Abstract

Successful control measures require proper design, maintenance, and monitoring to evaluate effectiveness. To study stormwater runoff mitigation techniques, a row of infiltration trenches with different designs was monitored for 2.5 years. The three trench designs included gravel-filled, gravel-filled with a leaf filter, and sand-filled trenches. Water level loggers in monitoring wells provided low-cost monitoring of effectiveness over time and differences between trench designs. In addition, infiltration experiments were conducted to deliver a controlled volume of water to each trench. The center gravel trench with leaf filter drained more slowly during experiments. The monitoring showed that the gravel trench tended to have the highest peaks and responded to more storms. These differences were related to uneven water delivery, based on field observations during storms, controlled experiments, and similarity in response for the other two trenches. The water level recession rate did not decrease over time, indicating that clogging was not a significant factor. Maintenance that consisted of removing fines captured on the top of the sand trench did not significantly change infiltration in that trench. Monitoring with water level loggers was an effective method of determining that uneven delivery of water occurred among the three trenches, but there was no decrease in effectiveness of the trenches over the observation period, conclusions that could not be drawn by visual inspection alone.

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