2020.11.30 - Response to further RFI - OPW200145

   Drawing SW24D
i) Provide a detail for how the flows in the kerb in the driveway are discharged to the bioretention basins
   Stockwell Response
   A Type B1 kerb and channel is located around the full length of the downstream perimeter of the internal fire
   access / driveway pavement. Runoff is then discharged at each end of the basins. Please refer to Barlow Shelley
   drawing 1856-SW24 E.
ii) Section F shows the pit crest as being higher than the downslope bund height, meaning no flow will
    ever get into the pit. Amend and indicate minimum setdown of pit crest from edge of pavement
   Stockwell Response
   The bund height is 50mm higher than the pit crest allowing the overflow pits to receive runoff after the 200mm
   extended detention depth. Please refer to Barlow Shelley drawing 1856-SW24 E.
   Drawings SW25 and SW26

i) Standard drawing DS-077 is intended for small, discrete systems consisting of a single tree and being
   approximately 1m2 in size and grated. Those types of systems would typically be interspersed with
   standard street tree plantings. Local examples exist in Sippy Downs Town Centre. What has been
   proposed here is a biopod system with trees in it and they are no different to the other biopod systems
   proposed as part of this application and have the same functional issues. It is suggested that DS-077 is
   of limited applicability to the current proposal and the details of the open biopod systems for these
   drawings should be fully documented as for the other systems

ii) Provide a section behind the stormwater pit showing how the biopod interfaces with the pathway. It
    appears retaining will be required. If so, identify how safety will be addressed


   Stockwell Response

   Following discussion with Council’s stormwater engineer, street tree treatment devices have been remodelled
   and redrawn as bioretention devices. For clarity, we are no longer proposing to rely on DS-077 as a standard
   detail. These have been detailed with the same or similar outcome to the bioretention devices already shown,
   except for an overflow riser pit. The “Street Tree Basins” are proposed to fill the extended detention level to
   the kerb invert level at the basin inlet at which point the runoff will bypass the basins in the kerb and channel
   to the adjacent downstream kerb inlet pits. Filter levels and adjacent surface levels have been provided for
   these treatment devices as well. Please refer to Barlow Shelley drawings 1856-SW19E - SW26E.




                                                                                                                       10
                                                                                                                        Page