Ponds and Sedimentation Basins are simply basins or water bodies (eg. ponds, retarding basins) reliant on the physical settling of suspended solids as the principal treatment mechanism and can reduce peak flows through detaining a volume of the runoff and allowing for slower release during and after the event. Other mechanisms associated with phytoplankton assimilation of soluble nutrients and ultra-violet disinfection are currently not included in the modelling algorithm.
...
Evaporation from the permanent pool of a pond, detention basin or sedimentation basin can be modelled by defining the evaporative loss rate, defined as a percentage of the daily Potential Evapotranspiration data contained in the Meteorological Template used to create the model. The water that evaporates from the permanent pool of the pond or sedimentation basin is lost from the catchment. Contaminants in the water that is lost to evaporation remain within the permanent pool.
The button 
allows you to estimate the surface area of the sedimentation basin. Clicking it opens the Estimate Parameter Properties dialogue box, which is explained further below.
Outlet Properties
The physical characteristics of the outlet pipe and weir are defined in this section of the dialogue box.
...
Defines the equivalent diameter of the outlet pipe (this may not be the diameter of the pipe itself, but the equivalent diameter of its orifices). The outlet pipe is notionally set with an invert at the standing water level of the permanent pool. The pond, detention basin or sedimentation basin dialogue box will display the notional detention time, based on the pond or basin volume, and the Equivalent Pipe Diameter.
| Info | ||
|---|---|---|
| ||
|
...
Note that for a sedimentation basin, the default values for k, C* and C** for each of the constituents are as shown in the diagram above.
Threshold Hydraulic Loading for C**
...