Sand traps are needed when water is collected from the street. The most efficient way to do this is to combine the sand trap with the gully function. Special separators exist for those situations where the gully and the trapping functions can not be combined.
When the collection function is not required and when flows get higher, the Hydrodynamic separator is an option to be used. This separator has a bypass function.
The most universal sand trap is the sand trap with the collection function combined. All the water has to pass through this separator. It does not include a bypass function so there is no risk that the silts pass to the rest of the storm water system.
A very basic solution is also available. With this solutions the silts are also separated.
Wavin Save gullies are incorporating the collection function into the separation function. When higher flow speeds are to be handled, then Certaro separators are available. And when there is a relatively high spillage of oils (petrol stations), the Certaro NS oil separator will do the job.