Multi-level outlet weir for enhanced volumetric separation for stormwater treatment

A hydrodynamic separator assembly configured for installation within a stormwater drainage infrastructure, wherein the hydrodynamic separator has substantially circular walls with a top, with one or more access openings, a bottom, at least one inlet opening and at least one outlet opening;

• wherein said hydrodynamic separator, contains an outlet weir, said outlet weir with weir shelves and wall is attached to said wall of hydrodynamic separator via mounts, and positioned so that the wall of the outlet weir is disposed across the outlet opening horizontally level;
• wherein the outlet weir has two or more orifices arranged in a vertical orientation, including one or more orifices on the shelf portion of the outlet weir to control water level and discharge rate at low flow conditions, one or more orifices on the wall portion of the outlet control weir to control water level and discharge rate at moderate flow conditions, and the top of the outlet weir set at a higher elevation than the orifices to control the water level at higher flows that exceed a flow capacity of the multiple orifices below;
• wherein a level and size of each orifice is set and designed based upon hydraulic calculations that optimize an overall performance curve for removal of particulate pollutants over all flow ranges by increasing a volume of water to a higher level during lower flow conditions and therefore decreasing gallons per minute per cubic foot of wet volume and increasing performance.