INFLUENCE OF PRINCIPAL SPILLWAY GEOMETRY AND PERMANENT POOL DEPTH ON SEDIMENT RETENTION OF SEDIMENTATION BASINS

Abstract

Sediment retained in a 197-m3 sedimentation basin during 12, two-year storms with identical 100-m3 inflowhydrographs and 454 kg sedigraphs was measured. Sediment discharged through the perforated riser and single-orificeprincipal spillways was similar at 23.1 kg. Of the average of 23.1 kg of sediment discharged during each event, 3.0 kgwas resuspended from previously deposited sediment, 9.1 kg originated from the basin floor and sides, and 11.0 kgoriginated from the soil injected during that event. Sediment discharge averaged 13.4 kg for the 0.46-m deep permanentpool and 24.0 kg for the 0.15-m deep permanent pool.