study into specific levels of a defined set of parameters in the MC drain. Before attempting to improve the quality of water in the storm drains, all significant forms of contamination and their sources should be identified. From the data gathered for this report, it was determined that chlorides are the main cause of contamination in the water collected by the Math and Computer Drainage network. Chlorides were present in samples year round at rates consistently above the background level of the Creek; however, the level was exponentially higher in the winter testing period due to salting of roads. Other contaminants present in samples collected for visual study or chemical tests included oil, sediment, lawn and tree debris, litter, and faeces. The presence of oil in the storm drains may be due to leakage from cars. The concentration of faecal coliforms may be due to wildlife faeces which are washed from lawns into storm drains. In the winter, thermal shock from warmed surfaces causes a temperature gradient of several degrees Celsius between the drain water and that of Laurel Creek and a decrease in dissolved oxygen. This is exacerbated by the absence of shade in winter that is provided by deciduous trees in the summer.
Although testing revealed the absolute levels of a few contaminants on a few specific dates, the researchers could only make assumptions as to the overall significance of contamination from the MC drain on Laurel Creek. This was based on rather crude calculations of the dilution factor. Therefore, it is strongly recommended that further research should be done to determine the cumulative impacts of the many storm drains which empty into the campus portion of Laurel Creek. Specific parameters tested in the MC drain also require further study. In particular, the abnormal levels of chloride, conductivity, and faecal and total coliforms found in the drain should prompt further study.
This study identified possible land uses and human activities that likely impact water quality in the drain and in the Creek. However, no sources could be pinpointed with absolute certainty. The identification of specific sources and locations of contamination would be helpful for remedial action. It may be useful to determine how people perceive the function of the drain. A survey of residents and industry adjacent to storm drains may reveal that storm drains are perceived as a place for waste water and/or chemical disposal. The survey may also indicate certain activities that misuse the storm drains. For example, a survey of gas station workers at the intersection of Philip Street and Columbia Street may reveal that the storm drains on site are used for old oil disposal, or that wastewater from the car wash is deposited directly into the storm drain system.
In some areas the storm drain system runs parallel to the sanitary sewer system. If there are cracks in the sanitary sewer it could contaminate the storm sewer, and in turn, Laurel Creek. This theory cannot be ruled out as a possible explanation for faecal coliforms.
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Last updated: June 26, 1995 jjk