Attachment 3 - Additional Information Barlow Shelley

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Figure Error! No text of specified style in document..1 - Water Surface Level at upstream end of subject
                                               site (from FHAR)




           Figure A - Water Surface Level at upstream end of subject site (full cross section)




1443-03 – Mitti Street, Noosa Heads                                                                    2
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Only detail for the subject site was included within the FHAR although modelling of the
entire catchment area and flow cross section was analysed. This was clearly conveyed
within the report, as noted above, and the additional full width cross section in Figure A
above shows that approximately 30% of the flow passes through the site west of the
new residence and the remaining 70% bypasses the site within the Noosa National Park
east of the new residence.


Item 2
The modelling makes no allowance for fence blockages and appears to be too
localised to provide meaningful results. While I have not inspected the site, aerial
imagery shows that a tennis court is situated immediately downstream. Given the
bushland catchment, there is a high potential for a chain wire fence to become
highly blocked with debris and this will increase flood levels through the site.

We acknowledge that the report only addresses the subject site and is not intended to
be a model of the full extent of flow path upstream and downstream of the site. From
Council’s Information Request dated 8 May 2018, information was only required to
demonstrate that the proposed drainage easement was of sufficient width/area to
encompass the 1% AEP stormwater flows. The submitted FHAR addresses this matter.

Furthermore, Section 7.2.2 of the report states – “It was found that the existing
residence is provided at least 580mm freeboard from the current calculated peak water
surface level (14.220m AHD), being 280mm higher than the required 300mm freeboard
in accordance with the latest Noosa Plan”.

Any local increases in flow depth due to debris build-up against the downstream tennis
court fence will not be significant enough to affect the existing residence as the floor
level is approx. 800mm above the 1% AEP at the downstream face and 580mm above
at the upstream face which provides an adequate factor of safety and complies with
Council’s codes and policies.


Item 3
No comments have been provided in regards to the flood resilience of the
dwelling. It is situated within a natural bushland flow path and it will be subject to
flooding from time to time (certainly below floor level). It would need to be
demonstrated that the house is resilient to flooding and given consideration to
the high levels of natural debris that is likely to be mobilised during a large flood.

We confirm that Barlow Shelley Consulting Engineers were the structural engineers for
the new eastern portion of the residence which was a known fact to Council. The
opening paragraph in the FHAR dated June 2018 states – “Barlow Shelley Consulting
Engineers Pty Ltd has been commissioned to undertake a Flood Hazard Assessment
Report (FHAR) for the existing residence at 20 Mitti Street, Noosa Heads. This report
has been prepared as an addendum above and over the previous overland flow review
undertaken by Barlow Shelley Consulting Engineers dated 3 August 2016.”



1443-03 – Mitti Street, Noosa Heads                                                        3
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As the structural engineers we confirm that the residence was designed to suit the suit
conditions and accommodates the flows notated in both our earlier report from August
2016 and the latter FHAR dated June 2018.


Item 4
Flood hazard risk associated with the proposed access should be assessed in
more detail and account for full catchment flows and debris.

As demonstrated above and noted throughout the FHAR, the modelling already
addresses the full catchment and provides sufficient detail for the subject development
application, particularly considering that the residence is existing and has been designed,
certified, approved and built to suit the site conditions.


We trust the above information and comments are suitable to assist you with finalising
this development application with Council. Should you require anything further, please
don’t hesitate to contact the undersigned.


Yours faithfully




TONY SHELLEY – Director
BEng ADCE RPEQ MIEAust
For and on behalf of:
BARLOW SHELLEY CONSULTING ENGINEERS PTY LTD
Encl:    Email from Noosa Shire Council (27 June 2018)




1443-03 – Mitti Street, Noosa Heads                                                       4
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From: Kerri Coyle <[email protected]>
Sent: Wednesday, June 27, 2018 6:07 PM
To: [email protected]
Cc: Peter Loxton
Subject: FW: RAL18/0009 - 20 Mitti Street

HI Nadine,

I refer to your email below and note your advice re stopping the current period. I have provided
some comments in red against your questions below.

regards

Kerri Coyle
Manager, Development Assessment I Noosa Council

Phone:       07 5329 6240
Email:    [email protected]
Website: www.noosa.qld.gov.au
Location: Level 2, 9 Pelican Street, Tewantin
Mail:     PO Box 141 Tewantin Qld 4565
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From: Nadine Gorton <[email protected]>
Sent: Thursday, 28 June 2018 9:37 AM
To: Kerri Coyle <[email protected]>
Cc: Peter Loxton <[email protected]>
Subject: RE: RAL18/0009 - 20 Mitti Street

Morning Kerri,
Please find attached a Notice about stopping the current period.

My client has also requested that you please provide the following to enable us to better understand
Councils position and facilitate future discussions:

    •     a copy of the hydraulic consultant’s report that was the basis for Councils change in
          position from the initial pre lodgement meeting;

I confirm my previous advice to you that Council officers did discuss the stormwater drainage path at
the prelodgement meeting and at the time had very little understanding of the extent of the
overland drainage flow through the site. It was not until the flood hazard assessment report by Tony
Shelly was lodged with Council in response to Council’s information request that showed the extent
of the flooding that occurs through the site.

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Council’s hydrology consultant simply undertook a peer review of Tony Shelly’s report and
confirmed that the flooding situation may actually be worse than identified by Tony Shelly’s
report. Council’s hydrology consultant provided the following comments in this regard:
     1. The flood report suggests that only 30% of the total catchment flow will drain through the
         site but there is no detail of how this has been determined. A review of the LiDAR ground
         level DEM of the area suggests most, if not all, of the total catchment runoff is likely to
         drain through the site.
     2. The modelling makes no allowance for fence blockages and appears to be too localised to
         provide meaningful results. While I have not inspected the site, aerial imagery shows that a
         tennis court is situated immediately downstream. Given the bushland catchment, there is a
         high potential for a chain wire fence to become highly blocked with debris and this will
         increase flood levels through the site.
     3. No comments have been provided in regards to the flood resilience of the dwelling. It is
         situated within a natural bushland flow path and it will be subject to flooding from time to
         time (certainly below floor level). It would need to be demonstrated that the house is
         resilient to flooding and given consideration to the high levels of natural debris that is likely
         to be mobilised during a large flood.
     4. Flood hazard risk associated with the proposed access should be assessed in more detail
         and account for full catchment flows and debris.
    • Confirmation of the sections of the planning scheme and policies that the proposal conflicts
         with.

The proposal is contrary to the Noosa Plan’s Noosa Heads Locality Code and Reconfiguring a Lot
Code as the proposed lots (lot 1) are not suitable for their intended use; do not contain house site
areas 100% above the 1%AEP flood level; will not maintain the safety of people and will not achieve
a high level of residential amenity given the overland drainage path that traverses the site. The
proposed reconfiguring a lot will ultimately place more people within an area which has a clear risk
of flooding compromising people’s safety. This would be particularly so where future residents are
unaware of the significance of the proposed drainage easement.


Thank you for your assistance.


Nadine Gorton
Senior Town Planner
martoo consulting pty ltd




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