Sediment Capture Effectiveness of Various Baffle Types in a Sediment Retention Pond

The relative sediment trapping effectiveness of a permanent-pool sediment retention pond was assessed due to theinstallation of baffles composed of different materials commonly used on construction sites. A suite of experiments wasperformed at the Sediment and Erosion Control Research and Education Facility (SECREF) at North Carolina StateUniversity in which an acoustic Doppler velocimeter was used to record steady-state flow velocity data at 50 grid points withinthe pond at three steady input flow rates. Hydrodynamic data were taken for free flow and for three different baffle materials:jute germination blanket backed by coir fiber, standard tree protection fence, folded and tied together into three layers toreduce pore size, and standard silt fabric with weirs. The experiments were conducted with a characterized soil injectedupstream at a fixed rate with sampling at the outlet. At the completion of each baffle experiment, particle size distributionwas determined for sediment deposits at fixed points in the pond bed. Analysis of the hydrodynamic data suggests that allbaffles greatly reduced and diffused flow compared to an open pond. The jute/coir baffle outperformed a standard silt fencewith weirs and a triple layer of tree protection fence. Results from soil composition analysis and exit turbidity measurementsper baffle configuration confirmed that the jute/coir baffle was the most effective in improving sediment retention in the pond.