RFI - Attachment 3 - Stormwater Management Plan

          4.1.2 MUSIC modelling results
The proposed treatment train for each site can achieve the required water quality improvements as shown below in
Table 4.4 - MUSIC Modelling results for Carpenters Road Development Site.

                           Table 4.4 - MUSIC Modelling results for Carpenters Road Development Site

 Pollutant                                  Sources          Residual      Percentage        Percentage
                                                             Load          Target            Reduction

 Total Suspended Solids (kg/yr)              6798.681            968.401        85                 85.756

 Total Phosphorus (kg/yr)                     11.871               2.682        65                 82.262

 Total Nitrogen (kg/yr)                       48.305              22.186        45                  54.07

 Gross Pollutants (kg/yr)                     453.489                 0         90                   100



          4.1.3 Maintenance Requirements
Periodic maintenance and monitoring of stormwater infrastructure proposed for this development should be
carried out to ensure they are operating effectively during the post-construction phase. After the on-maintenance
period, the responsibility for these maintenance activities shall be the body corporate for the site who may appoint
a suitably qualified maintenance contractor or caretaker to undertake these activities.

The field inlet grates, pits and underground pipes shall be inspected for blockage or damage at least 6 monthly or
after significant rainfall event. Any blockages shall be cleared from the system, and damage assessed to determine
if it impacts on the function of the system or may pose a hazard that will require repair.

The bioretention areas shall be maintained following a schedule of routine inspections undertaken after every
significant rainfall event (30mm of rainfall in a 24-hour period) or on a three (3) monthly basis within the first twelve
(12) months and on a six (6) monthly basis thereafter. The inspection shall ensure the proper functioning and
condition of the bioretention area and ensure that the planting and vegetation health is suitably maintained. An
inspection checklist from the Healthy Waterways Technical Design Guidelines for Southeast Queensland has been
provided in Appendix Bioretention Garden Maintenance Checklist that provides the structure for the inspections
to be undertaken.

In addition to regular inspections, the first 4 months of establishment of the bioretention areas requires a watering
frequency of:

    i.    Week 1 - 6 - 5 times per week


   ii.    Week 6-10 – 3 times per week


  iii.    Week 11-15 – 2 times per week


After 5 months, watering frequency shall be adjusted based on the local conditions to ensure plants are
maintained in a healthy state.
The pit inserts (nominally Ecosol litter baskets with 1500um screening mesh) are required to be maintained in
accordance with all manufacturers specifications. Indicatively, routine maintenance involving minor servicing shall
initially be carried out 2 to 4 times annually, with the ongoing frequency based upon the first year’s inspections. A
higher frequency may be required depending upon the catchment size and pollutant generating characteristics of
the site’s catchments.



Project number 21020                                                                                        Page 23 of 36
File RECOR Concept Stormwater Management Report - 21020.docx, 2022-09-05
Revision 0


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