12936 Information Request - 125 Myall Street

                                                                                     SDA-0714-012936




Item Information requested
Stormwater
1.    The proposed development is significantly increasing the impervious area of the site
      which is currently undeveloped to total site coverage of approximately 67 per cent.
      The submitted stormwater management report has briefly outlined the conceptual
      stormwater management strategy proposed to the extent of the detention required.
      However, detailed calculations are required to be supplied with the report.

          The applicant is requested to provide a stormwater report (quality and quantity) which
          assesses the potential stormwater impacts on the state controlled road networks as a
          result of the proposed development and recommends appropriate mitigation
          measures. Specifically, additional information to the currently provided stormwater
          report is required regarding the proposed method for discharging detained stormwater.

          The stormwater management plan must:
             a) Be certified by a Registered Professional Engineer of Queensland
             b) Be prepared in accordance with the Department of Transport and Main Roads’
                 Road Drainage Manual which can be accessed at
                 http://www.tmr.qld.gov.au/Business-industry/Technical-standards-
                 publications/Road-drainage-manual.aspx and with consideration given to the
                 Queensland urban Drainage manual 2013 available at
                 http://www.dews.qld.gov.au/water-supply-regulations/urban-drainage and the
                 Environmental Protection Act 1994 and Environmental Protection (Water)
                 Policy 2009 which are available at www.legislation.qld.gov.au.
             c) Demonstrate that the management of stormwater (quantity and quality) post
                 development can achieve a no worsening impact (on the predevelopment
                 condition) in accordance with the design criteria in the Department of Transport
                 and Main Roads’ Road Drainage Manual.
                 Stormwater management for the proposed development must ensure no
                 worsening or actionable nuisance to the state controlled road network caused
                 by peak discharges, flood levels, frequency/duration of flooding, flow velocities,
                 water quality, sedimentation, and scour effects.
             d) Incorporate appropriate hydraulic and hydrological analysis demonstrating:
                    design flood peak discharges for the site and surrounding area which
                        exist prior to the development for all flood and stormwater events up to a
                        1% Annual Exeedance Probability (AEP) (equivalent to 1/100 year
                        Average Recurrence Interval (ARI)). This should include at least the
                        following flood and stormwater events: 50%, 20%, 10%, 5%, 2% and 1%
                        AEP (equivalent to 2, 5, 10, 20, 50 and 100 year ARI events); and
                    design flood peak discharges for the site and surrounding area after the
                        development has occurred for all flood and stormwater events up to a
                        1% Annual Exeedance Probability (AEP) (equivalent to 1/100 year
                        Average Recurrence Interval (ARI)). This should include at least the
                        following flood and stormwater events: 50, 20, 10%, 5%, 2% and 1%
                        AEP (equivalent to 2, 5, 10, 20, 50 and 100 year ARI events).




Department of State Development, Infrastructure and Planning                         Page 2