Optimization of Sediment-Basin Configurations Using Intermediate-Scale Testing

Abstract

To better understand the performance of sediment basins, intermediate-scale experiments were conducted to examine performance impacts based on a sediment basin’s volumetric and geometric properties. Additionally, various treatment methods were evaluated to assess their effects on sediment capture, including baffles, silt-fence serpentine baffles, a level spreader, and chemical flocculants. Three intermediate-scale trapezoidal basins, Basin A (length twice the width, 2L:1W) with a volume of 0.43 m³ (15.3 ft³), Basin B (10L:1W) with a volume of 0.38 m³ (13.5 ft³), and Basin C (2L:1W) with a volume of 0.20 m³ (7.0 ft³), were designed and evaluated in a controlled environment. Basins A and B, reflecting typical volumetric sediment-basin designs with coir-baffle treatment and a skimmer, captured 88% of the introduced sediment. The inclusion of coir baffles enhances sediment capture by up to 10%. Basin C achieved 91% sediment retention using a single coir baffle and chemical flocculants. One-hundred-percent-natural coconut coir-fiber baffles were used within this study to spread the inflow across the width of the basin, which dissipates the energy of the inflow. These coir baffles are typically used within sediment basins for this purpose and to provide a conventional best management practice to be used in conjunction with chemical flocculant introduction. This study indicated that using a reduced basin volume along with chemical flocculants may provide equivalent or greater sediment capture than do typical basin designs with larger volumes, providing substantial cost savings.