Reference Document - MCU12/0133.04

                                                                                                                                                                                             Page 5 of 5
Noosa FLC Extension to Existing Gymnasium and Additional Pavements
19 February 2025                                                                                                                                                             Ref. No. 2025.0108




                         Figure 2           Comparison of Runoff Volumes and Pollutant Loads

Table 4        Comparison of runoff volumes and pollutant loads
                                        EXISTING


                                                         DEVELOPMENT
                                                         COMMERCIAL
                                                         CONVENTIONAL


                                                                              PRACTICE* BIORETENTION
                                                                              COMMERCIAL WITH BEST
                                                                              CONVENTIONAL


                                                                                                             NOOSA FLEXI SCHOOL

                                                                                                                                  TANKS
                                                                                                                                  NOOSA FLEXI SCHOOL WITH


                                                                                                                                                                  TANKS + INFILTRATION
                                                                                                                                                                  NOOSA FLEXI SCHOOL WITH

                                                                                                                                                                                            +ADDITIONAL HARDSTAND
                                                                                                                                                                                            TANKS + INFILTRATION
                                                                                                                                                                                            NOOSA FLEXI SCHOOL WITH
 Flow (ML/yr)                    2.9               7.8                  7.6                            4.6                        3.9                       2.0                             2.9
 Total Suspended Solids          160               1300                 270                            330                        300                       150                             228
 (kg/yr)
 Total Phosphorus (kg/yr)        0.19              3.0                  1.2                            0.8                        0.65                      0.22                            0.27
 Total Nitrogen (kg/yr)          2.1               25                   14                             7.3                        5.5                       1.9                             2.5
* sized to reduce pollutant loads by 80% (TSS) 60% (TP) and 45% (TN)

In summary, the mitigated pollutant loads are close to existing level and well below a conventional ‘best-
practice’ approach.
Conclusion
The proposed works are consistent with the original Stormwater Management Plan submitted for
MUC12/0133. Additionally, the erosion hazard assessment has been classified as ‘low risk,’ indicating
minimal environmental impact. The proposed works completed to date and proposed as part of this current
application result in pollutant loads in keeping with the optimum results modelled in the original Stormwater
Report and a significant improvement over more conventional approach.


Yours faithfully,

Vancy Li
Civil and Water Engineer
BLIGH TANNER PTY LTD