P0198-25-001_12_Gympie_Street_Tewantin_SWMP

Table 5-1 Pollutant Load Reduction

 Pollutant                            Pre-Treatment Load         Post-Treatment Residual Load    Reduction
                                            (kg/yr)                        (kg/yr)                  %

 Total Suspended Solids (TSS)                 1273.00                        50.60                 96.03%

 Total Phosphorus (TP)                           2.15                         0.24                 88.66%

 Total Nitrogen (TN)                           12.34                          4.70                 61.95%

 Gross Pollutants                              29.71                          0.00                100.00%



The results confirm that pollutant reduction targets have been achieved, exceeding the minimum thresholds
outlined in the Urban Stormwater Quality Planning Guidelines (2010):

     •    Total Suspended Solids (TSS) – 80% reduction

     •    Total Phosphorus (TP) – 60% reduction

     •     Total Nitrogen (TN) – 45% reduction

     •     Gross Pollutants – 90% reduction


These outcomes demonstrate that the stormwater discharges from the site will not degrade receiving waterways
and that the proposed treatment system achieves full compliance with best-practice stormwater quality
objectives.



     4.   Regulatory Compliance and Sustainable Outcomes

The proposed stormwater management measures align with QUDM, Noosa Shire Council requirements, and
Water by Design best-practice principles, ensuring:

     •    No adverse flooding impacts on surrounding properties.

     •    Effective peak flow attenuation via detention basin design.

     •    Significant pollutant load reductions, safeguarding downstream water quality.

     •    A hydraulically neutral post-development condition.

The proposed stormwater strategy will support the development application by demonstrating that the site’s
stormwater impacts have been adequately mitigated. Further detailed design and operational planning will
ensure successful implementation, maintaining a balance between development objectives and environmental
sustainability.




 12 GYMPIE STREET, TEWANTIN
 Stormwater Management Plan                                                                                 21
 Client Reference: P0198-25-001          4 November 2025
 Prepared for Novato Group