Final Engineering services report _62 Lake Macdonald Drive · OPW25/0057

The stormwater runoff from the proposed stormwater treatment catchments will be treated by one (1) bioretention
basin prior to discharge into the existing stormwater drainage network. Table 4 outlines bioretention basin details for
the proposed stormwater treatment train for the Catchment ‘A’.
Table 4: Proposed Bioretention Basin Design for Development Sub-Catchments
                                                                                   Filter Media         Extended
                                                 Surface Area   Filter Area
      Catchment          Sub-Catchment                                                 Depth         Detention Depth
                                                     (m²)           (m²)
                                                                                        (m)                (m)
           A                    N/A                    180          180                 0.7                0.3

3.9.4     Music Modelling

MUSIC modelling of the proposed catchments was performed to ensure the nominated treatment strategy achieves
the required pollutant reduction objectives. The target reductions in stormwater pollutants are based on comparing
an unmitigated scenario with no treatment on-site and the mitigated scenario with stormwater treatment measures
incorporated onto the site. Table 5 provides the modelling results for the treated catchment ‘A’. The MUSIC modelling
demonstrates that compliance has been met or exceeded for the objectives required by the Noosa Plan (2020) and
the SPP (2017) for TSS, TP, TN, and GP.
Table 5: Catchment A MUSIC Model Results
                                                                Reduction           Target
                          Unmitigated              Mitigated
        Pollutant                                               Achieved           Reduction          Compliance
                            (kg/yr)                 (kg/yr)
                                                                   (%)                (%)
          TSS                  2950                   576         80.5                 80                   Y
          TP                    6.3                   1.68        73.4                 60                   Y
          TN                   42.2                   20.1        52.5                 45                   Y
          GP                   467                      0          100                 90                   Y

3.10      Water and Sewerage

A sewer and water connection to the existing Unitywater networks will be provided for each of the proposed
allotments. A network analysis has been prepared for the proposed development. Refer to the “Water Supply and
Sewer Network Analysis” report by Covey Associates for further details.

4.0       CONCLUSION
The development of the 62 Lake Macdonald Drive site is proposed to provide 3 Community Use Lots and 1 Balance Lot
to support (if resolved by Council) the development of a maximum 130 units and future expansion of the Cooroy
Cemetery. Current Council resolution is for the development of Lot 1 for Community Housing only, no defined use has
been determined for Lot 2 or Lot 3.

The stormwater management proposal as outlined in this report achieves the water quality and treatment objectives
required under the Noosa Plan and Queensland Urban Drainage Manual 2017 (QUDM) by effectively treating
stormwater runoff where required.

A combination of underground and overland drains has been used to achieve the required stormwater quantity
outcomes for the development site, including stormwater connections for each allotment and external catchment
management.

Each allotment is provided with a sewer and water connection point to the existing Unitywater network. A water and
sewer network analysis has been prepared to support the connections, refer to the associated report.



62 Lake Macdonald Drive, Cooroy – Engineering Services Report                                                   Page 10
233467 | M24-1037Rpt – Issue A – April 2025