Design criteria of sediment detention ponds for characteristic regional conditions in Tennessee

Current methods for developing sediment pond design criteria for areas with land- disturbing activities (construction, mining, and agriculture) consist of rule-of-thumb techniques or more complex procedures involving computer analysis. Rule-of-thumb techniques often fail to adequately accommodate specific site conditions and may result in damaging off-site sediment transport. Available computer models accurately address site- specific conditions but require significant input data for satisfactory results. In addition to detailed hydrologic and surface condition information, these inputs include particle size distribution of the eroded soil in the drainage area.

A method which takes into consideration regional rainfall, soil, and slope conditions has been developed to assist designers in the sizing of sediment ponds. The developed method provides for a much more site-specific design to better meet the current best management practice criteria for off-site sediment transport.

The study was undertaken in three steps. First, sixty-five representative Tennessee soils based on SCS Soil Series were selected and evaluated in 6 hydrologic/erosion zones comprising Tennessee. Eroded particle size distributions for these soils were estimated using a computational method developed by G. R. Foster and others. Second, evaluations of the zone and soil conditions were made to estimate required pond sizes utilizing computer modeling software (SEDCAD+). This included an assessment of the trapping efficiency, volume-weighted average discharge, and annual sediment yield with respect to surface area, dead space, detention time and overflow rates using a basic pond geometry and drainage area with varied slopes. Third, the results were compiled and presented in a format that could be retrievable based on the site information, including: location by county, soil series, and slope. Estimates of flow rates, sediment accumulation, and trapping efficiency are also included in the compiled results.