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Effects of Stormwater Pipe Size and Rainfall on Sediment and Nutrients Delivered to a Coastal Bayou
Citation:
Grigas, D., J. Lehrter, J. Cebrian, Y. Chen, B. Ehmen, AND M. Woodrey. Effects of Stormwater Pipe Size and Rainfall on Sediment and Nutrients Delivered to a Coastal Bayou. WATER ENVIRONMENT RESEARCH. Water Environment Federation, Alexandria, VA, 87(9):796-804, (2015).
Impact/Purpose:
We examined the effects of pipe size and rainfall intensity on storm pipe discharges, and constituent concentrations and loads. Determining such a scaling relationship will aid in assessment of the relative importance of storm pipe loading. Such relationships could also allow stormwater management entities challenged with reducing pollutant loads to prioritize areas for stormwater retrofits or planning for implementation of low impact development BMPs.
Description:
Pollutants discharged from stormwater pipes can cause water quality and ecosystem problems in coastal bayous. A study was conducted to characterize sediment and nutrients discharged by small and large (, 20 cm and .20 cm in internal diameters, respectively) pipes under different rainfall intensities (, 2.54 cm and . 2.54 cm,respectively). Results showed that large pipes had greater discharge than small pipes. Pollutants concentrations did not vary by pipe size. Large pipes had greater loads of TSS (138.2 vs. 24.0 mg/s), NO3 ? (5.54 vs. 2.74 mg/s), and NH4þ (0.39 vs. 0.19 mg/s) than small pipes. Neither discharge nor constituents varied by rainfall events. Pipe size may be a useful metric for estimating loads to a system. Nutrient reduction efforts should be directed to reducing the dissolved nutrient pools, while stormwater management efforts should be directed to reducing pipe freshwater discharge volumes that drive constituent loads. Water Environ. Res., 87, 796 (2015).
