Flocculant Dosage Guidance for Construction Stormwater Treatment

Construction stormwater pollution constitutes an increased risk for downstream water bodies due to uncontrolled sediment-laden discharge exiting construction sites. Temporary sediment control practices are designed for capturing sediment particles and reducing the turbidity of the off-site discharge; however, these designs often show limited performance in capturing fine-sized sediment particles. The use of flocculants provides an effective solution for construction stormwater treatment. These chemical compounds build a bridging mechanism between particles to form larger flakes and create settlement out of suspension. Although flocculants are highly effective in reducing turbidity, improper dosing may pollute downstream water bodies and create risks for aquatic life. The effectiveness of flocculants for stormwater management has been well-investigated; however, a large gap in knowledge exits on guidance for application rates and dosage for construction site applications. This study aims to fill this gap by investigating the performance of various commercially available products and practices. This research provides design-based guidance for roadway construction sites in Alabama by integrating bench-scale testing methods. Bench scale testing will consist of laboratory experiments that characterize the behavior of different flocculant types across different soil types through soil assessment, match test and dosage experiments. The study will enhance the proper use of flocculants in construction stormwater management by providing design guidance on application rates and dosage. Results of this study will provide valuable knowledge for further research studies and practitioners by presenting application and dosage guidance based on laboratory testing findings.