Civil Engineering Cover Letter

25. Information Required
Demonstrate how O3 of the Water Sensitive Design Code is intended to be achieved.
Response
A rainwater tank has been included at the site as part of the proposed stormwater treatment
strategy. The SWMP includes the calculations used to determine the potential reuse on site
to enable the tank to be effectively sized. A 20,000 Litre underground rainwater tank has
been proposed.

Seqwater Third Party Advice
This letter also provides information in relation to information requested by Seqwater (ref
CE:DBF16/3997) dated 23 August 2016. Third party advice by Seqwater requested the
following information in relation to stormwater management:

Information Required
In accordance with the Seqwater Development Guidelines, development is to ensure the
stormwater is of a quality that is fit for purpose as a drinking water supply. Seqwater
recommends that the applicant demonstrate that the reduction in pollutant load calculations
can achieve the relevant Water Quality Objectives identified in the Environmental Protection
(Water) Policy 2009. It is recommended that the applicant specifically state the annual rainfall
assumptions used in the calculations. It is further recommended that any stormwater
management plan be signed off by a Registered Professional Engineer Queensland (RPEQ).

Response
In response to the Stormwater Management items requested by Seqwater we have included
the following information within the Stormwater Management Plan. The MUSIC modelling
rainfall data used to model pollutant reduction targets is from Cooroy Composite Station
1973 to 1983 as this is the most continuous dataset available. The annual rainfall for each
year has been included within the SWMP as requested. Refer to Table 3: Annual Rainfall in
the report.

The report demonstrates that the measures proposed to reach the WQOs identified in the
Environmental Protection (Water) Policy 2009. The proposed measures significantly
exceeded the required pollutant reduction targets by State Planning Policy and Noosa Shire
Council to ensure the best possible change of meeting the WQOs and prevent any potential
adverse impacts on Lake Macdonald. The daily loads estimated in MUSIC for TSS and TN
are mean values and only marginally over the WQOs due to the low concentration of the
remnant pollutants. There is no practical or reasonable way to address the remaining
concentrations. The report has been signed off by an RPEQ.

Trusting the above is to your satisfaction, and should further information be required please
contact this office.

Yours faithfully
COVEY ASSOCIATES PTY LTD



SHANE RYNNE
Senior Civil Engineer
Encl.