Water, Wastewater & Stormwater
394311 - Development of a High-Flow Structural Treatment Media for Improving Stormwater Quality
Wednesday, June 6
4:00 PM - 5:30 PM
Location: Greenway EF
Allen Davis, College Park, MD – University of Maryland
Phosphorus (P) loadings from urban runoff is a persistent contributor to water body impairment. However, dissolved phosphorus (DP) is not well-retained by many stormwater control measures (SCMs), including permeable pavements. Furthermore, captured particulate P can solubilize and be exported. This project evaluates a base material developed to enhance P removal in permeable paving. The novel media consists of a combination of expanded shale, water treatment residual (WTR), and a soil binder. The media has high hydraulic conductivity, 9.0 x 10-2 ± 0.002 cm/s, and is structurally suitable as a permeable pavement base material. Under continuous loading with synthetic stormwater, it reduced effluent DP from 0.19 mg/L to below 0.05 mg/L P for rainfall equivalents well beyond the pavement design lifetime. In rainfall simulations, the media effectively also removed P, Zn, and Cu to acceptable levels. In a field pilot study, the permeable pavement/media has demonstrated improved P retention compared to an impervious control surface. Adsorption to aluminum (hydr)oxides in the WTR is thought to be the primary mechanism for DP retention. DP uptake is described by a 1st order steady-state plug flow model developed and calibrated using experimental data. The model indicates performance dependence on media depth and treatment flow rate.