B07056.W-01A Complete - Stormwater [As Published] · 132007.2398

Concept Stormwater Management Plan
RSL Care – Cooroy Retirement Village


6.2                Stormwater Quality Management Strategy
A treatment train of suitable Stormwater Quality Improvement Devices (SQIDs) has been proposed to mitigate
the increase of stormwater pollution loads. The locations and distribution of these devices are shown on
Drawing No.’s B07056-SK04 and SK05 in Appendix A.

The treatment devices proposed for this development have been modelled for Total Suspended Solids (TSS),
Total Phosphorous (TP), Total Nitrogen (TN) and Gross Pollutants. The treatment devices however, are not
limited to the removal of these pollutants and are expected to mitigate the other pollutants. For example, if TSS
is adequately controlled the associated heavy metals are also controlled.

The treatment train will incorporate the following devices:

(a)      Bio-Filtration Basins

Bio-filtration basins will treat stormwater runoff from external sub-catchments.

One basin will be located within the site just downstream of the northern discharge point off Cooroy Connection
Road.

The other bio-filtration system incorporates two basins and will be within the site just downstream of the southern
Cooroy Connection Road discharge point. These basins will be located in series between proposed ILU’s. Refer
to Drawing B07056-SK04 and SK05 for locations of these basins.

Stormwater discharge from the two low points on Cooroy Connection Road will be directed to the basins by
swales. These basins will treat runoff from the external sub-catchment including part of the railway corridor and
Cooroy Connection Road. Treatment of an external catchment is proposed to improve the runoff entering the
site to assist with the on-site stormwater quality treatment devices. Bio-filtration devices act to remove fine
sediment and reduce nutrient concentrations.
(b)      Water Quality Control Ponds (WQCP’s)

Two WQCP’s are proposed for the site. These WQCP’s are located as part of the proposed stormwater
detention basins at the downstream ends of the northern and southern gullies. The water bodies / ponds will
have enhanced nutrient removal by incorporating macrophyte planting areas and open water zones. They will
ensure that adequate pollutant retention is achieved before discharging offsite to adjacent properties. Low flows
that do not overtop the low level outlet structure of the detention basin will be detained temporarily in the
WQCP’s. Each WQCP will also have a permanent water storage volume. Higher volumes of greater capacity
than the temporary storage volume of each pond will enter the low level outlet structure pit of the basin.
(c)      Bio-Filtration Pods

Bio-filtration pods are proposed in two locations to treat runoff from car park surfaces. Bio-filtration devices act to
remove fine sediment and reduce nutrient concentrations.
(d)      Enviropods

Fine mesh basket for installation in gully pits such as the ‘Enviropod’ product by Stormwater360 (formerly Ingal
Environmental). These are proposed to be installed in various internal road surface inlet pits. Details of these
devices are presented in Appendix F.
(e)      Rainwater Tanks

Upon reference to Noosa Council’s Schedule 8 Map, it is found the site falls within the designated rainwater tank
area. Three underground rainwater tanks are proposed to collect roof water runoff from ILU’s and apartment
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