Attachment C - Engineering Technical Note · 132008.1128.02

                                                               SUNRISE BEACH RETIREMENT AND AGED CARE DEVELOPMENT




                                                                                                                          CONTINUED



        Achieve appropriate interface with surrounding levels
        As far as practical, achieving grades of 1:20 (max) in paths of travel (roads and paths)
        As far as practical, minimise retaining wall extents and heights
Drawing 18-001942-4000-SK002 and 18-001942-5000-SK001 have been prepared to show concept bulk earthworks levels
proposed for the RL site and RAC sites (respectively). These drawings are attached to this memo for reference.
Internal Road Network
The site will be serviced by a series of low order access streets throughout. The design intent for the road network is described
as follows:
        Provide a safe, legible and traversable internal road network
        Achieve road grades suitable for use for the intended end user/s
        Constructed from concrete to minimise long term maintenance
        Ensure the Road geometry is such that a 12.5m WCV can traverse the site to service rubbish bins. Refer to drawings
         18-001942-4000-SK005 and 18-001942-5000-SK004 for vehicle swept paths.

The proposed minor change results in an optimised road layout that reduces the extent of pavement, when compared to the
existing DA. The proposed road layout is shown on drawings 18-001942-4000-SK004.
The RL site will be serviced by two accesses from Grasstree Crt. The eastern most access will serve as the main entrance to
the RL site as it forms the entrance road, which will provide the “front door” access to the community facilities. A second western
access is proposed to provide access to the apartment buildings along the western boundary of the site.
The RAC site will be serviced by three accesses from Grasstree Crt. The main entrance will be located at the eastern end of the
site and will serve as the main drop off/pick up point, as well as providing access to the service yard. The location of the main
driveway access is driven primarily by the WCV service manoeuvre into/out of the service yard and bin store, as shown on
drawing 18-001942-5000-SK004.
Two accesses (one entrance and one exit) will be located further the west providing access to the proposed visitor carpark.
The proposed driveways are consistent with the existing Development Approval. All driveway crossovers will be designed in
accordance with IPWEAQ standard drawings and Council’s PSP.
STORMWATER MANAGEMENT
The following assessment has been undertaken to identify and provide guidance on minor changes relevant to stormwater and
water sensitive urban design (WSUD). Minor changes proposed from the currently approved Plans and Documents listed in the
Amended Change to an Existing Approval notice dated 14 November 2017 include:
        Stormwater detention storage for downstream flood mitigation has been deleted from the design in accordance with
         Condition 63.1 of the Decision Notice.
        The southern (retirement living) bioretention basin size and location has been amended from that currently shown on
         RPS drawing 132938-01D. Additionally, a separate infiltration basin has been added in accordance with the Girraween
         Stormwater Management Plan. Drawing 18-001942-1000-SK008 is attached identifying these changes.
        The northern (Residential Aged Care) bioretention basin size and location has been amended to use a proprietary
         cartridge system for the treatment of water quality. Additionally, a separate infiltration basin has been added in
         accordance with the Girraween Stormwater Management Plan. Drawing 18-001942-1000-SK009 is attached
         identifying these changes. Additional discussion surrounding the use of a cartridge system is provided below.

It is expected that only minor changes (if at all) are required to allow the use of proprietary cartridge systems over the RAC site.
Condition 63 of the current Decision Notice requires a site based Stormwater Management Plan (SMP) be provided with the
application for Operational Works. As per the condition, the SMP is required to achieve compliance with the Management
Objectives specified in Section 4 of the Girraween Stormwater Management Plan. Importantly, Section 4 only identifies the
reductions required to be achieved, it does not mandate how those reductions are achieved. The ‘model’ stormwater
management response identified in Section 5 of the report is a deemed to comply solution to achieving the Management
Objectives and is not the sole design solution allowed to be adopted. Therefore, it is believed that the adoption of a proprietary
treatment device for the management of total suspended solids, total phosphorus and total nitrogen is in accordance with the
Girraween Stormwater Management Plan.

The proposed minor changes do not impact the remaining stormwater elements onsite. A detailed Stormwater Management
Plan will be provided with the Operational Works application detailing how the remaining stormwater conditions will be met
onsite.


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