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Attachment 6 - Stormwater Management Plan and Engineering Response. · MCU23/0078
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SITE BASED STORMWATER MANAGEMENT PLAN FOR THE PROPOSED NOOSA CIVIC VILLAGE MIXED USE DEVELOPMENT LOCATED AT 28 EENIE CREEK ROAD NOOSAVILLE QLD 4566 PREPARED FOR STOCKWELL DEVELOPMENT GROUP PTY LTD
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Section 2
Bornhorst & Ward Pty Ltd
A.B.N. 78 010 151 354
A.C.N. 010 151 354
Level 14, 133 Mary Street
Brisbane Qld 4000
Phone: (07) 3013 4699
E-mail: [email protected]
Bornhorst and Ward Project No: 22159
If you have any queries regarding this proposal, then please contact: Stewart Grant
Revision Date Description Author Rev. App.
A April 2023 Draft Issue for Client Review KHN SG
B May 2023 DA Issue KHN JD NR
C Nov 2023 RFI Response Draft for Client Review KHN SG
D Nov 2023 RFI Response Issue KHN SG NR
Nicholas Rozis: RPEQ 7729
COPYRIGHT: This document is and shall remain the property of Bornhorst & Ward Pty Ltd and shall not be copied in whole or part. Unauthorized use of this
document in any form is prohibited.
FileName: J:\2022\22159\07_REPORTS\DESIGNREPORTS\SWMP(D)\RPT_SWMP(D).docx
www.bornhorstward.com.au
Section 3
CONTENTS
1. INTRODUCTION ............................................................................................................................................................................. 1
2. SITE CHARACTERISTICS ................................................................................................................................................................ 1
2.1 LOCATION AND EXISTING FEATURES ........................................................................................................................................ 1
2.2 PROPOSED DEVELOPMENT .......................................................................................................................................................... 2
2.3 TOPOGRAPHY AND CATCHMENT CHARACTERISTICS ............................................................................................................ 3
2.3.1 Lot 3 – Western Lot ........................................................................................................................................................ 3
2.3.2 Lot 7 – Eastern Lot .......................................................................................................................................................... 3
2.4 EXISTING FLOODING CONDITIONS ............................................................................................................................................ 3
3. EXISTING AND PROPOSED STORMWATER INFRASTRUCTURE .............................................................................................. 4
3.1 EXISTING INFRASTRUCTURE ....................................................................................................................................................... 4
3.2 PROPOSED STORMWATER DRAINAGE ...................................................................................................................................... 5
4. STORMWATER QUANTITY ANALYSIS ........................................................................................................................................ 5
4.1 EXISTING NATURAL DRAINAGE CHANNEL FLOOD ASSESSMENT – XP STORM .................................................................. 6
4.1.1 Flood Assessment – Existing Scenario ......................................................................................................................... 6
4.1.2 Flood Assessment – Developed Scenario .................................................................................................................... 7
4.2 DETAILED HYDRAULIC MODELLING – XP STORM – DETENTION SIZING.............................................................................. 8
4.2.1 Existing Scenario Model ................................................................................................................................................ 8
4.2.2 Results for Existing Scenario ........................................................................................................................................ 8
4.2.3 XP Storm and Rational Method Comparison ...........................................................................................................10
4.2.4 Developed Scenario Model .........................................................................................................................................10
4.2.5 Results for Developed Unmitigated Scenario ..........................................................................................................11
4.2.6 Detention Basin Design ...............................................................................................................................................12
4.2.7 Results for Developed Scenario .................................................................................................................................13
4.2.8 Hydraulic Impacts on Downstream Waterway Corridor .........................................................................................14
5. STORMWATER QUALITY ............................................................................................................................................................16
5.1 CONSTRUCTION PHASE .............................................................................................................................................................16
5.2 OPERATIONAL PHASE.................................................................................................................................................................16
5.2.1 Pollutants of Concern ..................................................................................................................................................16
5.2.2 Modelling/Assessment Approach ..............................................................................................................................16
5.2.3 Meteorological Data ....................................................................................................................................................16
5.2.4 Source Nodes ................................................................................................................................................................17
5.2.5 Treatment Methodology .............................................................................................................................................17
5.2.6 Treatment Nodes .........................................................................................................................................................18
5.2.7 Proposed Treatment Train ..........................................................................................................................................19
5.2.8 Results............................................................................................................................................................................19
6. NOOSA SHIRE COUNCIL CODES ................................................................................................................................................20
7. SUMMARY ....................................................................................................................................................................................20
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Section 4
LIST OF FIGURES
Figure 1: Site Locality Plan ................................................................................................................................................................................................................... 2
Figure 2: Noosa Shire Council Interactive Flood Map ............................................................................................................................................................. 4
Figure 3: Proposed Treatment Train (Entire Development) ................................................................................................................................................ 19
LIST OF TABLES
Table 1: IFD Parameters ........................................................................................................................................................................................................................ 6
Table 2: XP Storm Existing Catchment Model Parameters .................................................................................................................................................... 6
Table 3: Existing Scenario Critical Peak Flow Runoff (m3/s)................................................................................................................................................... 7
Table 4: XP Storm Developed Catchment Model Parameters .............................................................................................................................................. 7
Table 5: Developed Scenario Critical Peak Flow Runoff (m3/s) ............................................................................................................................................ 8
Table 6: XP Storm Existing Model Parameters ............................................................................................................................................................................ 8
Table 7: XP Storm Existing Peak Flow Results – Lot 3 (m3/sec) ............................................................................................................................................ 9
Table 8: XP Storm Existing Peak Flow Results – Lot 7 (North) (m3/sec) ........................................................................................................................... 9
Table 9: XP Storm Existing Peak Flow Results – Lot 7 (South) (m3/sec) ........................................................................................................................... 9
Table 10: Comparison of Rational Method & XP Storm Existing Peak Flows – Lot 3 (m3/sec)........................................................................... 10
Table 11: XP Storm Developed Model Parameters – Lot 3 ................................................................................................................................................. 10
Table 12: XP Storm Developed Model Parameters – Lot 7 (North) ................................................................................................................................ 10
Table 13: XP Storm Developed Model Parameters – Lot 7 (South) ................................................................................................................................ 11
Table 14: XP Storm Developed Unmitigated Peak Flow Results – Lot 3 (m3/sec)..................................................................................................... 11
Table 15: XP Storm Developed Unmitigated Peak Flow Results – Lot 7 (North) (m3/sec).................................................................................... 11
Table 16: XP Storm Developed Unmitigated Peak Flow Results – Lot 7 (South) (m3/sec).................................................................................... 12
Table 17: XP Storm Developed Model Hydraulic Routing .................................................................................................................................................. 12
Table 18: XP Storm Developed Mitigated Peak Flow Results – Lot 3 (m3/sec).......................................................................................................... 13
Table 19: XP Storm Developed Mitigated Peak Flow Results – Lot 7 (North) (m3/sec) ......................................................................................... 14
Table 20: XP Storm Developed Mitigated Peak Flow Results – Lot 7 (North) (m3/sec) ......................................................................................... 14
Table 21: XP Storm Existing and Developed Mitigated Peak Discharge Comparison – Lot 3 (m3/sec) .......................................................... 15
Table 22: XP Storm Existing and Developed Mitigated Peak Discharge Comparison – Lot 7 (North) (m3/sec) .......................................... 15
Table 23: XP Storm Existing and Developed Mitigated Peak Discharge Comparison – Lot 7 (South) (m3/sec) .......................................... 15
Table 24: Noosa Shire Council Water Quality Objectives .................................................................................................................................................... 16
Table 25: Source Node Information – Lot 3 Catchment ...................................................................................................................................................... 17
Table 26: Source Node Information – Lot 7 Northern Catchment .................................................................................................................................. 17
Table 27: Source Node Information – Lot 7 Southern Catchment .................................................................................................................................. 17
Table 28: Selected Stormwater Quality Treatment Devices................................................................................................................................................ 18
Table 29: Pollutant Removal Rates Discharge (Entire Development) ............................................................................................................................. 19
APPENDICES
Appendix A DEVELOPMENT DRAWINGS
Appendix B ENGINEERING DRAWINGS
Appendix C EXISTING STORMWATER AND CONTOUR INFORMATION
Appendix D RATIONAL METHOD CALCULATIONS
Appendix E XP STORM FLOOD ASSESSMENT OUTPUTS
Appendix F XP STORM 1D DETENTION SIZING OUTPUTS
Appendix G MUSIC DATA
Appendix H COUNCIL CODES
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Section 5
1. INTRODUCTION
Bornhorst and Ward has been commissioned to investigate and report on the stormwater requirements pertaining to the
proposed mixed-use development located at 28 Eenie Creek Road, Noosaville QLD 4566 (Lot 1, 3 and Lot 7 on SP322201).
The proposal consists of constructing basement car parking, ground floor retail with civic open space, and entertainment,
commercial and residential apartments on the second and third floors. Plans of the proposed development can be seen in
Appendix A.
This document reports on the existing and proposed stormwater infrastructure required as part of the proposed
development as well as the stormwater quantity and quality management required for the site. The engineering
requirements for this proposal shall be in accordance with Engineering Best Management Practices, Noosa Shire Council
Planning Scheme, the Queensland Urban Drainage Manual (QUDM 2017) and the State Planning Policy 2017.
This report outlines the preliminary design methodology and calculations in support of a Development Application and
should be read in conjunction with other documents issued by the consultant team.
2. SITE CHARACTERISTICS
2.1 LOCATION AND EXISTING FEATURES
The development site, located at 28 Eenie Creek Road has the following existing characteristics:
− The site is bounded by Walter Hay Drive to the east, the existing Noosa Civic Shopping Centre to the west, and
future development lots to the north and south;
− The development site comprises of 2 separate lots currently made up of bushland separated by a private internal
roadway (known as Main Street) contained within an access easement;
− The total area of the site is approximately 5.8 ha;
− Lot 3 is located on the western side of the development site and is bounded by the Noosa Civic Shopping Centre
to the west, the private access roadway to the east, and vacant future development lots to the north and south.
There is a natural drainage channel located along the western boundary of Lot 3 between the proposed
development and the existing Noosa Civic Shopping Centre, contained within Covenant J;
− Lot 7 is located on the eastern side of the development site and is bound by Walter Hay Drive to the east, the
private access roadway to the west, and vacant future development lots to the north and south;
− The proposed development within Lot 3 has an area of approximately 2.98 ha and the proposed development
within Lot 7 has an area of approximately 0.587 ha, excluding the private internal roadway easement;
− The closest waterway is Eenie Creek which located approximately 500m to the south-west;
− The internal private access roadway is contained within an access easement in favour of Noosa Shire Council
within Lot 3, with a separate Unity Water easement located within the access easement to service Unity Water
sewer and water reticulation infrastructure; and
− A surface access easement in favour of Noosa Shire Council to facilitate pedestrian and active transport
movements is located along the western side of the Lot 3.
Refer to Figure 1 for locality details which notes Lot 3 and Lot 7 within the proposed development area.
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Section 6
Figure 1: Site Locality Plan
2.2 PROPOSED DEVELOPMENT
The following points outline the extent of works for the proposed development:
− Material change of use and building work in support of the proposed development;
− Construction of the mixed-use development within Lot 3, with basement carparking, commercial and retail
outlets, and residential build-to-rent apartments;
− Construction of mixed-use three-story buildings within Lot 7, with surface carparking, commercial and retail
outlets, and residential build-to-rent apartments;
− The existing private access roadway will remain. Access to both Lot 3 and 7 will be via five proposed driveway
crossovers onto the existing private roadway, and multiple pedestrian entrances to both sites;
− A new pedestrian bridge across the existing natural drainage channel within the environmental zone in Covenant
J between the proposed development and the existing shopping centre; and
− Modifications to the existing shopping centre loading bay to allow for the proposed pedestrian bridge landing.
Refer to the development drawings in Appendix A for further details of the proposed development.
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Section 7
2.3 TOPOGRAPHY AND CATCHMENT CHARACTERISTICS
The topography and catchment characteristics for the development site, broken down between both Lot 3 and Lot 7, are
discussed below:
2.3.1 Lot 3 – Western Lot
− The high point of the existing site is RL 9.47m AHD located on the eastern side of the site;
− The development falls from the high point at an approximate grade of 2.5% to a low point of RL 3.88m AHD in
the south-western corner;
− During both minor and major storm events, runoff from the site discharges as overland flow over the western
boundary of the development site and onto the environmental zone and natural drainage channel within
Covenant J and is ultimately conveyed through culverts below Hofmann Drive to Eenie Creek and Lake Weyba;
− As the roadways surrounding the site have been built assuming a fully developed catchment, there is no external
catchment.
2.3.2 Lot 7 – Eastern Lot
− The high point of the existing site is RL 10.63m AHD located on eastern side of the site;
− The development falls from the high point at an approximate grade of 1% to a low point of RL 9.2m AHD in the
south-west corner;
− During both minor and major storm events, runoff from the site discharges as overland flow over the western
boundary of the development site and onto the private access roadway, and is ultimately conveyed to the
stormwater drainage system along the access roadway to Eenie Creek and Lake Weyba;
− Lot 7 is split into two sub-catchments, with a high-point located midway along the private access road frontage,
with flows directed either towards the north-west onto the private access road and around Lot 3 to the
environmental zone and natural drainage channel, or towards the south-west onto the private access roads; and
− As the roadways surrounding the site have been built assuming a fully developed catchment, there is no external
catchment.
See the survey plan in Appendix C for more information.
2.4 EXISTING FLOODING CONDITIONS
The Noosa Shire Council Plan Interactive Mapping Flood Extents have been obtained for the site and states the following:
− No flood levels or flags for building development purposes exist for the development site;
− The interactive mapping system within the Noosa Shire Council Plan confirms that the development site is clear
of the mapped flood hazard overlay extents of Eenie Creek, and the site is expected to be at low risk of flood
inundation from Eenie Creek; and
− A local flood assessment of the are was undertaken to determine water levels within the natural drainage channel
through the environmental zone in Covenant J along the western boundary of Lot 3. Further details of this study
can be found in Section 4.1 below.
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Section 8
Figure 2: Noosa Shire Council Interactive Flood Map
3. EXISTING AND PROPOSED STORMWATER INFRASTRUCTURE
3.1 EXISTING INFRASTRUCTURE
A Before You Dig investigation, detailed survey, and examination of as-constructed documentation for the surrounding
roadways has been completed of the site and its surrounding area. The following stormwater infrastructure was noted:
− An existing 1200mm x 600mm box culvert and temporary field inlet is located at the south-west corner of the Lot
3 which conveys flows below Hofmann Drive and into Eenie Creek to the south of the development site;
− An existing 375mm dia. stormwater pipe with multiple gully pits is located along the southern half of the internal
access roadway which also conveys flows along Hofmann Drive and into Eenie Creek;
− An existing 750mm dia. stormwater pipe with multiple gully pits is located along the northern half of the internal
access roadway which conveys flows to the north into the upstream end of the environmental zone and natural
drainage channel bounding Lot 3;
− A 4-cell 1200mm x 600mm box culvert exists below Hofmann Drive which conveys flows from the environmental
zone and natural drainage channel below Hofmann Drive into Eenie Cree to the south; and
− The stormwater infrastructure within the access roadways have been built for a fully developed catchment.
As-constructed Drawings of the existing stormwater infrastructure and detailed survey can be found in Appendix C.
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Section 9
3.2 PROPOSED STORMWATER DRAINAGE
The following points outline the proposed stormwater infrastructure for the development site:
− Minor events from within Lot 3 will be conveyed by an internal stormwater piped network to the existing
1200mm x 600mm box culvert at the south-west corner of the development site;
− Minor events from within Lot 7 will be conveyed by an internal stormwater piped network to the existing gully
pits along the private access roadway along the western frontage of the development site;
− Major events will be conveyed via overland flow towards and onto the surrounding private access roadways and
environmental zones as per existing conditions;
− Run-off from the remaining un-developed areas of Lot 7 will be conveyed via catch drains around the proposed
development works area to the private access roadway as per existing conditions;
− As there will be an increase to the impervious area due to the proposed development, there will be an increase to
peak stormwater discharge rates from the development site. Based on this, stormwater detention measures are
required, and four below-ground stormwater detention tanks are proposed across both Lot 3 and Lot 7; and
− Considering the development works area is greater than 2500m2, stormwater quality treatment measures are
required for the proposed development as per the State Planning Policy and Noosa Shire Council Planning
Scheme. Treatment is proposed within multiple bio-retention basins across both development sites.
Refer to the engineering drawings in Appendix B for further information.
4. STORMWATER QUANTITY ANALYSIS
Under the Noosa Shire Council Guidelines, several design elements were identified in relation to stormwater management
issues. Noosa Shire Council must be satisfied that:
− The proposed development can be drained;
− The stormwater management system can follow the features and functions of the natural drainage system;
− The volume, timing, velocity and pollutant load of stormwater has no adverse effect on any surrounding
properties or receiving waters; and
− Suitable provision is made in the design layout to accommodate for major drainage.
All stormwater discharge will comply with Noosa Shire Council’s Stormwater Management Code with quantity calculations
completed in accordance with the requirements and methods outlined in the Queensland Urban Drainage Manual
(QUDM).
A detailed hydrologic and hydraulic analysis using XP Storm software has been undertaken to model the stormwater flow
characteristics of the site more accurately, specifically regarding water levels within the adjoining natural drainage channel.
XP Storm is a hydraulic modelling software tool that utilises detailed hydrograph flow analysis to provide an effective
representation of urban stormwater systems. Hydrographs are calculated using the Laurenson Method for runoff routing
in conjunction with the Uniform Loss model for determining catchment losses. XP Storm has been used to demonstrate
non-worsening on downstream properties through comparison of the results obtained for existing and developed
mitigated scenarios.
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Section 10
A flood assessment has been undertaken for the existing natural drainage channel within the environmental zone in
Covenant J along the western boundary of Lot 3. The flood assessment provides the 1% AEP flood depths, water surface
levels and velocities along the length of the natural drainage channel bounding Lot 3, for the existing and developed
scenarios, to allow assessment of potential impacts resulting from the proposed development.
4.1 EXISTING NATURAL DRAINAGE CHANNEL FLOOD ASSESSMENT – XP STORM
4.1.1 Flood Assessment – Existing Scenario
The hydrological modelling has been undertaken in XP Storm for the 100-year ARI (1% AEP) storm event using AR&R 87
IFD. In line with Noosa Shire Council requirements, these rainfall intensities were increased by 20% to determine flood
levels in the 2100 Year planning period, to account for predicted future increases in rainfall intensity and event severity.
The following table outlines the IFD Parameters used for the analysed storm durations.
Table 1: IFD Parameters
Storm Intensity (mm/hr)
Duration
(mins) 100 Year ARI
20 229
25 207
30 189
45 155
60 134
90 109
120 94
180 76
To establish the catchments contributing to runoff flowing through the natural drainage channel within the environmental
zone, DEM data was derived from the QLD Government’s Queensland LiDAR Data, in addition to detailed survey data.
Catchment boundaries were then determined based on the LiDAR & survey contours, and a review of the existing piped
stormwater network of the existing shopping Centre. Refer to the Existing Catchment Plan DA-C040 in Appendix E for
further information.
Table 2 below outlines the input parameters for each catchment within the model. The impervious fraction for each
catchment has been determined based on review of aerial imagery. For pervious areas within each catchment, an initial
loss of 27mm and a continuing loss of 2.6mm/hr was adopted, as per information obtained from the Australian Rainfall
and Runoff (ARR) Data Hub. No areal reduction factors have been applied to this local assessment.
Table 2: XP Storm Existing Catchment Model Parameters
Impervious Initial Loss Continuing
Catchment Area (ha) Slope (%) Mannings ‘n’
(%) (mm) Loss (mm/hr)
North 5.875 0 0.160 27 2.6
1.3
Catchment 8.812 100 0.013 0 0
South 4.156 0 0.160 27 2.6
1.8
Catchment 1.039 100 0.013 0 0
The storm durations listed in Table 3 were simulated in XP Storm for each catchment detailed within Table 2 to determine
the critical storm duration for each catchment. Determining the critical storm for each catchment allows the maximum
critical flow to be modelled in the hydraulics scenario, resulting in the maximum flow path along the drainage channel.
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Section 11
The following table highlights the peak flows for each catchment associated with the development site at the southern
extents of the study area where the natural drainage channel crosses below Hofmann Drive via a series of box culverts. It is
noted that Noosa Shire Council Flood Hazard Extents should be referred to for a holistic assessment of the flooding
experienced downstream of the development site and Hofmann Drive culverts.
Table 3: Existing Scenario Critical Peak Flow Runoff (m3/s)
Peak Flow (m3/s) Peak Water Level at
Catchment
10 Year ARI 50 Year ARI 100 Year ARI Hoffman Drive Culverts
North Catchment 6.959 8.418 9.243
4.500m
South Catchment 1.068 1.300 1.477
The results of the existing scenario flood assessment including water level depths, elevations, and velocities during the 1%
AEP storm event (in the 2100 Year planning period) can be found in Appendix E.
4.1.2 Flood Assessment – Developed Scenario
The hydrological modelling has been undertaken in XP Storm for the 100-year ARI storm event IFD parameters listed in
Table 1.
To establish the catchments contributing to runoff flowing through the natural drainage channel within the environmental
zone in Covenant J under the developed scenario, DEM data was derived from the QLD Government’s Queensland LiDAR
Data, in addition to detailed survey data. Catchment boundaries were then determined based on the LiDAR & survey
contours, a review of the existing piped stormwater network of the existing shopping Centre, and surface levels of the
proposed development modelled by Bornhorst & Ward. Refer to the Developed Catchment Plan DA-C041 in Appendix E
for further information.
Table 4 below outlines the input parameters for each catchment within the model. Stormwater detention is expected to be
required under the developed scenario to suitably mitigate peak run-off volumes from the site due to an increase to
impervious area when compared to existing conditions. As such, the impervious fractions adopted for each catchment in
this developed scenario were not changed from the existing scenario, to replicate peak discharge run-off from the site
when suitably mitigated to equal to or below that of existing.
The two changes between the developed scenario and the existing scenario for this flood assessment are the changes to
the shared boundary between the two catchments, and the land-use of the proposed development site limiting the
maximum theoretical flood extents of the natural drainage channel where it bounds with Lot 3 development.
For pervious areas within each catchment, an initial loss of 27mm and a continuing loss of 2.6mm/hr was adopted, as per
information obtained from the Australian Rainfall and Runoff (ARR) Data Hub. No areal reduction factors have been
applied to this local assessment.
Table 4: XP Storm Developed Catchment Model Parameters
Impervious Initial Loss Continuing
Catchment Area (ha) Slope (%) Mannings ‘n’
(%) (mm) Loss (mm/hr)
North 3.696 0 0.16 27 2.6
1.3
Catchment 8.812 100 0.013 0 0
South 6.335 0 0.160 27 2.6
1.8
Catchment 1.038 100 0.013 0 0
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Section 12
The storm durations listed in Table 5 were simulated in XP Storm for each catchment detailed within Table 4 to determine
the critical storm duration for each catchment. Determining the critical storm for each catchment allows the maximum
critical flow to be modelled in the hydraulics scenario, resulting in the maximum flow path through the site.
The following table highlights the peak flows for each catchment associated with the development site at the southern
extents of the study area where the natural drainage channel crosses below Hofmann Drive via a series of box culverts, for
the developed scenario where stormwater quantity detention is provided for all development site sub-catchments.
Table 5: Developed Scenario Critical Peak Flow Runoff (m3/s)
Peak Flow (m3/s) Peak Water Level at
Catchment
10 Year ARI 50 Year ARI 100 Year ARI Hoffman Drive Culverts
North Catchment 6.953 8.417 9.239
4.492m AHD
South Catchment 0.885 1.152 1.345
A comparison between Tables 3 & 5 shows that peak flow discharge and water levels across the Hoffman Drive culvert
crossing are not increasing for both catchments in the development scenario. Thus, this flood assessment has determined
that the proposed development will not worsen downstream water levels and flood extents across Hoffman Drive.
The results of the developed scenario flood assessment including water level depths, elevations, and velocities during the
1% AEP storm event (in the 2100 Year planning period) can be found in Appendix E. Developed flood levels are also shown
in the Earthworks Sections on Drawing C-DA020 in Appendix B.
4.2 DETAILED HYDRAULIC MODELLING – XP STORM – DETENTION SIZING
4.2.1 Existing Scenario Model
Initially the existing XP Storm model was built using catchments’ parameters outlined in Table 6. The initial and continuing
loss properties were assumed from site investigations and recent experience with stormwater modelling in the subject
area.
Table 6: XP Storm Existing Model Parameters
Parameter Lot 3 Lot 7 - North Lot 7 - South
Pervious Impervious Pervious Impervious Pervious Impervious
Data Data Data Data Data Data
Area (ha) 2.979 - 0.249 - 0.338 -
Slope (%) 2.0 2.4 2.0
Mannings ‘n’ 0.160 - 0.160 - 0.160 -
Initial Loss
27 0 27 0 27 0
(mm)
Continuing
2.6 0 2.6 0 2.6 0
Loss (mm/hr)
Laurenson ‘n’ -0.285 -0.285 -0.285 -0.285 -0.285 -0.285
4.2.2 Results for Existing Scenario
Table 7, Table 8, and Table 9 indicates the existing total peak discharge rate for the site as outputted by XP storm for both
Lot 3 and the two sub-catchments of Lot 7 (North and South). The critical storm duration for the existing catchment was
determined by simulating all storm events from the 1 to 100-year ARI storm events for 20, 25, 30, 45, 60, 90, 120 and 180-
minute durations. The critical storm events can be seen within tables below.
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Section 13
BORNHORST +\VARD Table 7: XP Storm Existing Peak Flow Results — Lot 3 (m?/sec) Storm Duration ARI & AEP . 1 Years | 2 Years | 5 Years | 10 Years 20 Years | 50 Years | 100 Years (min) 63% 39% 18% 10% 5% 2% 1% 20 0.005 0.014 0.049 0.077 0.113 0.139 0.187 25 0.012 0.021 0.058 0.090 0.123 0.172 0.218 30 0.014 0.032 0.075 0.111 0.150 0.209 0.263 45 0.031 0.049 0.119 0.168 0.227 0.311 0.392 60 0.048 0.067 0.153 0.215 0.295 0.391 0.480 90 0.072 0.099 0.209 0.293 0.375 0.497 0.591 120 0.090 0.125 0.238 0.326 0.413 0.535 0.634 180 0.104 0.139 0.255 0.341 0.433 0.548 0.648 Critical 0.104 0.139 0.255 0.341 0.433 0.548 0.648 Critical Even (Min) 180 180 180 180 180 180 180 Table 8: XP Storm Existing Peak Flow Results - Lot 7 (North) (m3/sec) Storm Duration ARI & AEP . 1 Years | 2 Years | 5 Years | 10 Years 20 Years | 50 Years | 100 Years (min) 63% | 39% | 18% 10% 5% 2% 1% 20 0.001 0.003 0.010 0.017 0.024 0.030 0.040 25 0.002 0.004 0.012 0.019 0.026 0.037 0.047 30 0.003 0.007 0.016 0.024 0.032 0.044 0.056 45 0.007 0.010 0.025 0.035 0.046 0.061 0.074 60 0.010 0.014 0.029 0.040 0.053 0.068 0.082 90 0.013 0.018 0.033 0.046 0.058 0.073 0.086 120 0.014 0.019 0.035 0.047 0.059 0.071 0.084 180 0.014 0.019 0.034 0.046 0.058 0.070 0.082 Critical 0.014 0.019 0.035 0.047 0.059 0.073 0.086 Critical Even (Min) 120 120 120 120 120 90 90 Table 9: XP Storm Existing Peak Flow Results - Lot 7 (South) (m3/sec) Storm Duration ARI & AEP (min) 1Years | 2 Years | 5Years | 10 Years | 20 Years | 50 Years | 100 Years 63% 39% 18% 10% 5% 2% 1% 20 0.001 0.003 0.011 0.018 0.026 0.032 0.043 25 0.003 0.005 0.013 0.021 0.029 0.040 0.051 30 0.003 0.007 0.017 0.026 0.035 0.048 0.061 45 0.007 0.011 0.027 0.039 0.051 0.070 0.086 60 0.011 0.015 0.034 0.046 0.061 0.079 0.095 90 0.015 0.021 0.040 0.054 0.068 0.086 0.102 120 0.017 0.023 0.042 0.056 0.071 0.087 0.102 180 0.017 0.023 0.042 0.056 0.071 0.085 0.100 Critical 0.017 0.023 0.042 0.056 0.071 0.087 0.102 Critical Even (Min) 120 120 120 120 120 120 90 Discharge hydrographs for the existing model have been included in Appendix F. www.bornhorstward.com.au Page 9
Section 14
4.2.3 XP Storm and Rational Method Comparison
Before utilising data from XP storm, a comparison of results from XP Storm and the Rational Method was undertaken to
ensure that the XP Storm model was functioning correctly. Peak discharge rates from the site in the existing case were
compared (“site” catchments defined in Table 6). The comparison was undertaken for the Lot 3 catchment only outlined in
Table 10. Detailed Rational Method calculations can be reviewed in Appendix D.
Table 10: Comparison of Rational Method & XP Storm Existing Peak Flows – Lot 3 (m3/sec)
AEP (%) ARI (Years) Rational Method Result XP Storm Result % Difference
63.21 1 0.152 0.104 -31.38
39.35 2 0.184 0.139 -24.38
18.13 5 0.286 0.255 -10.74
10 10 0.358 0.341 -4.87
5 20 0.436 0.433 -0.70
2 50 0.565 0.548 -3.01
1 100 0.660 0.648 -1.82
As indicated, the XP Storm peak discharge results are of the same magnitude as the results initially estimated using the
Rational Method. It was therefore concluded that the existing XP Storm model was functioning correctly.
4.2.4 Developed Scenario Model
A developed scenario model was then created with internal catchments and parameters modified from the existing model
to suit the proposed development as outline in Table 11, 12 and 13.
Table 11: XP Storm Developed Model Parameters – Lot 3
Parameter Lot 3 Catchment
Pervious Data Impervious Data
Area (ha) 0.209 2.770
Slope (%) 2.0 2.0
Mannings ‘n’ 0.03 0.013
Initial Loss (mm) 27 0
Continuing Loss (mm/hr) 2.6 0
Laurenson ‘n’ -0.285 -0.285
Table 12: XP Storm Developed Model Parameters – Lot 7 (North)
Parameter Lot 7 Northern Catchment
Pervious Data Impervious Data
Area (ha) 0.025 0.224
Slope (%) 2.5 2.5
Mannings ‘n’ 0.03 0.015
Initial Loss (mm) 27 0
Continuing Loss (mm/hr) 2.6 0
Laurenson ‘n’ -0.285 -0.285
www.bornhorstward.com.au Page 10
Section 15
Table 13: XP Storm Developed Model Parameters – Lot 7 (South)
Parameter Lot 7 Southern Catchment
Pervious Data Impervious Data
Area (ha) 0.034 0.304
Slope (%) 2.5 2.5
Mannings ‘n’ 0.03 0.013
Initial Loss (mm) 27 0
Continuing Loss (mm/hr) 2.6 0
Laurenson ‘n’ -0.285 -0.285
4.2.5 Results for Developed Unmitigated Scenario
Table 14, Table 15, and Table 16 indicates the developed unmitigated total peak discharge rate for the sites as outputted
by XP storm for both Lot 3 and the two sub-catchments of Lot 7 (North and South). The critical storm duration for the
existing catchment was determined by simulating all storm events from the 1 to 100-year ARI storm events for 20, 25, 30,
45, 60, 90, 120 and 180-minute durations. The critical storm events can be seen within tables below.
Table 14: XP Storm Developed Unmitigated Peak Flow Results – Lot 3 (m3/sec)
ARI & AEP
Storm Duration
1 Years 2 Years 5 Years 10 Years 20 Years 50 Years 100 Years
(min)
63% 39% 18% 10% 5% 2% 1%
20 1.219 1.386 1.892 2.222 2.535 2.704 2.978
25 1.217 1.380 1.880 2.218 2.543 2.652 2.936
30 1.114 1.264 1.729 2.045 2.351 2.492 2.766
45 0.997 1.132 1.562 1.850 2.129 2.347 2.619
60 1.051 1.202 1.690 2.028 2.368 2.619 2.938
90 0.895 1.026 1.471 1.785 2.089 2.180 2.452
120 0.865 0.992 1.425 1.744 2.057 2.138 2.420
180 0.565 0.659 0.944 1.141 1.337 1.425 1.618
Critical 1.219 1.386 1.892 2.222 2.543 2.704 2.978
Critical Even (Min) 20 20 20 20 25 20 20
Table 15: XP Storm Developed Unmitigated Peak Flow Results – Lot 7 (North) (m3/sec)
ARI & AEP
Storm Duration
1 Years 2 Years 5 Years 10 Years 20 Years 50 Years 100 Years
(min)
63% 39% 18% 10% 5% 2% 1%
20 0.105 0.119 0.161 0.188 0.214 0.227 0.250
25 0.102 0.115 0.157 0.187 0.216 0.226 0.250
30 0.093 0.105 0.144 0.173 0.200 0.212 0.236
45 0.085 0.096 0.132 0.155 0.178 0.196 0.221
60 0.089 0.102 0.145 0.175 0.204 0.224 0.250
90 0.077 0.090 0.130 0.155 0.180 0.186 0.208
120 0.075 0.086 0.126 0.153 0.178 0.184 0.206
180 0.048 0.055 0.082 0.099 0.116 0.123 0.139
Critical 0.105 0.119 0.161 0.188 0.216 0.227 0.250
Critical Even (Min) 20 20 20 20 25 20 20
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Section 16
Table 16: XP Storm Developed Unmitigated Peak Flow Results – Lot 7 (South) (m3/sec)
ARI & AEP
Storm Duration
1 Years 2 Years 5 Years 10 Years 20 Years 50 Years 100 Years
(min)
63% 39% 18% 10% 5% 2% 1%
20 0.143 0.161 0.218 0.255 0.290 0.308 0.339
25 0.138 0.156 0.212 0.254 0.292 0.306 0.339
30 0.126 0.143 0.195 0.234 0.270 0.287 0.319
45 0.115 0.130 0.179 0.211 0.242 0.266 0.299
60 0.121 0.138 0.196 0.237 0.277 0.304 0.339
90 0.105 0.121 0.176 0.210 0.244 0.253 0.283
120 0.102 0.117 0.171 0.207 0.242 0.249 0.280
180 0.065 0.075 0.111 0.134 0.157 0.167 0.189
Critical 0.143 0.161 0.218 0.255 0.292 0.308 0.339
Critical Even (Min) 20 20 20 20 25 20 20
Discharge hydrographs for the existing model have been included in Appendix F.
4.2.6 Detention Basin Design
For the developed mitigated scenario, storage nodes representing the proposed detention basins were included in the
model. Flows from all three development catchments were routed to the assigned detention tanks for each catchment.
The storage node inputs were sourced based on in-ground tanks for all three catchments, as well as the proposed bio-
basins discussed in Section 5. The six detention tanks modelled for each of the three catchments are outlined in Table 17.
Table 17: XP Storm Developed Model Hydraulic Routing
Development Sub-Catchment Invert Elevation Internal Height Surface Area Approximate Volume
(RL) (m) (m2) (m3)
Lot 3 Detention Tank 5.50 2.5 800 2,000
Lot 3 Bio-Retention Basin 3.80 1.5 560 840
Lot 7 (North) Detention Tank 6.50 1.8 110 200
Lot 7 (North) Bio-Retention Basin 6.30 1.8 27 49
Lot 7 (South) Detention Tank 6.50 1.8 160 228
Lot 7 (South) Bio-Retention Basin 6.30 1.8 33 60
The outlets to each of the three detention tanks were modelled as per the below:
• Lot 3 Catchment:
o Detention Tank:
▪ Low-flow outlet: 150mm diameter orifice with invert at RL 5.50m;
▪ Mid-flow outlet: 300mm diameter orifice with invert at RL 6.90m;
▪ High-flow outlet: 525mm diameter orifice with invert at R: 6.90m; and
▪ High-flow weir: 10m long weir with crest height at RL 7.20m.
o Bio-Retention Basin:
▪ Low-flow outlet: 300mm diameter orifice with invert at RL 5.30m;
▪ Mid-flow outlet: 300mm diameter orifice with invert at RL 6.60m;
▪ High-flow outlet: 100mm diameter orifice with invert at R: 6.80m; and
▪ High-flow weir: 10m long weir with crest height at RL 7.65m.
www.bornhorstward.com.au Page 12
Section 17
• Lot 7 (North) Catchment Tank Outlet:
o Low-flow outlet: 90mm diameter orifice with invert at RL 6.50m;
o Mid-flow outlet: 150mm diameter orifice with invert at RL 7.75m; and
o High-flow weir: 2m long weir with crest height at RL 8.0m.
• Lot 7 (South) Catchment Tank Outlet:
o Low-flow outlet: 100mm diameter orifice with invert at RL 6.50m;
o Mid-flow outlet: 150mm diameter orifice with invert at RL 7.60m; and
o High-flow weir: 2m long weir with crest height at RL 8.00m
See Engineering Drawings in Appendix B for further information.
4.2.7 Results for Developed Scenario
Tables 18, 19 and 20 indicates the developed total peak discharge rate from the development sites as outputted by XP
storm. The peak flow rate indicated is the combined flow of the site and external catchments. To determine the critical
storm event for the developed mitigated case, the 1-to-100-year ARI storm events for 20, 25, 30, 45, 60, 90, 120 and 180-
minute durations were simulated in the model.
From these simulations it was determined that the critical storm event for the Lot 3 Catchment was the 180-minute storm
for all storm event ARIs, and for the two Lot 7 catchment, the critical storm event varied between the 45-minute storm and
the 180-minute storm depending on the storm event ARI. The critical storm event results will therefore be compared
against the existing scenario discharges for both catchments, as identified in Section 4.2.8.
Further details of the outputs for the critical events have been located within Appendix F.
Table 18: XP Storm Developed Mitigated Peak Flow Results – Lot 3 (m3/sec)
Storm Duration ARI (Years)
(min) 1 2 5 10 20 50 100
20 0.037 0.042 0.051 0.068 0.104 0.143 0.170
25 0.041 0.045 0.061 0.099 0.137 0.174 0.193
30 0.044 0.048 0.080 0.126 0.163 0.191 0.217
45 0.049 0.055 0.132 0.179 0.203 0.280 0.337
60 0.054 0.077 0.163 0.210 0.259 0.343 0.409
90 0.075 0.107 0.194 0.270 0.338 0.419 0.563
120 0.090 0.122 0.206 0.318 0.357 0.462 0.626
180 0.102 0.132 0.220 0.327 0.373 0.481 0.628
Critical 0.102 0.132 0.220 0.327 0.373 0.481 0.628
Critical Event 180 180 180 180 180 180 180
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Section 18
Table 19: XP Storm Developed Mitigated Peak Flow Results – Lot 7 (North) (m3/sec)
Storm Duration ARI (Years)
(min) 1 2 5 10 20 50 100
20 0.011 0.012 0.014 0.016 0.017 0.019 0.020
25 0.011 0.013 0.015 0.017 0.018 0.020 0.023
30 0.012 0.013 0.016 0.018 0.019 0.022 0.031
45 0.013 0.014 0.017 0.019 0.021 0.036 0.055
60 0.013 0.014 0.018 0.020 0.028 0.043 0.066
90 0.013 0.015 0.019 0.021 0.033 0.053 0.073
120 0.013 0.015 0.019 0.024 0.035 0.052 0.069
180 0.013 0.015 0.019 0.025 0.035 0.048 0.082
Critical 0.013 0.015 0.019 0.025 0.035 0.053 0.082
Critical Event 45 90 90 180 120 90 180
Table 20: XP Storm Developed Mitigated Peak Flow Results – Lot 7 (North) (m3/sec)
Storm Duration ARI (Years)
(min) 1 2 5 10 20 50 100
20 0.013 0.014 0.017 0.019 0.021 0.023 0.026
25 0.014 0.015 0.018 0.020 0.022 0.026 0.036
30 0.014 0.016 0.019 0.021 0.023 0.034 0.043
45 0.016 0.017 0.021 0.023 0.034 0.047 0.064
60 0.016 0.018 0.022 0.027 0.040 0.052 0.080
90 0.016 0.018 0.023 0.033 0.044 0.064 0.091
120 0.017 0.018 0.023 0.036 0.046 0.065 0.089
180 0.016 0.018 0.023 0.036 0.047 0.062 0.098
Critical 0.017 0.018 0.023 0.036 0.047 0.065 0.098
Critical Event 120 60 90 120 180 120 180
4.2.8 Hydraulic Impacts on Downstream Waterway Corridor
A comparison of critical peak flows for the existing and developed mitigated scenarios has been included in Table 21, 22
and 23. The hydraulic modelling undertaken has demonstrated that the proposed development will not cause a worsening
impact downstream of the site in all storm events and that the detention has been adequately sized. Therefore, the
required detention volume for all three catchments across the development in the 1% AEP storm event is 3,377m3.
Note that 949m3 of this volume is provided within the three bio-retention basins across each of the three basins, with the
remainder of this volume provided in below-ground detention tanks.
Discharge hydrographs, stage/water elevations for the detention basin and associated XP Storm outputs have been
included in Appendix F of this report to demonstrate the performance of the proposed detention system.
www.bornhorstward.com.au Page 14
Section 19
Table 21: XP Storm Existing and Developed Mitigated Peak Discharge Comparison – Lot 3 (m3/sec)
ARI (Years) Existing Critical Discharge Developed Critical Discharge Discharge Difference
1 0.104 0.102 -0.002
2 0.139 0.132 -0.007
5 0.255 0.220 -0.035
10 0.341 0.327 -0.014
20 0.433 0.373 -0.060
50 0.548 0.481 -0.067
100 0.648 0.628 -0.020
Table 22: XP Storm Existing and Developed Mitigated Peak Discharge Comparison – Lot 7 (North) (m3/sec)
ARI (Years) Existing Critical Discharge Developed Critical Discharge Discharge Difference
1 0.014 0.013 -0.001
2 0.019 0.015 -0.004
5 0.035 0.019 -0.016
10 0.047 0.025 -0.022
20 0.059 0.035 -0.024
50 0.073 0.053 -0.020
100 0.086 0.082 -0.004
Table 23: XP Storm Existing and Developed Mitigated Peak Discharge Comparison – Lot 7 (South) (m3/sec)
ARI (Years) Existing Critical Discharge Developed Critical Discharge Discharge Difference
1 0.017 0.017 0.000
2 0.023 0.018 -0.005
5 0.042 0.023 -0.019
10 0.056 0.036 -0.020
20 0.071 0.047 -0.024
50 0.087 0.065 -0.022
100 0.102 0.098 -0.004
www.bornhorstward.com.au Page 15
Section 20
5. STORMWATER QUALITY
5.1 CONSTRUCTION PHASE
As a result of the proposed development, contaminants will be generated during the construction phase. A
comprehensive Erosion and Sediment control plan including the construction process will be prepared during the detailed
design. This is to be kept on site during the construction phase and will be in accordance with the State Planning Policy
2017 and Noosa Shire Planning Scheme.
5.2 OPERATIONAL PHASE
As the proposed development includes building work that involves greater than 2,500m2 of land the State Planning Policy
(2017) and Noosa Shire Council Planning Scheme requirements for water quality are applicable to the proposed
development.
5.2.1 Pollutants of Concern
The key pollutants to be targeted and the minimum reductions in mean annual loads described in Table 9.4.8.3 the State
Planning Policy (also consistent with the Noosa Shire Council Requirements) are outlined in Table 24 below.
Table 24: Noosa Shire Council Water Quality Objectives
Reduction in Mean
Pollutant
Annual Load
Total Suspended Solids (TSS) 80%
Total Phosphorus (TP) 60%
Total Nitrogen (TN) 45%
Gross Pollutants (GP) 90%
5.2.2 Modelling/Assessment Approach
A quantitative assessment of stormwater runoff quality was considered for the catchments ultimate developed scenario.
The predicted reductions in mean annual loads of key pollutants have been identified using the “Model for Urban
Stormwater Improvement Conceptualisation” (MUSIC), Version 6 (6.3.0). MUSIC is a stormwater quality modelling program
that provides estimates of stormwater pollution generation and the performance of stormwater management measures
used in series or parallel to form a ‘treatment train’.
5.2.3 Meteorological Data
The first step in creating the MUSIC model was to select the appropriate meteorological data set (period and time step) to
be used as the basis for the runoff algorithms. Section 3.1 – Meteorological Data and Section 3.2 – Modelling Period and
time-step, of the MUSIC Modelling Guidelines details the Rainfall Data and Time Step process requirements of the model,
respectively.
The time step used for the MUSIC modelling process was: Tewantin RSL Park 6 Minutes, Station No: 040908.
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Section 21
5.2.4 Source Nodes
The second step taken in creating the MUSIC models was to define ‘Source Nodes’ or Sub-Catchments. Source nodes for
modelling these catchments were based on the Water by Design reference material: Music Modelling Guidelines. The
MUSIC model uses the split catchment approach and consists of commercial source nodes. Catchment areas are outlined
in Table 25, 26 and 27 below with catchment extents illustrated in Appendix G for both proposed sites.
Table 25: Source Node Information – Lot 3 Catchment
Node type Area (ha) Fraction Impervious
Commercial Road 0.805 90%
Commercial Roof 1.504 100%
Commercial Ground 0.516 40%
South Site Future Commercial Road 0.200 90%
South Site Future Commercial Roof 0.237 100%
South Site Future Commercial Ground 0.099 40%
Private Access Roadway Un-Treated Road Areas 0.116 75%
Table 26: Source Node Information – Lot 7 Northern Catchment
Node type Area (ha) Fraction Impervious
Commercial Road 0.145 80%
Commercial Roof 0.106 100%
Table 27: Source Node Information – Lot 7 Southern Catchment
Node type Area (ha) Fraction Impervious
Commercial Road 0.216 75%
Commercial Roof 0.110 100%
Note that the future business use within Lot 3 immediately to the south of the proposed development was included in the
source node information found in Table 25 above. This is to ensure that the proposed bio-retention basin for the Lot 3
catchment is adequately sized to also treat pollutant run-off from the future business development as well. Roof, road and
ground areas for each source node within this future development area were calculated based on a 45% site coverage
requirement of the Noosa Shire Council planning scheme for this future development.
Note also that Table 25 above includes existing roadway catchments within the private access Road. As per the catchment
extents illustrated in Appendix F and the engineering drawings shown in Appendix B, two of the existing bio-retention
pods along the private access road are proposed to be removed to suit the proposed streetscape works. To mitigate this
catchment area that will be discharged from the private access road without first going through treatment, an additional
source note was added to the MUSIC modelling for Lot 3.
The input parameters used are listed in Appendix G.
5.2.5 Treatment Methodology
Runoff from the development site will be conveyed through three independent bio-retention basins owned and
maintained by the development owners. Lot 3 is to have a single bio-retention basin in the south-west corner of the site,
whilst each of the two sub-catchments within Lot 7 are to each have a bio-retention basin.
www.bornhorstward.com.au Page 17
Section 22
The Lot 3 treatment model was developed with an additional source node that showed the road catchments where bio-
retention pods are being removed, with stormwater being discharged from the private access road un-treated. This was
done to provide an increased bio-retention area within Lot 3 to appropriately mitigate the increased pollutant run-off
from the access roadway, with the total pollutant discharge from the entire development and the access roadway meeting
the objectives noted in Table 23 above.
5.2.6 Treatment Nodes
The MUSIC model consisted of 3 bio-retention treatment nodes as detailed in Table 28. Treatment node input parameters
were based on the MUSIC Modelling Guidelines and Noosa Shire Council expectations. Refer to Appendix B for locations
of the bio-retention treatment devices. Refer to the MUSIC information attached in Appendix G for further details.
Table 28: Selected Stormwater Quality Treatment Devices
Treatment Device Discussion
Bio-Retention Basins A bio-retention system is a combination of vegetation and filter substrate that provides
treatment of stormwater through filtration, extended detention and some biological
uptake. Three Bio-retention systems are proposed across both Lot 3 and Lot 7 – as per
the details below.
Lot 3 Proposed Bio-Retention Area (as modelled):
• Filter Area = 560m2
• Surface Area = 560m2
• Filter Depth = 700mm
• Extended Detention Depth = 0.5m
Lot 7 North Proposed Bio-Retention Area (as modelled):
• Filter Area = 27m2
• Surface Area = 27m2
• Filter Depth = 700mm
• Extended Detention Depth = 0.5m
Lot 7 South Proposed Bio-Retention Area (as modelled):
• Filter Area = 33m2
• Surface Area = 33m2
• Filter Depth = 700mm
• Extended Detention Depth = 0.5m
Note that per the MUSIC Modelling Guidelines, the filter media depth was increased to
700mm to allow for tree and shrubbery planting within the bio-retention basins. This
increase minimises the potential for tree roots damaging the filter media and sub-soil
drainage systems. Larger trees within the proposed bio-retention basins allow for some
landscape screening of the area, and improve the visual amenity of the bio-retention
systems.
Further details on planting schedules in the bio-retention system, including larger trees to
provide landscape screening, will be determined in later detailed design phases.
www.bornhorstward.com.au Page 18
Section 23
5.2.7 Proposed Treatment Train
A ‘Treatment Train’ was developed to target each of the pollutants of concern using bio-retention systems to be
incorporated into the development site layout. This treatment train is illustrated in Figure 3.
Figure 3: Proposed Treatment Train (Entire Development)
5.2.8 Results
The pollutant reductions for the ultimate developed phase of the site using bio-retention basins, with the inclusion of the
detailed treatment train, as obtained from the MUSIC model and analysis are summarised in Table 29. below
Table 29: Pollutant Removal Rates Discharge (Entire Development)
Pollutant TSS (%) TP (%) TN (%) GP (%)
Treatment Train Effectiveness 81.4 70.0 62.7 97.3
WQOs 80.0 60.0 45.0 90.0
As indicated in the table above, the removal rates for the target pollutants; total suspended solids (TSS), total phosphorus
(TP), total nitrogen (TN) and gross pollutants (GP) are all above the water quality objectives stipulated in the State
Planning Policy and Noosa Shire Council Planning Scheme. Therefore, the proposed treatment train for these areas will
yield satisfactory pollutant removal.
www.bornhorstward.com.au Page 19
Section 24
6. NOOSA SHIRE COUNCIL CODES
The relevant Noosa Shire Council Codes with respect to engineering aspects for assessment of the Development
Application have been addressed. The codes will assist in assessing operational works requirements. The codes addressed
in this report include: -
− Acid Sulfate Soils Overlay Code;
− Earthworks Code; and
− Water Quality and Drainage Code.
The completed codes can be found attached in Appendix H of this Report.
7. SUMMARY
This Engineering Report has demonstrated that the proposed development located at 28 Eenie Creek Road, Noosaville
QLD 4566, can be developed in accordance with Engineering Best Management Practice, Noosa Shire Council guidelines,
QUDM 2017 and the State Planning Policy 2017. The following points summarise the findings and recommendations:
− The proposed development site has no mapped flood levels or flags for building or development purposes and is
expected to be at low risk of flooding from Eenie Creek;
− A local flood assessment was undertaken to ensure adequate protection from local flood events within the
natural drainage channel in the environmental zone within Covent J adjoining the development site;
− New stormwater connections are proposed from the development site to the existing stormwater piped network
located along the private access roadway and the adjoining environmental zone and natural drainage channel;
− Minor storm events will be collected by internal stormwater infrastructure within the development sites and
surface car parking areas. This infrastructure will convey flow towards the surrounding stormwater infrastructure
within the surrounding private access roadways, to ultimately discharge into Eenie Creek to the south;
− Major storm events will be conveyed via overland flow onto the surrounding private access roadways or
adjoining environmental zone and natural drainage channel as per existing conditions;
− Stormwater detention is proposed across all three sites as there will be an increase to the impervious area across
as a result of the proposed development, which will take the form of below-ground detention tanks;
− The local flood assessment also determined that the proposed development will increase flood event water levels
downstream of the development site if stormwater quantity run-off is not mitigated to below those of existing
levels;
− In accordance with the State Planning Policy and the Noosa Shire Council Planning Scheme, stormwater quality
treatment measures are proposed as the site area is over 2,500m 2, and quality treatment devices in the form of
bio-retention systems will be located across the three sub-catchments of the development site; and
− The characteristics of the three catchments across the development site remain unchanged due to the proposed
development.
www.bornhorstward.com.au Page 20
Section 25
BORNHORST +WARD APPENDIX A DEVELOPMENT DRAWINGS www.bornhorstward.com.au
Section 26
1 1 2 Sim
Rev. Date Description Iss. Appr.
3000 2000 2000 A 23.05.2023 DEVELOPMENT APPLICATION ISSUE MM GS
B 20.11.2023 INFORMATION REQUEST RESPONSE MM GS
2 01
1
4
300
30
Do not scale this drawing. Verify all dimensions on site before commencing
any work. Copyright © 2023 Buchan. This drawing remains the property of
The Buchan Group Australia Pty Ltd. Reproduction in whole or in part without
prior consent is forbidden.
File
\ACCDocs\Buchan\719021-R22-Noosa_Civic_Precinct\
NOOSA CIVIC
EXISTING CENTRE
CAR PARKING SCHEDULE
LOT 3 GROUND LEVEL NORTH 192
inclusive of STANDARD 188
PWD 4
BASEMENT 444
1 inclusive of STANDARD
PWD
435
9
8500
STORAGE
STORAGE
STORAGE
LOT 7 GROUND LEVEL 86
BICYCLE
BICYCLE
BICYCLE
2 3
inclusive of STANDARD 85
PWD 1
2000
8500
444 PARKING BAYS STREET GROUND LEVEL 28
inclusive of STANDARD 28
3 PWD N/A
4
8500
TOTAL COMBINED LOT 3 / 7 / STREET 750
inclusive of STANDARD 736
5
PWD 14
8500
BICYCLE PARKING SCHEDULE
6 4
LOT 3 PUBLIC BICYCLE RACK
END OF TRIP SECURE STORAGE
44
62
3000
8500
LOT 7 PUBLIC BICYCLE RACK 12
7 TOTAL COMBINED LOT 3 / 7 / STREET 118
8500
APARTMENT SCHEDULE
8
(SMALL DWELLING)
LOT 3 1 BEDROOM, 1 BATH 52
8500
LOBBY
2 BEDROOM, 2 BATH 33
9 LOT 7 1 BEDROOM, 1 BATH
2 BEDROOM, 2 BATH
13
23
BICYCLE
8500
RACKS
PLANT
TOTAL COMBINED LOT 3 / 7 121
10 RAMP UP
TO GROUND
8500
11 ARTS AND
INNOVATION
RAMP DOWN
FROM GROUND
8500
225m2 BICYCLE
STORAGE
BICYCLE
STORAGE
12 LOBBY
8500
13 ARTS AND
8500
INNOVATION Project
2 145m2 NOOSA CIVIC VILLAGE
14 2002 MIXED USE DEVELOPMENT
8500
28 Eenie Creek Rd
15
BICYCLE
Noosaville QLD 4566
RACKS
ARTS AND
PLANT
8500
PLANT
INNOVATION
75m2
16
Project Number
719021
Status
DEVELOPMENT PRECINCTS TOTAL AREA USE DEVELOPMENT APPLICATION
Date Plotted
BIO BASIN 20/11/2023 9:13:55 PM N
VILLAGE MIXED USE 7,500m2 SHOP
Date Issued
FOOD AND DRINK OUTLET 20.11.2023
OFFICE Scale
1 : 500 @A1
HEALTH CARE SERVICE 0 5 10 20 30M
BAR AND DINING 1,100m2 BAR Drawing Title
FOOD AND DRINK OUTLET
BASEMENT PLAN
RECREATION 2,700m2 INDOOR SPORT AND RECREATION
CINEMA 3,070m2 THEATRE
BUSINESS 3,000m2 OFFICE
HEALTH CARE SERVICE
ARTS AND INNOVATION 445m2 RESEARCH AND TECHNOLOGY
Drawing Number Revision
MULTIPLE DWELLING number of apartments A-DA-1010 B
1 BEDROOM, 1 BATH 17
2 BEDROOM, 2 BATH 28
8750 4400 8500 8500 8500 8500 8500 8500 8500 8500 8500 8500 8500 8500 8500 8500 8500 8500 8500 RESIDENTIAL 8,450m2
SHORT TERM ACCOMMODATION
1 BEDROOM, 1 BATH 48
A B C D E F G H I J K L M N O P Q R S T 2 BEDROOM, 2 BATH 28
2 1 2 Brisbane Studio
3000 2000 2000 + 61 7 3859 9222 / buchangroup.com.au
Section 27
Sim
1 1 2 Rev. Date Description Iss. Appr.
3000 2000 2000 A 23.05.2023 DEVELOPMENT APPLICATION ISSUE MM GS
B 20.11.2023 INFORMATION REQUEST RESPONSE MM GS
NOMINAL FUTURE PEDESTRIAN CONNECTION
RL 8.00
NOMINAL
2 01
1
4
300
EX
30
BIO
IST
ING
-BA
SIN
FO
STAIR TO LEVEL 1
BUSINESS BUSINESS
OT
PA
2
TH
BICYCLE
565m2 RACKS 660m2
2003
STAIR TO STAIR TO
LEVEL 1 LEVEL 1
VE
HIC
LIFT & STAIR
EX
TO LEVEL 1
LE
IST
C
ING
RO
FO
SS
SRV
OT
OV
PA
ER
BIO
TH
-BA
REFUSE
SIN
192 PARKING BAYS
BIO
BIO-BASIN
POSSIBLE CONNECTION TO
-BA
FUTURE DEVELOPMENT
SIN
REFUSE
LOADING
3001
CRO
VEH OVER
3002
SS
ICLE
Do not scale this drawing. Verify all dimensions on site before commencing
REFUSE AND LOADING any work. Copyright © 2023 Buchan. This drawing remains the property of
NOOSA CIVIC
BICY KS
RAC
The Buchan Group Australia Pty Ltd. Reproduction in whole or in part without
1
SCREENED AND prior consent is forbidden.
CLE
SETBACK FROM
EXISTING CENTRE
TO LEVEL 1
& LEVEL 2
STREET
5000
STAIR
File
BIO-BA
VILLAGE MIXED USE
\ACCDocs\Buchan\719021-R22-Noosa_Civic_Precinct\
SIN
370m2
CAR PARKING SCHEDULE
REFUSE
MRV LIGHTWEIGHT SHADE LOT 3 GROUND LEVEL NORTH 192
RL STRUCTURE ABOVE inclusive of STANDARD 188
BICYCLE
8.95 RACKS CARPARKING PWD 4
EASEMENT AM LIFT & STAIR
SHOWN DASHED
BASEMENT 444
1
0
TO LEVEL 1 inclusive of STANDARD 435
00
STAIR FROM
& LEVEL 2
PE
BASEMENT
LIFT & STAIR LIFT & STAIR LIFT & STAIR
11
PWD 9
DE TO LEVEL 1
& LEVEL 2
TO LEVEL 1
& LEVEL 2
TO LEVEL 1
& LEVEL 2
S AMENITIES
CO TRIA LOT 7 GROUND LEVEL 86
BICYCLE
RACKS
2 3 NN N 3
inclusive of STANDARD 85
(WHEELCHAIR ACCESSIBLE)
EC BR PWD 1
2000 TIO IDG STAIR FROM STAIR FROM STAIR FROM
2000
N E LEVEL 1 & LEVEL 2
6000
LEVEL 1 & LEVEL 2
6000
LEVEL 1 & LEVEL 2
STAIR FROM
BASEMENT
STREET GROUND LEVEL 28
inclusive of STANDARD 28
BAR AND DINING VILLAGE MIXED USE VILLAGE MIXED USE
COV
3
VILLAGE MIXED USE
TAXI RANK
PWD N/A
620m2 895m2 690m2
BICYCLE LANE
BICYCLE LANE
ENA
4 COVENANT J LOT 7
340m2
TOTAL COMBINED LOT 3 / 7 / STREET 750
inclusive of STANDARD 736
FUTURE
4000
NT A
5
PWD 14
TO LEVEL 1
DEVELOPMENT
& LEVEL 2
CARPARING
CARPARING
PARALELL
PARALELL
STAIR
J
BICYCLE PARKING SCHEDULE
BASEMENT BELOW
6 4 2 3
LOT 3 PUBLIC BICYCLE RACK 44
20500
3002
VILLAGE GREEN 86
END OF TRIP SECURE STORAGE 62
3000 3003 3002 3000
3000m2 PARKING LOT 7 PUBLIC BICYCLE RACK 12
BAYS
7 PEDESTRIAN
CROSSING TOTAL COMBINED LOT 3 / 7 / STREET 118
RL
4000
LIFT FROM BASEMENT
TO LEVEL 1
TRAVELATORS STAIR
& LEVEL 2
8.95 FROM BASEMENT TO LEVEL 1
APARTMENT SCHEDULE
VILLAGE MIXED USE
8
(SMALL DWELLING)
STAIR
BAR AND DINING VILLAGE MIXED USE VILLAGE MIXED USE VILLAGE MIXED USE LANDSCAPED RETAINING LOT 3 1 BEDROOM, 1 BATH 52
340m2
BATTER TO TIE INTO 2 BEDROOM, 2 BATH 33
480m2 615m2 340m2 410m2 EXISTING TOPOGRAPHY
9 LOT 7 1 BEDROOM, 1 BATH 13
EASEMENT AK
MAIN STREET
2 BEDROOM, 2 BATH 23
BICYCLE
RACKS
(PRIVATE ROAD)
BIO-BASIN
RL LIFT & STAIR TOTAL COMBINED LOT 3 / 7 121
8.25 TO LEVEL 1
10 STAIR FROM STAIR FROM STAIR FROM
& LEVEL 2
LEVEL 1 & LEVEL 2
LEVEL 1 BASEMENT LEVEL 1
SECURE PRIVATE
STAIR FROM
CORRDIOR TO Section 28
ACCESS
N
TIO
11
GROUND FLOOR
BEL NOVA
28 APARTMENTS
OW
RECREATION VILLAGE MIXED USE PARKING
IN
ND
BAYS
SA
RL 1500m2 3500m2
ART
3 3
LIFT & STAIR
12
7.50 TO LEVEL 1 & LEVEL 2
AMENITIES
1102 1103
STAIR FROM
BASEMENT
LOADING DOCK
13
TO LEVEL 1
& LEVEL 2
Project
STAIR
N
NOOSA CIVIC VILLAGE
TIO
RL
2
SIN
LO VA
PLANT
14
6.75
BE INNO
BIO-BA
W
2002 MIXED USE DEVELOPMENT
D
AN
BICYCLE
TS
AR
RACKS
POSSIBLE CONNECTION TO
28 Eenie Creek Rd
15
SWITCHROOM
VER
BIO-BASIN FUTURE DEVELOPMENT
SUBSTATION
Noosaville QLD 4566
N
SSO
O
STAIR
TI
REFUSE
W VA
FROM LEVEL 1
CRO
LO NO
PLANT
REFUSE STAIR FROM STAIR FROM & LEVEL 2
BE IN
D
LE
BASEMENT LEVEL 1
AN
IC
TS
VEH
16
AR
RL RAMP TO
6.00 BASEMENT
Project Number
719021
Status
DEVELOPMENT PRECINCTS TOTAL AREA USE DEVELOPMENT APPLICATION
BIO Date Plotted
BE BA 21/11/2023 9:46:58 AM N
LO SIN
W
VILLAGE MIXED USE 7,500m2 SHOP
Date Issued
20.11.2023
SIN
FOOD AND DRINK OUTLET
-BA
RL
OFFICE Scale
BIO
5.25 1 : 500 @A1
HEALTH CARE SERVICE 0 5 10 20 30M
BAR AND DINING 1,100m2 BAR Drawing Title
FOOD AND DRINK OUTLET
FLOOR PLAN
PATH
LOT 3 RECREATION 2,700m2 INDOOR SPORT AND RECREATION
FOOT
FUTURE
CINEMA 3,070m2 THEATRE
NG
RL
EASEMENT AL DEVELOPMENT
EXISTI
4.50
ALONG FULL LENGTH BUSINESS 3,000m2 OFFICE
HEALTH CARE SERVICE
OF WEST BOUNDARY
RL ARTS AND INNOVATION 445m2 RESEARCH AND TECHNOLOGY
EASEMENT CB 4.20 Drawing Number Revision
MULTIPLE DWELLING number of apartments A-DA-1000 B
1 BEDROOM, 1 BATH 17
2 BEDROOM, 2 BATH 28
RESIDENTIAL 8,450m2
SHORT TERM ACCOMMODATION
1 BEDROOM, 1 BATH 48
A B C D E F G H I J K L M N O P Q R S T 2 BEDROOM, 2 BATH 28
2 1 2 Brisbane Studio
3000 2000 2000 + 61 7 3859 9222 / buchangroup.com.au
The text continues on section 29.
Used in these records
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