RFI - P0478-26-001_45_Maple_Street_Cooroy_SWMP

5           Stormwater Quality
5.1         Introduction

A stormwater quality assessment has been undertaken for the proposed development in accordance with the
Urban Stormwater Quality Planning Guidelines (2010) and the Water by Design framework. The objective of this
assessment is to demonstrate compliance with pollutant load reduction targets through the integration of an
engineered treatment solution within the stormwater detention infrastructure.

Rather than a conventional bioretention system, the proposed development will adopt a proprietary cartridge-
based treatment device, such as the Atlan Filter or a similar approved product, housed within the proposed on-
site detention (OSD) tank. This approach provides a compact and highly efficient solution to stormwater pollutant
removal, suited to constrained development footprints and high-performance treatment requirements.


5.2         Proposed Treatment System

The proposed stormwater quality solution involves the integration of a cartridge-based filtration system (e.g. Atlan
Filter or similar proprietary system) within the base of the OSD tank. The filter unit will be positioned to intercept
and treat stormwater prior to discharge to the lawful point. The filter unit provides multiple treatment stages
including sedimentation, filtration, and nutrient removal within a self-contained cartridge unit, and is designed for
high-flow bypass scenarios.

The final configuration, cartridge sizing, and number of filter units will be refined during the Operational Works
design phase in consultation with Atlan or an equivalent proprietary system supplier.


5.3         Expected Pollutant Reduction Performance

Based on verified performance data from the Atlan Filter system (refer to https://atlanstormwater.com/au/atlan-
filter), the treatment device has been demonstrated to achieve the following pollutant load reductions under typical
urban runoff conditions:
Table 5-1 Pollutant Reduction Targets

 Parameter                                                  Expected Reduction (%)

 Total Suspended Solids (TSS)                               ≥ 90%

 Total Phosphorus (TP)                                      ≥ 65%

 Total Nitrogen (TN)                                        ≥ 45%

 Gross Pollutants                                           ≥ 99%



These results align with or exceed the Water by Design pollutant reduction targets for Southeast Queensland.




 45 MAPLE STREET, COOROY
                                         24 June 2026                                                 P a g e | 16
 Stormwater Management Plan
 Client Reference: P0478-26-001
 Prepared for Myall Rise PTY LTD