RFI - Attachment E - SWMP Callaghan and Toth

                                                                                   Callaghan & Toth


1.0 SUMMARY
The key points of this investigation are as follows:

    1. Runoff from new sealed areas for access roads/driveway, car parks and landscaped
       areas around the existing Lower Mill site buildings is to be cleaned of nutrients and
       gross pollutants via the existing refurbished biobasins and existing and new grass
       swale. Treated runoff is then released to existing outlets into the adjacent Cooroy Creek.
    2. Pollutant loads from the development are to be attenuated.
    3. The flood study detailed that filling for the new carpark areas will not affect flood levels in
       the Cooroy Flood Study.
    4. The proposed carpark on Lot 7 is no longer part of the proposal, and carparking will be
       incorporated into the existing grassed area on Lot 5. This area is used informally for
       carparking and will now be improved to provide 47 carparks.


2.0 INTRODUCTION
This Stormwater Quality Management Plan (SQMP) has been prepared as part of a Material
Change of Use application to Noosa Council. This SQMP is in accordance with:
   1. Water Sensitive Design Code in the Noosa Plan, and
   2. The latest Water Sensitive Urban Design Technical Design Guidelines for South East
       Queensland, published by Health Waterways.

The proposed carparking and new access road works are located on Lot 5 SP213104 and Lot 7
SP173771 and the site is shown in Site Location Plan, Fig 1.1. The site is located at 4-8 Lower
Mill Road, Cooroy and the Cooroy Creek Bushland Reserve (Environmental Reserve 16 Lower
Mill Road, Cooroy).

This SQMP considers the new hardstand areas, including new access road/driveway, carparks,
and pathways, for the existing community uses at the Lower Mill site. The proposed new
carparks will also service the existing Library and the proposed new Hinterland Playground.

There is a total of 67 new carparks proposed in two locations at the Lower Mill site:
    22 carparks adjacent the existing buildings on Lot 5 require formalisation with some
       extension to existing asphalt or concrete; and
    47 new carparks on Lot 5 in the raised grassed area north of the buildings.

In order to receive planning approval from Noosa Council, this site must demonstrate that it
complies with Council’s Water Sensitive Design Code and that the storm water runoff will not
change the surrounding hydrology. There is an existing biobasin located on Lot 7 SP173771
which can accept the flows from the new hardstand areas for treatment. Two existing grass
swales will also treat runoff and one new grass swale will treat and convey flows to the existing
biobasin. These devices will enable the water quality objectives to be achieved.

The Model for Urban Stormwater Improvement Conceptualization (MUSIC) has been used to
assess the suitability of various treatment devices and to model existing and predicted pollution
export loads and concentrations.




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2001 Lower Mill Carpark Extension SWMP                                              July 2020