LATE RFI Attachment 6 - Stormwater Management Plan

    5. Maintenance
                                                                Depending on the design of the SPELBasin®, the
                                                                material captured in the Stormsack and inlet chamber
                                                                should be mostly dry.

    The SPELBasin® system requires regular, simple
    maintenance to ensure its long-term effectiveness.

    5.1 ACCESS

    The inlet chamber and Stormsack are the areas of
    the SPELBasin® that will require the most attention for
    regular maintenance. These items are likely to capture
    the highest loads of sediment and litter (organic and
    anthropogenic) and therefore will need cleaning on a
    regular basis (eg. Quarterly). Whilst these are not large
    areas, a Stormsack full of sediment and organic matter
    can be heavy, and so access to the inlet chamber
    should be provided.

    Suitable access could consist of a concrete or              FIGURE 8. SPELBASIN® INSPECTION OPENINGS
    compacted crusher dust pathway, pavers, or
    permeable paving.
                                                                5.4 SLOTTED-DRAINAGE PIPES
    5.2 INLET STRUCTURES
                                                                Filtered stormwater is captured by slotted drainage
                                                                pipes within the SPELBasin® filter media. These are
    The inlet to the SPELBasin® may be via a kerb inlet
                                                                installed within a geofabric sleeve, and protrude above
    or surface grate. Regular inspections should check
                                                                the media surface. Each end of the drainage pipes is
    that these remain clear of debris and free-flowing.
                                                                capped with an inspection fitting.
    Underground pipe inlets to the SPELBasin® should
    also be checked to ensure debris is not settling in the
                                                                Maintenance activities should ensure that sediment
    upstream pipe, and if observed, should be removed
                                                                is not collecting in the slotted pipes, and flow to the
    during the inlet chamber maintenance.
                                                                outlet is not obstructed.

                                                                If treatment flow is reduced and occlusion due to
                                                                sedimentation in the pipes is suspected, they can be
                                                                jetrodded and vacuum-cleaned at the outlet chamber.
                                                                If this breakthrough of sediment is observed in the
                                                                drainage pipes, it may be an indicator that replacement
                                                                of the filter media is required.

                                                                5.5 FILTER MEDIA HYDRAULIC CONDUCTIVITY

                                                                The proprietary filter media blend in the SPELBasin®
                                                                has a high hydraulic conductivity compared with
                                                                traditional biofilters. This allows the SPELBasin® to
                                                                treat higher flows per square metre, whilst maintaining
    FIGURE 7. SPELBASIN® KERB AND GRATED INLET
                                                                high pollutant removal rates. To ensure treatment flow
                                                                rates are maintained, annual maintenance inspections
    5.3 SEDIMENT & LITTER REMOVAL                               should check that the water level of the SPELBasin®
                                                                returns to the “standby” level after 2 hours. If the
    Removal of sediment and litter from the inlet chamber       water level remains high after more than 2 hours,
    and Stormsack may require a small vehicle and               replacement of the media may be required.
    hoist, as well as vacuum eduction to ensure optimal
    operation of the SPELBasin®. Since the inlet is a           Filter media infiltration rates (hydraulic conductivity)
    relatively small volume, a commercial wet/dry vacuum        may be tested using the FAWB methodology, or the
    may be sufficient, removing the need for large              AS1547:2000 Australian Standard Constant Head test.
    eduction trucks. The inlet coarse sediment filter is        This should be conducted in at least two locations, and
    the SPEL coalescer media cartridge. Annual removal          boreholes at two depths (150mm & 400mm).
    of the cartridge and low pressure rinse will maintain
    the treatment flow rate. The coarse sediment filter         Contact SPEL Stormwater for more details.
    cartridge should be replaced on a 10 year interval.


8        Technical Design Guidelien SPELBasin