16-001014-02A (Ultimate SCMMP)

    System operation                                               Treatment chamber


    The HumeGard® GPT utilises the processes of physical           1.   Once diverted into the treatment chamber, the
    screening and floatation/sedimentation to separate the              flow continues underneath the internal baffle wall,
    litter and coarse sediment from stormwater runoff. It               passes through the stainless steel comb and flows
    incorporates an upper bypass chamber with a floating                over the flow controlling weir to the outlet.
    boom that diverts treatable flows into a lower treatment       2.   Pollutants with a specific gravity less than water
    chamber for settling and capturing coarse pollutants                (S.G.<1) remain floating on the water surface in the
    from the flow.                                                      storage/treatment chamber. Sediment and other
                                                                        materials heavier than water (S.G.>1) settle to the
                                                                        bottom of the chamber. The design and depth of
    Bypass chamber                                                      the chamber minimises turbulent eddy currents
                                                                        and prevents re-suspension of settled material.
    1.   Stormwater flows into the inlet (boom) area of the             The comb prevents any neutrally buoyant litter in
         bypass chamber (refer to Figure 1).                            the treatment chamber from escaping under the
    2.   During flows up to and including the design                    baffle wall.
         treatment flowrate, the angled boom directs the
         total flow into the storage/treatment chamber.
    3.   During higher flow conditions, the angled boom            Figure 1 – Operation during design flow conditions
         continues to direct all floating litter from the bypass
         chamber into the storage/treatment chamber. The
         inlet area of the bypass chamber floor is angled
         towards the treatment chamber to ensure the bed
         load sediment material continues to be directed
         into the storage chamber even when the boom
         is floating.
    4.   At peak flows, the boom remains semi-submerged
         and enables excess flow to pass underneath,
         regulating the flow into the storage/treatment
         chamber. This ensures that higher flows, which
         could otherwise scour and re-suspend previously
         trapped materials, are not forced into the storage/
         treatment chamber. The floating boom bypass
         ensures previously trapped floating materials are
         retained. Each HumeGard® GPT is designed to
         achieve an operating velocity below 0.2 m/s through
         the storage chamber to ensure the settling of coarse
         sediment and keep the comb clean.




2   HumeGard® GPT