Storm water filtration system

1. A storm water filtering system located in a storm water catch basin, the basin having a storm water inlet spaced from at least one storm water outlet and defining a chamber for storm water collection between the inlet and the outlet, the filtering system comprising:

a plate for dividing the basin into a first chamber for receiving storm water and a second chamber for passing storm water out of the basin;

a filter assembly mounted within a hole formed in the plate, the filter assembly including a filter media having a predetermined effective flow rate for removing pollutants from the storm water;

an overflow tube coupled to the plate at another hole formed therein for passing storm water through the plate and bypassing the filter assembly, the overflow tube having a storm water inlet at a height above the filter media so as to limit the maximum water pressure applied to the filter media; and

a diverter lid mounted to a top of the overflow tube, the diverter lid having downwardly depending sides spaced from and overlapping the storm water inlet in the overflow tube such that pollutants floating on a surface of the storm water when the storm water is above the level of a lower edge of the lid sides cannot enter into the overflow tube.

2. The storm water filtering system of claim 1 and including a plurality of filter assemblies mounted within corresponding ones of a plurality of holes in the plate, the number of filter assemblies being determined by matching the outflow rate of the catch basin to the maximum effective filtering rate of the filter assemblies.

3. The storm water filtering system of claims 2 and including a plurality of overflow tubes mounted to the plate, the bypass volume of the overflow tubes being selected to match the effective filtering rate of the filter assemblies such that the water head pressure at the filter media does not exceed a selected maximum value.

4. The storm water filtering system of claim 3 wherein each of the overflow tubes includes a diverter lid mounted to a top of the overflow tube, the diverter lid having downwardly depending sides spaced from and overlapping a storm water inlet in the overflow tube such that pollutants floating on a surface of the storm water when the storm water is above the level of a lower edge of the lid sides does not enter into the overflow tube.

5. The storm water filtering system of claim 1 wherein the filter assembly includes a canister containing a filter media, the canister protruding through the plate, and an enlarge support attached to an upper end of the canister for support the canister against an upper surface of the plate, the system further including apparatus coupled to the support for determining the weight of pollutants captured in the filter media.

6. The storm water filtering system of claim 5 wherein the apparatus for determining the weight of the pollutants comprises;

a spring mounted between the support and the plate such that the spring is compressed by the weight of the pollutants; and

means for determining the degree of compression of the spring.

7. The storm water filtering system of claim 5 and including a gasket positioned between the support and the plate.

8. The storm water filtering system of claim 1 and including a pre-filter mounted in the catch basin above the filter assembly, the pre-filter comprising a mesh basket for capturing large items of debris entering the basin.

9. A storm water filtering system located in a storm water catch basin, the basin having a storm water inlet spaced from at least one storm water outlet and defining a chamber for storm water collection between the inlet and the outlet, the filtering system comprising:

a plate for dividing the basin into a first chamber for receiving storm water and a second chamber for passing storm water out of the basin;

a plurality of filter assemblies mounted within corresponding ones of a plurality of holes formed in the plate, each of the filter assemblies including a filter media having a predetermined maximum flow rate at which the media is effective for removing pollutants from the storm water;

a plurality of overflow tubes coupled to the plate at respective spaced holes formed therein for passing storm water through the plate and bypassing the filter assemblies, the number of overflow tubes being selected to establish a flow rate corresponding to the expected first flush volume of flow into the catch basin, each of the tubes having a storm water inlet at a height above the filter media so as to limit the maximum water pressure applied to the filter; and

a diverter lid mounted to a top of the overflow tube, the diverter lid having downwardly depending sides spaced from and overlapping the storm water inlet in the overflow tube such that pollutants floating on a surface of the storm water when the storm water is above the level of a lower edge of the lid sides cannot enter into the overflow tube.