 |
|
|
|
|
|
|
 |
 |
 |
 |
 |
|
|
 |
 |
 |
 |
 |
|
 |
|
|
|
 |
|
||
 |
 |
 |
|
Hydrodynamic Separators
Hydrodynamic separators are flow-through structures with a settling or separation unit to remove sediments and other pollutants. No outside power source is required, because the energy of the flowing water allows the sediments to efficiently separate. Depending on the type of unit, this separation may be by means of swirl action or indirect filtration. A generalized schematic of a unit is shown in Figure 7-1 (Source: Fenner and Tyack, 1997). Variations of this unit have been designed to meet specific needs. Hydrodynamic separators are also known as gravity separators, oil and grit separators, or water quality inlets).
Hydrodynamic separators are most effective for the removal of heavy particulates or floatables, however, suspended solids are not effectively removed. The removal efficiency can be increased by reducing the entering flow velocity so more sediments can settle out. Hydrodynamic separators come in a wide size range and some are small enough to fit in conventional manholes. This makes hydrodynamic separators ideal for areas where land availability is limited. Also, because they can be placed in almost any specific location in a system, hydrodynamic separators are ideal for use in potential stormwater “hotspots” such as areas near gas stations, where higher concentrations of pollutants are more likely to occur.
Figure 7-1. Source: Fenner and Tyack, 1997. (EPA Hydrodynamic Separators Fact Sheet)
In general, hydrodynamic separators require a minimal amount of maintenance, but lack of attention will lower their overall efficiency. Proper maintenance involves frequent inspections throughout the first year of installation. The unit is full when the sediment level comes within one foot of the unit’s top. This is recognized through experience or the use of a “dip stick” or rod for measuring the sediment depth. When the unit has reached its capacity, it must be cleaned out by a sump vac or vacuum truck, depending on which unit is used. Sediment should be tested for toxicants in compliance with current disposal requirements .
Click here for the detailed design of water hydrodynamic separators from the EPA’s Storm Water Technology Fact Sheet: Hydrodynamic Separators
 |
|
|
|
|
|
|
|
|
|
 |
|
||||||||
 |
 |
 |
|
||||||
 |
 |
 |
|
||||||
 |
|
||||||||
 |
|
||||||||
 |
 |
 |
|
||||||
 |
 |
 |
|
||||||
 |
 |
|
|||||||
 |
|
|
|
|
|
|
 |
 |
 |
 |
 |
 |
|
 |
|
|
|
|
|
 |
 |
 |
 |
|
 |
|
|
|
 |
|
Copyright @ January,2005 Prepared by Transportation Environmental Resource Center (TERC)