Coagulant Use for Sediment Reduction in Construction Site Stormwater Runoff

Abstract

Sedimentation basins are used at construction sites to reduce sediment-laden stormwater runoff into local water bodies. During storm events, these ponds can have reduced efficiency, causing very turbid water to exit the basin. This project evaluates the performance of coagulants for sediment reduction in construction site runoff in a laboratory setting. The performance of polymers for sediment reduction was assessed. A protocol was developed for coagulant selection at future sites. Four sedimentation basins at a MD 43 construction site in Baltimore County were used in the study. Twelve different coagulants were tested and four were selected for further trials, two anionic, one cationic, plus alum. All samples with coagulants increased sediment reduction efficiency over samples without coagulant, increasing turbidity reduction from 51% up to 85%. A field coagulant dosing system was designed for future studies.