Storm drain filter system

DETAILED DESCRIPTION In accordance with an important feature of the invention, the filter system is constructed in multiple parts that can be passed through a gutter inlet and assembled in the collection box of the storm drain.
The filter includes a multi-part tubular frame that can be quickly assembled in the collection box.
The frame is constructed so that it can be fully expanded between the internal sidewalls and butted against a front wall of the collection box.
The frame is telescopic to accommodate collection boxes of different sizes and includes legs attachable thereto for supporting a filter bed portion and a filter back portion of the frame above the floor of the collection box.
In this regard, the filter achieves the shape similar to a bench.
A coarse screen is then laid on the bed of the filter, as well as fastened against the back portion of the filter.
The screen is perforated to filter particles of a certain size, or if exceptionally small size articles such as silt are to be filtered, a sheet of woven filter material is laid over the screen on the bed and back portions of the filter frame.
In this latter instance, the coarse screen functions as a support for the woven filter material.
Preferably, the filter material is draped over the frontal and side edges of the filter bed, with a seal material attached between the woven filter material and the frontal and side edges of the frame.
The filter material is also draped over the top edge of the back of the filter.
Once the filter bed and filter medium is situated in the collection box, the frame is fully expanded laterally for sealing against the sidewalls of the collection box.
In addition, the filter frame is urged against the frontal sidewall of the collection box and maintained in such position.
The frame position is maintained, preferably by pneumatic cylinders actuated laterally between the filter bed and the back wall of the collection box.
By expanding the pneumatic cylinders with compressed air, the filter frame is pushed tightly against the front wall of the collection box and maintained in such position