H - Revised Integrated Water Management Plan by Cardno (inc MUSIC file) (13.09.19)

3.2 Strataflow Configurations
A number of standard configurations have been detailed to aid in implantation of the design solution. These are described
below. A decision tree, provided in Appendix A, assists the designer to choose the right configuration for the appropriate
application (dependent on project objectives). The drawings located in Appendix B illustrate the standard configurations.


   WSUD Strataflow Tree Pit
  • Street tree pit modified to incorporate a bioretention function. This system provides stormwater treatment as
    well as passive watering for the tree.


   StrataflowRaingarden
  • A vegetated bioretention system or ‘raingarden’ incorporating a tree in addition to smaller shrubs and
     groundcovers.
  • This system provides a greater level of stormwater treatment due to it’s footprint, and provides passive
     watering for the tree and vegetation within the garden bed.


   StrataflowTree Pit with Permeable Pavement Surround
  • Street tree pit incorporating a permeable pavement surround.
  • Permeable pavement encourages infiltration of stormwater and can facilitate passive watering for the tree.


   StrataflowTree Pit configured for passive watering
  • Street tree pit incorporating an inlet for stormwater and detention storage.
  • This system provides passive watering for the tree and may enable capture of stormwater pollution.


   StrataflowTank for Detention or Retention
  • Underground modular and trafficable storage system that can be configured for detention, retention and/or
     infiltration of stormwater.
  • Tanks can be linked to tree pit systems.




3.3 Design Considerations
The following design considerations should be accounted for prior to undertaking the functional design of a
WSUD Tree Pit system.

    3.3.2 Siting the System
    A typical street tree is usually confined by impervious pavements and relies on a catchment of a few square metres for
    passive watering. In this typical scenario a street tree will seldom receive a sufficient supply of water from stormwater
    runoff and would be reliant on active watering to facilitate growth and maintain tree health.
    Understanding the characteristics of the stormwater catchment draining to a street tree or raingarden is important for
    determining the feasibility and opportunities for WSUD. During the initial feasibility assessment, catchments should be
    assessed and the extents of directly connected impervious area draining to the tree system delineated.
    An understanding of stormwater catchments is critical for determining the following;
      • Feasibility of passively watered tree systems;
      • The amount of water that is generated by the site and that can be delivered to the tree for passive watering and
        stormwater treatment;
      • The optimal tree spacing, and
      • The pollution retention potential of WSUD systems.




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