Assessing Change in Runoff Water Parameters Through Road Shoulder Vegetated Filter Strips: Experimental Comparison of Soils and Engineered Infiltration Media

Placement of Vegetated Filter Strips (VFS) along roadways may facilitate removal of nutrients from stormwater runoff. The objective of this research is to compare water quality performance of a VFS containing engineered media to that of typical Florida sandy soil. Storms of variable intensity were simulated over two 1:1 scale physical models of typical one- and two-lane roadway shoulders, one with engineered media (treatment), and one without (control). Simulated roadway runoff was introduced as sheet flow from the roadway and precipitation was applied with a rainfall simulator. Samples of runoff and infiltrate were tested for Dissolved Oxygen (DO) concentration and pH at regular intervals along each model and analyzed to detect changes both in time and location. Within four hours of the experiment start, pH decreased on average by 0.74 ± 0.21 in the treatment model, and less so (by 0.39 ± 0.16) in the control model (p\u3c0.0001). pH continued to decrease with time in both models, though more significantly in the treatment model. The DO saturation decreased in the treatment model by a mean 12.18 ± 18.54% and increased in the control model by a mean 6.74 ± 13.21% over 4 hours (p\u3c0.001). However, DO monitoring over 72 hours indicated minimum DO concentrations of 5.83 ± 1.28 mg/L and 7.84 ± 0.92 mg/L in treatment and control models, respectively, suggesting that pore water was not oxygen limited. This analysis provides a deeper understanding of how nutrient removal processes may have varied within each media type