Original source · versioned page text
2576 - SBSMP-01 (Feb 2026)
Attached to the e-mail Fw_ Email 2 of 3 - DA lodgement - 18 Taylor Ct Cooroy Lot 2SP197518 - Combined MCU_ OPW_ RAL under CTS (Pt 2).msg.
Original PDF page 1, section 1. The text section number identifies this passage in the reader.
SITE-BASED STORMWATER
MANAGEMENT PLAN
In Association with the Material Change of Use
Application for the Proposed Industrial Development
at
18 Taylor Court, Cooroy
Lot 2 on SP197517
for
RMD Capital Pty Ltd
Ref: 2576-SBSMP-01_Version 1.0
February 2026
See the original
The page text is free to read. Viewing or downloading an original file needs an account.
Log in to see the originalLog in to download the original (2576 - SBSMP-01 (Feb 2026).pdf)
Searchable page text hides email addresses. Original files are unchanged and may show email addresses.
Full text of sections 2 to 32 (of 107)
Section 2
DOCUMENT INFORMATION
Document Title: Site-Based Stormwater Management Plan
Document Reference No. 2576-SBSMP-01 – Version 1.0
Commissioned By: RMD Capital Pty Ltd
Prepared By: Barlow Shelley Pty Ltd
Author: Sheng Xie (BEng(Civil))
Tim Burke (BEng (Civil), CPEng, MIEAust,
Reviewed & Authorised By:
RPEQ, NER)
DOCUMENT CONTROL
Version Date Author Reviewer
1.0 27 February 2026 Sheng Xie Tim Burke
“©2026 Barlow Shelley Pty Ltd All Rights Reserved. Copyright in the whole and every part of this document belongs to
Barlow Shelley Pty Ltd and may not be used, sold, transferred, copied or reproduced in whole or in part in any manner or
form or in or on any media to any person without the prior written consent of Barlow Shelley Pty Ltd”.
Section 3
EXECUTIVE SUMMARY An assessment of the stormwater quality and quantity requirements has been carried out for the proposed development at 18 Taylor Court, Cooroy, in accordance with the Noosa Shire Council Planning Scheme Policy (PSP). The project involves the construction of 54 industrial tenancies, each with a gross floor area ranging from 120 to 370m². The key stormwater management components include a combined bioretention and detention basin. Stormwater quality modelling, conducted using MUSIC software, confirms that the proposed treatment train will meet the required pollutant export removal targets. A bioretention basin with a filter area of 210 m² will provide adequate treatment to meet the pollutant export removal targets in the Noosa Shire Council Planning Scheme and QLD SPP (2017). Stormwater runoff volumes from the pre- and post-development catchment were modelled with a Watershed Bounded Network Model (WBNM) using the initial and constant loss method as per the Australian Rainfall and Runoff (ARR) and Queensland Urban Drainage Manual (QUDM 2016) guidelines. The proposed 472m³ detention basin is sufficient to attenuate total post-development peak flows from the site to pre-development levels for all design storm events up to and including the 1% AEP + CC event. The drainage strategy directs the majority of runoff to the southeast lawful point of discharge (LPOD1). At this location, runoff from LPOD1 is both treated and attenuated before being released into the adjacent stormwater reserve, ensuring that increases in runoff do not cause actionable nuisance to surrounding properties. A smaller, separate catchment discharges to the northeast lawful point of discharge (LPOD2), where flows travel east toward Taylor Court. This discharge is negligible, with a maximum flow of 29 L/s during a 1% AEP event. The overall approach is fully compliant with the requirements of Clause 3.9 in QUDM (2016).
Section 4
CONTENTS 1.0 INTRODUCTION..................................................................................................... 1 2.0 SITE DESCRIPTION ............................................................................................... 2 2.1 Reference Standards and Guidelines .............................................................. 3 2.2 Catchment Hydrology ....................................................................................... 3 3.0 STORMWATER QUALITY MANAGEMENT ........................................................... 5 3.1 Construction Phase .......................................................................................... 5 3.2 Post-Construction Phase ................................................................................. 6 3.3 MUSIC Modelling ............................................................................................... 8 3.4 Stormwater Assets – Maintenance ................................................................ 12 4.0 STORMWATER QUANTITY MANAGEMENT ...................................................... 14 4.1 Summary.......................................................................................................... 14 4.2 Design Storm Events ...................................................................................... 15 4.3 WBNM Hydrologic Model ................................................................................ 16 4.4 WBNM Analysis Pre-Development Scenario ................................................. 17 4.5 WBNM Analysis Post-Development, Unmitigated Scenario......................... 18 4.6 WBNM Analysis Post-Development, Mitigated Scenario.............................. 19 5.0 FLOODING ........................................................................................................... 21 6.0 CONCLUSION ...................................................................................................... 22 7.0 LIMITATIONS AND CLOSURE ............................................................................ 23
Section 5
APPENDICES APPENDIX A - Stormwater Drawings by Barlow Shelley APPENDIX B - Stormwater Quality Objectives APPENDIX C - Previous Approved Engineering Plans by Leddy Sergiacomi APPENDIX D - Rational Method Verification of WBNM Runoff Calculations APPENDIX E - Swale Capacity Calculations by Barlow Shelley APPENDIX F - Noosa Shire Council Flood Search Response
Section 6
1.0 INTRODUCTION
Barlow Shelley Pty Ltd was commissioned by RMD Capital Pty Ltd to prepare a Site-Based
Stormwater Management Plan (SBSMP) for the proposed development located at 18 Taylor
Court, Cooroy, Queensland (Lot 2 on SP197517). The 2.01-hectare site, as shown in Figure
1-1, is proposed for the development of 54 industrial tenancies.
This SBSMP has been prepared to support a Development Approval on this property. Its
primary purpose is to demonstrate that the proposed development complies with the
stormwater quantity and quality management requirements of the Queensland State Planning
Policy (QLD SPP 2017) and the Noosa Shire Council Planning Scheme. The report outlines
the proposed stormwater management strategy, including treatment measures and flow
attenuation, to ensure no worsening of downstream conditions.
Subject
Site
Figure 1-1 Locality map of subject site
2576-SBSMP-01_Version 1.0 (February 2026) Page 1 of 23
SX/TB
Section 7
2.0 SITE DESCRIPTION
The 2.01-hectare (20,139 m²) subject site is situated within a Low Impact Industrial Zone, as
designated by the Noosa Shire Council Planning Scheme. The north and east boundaries
adjoin other industrial lots, while the remaining boundaries border a stormwater reserve. The
entire site is currently paved with compacted aggregate hardstand.
The site grades from approximately RL 127.1m AHD on the southwest boundary down to RL
122.8m AHD on the northeast boundary. The site currently has two lawful points of discharge
(LPODs): LPOD1 in the southeast corner, discharging to the stormwater reserve, and LPOD2
on the northeast corner, discharging to Taylor Court.
The proposed earthworks and regrading will unify the site's surface drainage to direct most of
the stormwater to LPOD1. This report details the hydrologic impact of this flow redistribution
and the proposed mitigation measures.
Subject
Site
Figure 2-1 Subject site and planning zones within the vicinity of Joyner
2576-SBSMP-01_Version 1.0 (February 2026) Page 2 of 23
SX/TB
Section 8
2.1 Reference Standards and Guidelines
The development is subject to the following set of standards and guidelines:
Australian Rainfall and Runoff (ARR) Version 4.2
Queensland State Planning Policy (QLD SPP) 2017
Queensland Urban Drainage Manual (QUDM) 2016
Noosa Shire Council Planning Scheme (Noosa Plan) 2020
2.2 Catchment Hydrology
As shown in Drawings 45113-C02 and 45113-C20 in Appendix C, the previously approved
engineering plans show a single discharge point to LPOD1 in the southeast corner. In the
absence of further information, this assessment assumes a single discharge to LPOD1 in the
pre-development scenario.
Catchment plans delineating pre-development and post-development conditions are shown in
Figure 2-2 and Figure 2-3 below. Runoff from the developed site will be conveyed through the
pipe network and overland flows. Runoff from Catchment 1 (shown in purple) will be conveyed
to a combined bioretention and attenuation basin. This basin is located at the southeast corner
of the site and designed to treat and attenuate flows prior to discharge at LPOD1 into the
stormwater reserve. Runoff from Catchment 2 (shown in yellow) represents the area which is
unable to be directed to LPOD1 through the pipe network and overland flow, which will
discharge to LPOD2 on the northeast corner.
2576-SBSMP-01_Version 1.0 (February 2026) Page 3 of 23
SX/TB
Section 9
Hydrologic modelling of both pre-development and post-development scenarios was
undertaken to quantify the impact of the development on the local hydrology. The analysis
demonstrates that the proposed system achieves no worsening of peak runoff discharge
across the overall site.
Figure 2-2 Pre-development catchment plan
Figure 2-3 Post-development catchment plan
2576-SBSMP-01_Version 1.0 (February 2026) Page 4 of 23
SX/TB
Section 10
3.0 STORMWATER QUALITY MANAGEMENT
The proposed development is located within the Noosa Shire Council local government area.
Stormwater quality will be managed in accordance with Section SC6.7.6 of the Noosa Shire
Council Planning Scheme and Tables A and B of Appendix 2 of the QLD SPP 2017. A Model
for Urban Stormwater Improvement Conceptualisation (MUSIC) model was developed to
assess the performance of the proposed Stormwater Quality Improvement Devices (SQIDs).
3.1 Construction Phase
The design objectives for water quality during the construction phase of the development will
be in accordance with Table A in Appendix 2: Stormwater Management Design Objectives,
Part G, QLD SPP (2017) included in Appendix B of this report. The design objectives will be
achieved through appropriate Erosion and Sediment Control procedures during construction.
Typical pollutants generated during construction phase of a development are listed in Table
3-1.
Pollutant Potential Source Priority
Litter Paper, construction packaging, food packaging, High
cement bags, off cuts
Sediment Unprotected exposed soils and stockpiles during High
earthworks and building works
Hydrocarbons Fuel and oil spills, leaks from construction High
equipment and temporary car park areas.
Toxic Materials Cement slurry, asphalt primer, solvents, cleaning Medium
agents, wash waters (e.g. From tile works)
Alkaline substances Cement slurry and wash waters High
Table 3-1 Typical construction phase pollutants
2576-SBSMP-01_Version 1.0 (February 2026) Page 5 of 23
SX/TB
Section 11
The following are typical treatment measures that will be implemented, as required, before the
commencement of any construction works. Detailed erosion and sediment control procedures
are to be undertaken in accordance with the IECA Best Practice Sediment & Erosion Control
and the Erosion and Sediment Control drawings lodged as part of an Operational Works
application.
sensible site planning
diversion of up-slope water (where appropriate)
stabilised site entry/exit point
minimisation of site disturbance and duration of disturbance
installation of sediment control along the lower edge of the site
appropriate location and protection of stockpiles
early connection of roof water downpipes
trap on-site runoff from tool, paint and concrete washing and brick, tile and concrete
cutting
continual monitoring and maintenance of all control measures
compaction of backfilled trenches
revegetation and stabilisation of the site
development and implementation of Erosion and Sediment Control Plans when
appropriate.
3.2 Post-Construction Phase
During the post-construction phase, water quality objectives will adhere to the standards in
Table SC6.7.6.1 of the Noosa Shire Council Planning Scheme and Table B of Appendix 2:
Stormwater Management Design Objectives, Part G, QLD SPP (2017), as provided in
Appendix B of this report. Targets for this site are covered under the limits for South East
Queensland:
Total suspended solids (TSS): 80% reduction from unmitigated development
Total phosphorus (TP): 60% reduction from unmitigated development
Total nitrogen: 45% reduction from unmitigated development
Gross pollutants (>5 mm): 90% reduction from unmitigated development
2576-SBSMP-01_Version 1.0 (February 2026) Page 6 of 23
SX/TB
Section 12
Bioretention Basin
Bioretention basins are densely vegetated filtration devices, where runoff (for small/frequent
storm events) enters the basin and is filtered through a filter media layer (e.g. sandy loam with
organics) as it percolates downwards. Bioretention basins often have an extended detention
volume above the filter media which increases the volume of runoff treated through the
system. The runoff is treated as it passes through the system through fine filtration, absorption,
and some biological uptake. Refer to Figure 3-1 below showing a typical cross section of a
bioretention basin.
Figure 3-1 Typical cross section of a bioretention basin (Source: Healthy Waterways WSUD Technical Design Guidelines)
Bioretention provides a number of functions including:
Reduce the total volume & velocity of runoff.
Trap sediment and associated pollutants; and
Reduce concentrations of nutrients such as Nitrogen and Phosphorous.
2576-SBSMP-01_Version 1.0 (February 2026) Page 7 of 23
SX/TB
Section 13
3.3 MUSIC Modelling
MUSIC (Version 6.3.0) was used to model both the expected pollutant loads generated by the
development and the effectiveness of the proposed WSUD treatments. Rainfall, pollutant
loads, and treatment node parameters were derived from the MUSIC Modelling Guidelines
(for South East Queensland) V1.0 (Water by Design, 2010).
3.3.1 Split Catchment Approach
The development site was divided into catchments based on surface types (roof, paved,
pervious) as shown in Table 3-2. This approach allows for accurate representation of runoff
volumes and pollutant generation from different surfaces. Surface areas were calculated from
electronic CAD drawings of the development plan, consistent with the methodology outlined
in Table 3.4 of the MUSIC Modelling Guidelines.
The developed site has an average impervious area of 86%. The pervious "Mixed" surface
type (0% impervious) encompasses all landscaped and vegetated areas, accounting for their
rainfall absorption capacity.
Source Node Area (Ha) Surface Type % Impervious
C1-Roof 0.900 Roof 100
C1-Hardstand 0.647 SealedRoad 100
C1-Pervious 0.259 Mixed 0
C2-Roof 0.000 Roof 100
C2-Hardstand 0.035 SealedRoad 100
C2-Pervious 0.000 Mixed 0
Table 3-2 Adopted areas and percentage imperviousness for the subject site
2576-SBSMP-01_Version 1.0 (February 2026) Page 8 of 23
SX/TB
Section 14
3.3.2 MUSIC Meteorological Data
Meteorological data from Nambour Station (040282) was used for the MUSIC analysis. In
accordance with Section 3.2 of the MUSIC Modelling Guidelines, a 10-year climate period and
a 6-minute time step were selected. The model used rainfall and evapotranspiration data from
01/01/1989 to 31/12/1998, as specified in Table A1.1, Appendix A.1 of the guidelines.
Input parameters for the rainfall-runoff, source nodes and treatment devices were also
obtained from the guidelines. The following parameters were selected based on a
commercial/industrial development.
3.3.3 Rainfall-Runoff Parameters
The rainfall-runoff parameters listed in Table 3-3 below were used in the model. These
parameters are as recommended by the MUSIC Modelling Guidelines.
Parameter Commercial / Industrial
Rainfall Threshold (mm/day) 1
Soil Storage Capacity (mm) 18
Initial Storage (% of Capacity) 10
Field Capacity (mm) 80
Infiltration Capacity Coefficient – a 243
Infiltration Capacity Exponent – b 0.6
Initial Depth (mm) 50
Daily Recharge Rate (%) 0
Daily Baseflow Rate (%) 31
Daily Deep Seepage Rate (%) 0
Table 3-3 Recommended rainfall-runoff parameters
3.3.4 MUSIC Pollutant Export Parameters for Split Catchment Land Use
TSS log10 (mg/L) TP log10 (mg/L) TN log10 (mg/L)
Flow Type Surface Type
Mean St. dev. Mean St. dev. Mean St. dev.
Roof N/A N/A N/A N/A N/A N/A
Base Flow Road 0.78 0.45 -1.11 0.48 0.14 0.20
Ground 0.78 0.45 -1.11 0.48 0.14 0.20
Roof 1.30 0.44 -0.89 0.36 0.25 0.32
Storm Flow Road 2.43 0.44 -0.30 0.36 0.25 0.32
Ground 1.92 0.44 -0.59 0.36 0.25 0.32
Table 3-4 Pollutant export parameters
2576-SBSMP-01_Version 1.0 (February 2026) Page 9 of 23
SX/TB
Section 15
3.3.5 MUSIC Treatment Node Parameters
Bioretention Basin
Figure 3-2 shows the parameters used for the bioretention basin node. The basin has been
sized to fit within the available space at the southeast corner of the site, resulting in a filter
area of 210m². It features an extended detention depth of 300mm and has no saturated zone.
Figure 3-2 Bioretention parameters for the bioretention strip
Note: *Healthy Waterways recommends using MUSIC version 6 to ensure compliance with stormwater pollutant load reduction
objectives, with the following parameters adopted when modelling bioretention filter media:
• Minimum 30 mg/kg Orthophosphate (OP)
• Minimum 400 mg/kg Total Nitrogen (TN)
Source: http://hlw.org.au/initiatives/waterbydesign/water-sensitive-urban-design-wsud, viewed 28/05/19.
2576-SBSMP-01_Version 1.0 (February 2026) Page 10 of 23
SX/TB
Section 16
3.3.6 MUSIC Model Results
The model schematic is shown in Figure 3-3. The MUSIC contaminant sources, residual
loading at the discharges from site, and pollutant load reductions are shown in Figure 3-4
below. These results were generated stochastically as per the MUSIC Modelling Guidelines.
Figure 3-3 Pollutant export model schematic for post-development scenario
Figure 3-4 Post-development MUSIC result summary from the site
Discharge targets for the overall site were compliant with the requirements specified in QLD
SPP (2017), Table B in Appendix 2: Stormwater Management Design Objectives, Part G.
2576-SBSMP-01_Version 1.0 (February 2026) Page 11 of 23
SX/TB
Section 17
3.4 Stormwater Assets – Maintenance Each aspect of a water quality treatment train must be maintained to function as designed and achieve the performance targets calculated in the MUSIC model. Proprietary treatment devices shall be regularly serviced in accordance with manufacturer’s requirements to maintain treatment efficiencies. 2576-SBSMP-01_Version 1.0 (February 2026) Page 12 of 23 SX/TB
Section 18
3.4.1 Bioretention Basin
There are a number of regular maintenance tasks required to keep the planters in efficient
working order and preserve their amenity:
Minor Erosion is to be treated by reprofiling the basin surface (adding new filter media
as required) with hand tools and replanting with replacement vegetation from other
parts of the basin.
Litter is to be manually removed from the basin surface and especially near all grated
outlets to prevent blockages.
Sediment, although primarily controlled by other means, needs to be removed from
the basin occasionally. The basin surface is to be cleared of sediment build-up using
a flat bladed shovel or vacuumed in dry weather only.
Weeds must be controlled in bioretention basins to prevent clogging of the filter media
surface and competition with the established macrophyte planting in the basin. Weeds
can be physically removed or chemically controlled using herbicides. Care must be
taken when selecting herbicides to ensure they are suitable for use in aquatic areas
and should only be applied by a competent, experienced person with ChemCert
Training. Herbicide shall be applied by either foliar spot spraying or rope/wick
application to limit contact with other plants.
The majority of bioretention maintenance is within the initial two-year establishment period. It
is recommended that the road reserve bioretention basins are provided with geofabric and a
temporary turf covering to the filter surface while the residential lots in the proposed
subdivision are being built out.
3.4.2 Maintenance Schedule
The maintenance schedule set out in Table 3-5 shall be adopted for the development and the
vegetated stormwater treatment areas maintained in accordance with this section and the
guidelines from Water by Design.
Stormwater Treatment Maintenance
Tasks
Asset Frequency
Repair erosion, remove litter and sediment,
Bioretention Basin 12 months
control weeds
Table 3-5 Maintenance schedule
2576-SBSMP-01_Version 1.0 (February 2026) Page 13 of 23
SX/TB
Section 19
4.0 STORMWATER QUANTITY MANAGEMENT
4.1 Summary
Stormwater quantity management for the proposed development has been assessed in
accordance with the Noosa Shire Council Planning Scheme and the Queensland Urban
Drainage Manual (QUDM 2016).
The post-development condition will generate an increase in impervious area. The key
objective is to ensure that post-development peak discharge rates do not exceed pre-
development levels for all design storm events up to the 1% AEP + CC event, and that
changes to flow distribution do not cause an actionable nuisance on surrounding properties
or infrastructure.
The existing site generally grades from west to north-east. The lot sits at the crest of a broader
regional catchment which also grades to the east. In the developed scenario, the proposal
sees of most of the site runoff directed to LPOD1, with only minor flow discharging to LPOD2.
The catchment plan is shown in Figure 2-3.
LPOD1: To the southeast, discharging to the adjacent stormwater reserve.
LPOD2: To the northeast, discharging to Taylor Court.
2576-SBSMP-01_Version 1.0 (February 2026) Page 14 of 23
SX/TB
Section 20
4.2 Design Storm Events
The major storm was identified as the 1% AEP + CC storm in accordance with Noosa Shire
Council Planning Scheme Section SC6.7.6 d (Engineering Design Standards – Stormwater
Management). This event is also known as the defined flood event (DFE).
Peak stormwater discharge for pre- and post-development conditions were modelled using
the Australian Rainfall and Runoff (ARR) guidelines and data from the Bureau of Meteorology
(BOM) Design Rainfall Data System. The hydrological model was developed using Watershed
Bounded Network Model (WBNM) 2019, using the 10 location-specific temporal patterns
provided by ARR Data Hub.
The analysis assessed the following annual exceedance probability (AEP) events. Annual
recurrence interval (ARI) and exceedances per year (EY) are alternative measures.
63.2% AEP (1 EY, 1-year ARI)
50% AEP (1.44-year ARI)
20% AEP (4.48-year ARI)
10% AEP (9.49-year ARI)
5% AEP (20-year ARI)
2% AEP (50-year ARI)
1% AEP (100-year ARI) (Major, DFE)
A 20% increase in rainfall depth has also been applied across all design rainfall data to
account for climate change as specified in Noosa Shire Council Planning Scheme Section
SC6.7.6 d.
All permutations of the 10 ARR temporal patterns and storm durations (10 min – 7 days) were
simulated. The critical storm pattern and duration for each node was used to calculate the
peak discharge.
2576-SBSMP-01_Version 1.0 (February 2026) Page 15 of 23
SX/TB
Section 21
4.3 WBNM Hydrologic Model
A lumped parameter hydrological model was developed to simulate the rainfall-runoff
response for pre-development and post-development scenarios. Rainfall losses due to
infiltration were taken from the ARR Data Hub provisions for the catchment location. A stream
lag factor of 0.5 was applied for artificial channels and 1.0 for natural channels.
Initial Losses (mm) Continuing Losses (mm/h)
Pervious (ARR Data Hub) 32 2.6
Impervious 0 0
Table 4-1 ARR2016 Initial and continuing losses from the ARR Data Hub
The pre-development and post-development catchments are shown in the tables below. Catchment 1 encompasses the entire
site. Refer to Figure 2-2 Pre-development catchment plan
Figure 2-3 for the post-development catchment plan.
Area (m²) % Imperv
Catchment 1 18403 0%
Table 4-2 Pre-development catchment parameters
Area (m²) % Imperv
Catchment 1 18054 86%
Catchment 2 349 100%
Total 18403 86%
Table 4-3 Post-development catchment parameters
The proposed stormwater system generally functions as follows:
Runoff from roof areas will collect in gutters, which is conveyed through the pipe
network to the stormwater basin. The paved areas are shaped to direct flows
southward to the stormwater basin.
In a storm exceeding the primary event, the overland flow paths have sufficient
capacity to convey the flows to the basin, where it is discharged via the spillway. The
discharge point of the basin is to be directed into the stormwater reserve. The
catchment at the northeast side unable to be graded toward LPOD1 runs eastward to
LPOD2 toward Taylor Court.
2576-SBSMP-01_Version 1.0 (February 2026) Page 16 of 23
SX/TB
Section 22
4.4 WBNM Analysis Pre-Development Scenario
A WBNM was approximated for the existing catchments according to existing site parameters.
The model estimated that the existing 1% AEP peak flow discharge from the site was
0.8m3/s overall. Pre-development peak flow rates for all design storms are provided in Table
4-4.
EXISTING CASE - COMBINED
Peak Flow Rates - Q (m3/s)
AEP WBNM RM Difference
63.2% 0.197 0.209 6.1%
50% 0.242 0.277 14.5%
20% 0.457 0.384 -16.0%
10% 0.485 0.465 -4.1%
5% 0.578 0.552 -4.5%
2% 0.725 0.704 -2.9%
1% 0.801 0.807 0.7%
Table 4-4 WBNM discharge flow rates for pre-development catchments
The Rational Method was used to provide an estimate of a range of flows for the total pre-
development catchment for comparison and verification of the WBNM model. See Appendix
D for calculations. The Rational Method results are within 20% of the results obtained from
the WBNM analysis for the pre-development case across all storm events. From the
comparison of results, it is determined that the Rational Method verification corresponds well
with the WBNM analysis results.
2576-SBSMP-01_Version 1.0 (February 2026) Page 17 of 23
SX/TB
Section 23
4.5 WBNM Analysis Post-Development, Unmitigated Scenario
Peak flow rates, for the post-development scenario without any intervention measures, were
generated by WBNM to provide a comparison to the pre-development runoff. The table below
shows peak discharge in all storm events for the unmitigated post-development scenario,
including a difference comparison to the pre-development scenario.
DEVELOPED CASE - LPOD1
Peak Flow Rates - Q (m3/s)
AEP EXISTING DEVELOPED Difference
63.2% 0.197 0.493 150.3%
50% 0.242 0.556 129.8%
20% 0.457 0.748 63.7%
10% 0.485 0.905 86.6%
5% 0.578 1.072 85.5%
2% 0.725 1.212 67.2%
1% 0.801 1.347 68.2%
Table 4-5 WBNM discharge flow rates at LPOD1 for the unmitigated post-development scenario
DEVELOPED CASE - LPOD2
Peak Flow Rates - Q (m3/s)
AEP EXISTING DEVELOPED Difference
63.2% 0.000 0.012 N/A
50% 0.000 0.013 N/A
20% 0.000 0.018 N/A
10% 0.000 0.024 N/A
5% 0.000 0.025 N/A
2% 0.000 0.026 N/A
1% 0.000 0.029 N/A
Table 4-6 WBNM discharge flow rates at LPOD2 for the unmitigated post-development scenario
DEVELOPED CASE - COMBINED
Peak Flow Rates - Q (m3/s)
AEP EXISTING DEVELOPED Difference
63.2% 0.197 0.504 155.8%
50% 0.242 0.569 135.1%
20% 0.457 0.766 67.6%
10% 0.485 0.929 91.5%
5% 0.578 1.097 89.8%
2% 0.725 1.239 70.9%
1% 0.801 1.376 71.8%
Table 4-7 WBNM discharge flow rates from the site for the unmitigated post-development scenario
2576-SBSMP-01_Version 1.0 (February 2026) Page 18 of 23
SX/TB
Section 24
The overall site discharge for the unmitigated scenario shows a net increase for all storm
events, due to the increase in imperviousness across the site. The increase in peak site
discharge ranges from 70% to 160%, with a greater increase in more frequent events. Note
that LPODs are hydrologically disconnected and overall values are only provided for gross
assessment. These increased flows will be mitigated through stormwater management
measures to ensure discharge rates do not exceed pre-development conditions.
4.6 WBNM Analysis Post-Development, Mitigated Scenario
To mitigate the effect of the increase in runoff volume from the developed site, a detention
basin has been proposed to attenuate flows such that post-development peak discharge rates
do not exceed pre-development rates for all design storms. The WBNM results confirm this
objective is met, with a reduction in flows from the pre-development peak discharge across all
events.
MITIGATED CASE - LPOD1
Peak Flow Rates - Q (m3/s)
AEP EXISTING MITIGATED Difference
63.2% 0.197 0.187 -5.1%
50% 0.242 0.228 -5.8%
20% 0.457 0.365 -20.1%
10% 0.485 0.437 -9.9%
5% 0.578 0.525 -9.2%
2% 0.725 0.608 -16.1%
1% 0.801 0.662 -17.4%
Table 4-8 WBNM discharge flow rates at LPOD1 for the mitigated post-development scenario
MITIGATED CASE - LPOD2
Peak Flow Rates - Q (m3/s)
AEP EXISTING MITIGATED Difference
63.2% 0.000 0.012 #DIV/0!
50% 0.000 0.013 #DIV/0!
20% 0.000 0.018 #DIV/0!
10% 0.000 0.024 #DIV/0!
5% 0.000 0.025 #DIV/0!
2% 0.000 0.026 #DIV/0!
1% 0.000 0.029 #DIV/0!
Table 4-9 WBNM discharge flow rates at LPOD2 for the mitigated post-development scenario
2576-SBSMP-01_Version 1.0 (February 2026) Page 19 of 23
SX/TB
Section 25
MITIGATED CASE - COMBINED
Peak Flow Rates - Q (m3/s)
AEP EXISTING MITIGATED Difference
63.2% 0.197 0.188 -4.6%
50% 0.242 0.230 -5.0%
20% 0.457 0.368 -19.5%
10% 0.485 0.444 -8.5%
5% 0.578 0.530 -8.3%
2% 0.725 0.614 -15.3%
1% 0.801 0.668 -16.6%
Table 4-10 WBNM discharge flow rates from the site for the mitigated post-development scenario
To suitably attenuate flows at LPOD1, a detention basin will be integrated with the proposed
bioretention system. The basin features a weir height of 1.35m from the base, providing a
storage volume of 472m³. The weir is 5m wide, designed to operate with less than 10mm
depth of flow. Outlets include a 300 mm orifice for low flows, a 300 mm orifice outlet located
0.45m above the base, and a 375 mm orifice outlet located 0.6m above the base for mid flows.
The location of the detention basin is shown in Drawing C300 in Appendix A.
No stormwater flow mitigation measures are proposed for Catchment 2 flowing to LPOD2, as
the area of 349 m² is considered sufficiently small, with a maximum discharge of 29 L/s in a
1% AEP event, for any adverse effects from uncontrolled discharge to be negligible.
2576-SBSMP-01_Version 1.0 (February 2026) Page 20 of 23
SX/TB
Section 26
5.0 FLOODING
The subject site is not shown to be impacted by regional flooding. Flood mapping from Noosa
Shire Council Disaster Management Mapping (see Figure 5-1) shows that there is no flood
encumbrance for this site. Noosa Shire Council has confirmed that no modelling or historical
flood data is available for this site (see Appendix F).
The site is situated at the high point of the local catchment. The terrain data indicates a 1m
high constructed berm along the western and southern boundaries, each containing a swale
that extends north and west, respectively. These swales average 5 meters in width and 0.3
meters in depth, with a longitudinal grade of 1%. Each swale has a flow capacity of 0.9 m³/s,
resulting in a total combined capacity of 1.8 m³/s (see Appendix E for swale capacity
calculations).
This capacity is equivalent to the runoff generated by 1 Ha of pervious land in each direction.
The upstream catchment area draining to these swales is conservatively estimated at up to
1.2 Ha of pervious surface. Therefore, the swales provide more than sufficient capacity to
convey flows from the upstream catchment, with adequate freeboard provided by the bund.
Figure 5-1 Extents of various flood events from Noosa Shire Council Disaster Management Mapping
2576-SBSMP-01_Version 1.0 (February 2026) Page 21 of 23
SX/TB
Section 27
6.0 CONCLUSION
This stormwater management plan has assessed the proposed development with respect to
both stormwater quality and quantity. The catchment hydrology has been assessed to
ensure the development will not cause actionable nuisance, flooding, or degradation of
runoff quality, and that outcomes are consistent with the requirements of the Noosa Shire
Council Planning Scheme.
Based on this assessment, the following conclusions are made:
A bioretention device with a total of 210m² of filter media is required to achieve
water quality treatment targets.
Hydrological modelling was undertaken in WBNM across a full range of design storm
events, supported by Rational Method verification.
The drainage strategy directs the majority of runoff to the southeast discharge point.
This is consistent with the previous approval for this site.
Increased post-development flows to LPOD1 are attenuated through a 472m³
detention basin, ensuring the overall discharge from the site does not exceed pre-
development levels.
Council mapping has confirmed that the site is not subject to flood encumbrance.
In conclusion, while the peak flow rates and distribution of flows are altered, the overall post-
development discharges are managed such that they do not worsen existing conditions. The
proposed stormwater management system achieves compliance with Noosa Shire Council
requirements, meets water quality treatment targets, and ensures all stormwater is
discharged lawfully in accordance with QUDM (2016).
2576-SBSMP-01_Version 1.0 (February 2026) Page 22 of 23
SX/TB
Section 28
7.0 LIMITATIONS AND CLOSURE This report has been commissioned by RMD Capital Pty Ltd and specifically investigates the subject site as described in this report. We consider that the study addresses the requirements for development of the subject site at the time the study was undertaken. If these conditions are known to change, the results of this study should be reviewed. This report is only to be used in full and may not be used to support objectives other than those set out herein, except where written approval is provided by Barlow Shelley Pty Ltd. Barlow Shelley Pty Ltd accept no responsibility for the accuracy of information supplied to them by second and third parties. Should further information be required please contact the undersigned. AUTHORED BY SHENG XIE – Senior Civil Engineer BEng (Civil) APPROVED BY TIM BURKE – Director BEng (Civil), CPEng, MIEAust, RPEQ (25245), NER For and on behalf of: BARLOW SHELLEY PTY LTD 2576-SBSMP-01_Version 1.0 (February 2026) Page 23 of 23 SX/TB
Section 29
Appendix Stormwater Drawings - Prepared by Barlow Shelley Pty Ltd [OCR of page images] Stormwater Drawings - Prepared by Barlow Shelley Pty Ltd
Section 30
CIVIL OPERATIONAL WORKS
PROPOSED INDUSTRIAL DEVELOPMENT
AT 18 TAYLOR COURT, COOROY
FOR RMD CAPITAL PTY LTD
JOB No. 2576
SCHEDULE OF DRAWINGS
DWG DESCRIPTION
2576 - C000 LOCALITY & SCHEDULE OF DRAWINGS
2576 - C001 GENERAL NOTES
H
O 2576 - C010 OVERALL DEVELOPMENT LAYOUT PLAN
LT
S 2576 - C100 BULK EARTHWORKS PLAN
R
O
AD 2576 - C120 EARTHWORKS TYPICAL SECTIONS (SHEET 1 OF 2)
2576 - C121 EARTHWORKS TYPICAL SECTIONS (SHEET 2 OF 2)
2576 - C200 SITE LEVELS LAYOUT PLAN
N 2576 - C210 PAVEMENT JOINTING PLAN
A
N 2576 - C211 PAVEMENT JOINTING DETAILS
D
R
O 2576 - C270 WASTE COLLECTION & TURN PATHS
YA
B
R R 2576 - C300 STORMWATER DRAINAGE PLAN
U O
C A
T
E D 2576 - C310 STORMWATER CATCHMENT PLAN
UR
H
IG
2576 - C320 STORMWATER LONGITUDINAL SECTIONS
CO
H
W
AY 2576 - C360 BIO & DETENTION BASIN DETAILS & PLAN
S
OR
2576 - C390 STORMWATER CALCULATIONS
YL
SUBJECT
TA
SITE
THESE PLANS HAVE BEEN PREPARED FOR A COMBINED
MATERIAL CHANGE OF USE AND OPERATIONAL WORKS
PERMIT APPLICATION ONLY AND ARE NOT SUITABLE FOR
SUBMISSION WITH ANY OTHER COUNCIL APPLICATION.
CIVIL DESIGN BASED ON:
FIELD SURVEY BY ##DSQ LAND SURVEYORS##
DWG No. 16149-DTM-01 DATED 16/12/2025
GDA2020 MGA56
p:\2576-18 taylor ct, cooroy\02 design\01 acad\c000 locality & schedule of drawings.dwg
ARCHITECTURAL PLANS BY
##BUILDING SUNCOAST GREEN##
LOCALITY PLAN DWG No. 2025-68 02 DATED 03/12/2025
SCALE 1:2000
IMAGE SOURCE: NEARMAP
PROPERTY DESCRIPTION NOTE:
LOT 2 ON SP197517 THESE DESIGN DRAWINGS HAVE BEEN PREPARED FROM THIRD PARTY INFORMATION RECEIVED FROM THE FOLLOWING
18 TAYLOR COURT, COOROY CONSULTANTS. ALL SET-OUT, LEVELS AND LOCATIONS MUST BE CROSS CHECKED BY A LICENSED SURVEYOR BEFORE
NOOSA SHIRE COUNCIL COMMENCING CONSTRUCTION TO ENSURE COMPLIANCE WITH CURRENT MAPPING GRIDS, HEIGHT DATUMS AND BUILDING
SITE AREA = 20.016 Ha SETBACKS.
SURVEYOR : <DSQ LAND SURVEYORS> PH: <5437 8555>
PROJECT: JOB NUMBER
REV DATE DESCRIPTION BY CHKD DETAILS SCALE APPROVED PROPOSED INDUSTRIAL DEVELOPMENT
A 27.02.26 FOR APPROVAL GS DTB
Barlow Shelley Pty Ltd
ABN 29 679 702 599
AT 18 TAYLOR COURT, COOROY 2576
DATUM AHD
DESIGN DTB 1:2000 20 0 20 40 60 80 100 A1
................. 07 5443 8285 FOR RMD CAPITAL PTY LTD
PO Box 899
1:4000 Engineer: TIM BURKE Maroochydore 4558 DRAWING TITLE: DRAWING NUMBER REV
DRAWN GS A3
[email protected]
DESIGN CHECK TB
(RPEQ 25245)
barlowshelley.com.au
LOCALITY & SCHEDULE OF DRAWINGS C000 A
DRAWING STATUS
DATE FEB 2026 This drawing is not to be copied or amended without written permission from Barlow Shelley Pty Ltd
FOR APPROVAL
Section 31
/ / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / / /
>
>
>
>
>
/
STAGE 5
/
>
STAGE 3
/
>
/
>
>
7.0
>
>
/ >
12
/
>
/
>
/
>
>
43 44 45 46 47 48 49 50 51 52 53 54
>
37 38 39 40 41 42
>
/ >
/
>
WHEEL STOPS IN
>
/
/
>
>
>
>
/
5
>
26.
/
>
ACCORDANCE WITH AS 2890.
>
/
1
/
>
>
1.3m 5.4m
>
/
>
>
125.00
/
>
>
/
/
>
>
12
>
/
4.9
>
>
0
/
2.4m 124.90
>
.90
>
/
124
/
>
124.90
124.90
>
>
124
/
STAGE LEGEND
Section 32
>
.80
>
/
124.80
13.7m
13.7m
>
>
0 0
/
124.8 4.8
>
/
124.8
12
>
SW SW SW SW 0
SW SW SW SW
>
/
SW SW
>
.0 SW
>
1
/
26 SW
24.8
>
0 124.8
0
SW 124.8
>
1 124.80 SW
/
124.70 0
>
/
SW
>
SW
7.0m
7.0m
/
>
124
>
.90
SW PAVED STAFF SUBJECT SITE
>
.90
/
124.9 124
>
0
>
124.90
12
124.90
/
124.90 124.90
>
/
>
4
/
SW
>
3.6m
.70
6.0m
>
RECREATIONAL AREA
>
/
>
>
STAGE 1 BOUNDARY
/
2.5m
>
2.5m
/
>
/
>
>
.0 6.5m 5.4m (3.0m X 3.0m)
>
/
125
>
OOHH
>
/
>
/
/
>
>
30
BIN ENCLOSURE 16.7m STAGE 2 BOUNDARY
>
5.
>
/
SW
BIN The text continues on section 33.