SIZING

 

Sizing of the StormTree system is based on ratio of filter media bed to the area of drainage or catchment, as determined by studies and testing carried out by university and LID design centers.  Such factors as the rate of infiltration and depth of the filter media also play an important role in system design and appropriate sizing.

Unlike closed tree box systems, StormTree’s  “open”  design allows for greater flexibility in the design and installation of the filter media.  The size of the media filter is not dependent on the dimensions of a 4-sided box.  Therefore, treating a larger drainage area doesn’t require the building a bigger box.  Filter media dimensions are based on total square footage, not specific shape, length, or width.

Think of the StormTree system as an underground rain garden.

 

                                                                              QUICK SIZING TABLE

 

SYSTEM

 

MINIMUM   MEDIA FILTER SIZE (FT2)

 

DRAINAGE   AREA (ACRES)(75%   IMPERVIOUS)

 

DISCHARGE/OVERFLOW   PIPE

 

ST-25

24

Up to 0.25

  6” or 8”  SDR-35, SCHD-40, or ABS

ST-50

48

0.25 to 0.50

  6” or 8”  SDR-35, SCHD-40, or ABS

ST-75

64

0.50 to 0.75

 6”, 8” or 12”  SDR-35 or ABS

NOTES:

System filter media depth is approximately 28″

System discharge/overflow pipe is positionable in the field.  Elevation of invert for discharge pipe can be set at a minimum 3.4 feet to a maximum of 4.2 feet below top of surface frame