Flocculated sediments can reduce the size of sediment basin at construction sites

• Published in: Journal of environmental management Vol. 166; pp. 450 - 456
• Main Authors: Kang, Jihoon, King, Scott E., McLaughlin, Richard A.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15.01.2016; Academic Press Ltd
• Subjects: Acrylic Resins; Basins; Construction Industry; Flocculation; Geologic Sediments - chemistry; North Carolina; Polyacrylamide; Polymers; Sediment basin; Sediments; Settling velocity; Soil; Suspensions; Total suspended solids; Water Quality; North Carolina; ANW, USA, North Carolina; USA, North Carolina, Piedmont; Settling velocity; Sediment basin; Total suspended solids; Flocculation; Polyacrylamide
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2015.10.049

Due to stringent water quality regulations on stormwater discharges, there is increasing interest in chemically-assisted settling of suspended sediments at construction sites. This study investigated settling characteristics of flocculated sediment by polyacrylamide (PAM) in a top-loading settling tube. Studied sediment materials were obtained from construction sites in North Carolina, USA: Coastal Plain loamy sand (CPLS), Piedmont sandy clay loam (PSCL), Piedmont silt loam (PSL), and Mountain clay loam (MCL). The four different sediment suspensions mixed with and without dissolved PAM were introduced to the top of the column individually. During a 1-h settling period, samples were taken at 1-m depth from surface at various times and analyzed for total suspended solids (TSS). Flocculated sediment by PAM greatly increased its settled TSS fraction up to 95–97% only in 1-min settling period compared to those of unflocculated sediment (16–72%). The settling improvement by PAM was profound in the finer-textured soils (PSL and MCL) by increasing their median particle settling velocity (>2 cm s−1) compared to unflocculated counterparts (<1.1 cm s−1). Estimated surface area requirement of sediment basin suggested that the basins receiving flocculated sediment could be reduced in size (surface area) by 2- to 4-times compared to those receiving unflocculated sediment. Our results suggests that current sediment basin design could be modified when chemically-assisted settling is implemented, taking up less space and cost in construction sites. •Flocculated sediments by polyacrylamide promote settling of suspended solids.•Settling improvement by flocculation was profound in the finer-textured soils.•Sediment basin receiving flocculated suspended particles could be reduced in size.