2015-01-12 General Committee Agenda

GENERAL COMMITTEE MEETING AGENDA                                                12 January 2015


         Bioretention Basins
   31.   During construction and establishment of the bioretention devices, the supervising
         RPEQ must certify that the device was constructed in accordance with Construction
         and Establishment Guidelines: Swales, Bioretention Systems and Wetlands (Water
         by Design, 2009) and that the forms contained in section 3.15 of the guidelines,
         including the associated supporting information and data, are completed. These
         forms and certification must be submitted to council prior to commencement of use.
   32.   A construction hold point with a council delegate must be established once the
         contributing catchment is effectively stabilised with at least 80% groundcover, and
         bioretention device underdrainage pipe work is installed.
   33.   At the time of the construction holdpoint, a sample of the drainage layer, transition
         layer, and filtration media materials must be stockpiled onsite accompanied by
         laboratory results that demonstrate that the media complies with the specifications
         contained in the latest version of the Guidelines for Soil Filter Media in Bioretention
         Systems (Facility for Advancing Water Biofiltration) and that the minimum hydraulic
         conductivity of 180mm/hr or as specified on the approved engineering plans will be
         achieved.
   34.   The bioretention underdrains and cleanout points must be provided as uPVC pipe
         generally as shown on IPWEAQ Standard DrawingWSUD-003.
   35.   Where the bioretention filter media interfaces with stormwater pits and retaining walls,
         nonwoven geotextile must be fixed to the pit/retaining wall and extend 300mm out
         into the filter media generally in accordance with IPWEAQ Standard Drawing WSUD-
         001 to prevent tunnelling of water along the interface.
   36.   All overflow pits within the bioretention devices must be provided with letterbox type
         grates in accordance with IPWEAQ Standard Drawing WSUD-001.
   37.   A minimum of five of the following species must be planted in the bioretention basin
         surface at a minimum density of 8 plants/m2:
         a.    Carex appressa.
         b.    Carex fascicularis.Ficinia nodosa.
         c.    Juncus usitatis.
         d.    Lomandra longifolia.
         e.    Ghania sieberiana.
   38.   Where landscaping/garden beds are proposed adjacent to the bioretention basin, a
         900mm deep root barrier must be installed to the interface between the
         landscape/garden area and the bioretention basin.
   39.   Following Construction - Prior to issuing of a final compliance certificate, council must
         receive evidence that the results for the in situ hydraulic conductivity testing
         conducted in accordance with PRACTICE NOTE 1: In Situ Measurement of Hydraulic
         Conductivity (FAWB, April 2008) for the bioretention filter media achieve the design
         criteria.
   40.   Maintenance - All stormwater quality treatment devices must be maintained in
         accordance with the Maintaining Vegetated Stormwater Assets, Version 1 (Water by
         Design, 2009). Records of all maintenance activities undertaken must be kept and
         made available to council upon request.




                                                                                 Page 58 of 147