Reference Documents - MCU23 0070

          INTRODUCTION
JFP Urban Consultants Pty Ltd has been commissioned by Cambooya Pty Ltd to compile this Site Based
Stormwater Management Plan (SBSMP) for the proposed development at 36 & 38 Duke Street,
Sunshine Beach (‘the site’). Noosa Council Application Number is MCU23/0070.

The site currently contains a restaurant located fronting Duke Street. It is understood that the proposal
is for a mixed-use development comprising the existing tenancy fronting Duke Street and five
residential apartments developed above. Refer to Appendix A for the survey of the existing site and for
the proposed development plans.

Revision B has been updated to address Stormwater Drainage issues (item 13) raised in the
Information Request dated 14th June 2023. Refer to Section 1.2 for summary responses.


1.1       OBJECTIVE & SCOPE
The design objectives for this report are:
     Nominate the lawful point of discharge.
     Ensure post-development peak flow rates are mitigated back to the pre-development peak flow
      rates via onsite detention.
     Confirm if the Water Quality Objectives (WQOs) in accordance with the State Planning Policy
      (2017) is applicable for the site.

The scope of investigations undertaken for this report is as follows:
     Nominate lawful point of discharge.
     Undertake hydrological and hydraulic analysis for the site using the XP-STORM 1D. This analysis
      includes the sizing of onsite detention to achieve peak flow mitigation.
     Provide commentary regarding possible performance-based stormwater quality management
      strategies for the operational phase of the development.

Based on the outcomes of the above investigations, this report provides recommendations, including
concept drawings for stormwater management. These recommendations should be incorporated into
future detailed design and subsequent construction documentation.


1.2       INFORMATION REQUEST ITEMS
Issue – Stormwater Drainage
The submitted documentation does not include sufficient information for Council to assess how
stormwater generated by the development will be controlled, collected, and discharged.
 It is unclear what the proposed structure downstream from the proposed detention tank is and
    how it will integrate into the proposed drainage system (indicated by a blue circle).
 It is unclear how the proposed detention tank overflows during events up to, and including, a 1%
    AEP event (volume, discharge rate).
 It is unclear how the infiltration outlet of the detention tank will operate. Given the large
    catchment area of the detention tank, Council is concerned the soil may become oversaturated
    and the filtration rate of the soil will reduce which may adversely affect the overall drainage
    system and the structural elements of the development.


SITE BASED STORMWATER MANAGEMENT PLAN – Revision B                        36 & 38 DUKE STREET, SUNSHINE BEACH
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