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

   3.3.2 System Sizing
   WSUD devices should ideally be sized to optimise treatment efficiency and to achieve a set of stormwater
   management objectives which may vary across different regions.
   Sizing of WSUD systems should be undertaken during the concept design phase. In some cases performance
   curves, and deem to comply tools can be used to approximate the size of WSUD systems to achieve stormwater
   management objectives.
   For most projects a water quality model should be developed for the project using eWater’s MUSIC software.
   MUSIC can assist with optimising the size of WSUD elements and to determine its efficiency in meeting stormwater
   management objectives for the project. Refer to Section 4.0 for more detail on modelling WSUD systems in MUSIC.
   The additional tools available to be used in conjunction with MUSIC are:
     • Strataflow Infiltration Sizing Calculator – to be used to help determine the filter area to enter into MUSIC based on
       the soil selection and the desired storm event to be treated
     • Stormwater Quantity Calculator – can be used to understand the total number of Stratacells required to treat the
       desired storm event particularly if detention is also a project objective.
   Figure 4 depicts a graphical representation of these tools with key inputs being catchment area, runoff depth or storm
   intensity and soil properties.

   3.3.3 Existing Services
   Asset location and/or service proving should be undertaken to identify any services that might constrain the site and
   impact on the feasibility of the proposed tree pit system.
   As a minimum a Dial-Before-You-Dig (DBYD) enquiry should be made and service information requested. A services
   plan should be developed to map out service conduits in the vicinity of the proposed works.
   Some services can be accommodated with ease within a Strataflow tree pit, others may require costly protection
   works to accommodate within a tree pit system. Where services may impact on a tree pit design a service proving
   contractor should be engaged to determine the alignment and depth to conduit, and the asset owner should be
   contacted to ensure that their requirements are known prior to finalising the design.




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