Appendix C - Stormwater Management Plan

1.2.3 Basic function                                               1.2.5 Maintenance overview

The StormFilter is designed to siphon stormwater runoff            The primary purpose of the StormFilter is to filter out and
through a filter cartridge containing media. The variety of        prevent pollutants from entering our waterways. Like any
media available can be designed to act as a mechanical             effective filtration system, these pollutants must be removed
filter to remove sediments, as an ion exchanger to remove          periodically to restore the StormFilter to its full efficiency and
dissolved heavy metals, and as an absorber to remove oils          effectiveness. Maintenance requirements and frequency are
and greases.                                                       dependent on the pollutant load characteristics of each site.
                                                                   To assist the owner with maintenance issues, Stormwater360
                                                                   provides detailed Operation and Maintenance Guidelines with
1.2.4 Priming system function
                                                                   each unit.

The treated stormwater collects in the centre tube of the          Stormwater360 can provide maintenance services completely,
cartridge, which is equipped with a self-priming siphon            or in part. Available services include tracking of installed
system. (Figure 1 illustrates this system.) The key component      systems, advising the system’s owner of maintenance needs,
of the system is the plastic float, consisting of a ball located   and notification of the regulatory agency once the system has
at the base leading up to a larger portion, which provides         been maintained.
increased buoyancy. Initially the ball rests in a seat,
                                                                   Maintenance is usually performed in the dryer periods
effectively closing off the port to the drainage manifold.
                                                                   to rejuvenate the filter media and prepare the system for
As a result, the filter fills the centre drainage tube until the   the next rainy period. Maintenance activities can also
water level has risen high enough to purge the air from the        be required in the event of a chemical spill or excessive
filter cartridges and displaces the float. At a water depth of     sediment loading due to site erosion or extreme storms.
22 inches the float pulls loose and allows the filtered water      It is good practice to inspect the system after severe
to drain out through the manifold. This effectively “primes”       storm events.
a siphon within the drainage tube and greatly increases the
potential across the filter. The priming system increases
StormFilter’s ability to be loaded with sediment. A related                      AIR LOCK CAP WITH CHECK VALVE
                                                                                                                               LIFTING TAB

feature is the cartridge “hood”. This hood maintains the                                                                            FLOAT VALVE

siphon effect by preventing air from being drawn into the
cartridge until the external water level drops below the                                                                                 OUTER MESH
                                                                              FILTER MEDIA
bottom of the hood.
                                                                                                                                               HOOD
                                                                           CENTER TUBE
Cartridges are connected to the manifold with a plastic
                                                                        SCRUBBING REGULATOR
connector. These can be either quarter turn connectors or in
the older systems, threaded connectors.                                     UNFILTERED WATER

                                                                                                                                             UNFILTERED WATER
StormFilter is also equipped with flow spreaders that trap            UNDER- DRAIN
                                                                                                                                                   FILTERED WATER
                                                                      MANIFOLD
floating debris and surface films, even during overflow
conditions. Depending on individual site characteristics,                   FILTERED
                                                                             WATER
some systems are equipped with high and/or low flow
bypasses. High flow bypasses are installed when the                                                              UNDER-DRAIN MANIFOLD
                                                                                                                                               VAULT FLOOR
                                                                                                                 CAST INTO VAULT FLOOR
calculated peak storm event generates a flow that
overcomes the overflow capacity of the system. This is              Figure 1 Filter cartridge
especially important for precast systems. Low flow bypasses
are sometimes installed to bypass continuous inflows
caused by ground water seepage, which usually do not
require treatment. All StormFilter units are designed with
an overflow. The overflow operates when the inflow rate is
greater than the infiltration capacity of the filter media.




                                                                                                        Stormwater360 Operations and maintenance                    19