How It Works
The First Defense® High Capacity separator has internal components designed to remove and retain gross debris, total suspended solids (TSS) and hydrocarbons.
Contaminated stormwater runoff enters the inlet chute from a surface grate and/or inlet pipe. The inlet chute introduces flow into the chamber tangentially to create a low energy vortex flow regime that directs sediment into the sump while oils, floating rubbish and debris rise to the surface.
Treated stormwater exits through a submerged outlet chute located opposite to the direction of the rotating flow. Enhanced vortex separation is provided by forcing the rotating flow within the vessel to follow the longest path possible rather than directly from inlet to outlet.
Higher flows bypass the treatment chamber to prevent turbulence and washout of captured pollutants. An internal bypass conveys infrequent peak flows directly to the outlet eliminating the need for, and expense of, external bypass control structures. A floatables draw off slot functions to convey floatables into the treatment chamber prior to bypass.