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MATERIALS AND METHODS
Soil samples were collected before the first snowfall of the winter season from three different areas - ranging from low vehicular traffic volume areas to high traffic volume areas - (1) Edgewood's parking lot rain garden, (2) Wingra Drive - a main city street, and (3) 12/18 beltline - a divided highway (See map below for locations). Near the end of the winter season, three more soil samples were collected from the same areas for comparison. Two additional samples were taken in the rain garden to compare the affects of water flow with in the rain garden. A sample of sand distributed by the city was also obtained.
Every sample was baked to insure equal dryness. To test samples 150g of each sample was placed in a 500ml beaker and 300ml of de-ionized water was stirred in. Each sample was allowed to settle for four days. One the fourth day water was extracted from each sample and then measured for level of chloride concentration by using a Hach kit. Some samples had low enough concentrations of chloride to use the low range test; however some samples required the high range test. For the low range test the chloride is calculated by multiplying the number of drops used for a reaction in the water sample by 5, and where in the high range test there is a different size water sample and the number of drops used are then multiplied by 20. From the chloride concentration data collected the sodium concentrations were calculated by using the Hach kit's conversion: 1.6x = y; when x = Cl mg/L and y = Na mg/L. From the unit of mg/L the data was then converted to parts per million (ppm). Therefore, the calculations for sodium levels are figured under the assumption that every one part chloride is associated with one part sodium.
The test for the sand sample was attempted the same way as the soil sample, however contained too much sodium and chloride to produce a reliable result. For this reason displacement was used to calculate the concentration of salt in the sand. First the sand was completely dried, and 150g was measured out. This was soaked in 300mL of de-ionized water, and then dried. At this point not all of the salt had been dissolved, so 300mL of de-ionized water was again added to the sample, and then dried. The remaining sand was then weighed and a percentage of salt to sand was calculated.
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