Request for Further Information - 010.2007.00002398.001 [As Published] · 132007.2398

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4.    The Concept Stormwater Management Plan for Cooroy Retirement Village by Brown
      Consulting dated June 2008 (the SMP) indicates that the proposed stormwater treatment train
      will not remove sufficient amounts of pollutants in order to achieve the long term objectives
      required by the Environmental Protection (Water) Policy 1997 Mary River Environmental
      Values and Water Quality Objectives Basin No. 138 including all tributaries of the Mary River
      (EPP WQO). In addition, Table 6.8 of the SMP indicates that nitrogen loads discharged from
      the site will increase as a result of the development. Council will not support an application
      that will increase pollutant loads (i.e. Total Nitrogen) from the existing scenario and not meet
      the EPPWQO of the area. In this respect, provide a revised storm water management strategy
      or propose measures to reduce the pollutant loads, with particular reference to Nitrogen to
      demonstrate an improvement in the quality of stormwater discharges in comparison to the
      existing situation.
5.    The Healthy Waterways Water Sensitive Urban Design Technical Design Guidelines for South
      East Queensland (the guidelines) recommend that bioretention basins constitute 2% of the
      catchment area to ensure effective pollutant removal. Preliminary calculations based on data
      presented indicate that bioretention basins constitute less than 2% of the catchment area.
      Please reconsider increasing the treatment area to comply with the guidelines.
6.    Demonstrate how the proposed staging of development will affect the overall water balance
      requirements and performance of the Water Quality Control Ponds.
7.    In order to justify the overall increased runoff, Section 7.3.2 of the SMP indicates that:
              the modeled equivalent occupancy rates are low and may underestimate the demand
              on rainwater use; and
              overflow from rainwater tanks is required to maintain water levels in the Water Quality
              Control Ponds for submerged plant species and continuous turnover of the water bodies
              for stormwater quality treatment.
      Demonstrate to Council that in the event rainwater use demand increases, as is inferred will
      occur in Section 7.3.2 of the SMP, a reduction in the modeled overflow from rainwater tanks
      will not compromise the performance of the Water Quality Control Ponds.
8.    Section 8 of the SMP states that
               “the modelled increase in runoff will be within acceptable limits and natural
              yearly variability”.
      Please provide further comment regarding the source of the qualitative values for ‘acceptable
      limits and natural variability’ that the abovementioned statement refers to. Also provide
      ecologist comment on the impact of increased water velocities to the receiving environment.
      Particular reference is required in relation to the impact of increased flows on protected
      species within downstream essential habitat areas.
9.    The SMP demonstrates that peak flows will be reduced to below existing ARI’s. Ecologist
      comment is required in relation to:
      9.1     the relationship between the lifecycle of downstream populations of protected species
              and the existing peak flow levels; and
      9.2     the impact any proposed changes to the hydrological variability will cause to
              downstream populations of protected species and their lifecycle – i.e. breeding patterns.
Engineering
10.   Ensure that grease and oil arrestors are incorporated into all car parking stormwater drainage
      designs.
11.   Provide information regarding the relevance of the proposed sediment and erosion control
      plan in response to the soil types on site.
12.    The Erosion and Sediment Control Plan refers to allotments and parkland. Given that the
      development does not involve subdivisions to create allotments or parkland Council is
      concerned the Sediment and Erosion Control Plan is generic and not site specific. Please
      provide comment in relation to this concern.