LATE RFI - SCG 33114 - CD Issue 3 07.03 (2)

Page 2

Issue: Location of Stormwater Discharge Outlet

The submitted Stormwater Management Plan (33114-SW1.1, dated June 2023) proposes a stormwater structure
(headwall) that is wholly located outside the subject site and within State property, with Council as trustee. The
proposed development must be wholly contained within the subject site unless written owners’ consent is provided
to Council.

Council recognises that if the proposed location of the proposed headwall wishes to be pursued, a drainage
easement must be registered against proposed Unit 10 (subject to any plan changes) and 12 Lake MacDonald
Drive. The easement would need to be of sufficient width to accommodate the ongoing maintenance and
construction of the headwall.

Information Required
4.      Provide written owners’ consent from Council’s Property and Infrastructure departments indicating their
        support for the proposed infrastructure to be constructed and maintained within the lot, and to be
        burdened by the easement described above.

5.       Alternatively, provided a full suite of amended plans demonstrating that all stormwater structures
         (headwall) are contained entirely within the subject site. The amended plans must be prepared by a
         suitably qualified person (RPEQ – Registered Professional Engineer of Queensland) and include the
         necessary drainage easements.

Response
We have amended our Stormwater Management Plan to remove the stormwater structure external to the site.

Issue: Sustainable Building Design Code

The proposed stormwater management plan does not include 3,000 litres of rainwater storage per dwelling as
required by Performance Outcome PO2 of the Sustainable Building Design Code.

Information Required
6.      Provide sufficient detail to demonstrate that the development achieves compliance with Performance
        Outcome PO2 of the Sustainable Building Design Code. The detail must be prepared by a suitably
        qualified person (RPEQ – Registered Professional Engineer of Queensland).

Response
As raised on recent development applications, we are of the opinion the inclusion of a 3000Lt water tank per
dwelling on higher density developments results in over development of unnecessary infrastructure. We request
Noosa Council to consider the reuse of stormwater for the proposed development for external uses only.

In addition, Waterwise Queensland – “Efficient irrigation for water conservation: guideline for water efficient urban
gardens & landscape” (attached) outlines irrigation requirements across Queensland (see extracted table below).
Based on a month’s supply using the August median irrigation rates of 15mm/week/ 1m2. The required storage to
service all communal landscaped areas (150m2) within the development would require approximately 9 kL of
stored water. Therefore we consider the proposal for 14kL adequate for the development.




SCG Consulting Engineers                             Page 2 of 4                                    SCG Ref:33114(L1)

Page 3

Issue: Service Connections to Units 8-10

The proposed Reconfiguring a Lot application proposes to subdivide by Community Title Scheme as shown in
Black Wood’s Property Plan (DA.05, Rev. A). Insufficient information has been provided demonstrating that
proposed Units 8-10 are capable of being serviced by reticulated sewer due to the gradient of the site as required
by Performance Outcome PO12(e) of the Reconfiguring a Lot Code.

Information Required
7.      Provide additional detail demonstrating how proposed Units 8-10 will be serviced by reticulated sewerage.
        The additional detail must be prepared by a suitably qualified person (RPEQ – Registered Professional
        Engineer of Queensland).

Response
All sewer reticulation is under the authority of Unitywater. The proposed lower units will be pumped to a new
sewer connection in accordance with a Unitywater Connection Application.

Issue: Stormwater Quality Treatment

The subject site is approximately 2,028m2 in area and proposes to increase the total impervious area from ~5%
to ~70%. While the area does not trigger assessment with the stormwater quality design objectives (>2,500m2),
the site drains into a High Ecological Value site. Council is concerned that stormwater runoff may not be
adequately treated to maximise the removal of nutrients as required by Performance Outcome PO6 of the Water
Quality and Drainage Code.

Section 4.6 of Pivotal Perspective’s Planning Report proposes a bioretention basin in the south-western corner of
the site. A bioretention basin has not been proposed as part of SCG Consulting’s Stormwater Management Plan
(33114-SW1.1, Rev. A).




SCG Consulting Engineers                            Page 3 of 4                                  SCG Ref:33114(L1)

Page 4

Information Required
8.      Provide additional information demonstrating that the proposed development has been designed to
        protect receiving waters by means of ensuring stormwater runoff is treated to achieve maximum removal
        of nutrients. The additional information must be prepared by a suitably qualified person (RPEQ –
        Registered Professional Engineer of Queensland) and include, but not be limited to:

8.1.     demonstrate compliance with Performance Outcome PO6 of the Water Quality and Drainage Code; and

8.2.     demonstrate stormwater runoff is suitably treated to achieve a:
         •     60% reduction in total phosphorous; and
         •     45% reduction in total nitrogen.

9.       Clarify if a bioretention basin is to be constructed as part of the proposed development.

Response
The editors note on PO6 of Noosa Council’s Water Quality and Drainage Code notes “Areas identified on the
State Planning Policy (SPP) Interactive Mapping System”. The SPP Mapping System does not identify the site is
within a high ecological value waterway area and therefore stormwater quality treatment is not a requirement.

Following discussions with Council’s Engineer Mark Lewis, it was agreed that as per the State Planning Policy
Mapping, the site is not mapped in a high ecological value waters area. However even though the site is less than
the trigger value of 2500m2 as mentioned above, Council still require the stormwater quality targets mentioned in
item 8.2 of the information request.

We have revised our Stormwater Management Plan to include an onsite bio-retention basin to meet the
stormwater quality targets outlined in this information request.

If you require any further information, please do not hesitate to contact our office.

Yours faithfully




TOM HARRINGTON – RPEQ 27698
For and on behalf of
SCG CONSULTING ENGINEERS


Enc      SCG Drawings Numbers: 33114 – CS, OW1.1, OW2.1, OW3.1, OW4.1.B, OW4.2.B, OW4.3, OW5.1,
         SW1.1.B, SW1.2.A, SW1.3.A

         33114 SWMP.RevA




SCG Consulting Engineers                              Page 4 of 4                                    SCG Ref:33114(L1)