Reference Documents - MCU23 0070

4.2      OPERATIONAL PHASE STORMWATER QUALITY MANAGEMENT
The development footprint is 486m² which is less than 2,500m². Therefore, the site does not trigger
compliance with the State Planning Policy (2017) for stormwater quality management and meeting the
required Water Quality Objectives (WQOs). The development is also not discharging into ‘High
Ecological Value’ waters. On that basis, no conventional stormwater improvement devices such as
bioretention are proposed and MUSIC modelling has not been undertaken for the site.

While no active stormwater treatment measures such as bioretention is proposed, the site will have
some passive stormwater quality treatment measures. For instance, most of the site is covered by the
building footprint and most of the building runoff is directed into a detention tank. Most of the gross
pollutants such as tree leaves and visible rubbish will be captured in the roof gutters. Smaller gross
pollutants and Suspended Solids that travel through the roof drainage system will enter the detention
tank where runoff will pond for a period of time allowing the pollutants to settle into the bottom of
the bank. Periodic maintenance of the roof drainage system and the detention tank will ensure most
of the gross pollutants and Suspended Solids are captured within the site prior to discharging into the
downstream drainage network.

The landscaping proposed within the site will also provide water quality benefit to runoff that is
directed to them. The vegetation will capture primary pollutants and the soil underneath will provide
some level of nutrient treatment.


4.3      WATERWAY STABILITY MANAGEMENT
The waterway stability management in accordance with the State Planning Policy (2017) is not
applicable for this site, as the site flows are connected to an urban underground drainage network
which then discharges into tidal waters.




SITE BASED STORMWATER MANAGEMENT PLAN – Revision B                       36 & 38 DUKE STREET, SUNSHINE BEACH
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