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Attachment 4 - Stormwater Management Plan by O2 · MCU13/0251
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STORMWATER MANAGEMENT PLAN – PEREGIAN VILLAGE MARKET 215 DAVID LOW WAY, PEREGIAN BEACH CLIENT: Scanlon Property Group STATUS: FINAL REPORT NUMBER: R002616 ISSUE DATE: December 2013 O2 ENVIRONMENTAL PTY LTD PO Box 199 Peregian Beach Qld 4573 ABN 79 136 340 924 www.o-2.com.au
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Important Note This report and all its components (including images, audio, video, text) is copyright. Apart from fair dealing for the purposes of private study, research, criticism or review as permitted under the Copyright Act 1968, no part may be reproduced, copied, transmitted in any form or by any means (electronic, mechanical or graphic) without the prior written permission of the O2. This report has been prepared for the sole use of the Scanlon Property Group (herein, ‘the client’), for a specific site (herein ‘the site’, the specific purpose specified in Section 1 of this report (herein ‘the purpose’). This report is strictly limited for use by the client, to the purpose and site and may not be used for any other purposes. Third parties, excluding regulatory agencies assessing an application in relation to the purpose, may not rely on this report. O2 waives all liability to any third party loss, damage, liability or claim arising out of or incidental to a third party publishing, using or relying on the facts, content, opinions or subject matter contained in this report. O2 Environmental waives all responsibility for loss or damage where the accuracy and effectiveness of information provided by the Client or other third parties was inaccurate or not up to date and was relied upon, wholly or in part in reporting. STORMWATER MANAGEMENT PLAN – PEREGIAN VILLAGE MARKET Page i Scanlon Property Group R002616
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O2 Environmental Pty Ltd t/as O2 ABN 79 136 340 924
Originating Office – Sunshine Coast
Unit 7, 8 Grebe St Peregian Beach Qld
PO Box 199 Peregian Beach Qld 4573
T 61 7 5448 3288 | F 61 7 5448 3288 | [email protected]
Version Register
Version Status Author Reviewer Change from Authorised for Release
Previous Version
Signature Date
- FINAL Binh Nguyen Steven
Chamberlain 12/12/2013
Transmission Register
Controlled copies of this document are issued to the persons/companies listed below. Any copy of this
report held by persons not listed in this register is deemed uncontrolled. Updated versions of this report if
issued will be released to all parties listed below via the email address listed.
Name Email Address
Tony Scanlon [email protected]
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Table of Contents
1. Introduction 1
2. Site Characteristics 2
2.1. Land Use 2
2.2. Topography and Drainage 2
3. Construction Phase Stormwater Quality Management 4
4. Operational Phase Stormwater Quality Management 5
4.1. Bioretention Systems 5
4.1.1. Maintenance 5
4.2. Additional Treatment Considerations 6
5. MUSIC Modelling 7
5.1. Software Version 7
5.2. Guidelines 7
5.3. Water Quality Objectives 7
5.4. Rainfall and Evapotranspiration Data 7
5.5. Rainfall Runoff Parameters 7
5.6. Pollutant Export Parameters 8
5.7. Catchments 8
5.8. Bio-retention Systems 9
5.9. MUSIC Model 10
5.10. Results 11
6. Water Quantity Management 12
6.1. Introduction 12
6.2. Rational Method 12
6.3. Catchments 12
6.4. Coefficient of Runoff 12
6.5. Time of Concentration 14
6.6. Rainfall Intensities 14
6.7. Site Hydrology 15
6.8. Hydrologic Modelling 15
6.8.1. Rational Method Comparison 15
6.9. Hydraulic Modelling 16
6.9.1. Mitigation Measures 16
7. Summary 18
8. Reference List 19
Figures
Figure 1– Site Location (Source: Nearmap) 1
Figure 2 – Coastal Creeks Catchment (Source: Healthy Waterways) 2
Figure 3– Site Topography and Drainage Plan 3
Figure 4– Typical phases in the creation of a development site(Source: Water by Design, 2009) 4
Figure 5– Typical Cross-Section through a Bioretention System (Source: Water by Design, 2009) 5
Figure 6 - MUSIC Catchment Plan 9
Figure 7– MUSIC Model Layout and Results 11
Figure 8 – Pre Development Catchment Plan 13
Figure 9 – Post Development Catchment Plan 13
Figure 10 - Baffle Weir and Orifice Configuration 17
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Tables Table 1 – Water Quality Objectives 7 Table 2 – MUSIC Rainfall Data 7 Table 3 – MUSIC Monthly Evapotranspiration Data (mm) 7 Table 4 – MUSIC Rainfall Runoff Parameters 8 Table 5 – MUSIC Pollutant Export Parameters 8 Table 6 – MUSIC Catchment Parameters 9 Table 7 – MUSIC Bioretention Parameters 10 Table 8 – MUSIC Results 11 Table 9 – Pre Development Time of Concentration 14 Table 10 – IFD Data Applied to Hydrologic Assessment 14 Table 11 – Site Hydrology 15 Table 12 – Rational Method comparison 15 Table 13 – Detention Tank Configuration 16 Table 14 – Basin Performance 17 Appendices Appendix A Operational Control Concept Plan A STORMWATER MANAGEMENT PLAN – PEREGIAN VILLAGE MARKET Page iv Scanlon Property Group R002616
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1. Introduction This Stormwater Management Plan (SMP) has been prepared to support a Development Application to the Sunshine Coast Regional Council (SCRC). The proposed mixed-use development is located at 215 David Low Way, Peregian Beach and is described as Lot 77 on SP231615 The SMP has been prepared to satisfy the requirements of the SCRC and the State Planning Policy (2013) in terms of water quality and quantity for the proposed development. The proposed development will include retail space, supermarket trading area, specialty retail and carparks. The total area of the proposed development is approximately 0.58ha. The location of the site is shown below in Figure 1. Figure 1– Site Location (Source: Nearmap) STORMWATER MANAGEMENT PLAN – PEREGIAN VILLAGE MARKET Page 1 Scanlon Property Group R002616
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2. Site Characteristics
2.1. Land Use
The proposed development site is currently vacant, with the exception of the caretakers residence, but was
previously used as the Peregian Beach Caravan Park. The site is bound by the Peregian Beach Hotel to the
north, the David Low Way to the east and the Noosa National Park to the south and west.
2.2. Topography and Drainage
Based on mapping undertaken by Healthy Waterways and analysis of Google Earth imagery, it appears the
site is located on the northern boundary of the Coast Creeks Catchment, as illustrated by Figure 2.
Therefore, rather than flowing into Lake Weyba, runoff from the site appears to flow in a southerly
direction towards Stumers Creek.
The site can be considered as a single catchment, with all runoff draining in a west/south-westerly
direction. A heavily vegetated drainage path is located in the south western corner of the site, and receives
runoff from the site as well as the stormwater infrastructure located in the un-named road to the south of
the site. This drainage path is considered to be the sites Legal Point of Discharge (LPD). An existing gully
inlet is located in this road, with the pipe network connected to the vegetated drainage path discussed
above.
A conceptual drainage plan is included as Figure 3.
Approx. Site Location
Figure 2 – Coastal Creeks Catchment (Source: Healthy Waterways)
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Legal Point of
Discharge
Approximate
Pipe Alignment
Existing Stormwater
Gully Inlet
Figure 3– Site Topography and Drainage Plan
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3. Construction Phase Stormwater Quality Management
Management of stormwater during the construction phase is to be undertaken in accordance with the site
specific Erosion and Sediment Control Plan and other management plans provided by the Supervising
Engineers or Civil Contractors.
Construction and establishment of the proposed bioretention basin should be undertaken in accordance
with Council guidelines and conditions and the approved engineering and landscape plans. The Water by
Design ‘Construction and Establishment Guidelines – Swales, Bioretention Systems and Wetlands, 2009’ are
an advantageous guide to utilise during the construction and establishment phase of the bioretention
systems.
A major risk for establishing functioning bio-retention systems is the inflow of sediment-laden runoff during
the construction and building phases. Captured sediment can potentially clog the filter media minimizing
the overall effectiveness of the constructed treatment system.
Managing sediment during the construction and building phases is critical for the establishment of the bio-
retention system and in reducing the risk and costs associated with reconstructing the system. The typical
phases associated in the creation of a development site are detailed below in Figure 4.
Figure 4– Typical phases in the creation of a development site(Source: Water by Design, 2009)
To overcome challenges associated with delivering bio-retention systems, one of the following four options
for construction and establishment are recommended:
Option 1: Surface Protection;
Option 2: Bypass flows and early establishment of vegetation;
Option 3: Sediment basin and bio-retention function; and
Option 4: Leave as sediment basin.
Further information on each option is provided in the Water by design‘Construction and Establishment
Guidelines – Swales, Bioretention Systems and Wetlands, 2009’. More details in relation to the construction
of the bioretention systems will be provided prior to Operational Works Approval.
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4. Operational Phase Stormwater Quality Management It is proposed to divert site runoff to bioretention systems to capture and treat runoff from the development site. The bioretention systems will be incorporated into the landscape buffers located around the carpark areas. 4.1. Bioretention Systems A bioretention system’s primary function is to remove pollutants from stormwater prior to the stormwater being discharged from the site and ultimately into a local waterway. Bioretention systems operate by filtering stormwater through a prescribed soil media prior to being collected at the base of the system via perforated pipes located within a gravel drainage layer. During percolation through the soil media, pollutants are retained through fine filtration, adsorption and some biological uptake. The vegetation on the surface of the soil media is vital to the overall performance of the system. In conjunction with facilitating pollutant removal, the species also need to be relatively hardy and tolerant of freely draining sandy soils and regular inundation. A typical section of a bio-retention system is shown below in Figure 5. Figure 5– Typical Cross-Section through a Bioretention System (Source: Water by Design, 2009) Details of the proposed system are detailed in Section 5.9. MUSIC modelling has been undertaken to size the systems, as detailed in Section 5. 4.1.1. Maintenance It is recommended that a Bioretention System Maintenance Plan for the site be provided at the Operational Works stage of the development. STORMWATER MANAGEMENT PLAN – PEREGIAN VILLAGE MARKET Page 5 Scanlon Property Group R002616
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4.2. Additional Treatment Considerations Due to the site’s location (i.e. part of the Coastal Creeks Catchment and proximity with Lake Weyba), additional infiltration of runoff to reduce the volume and frequency of runoff events occurring should be taken into consideration. As detailed in the Girraween Stormwater Management Plan (Ecological Engineering, 2006), where possible, the frequency and volume of surface runoff discharged to the wet heath vegetation should be reduced by maximising the infiltration of stormwater runoff to groundwater. Bioretention is considered to represent the most effective stormwater treatment technology currently available for nutrient removal and has the smallest land take per kg of nutrient removed of all current treatment technologies. By constructing these systems with a “leaky” base, the opportunity to infiltrate runoff into the underlying dune sands is increased (Ecological Engineering, 2006). Other options for “leaky bases” and increased infiltration include stormwater pits and the proposed detention tank system detailed in Section 6. Measures such as these are commonly used in Western Australia and can be further investigated during the detailed design phase following discussions with SCRC officers. STORMWATER MANAGEMENT PLAN – PEREGIAN VILLAGE MARKET Page 6 Scanlon Property Group R002616
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5. MUSIC Modelling
5.1. Software Version
MUSIC Version 6.0 was utilised to analyse the proposed stormwater quality treatment train.
5.2. Guidelines
The MUSIC analysis has been undertaken utilising the following guidelines:
Water by Design, ‘MUSIC Modelling Guidelines for South East Queensland, 2009’
5.3. Water Quality Objectives
The following water quality objectives have been adopted from the Department of State Development,
Infrastructure and Planning State Planning Policy 2013.
Table 1 – Water Quality Objectives
Minimum reductions in Mean Annual Loads from unmitigated catchment
Total Suspended Solids Total Phosphorus Total Nitrogen Gross Pollutants
(TSS) (TP) (TN) > 5mm
80% 60% 45% 90%
5.4. Rainfall and Evapotranspiration Data
The following rainfall and evapotranspiration data was utilised for the analysis, in accordance with the
MUSIC Modelling Guidelines for South East Queensland.
Table 2– MUSIC Rainfall Data
Rainfall Location Time step Period Mean Annual Rainfall
(mm)
Nambour DPI 6 min 1989 - 1998 1,517
Note, the MUSIC Modelling Guidelines for South East Queensland indicate the rainfall depth for the nominated simulation period is
1,527mm. However, the data provided by the BOM for gauging station 40282 – Nambour DPI results in a rainfall depth for the
period of 1,517mm
Table 3 – MUSIC Monthly Evapotranspiration Data (mm)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
204 166 169 125 89 76 78 93 121 168 187 199
5.5. Rainfall Runoff Parameters
The rainfall runoff parameters for the site were determined from the Water by Design MUSIC Modelling
Guidelines for South East Queensland.
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Table 4– MUSIC Rainfall Runoff Parameters
Parameter Value (Commercial)
Rainfall Threshold (mm) 1
Soil Capacity (mm) 18
Initial Storage (%) 10
Field Capacity 80
Infiltration Capacity Coefficient a 243
Infiltration Capacity Coefficient b 0.6
Initial Depth (mm) 50
Daily Recharge Rate (%) 0
Daily Baseflow Rate (%) 31
Deep Storage (%) 0
5.6. Pollutant Export Parameters
The pollutant export parameters for the site were determined from the Water by Design MUSIC Modelling
Guidelines and are shown below in Table 5.
Table 5– MUSIC Pollutant Export Parameters
Log10 TSS (mg/L) Log10 TP (mg/L) Log10 TN (mg/L)
Land Use
(Commercial)
Base Flow Storm Flow Base Flow Storm Flow Base Flow Storm Flow
Mean 0.78 2.43 -0.60 -0.30 0.32 0.37
Road
Std Dev 0.39 0.38 0.50 0.34 0.30 0.34
Mean - 1.30 - -0.89 - 0.37
Roof
Std Dev - 0.38 - 0.34 - 0.34
Mean 0.78 2.16 -0.6 -0.39 0.32 0.37
Ground
Level
Std Dev 0.39 0.38 0.5 0.34 0.30 0.34
5.7. Catchments
To analyse the proposed development in MUSIC, the site was split into various surface types:
Carpark,
Road,
Roof, and
Commercial Ground Level.
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Details on the catchments utilised for the analysis are shown below in Table 6. The site specific MUSIC catchment plan is shown in Figure 6. Table 6 – MUSIC Catchment Parameters Catchment Area (ha) Percentage Impervious Land Use Carpark 0.239 100 Road Road 0.051 80 Road Roof 0.226 100 Roof Commercial area 0.023 100 Ground level Figure 6 - MUSIC Catchment Plan 5.8. Bioretention Systems The parameters utilised to analyse the bio-retention systems are shown below in Table 7. STORMWATER MANAGEMENT PLAN – PEREGIAN VILLAGE MARKET Page 9 Scanlon Property Group R002616
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Table 7– MUSIC Bioretention Parameters
Catchment ID Bio-1 Bio-2 Bio-3 Bio-4
High flow bypass (m³/s) 0.033 - 0.02 -
2
Surface area (m ) 20 10 16 10
Extended detention depth (m) 0.3 0.3 0.3 0.3
2
Filter area (m ) 20 10 16 10
Unlined filter media perimeter (m) 42 19.1 24 19.1
Saturated hydraulic conductivity (mm/hr.) 200 200 200 200
Filter depth (m) 0.4 0.4 0.4 0.4
TN content of filter media (%) 400 400 400 400
Orthophosphate content of filter media (mg/kg) 50 50 50 50
Is the base lined? No No No No
Vegetated with effective nutrient removal plants Yes Yes Yes Yes
Overflow weir width (m) 2.8 1 2.1 1
Exfiltration rate (mm/hr.) 0.00 0.00 0.00 0.00
If an exfiltration rate has been used, have node water balance losses been used
N/A N/A N/A N/A
in calculation of treatment train effectiveness
If exfiltration rate has been used is the exfiltration rate justified? N/A N/A N/A N/A
Underdrain present? Yes Yes Yes Yes
Submerged zone with carbon present? No No No No
*
Confirmation that K an C remain default Yes Yes Yes Yes
NOTE: High flow bypasses have been specified for the bioretention systems receiving runoff from the roof
catchments. This is considered to be a conservative modelling approach and takes into consideration the likelihood
that flows in excess of the minor (2 year ARI event) may surcharge the drainage network and potentially bypass the
bioretention system.
This SMP does not locate or provide detailed design of the bioretention filter. It is proposed that the
treatment system will be located within the landscape buffers proposed as part of the carpark area. The
final location and design of the system will be undertaken by the civil consultant in conjunction with the
landscape architect and will be provided as part of the detailed design phase of the project.
The conceptual layout of the drainage system is included as Appendix A.
5.9. MUSIC Model
The MUSIC model produced to analyse the proposed development is shown in Figure 7.
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Figure 7– MUSIC Model Layout and Results 5.10. Results The results of the MUSIC analysis are shown below in Table 8. Table 8 – MUSIC Results Pollutant Reduction (%) Objective (%) Objective Achieved TSS 80.6 80 YES TP 61.4 60 YES TN 49.8 45 YES Gross Pollutants 99.1 90 YES As can be seen in Table 8, the proposed treatment train for the development site is adequate in achieving the required pollutant load based reduction targets. STORMWATER MANAGEMENT PLAN – PEREGIAN VILLAGE MARKET Page 11 Scanlon Property Group R002616
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6. Water Quantity Management
6.1. Introduction
Hydrologic and hydraulic modelling has been undertaken of the site to establish the flow regime and peak
discharges at the outlet of the site to the west. The modelling has been undertaken in XP-SWMM for both
the pre and post development scenarios.
6.2. Rational Method
The Rational Method formula was used to calculate the stormwater runoff flows through and off the site
for the pre and post development scenarios. The Rational Method formula is as follows:
Q = (2.78 x 10-3) C I A Equation 1 (QUDM, 2007)
Where:
Q is the peak flow rate (m3/s)
C is the coefficient of runoff
A is the area of catchment (ha)
I is the rainfall intensity (mm/hr)
6.3. Catchments
For both the pre and post development scenarios, it was assumed that the entire site discharges to the
west. The site has a total area of approximately 0.58ha.
The subject site was considered as a single catchment in both the pre and post development scenarios. The
pre and post development catchment plans and indicative flow directions are shown below in Figure 8 and
Figure 9 respectively.
6.4. Coefficient of Runoff
Based on the 10 year 1 hour rainfall intensity and the fraction impervious in the pre and post development
scenarios, a runoff coefficient has been adopted in accordance with Section 4.05 of QUDM as summarised
below:
Pre Development: fi = 0.26 C10 = 0.74
Post Development: fi= 0.92 C10 = 0.88
Frequency factors have been applied in accordance with QUDM to determine runoff coefficients for other
ARI events.
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PRE DEVELOPMENT
Figure 8 – Pre Development Catchment Plan
POST DEVELOPMENT
Figure 9 – Post Development Catchment Plan
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6.5. Time of Concentration
The time of concentration has been calculated for the pre and post development scenarios following the
procedures recommended in Section 4 of QUDM.
For the pre development scenario, the time of concentration was calculated using Friend’s Equation for
overland sheet flow. Details of the pre development time of concentration are shown below in Table 9.
The time of concentration for the remaining portion of flow was calculated using an average flow velocity
that was verified with the results of the hydraulic model described in Section 6.9.
Table 9 – Pre Development Time of Concentration
Sheet Flow Length Sheet Flow tc Channel Flow Velocity tc Total tc (min)
(m) Gradient (mins) Length (m) (m/s) (mins)
20 13.4% 7.77 63 0.9 1.17 8.94
For the post development scenario, the time of concentration of 5 minutes was estimated from the
recommended standard inlet times provided in Table 4.06.1 of QUDM, with an additional 0.5min was
added for the pipe flow component.
6.6. Rainfall Intensities
Intensity Frequency Duration (IFD) data for the site has been derived in accordance with Australian Rainfall
and Runoff (ARR) though the use of the AUS-IFD software. The rainfall intensities generated for the site are
shown below in Table 10.
Table 10 – IFD Data Applied to Hydrologic Assessment
Duration I1 I2 I5 I10 I20 I50 I100
(mins) (mm/hr) (mm/hr) (mm/hr) (mm/hr) (mm/hr) (mm/hr) (mm/hr)
10 100.0 127.0 156.0 173.0 195.0 225.0 248.0
15 84.0 107.0 131.0 145.0 165.0 190.0 209.0
20 73.0 93.0 115.0 127.0 144.0 167.0 184.0
25 66.0 84.0 103.0 114.0 130.0 150.0 165.0
30 60.0 76.0 94.0 104.0 118.0 137.0 151.0
45 48.2 61.0 76.0 84.0 96.0 111.0 122.0
60 41.1 52.0 65.0 72.0 82.0 95.0 105.0
90 31.4 40.1 51.0 57.0 65.0 76.0 84.0
120 25.8 33.2 42.3 47.7 55.0 64.0 72.0
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6.7. Site Hydrology
Using the data provided above, Rational Method calculations have been undertaken for the site to
determine the peak flow rates associated with the standard ARI events. A summary of the Rational Method
calculations are provided in Table 11 for the pre and post development scenarios. The Rational Method
calculations have been used for comparison against the results of the hydrologic modelling.
Table 11 – Site Hydrology
Q1 Q2 Q5 Q10 Q20 Q50 Q100
Catchment 3 3 3 3 3 3 3
(m /s) (m /s) (m /s) (m /s) (m /s) (m /s) (m /s)
Pre Development
Site 0.10 0.14 0.19 0.22 0.26 0.32 0.37
Post Development (unmitigated)
Site 0.14 0.19 0.26 0.31 0.36 0.45 0.50
6.8. Hydrologic Modelling
The XP-SWMM runoff-routing model been has used to estimate design flood discharges within the site.
The model represents the sub-catchments as a network of nodes linked to a 1D drainage network. Each
node is defined by its pervious (undeveloped) and impervious (developed) area, fraction impervious and
average catchment slope. A fraction impervious of 0% has been applied to the undeveloped portion and
100% to the developed portion. The net rainfall is routed through the network after appropriate losses
(initial and continuing) and roughness factors are applied, resulting in a surface runoff hydrograph for each
sub-catchment. Hydrologic modelling has been undertaken using the Laurenson Runoff Routing Method.
6.8.1. Rational Method Comparison
The peak discharges provided by the hydrologic model have been compared against those obtained from
the Rational Method calculations to ensure the model is providing reasonable results. The results of this
comparison are provided in Table 12.
Table 12 – Rational Method comparison
Q1 Q2 Q5 Q10 Q20 Q50 Q100
Catchment 3 3 3 3 3 3 3
(m /s) (m /s) (m /s) (m /s) (m /s) (m /s) (m /s)
Pre Development
Site – Rational Method 0.10 0.14 0.19 0.22 0.26 0.32 0.37
Site – XP-SWMM 0.10 0.14 0.19 0.22 0.26 0.31 0.35
Post Development
Site – Rational Method 0.14 0.19 0.26 0.31 0.36 0.45 0.50
Site – XP-SWMM 0.20 0.26 0.29 0.32 0.37 0.43 0.47
The hydrologic model is providing results within a reasonable range of the Rational Method calculations
and is therefore considered appropriate for use in this analysis.
The XP-SWMM model was analysed for the 20, 25, 30, 45, 60, 90 and 120 minute storm events, with the 25
minute storm producing the peak flow rate for the majority of events.
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6.9. Hydraulic Modelling
The unsteady state, 1D hydrodynamic model XP-SWMM was used to analyse the flood behaviour of the site
with the proposed mitigation measures. Flood levels, discharge and velocity can be extracted from the
model as functions of time at required locations.
The key objective of the hydraulic modelling was to demonstrate that the post development peak discharge
from the site for all events up to and including the 100 year ARI storm event is less than or equal to the pre
development peak discharge.
6.9.1. Mitigation Measures
For the purposes of this assessment, it has been assumed an underground detention tank will be provided
to maintain pre development discharges from the site. This detention system will require 2 chambers
separated by the baffle weir and staged outlet structure, to ensure the peak flow rates for all ARI events
can be maintained.
6.9.1.1. Depth-Area Relationship
The depth-area relationship applied to the hydraulic model is summarised in Table 13 for the primary and
secondary chamber respectively. Further hydraulic modelling will be undertaken prior to Operational
Works approval in conjunction with detailed design.
Table 13 – Detention Tank Configuration
Primary Chamber Secondary Chamber
2 2
Depth (m) Area (m ) Depth (m) Area (m )
0 90 0 10
1.0 90 1.0 10
6.9.1.2. Outlet Structure
To ensure the pre development peak discharges are not exceeded for all ARI events, a staged outlet
structure has been designed for underground rainwater tank system.
The outlet structure for the detention provided in the underground rainwater tank consists of:
4m wide baffle weir at a depth of 0.85m
2 x 150mm diameter orifices at invert level of tank
3 x 100mm diameter orifice at a depth of 0.65m
The outlet structure will be refined prior to the Operational Works approval when the final tank
configuration is known.
6.9.1.3. Basin Performance and Detention Volumes
The performance of the detention tank and proposed outlet structure has been assessed by comparing the
mitigated post development peak flow rate with the pre development peak flow rate. A summary of this
assessment is shown below in Table 14 along with the storage volume required for each event.
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Table 14 – Basin Performance
3 3 3
ARI (years) Pre (m /s) Total Post (mitigated) (m /s) Total Volume Required (m )
100 0.35 0.27 98.8
50 0.31 0.25 96.5
20 0.26 0.22 93.3
10 0.22 0.20 90.7
5 0.19 0.18 88.9
2 0.14 0.14 86.1
1 0.10 0.10 74.9
As can be seen in Table 14, the post development peak discharges have been mitigated to below the pre
development peak discharges for the 1 to 100 year ARI events. The minimum detention volume required
to maintain pre development peak flow rates is 98.8m³.
To maintain the pre-development flow rates for all ARI events, it is necessary to include an additional
control structure within the detention tank. This structure required an internal weir and orifice
arrangement to further reduce the flow rates associated with the minor ARI events.
For the purposes of this assessment, the primary chamber was assumed to have a volume of 90m³, with an
additional 10m³ of detention capacity provided by the secondary chamber. The general arrangement of
this structure is illustrated as Figure 10. The tank and outlet structure will be revised as part of the detailed
design phase when the exact configuration can be determined.
Figure 10 - Baffle Weir and Orifice Configuration
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7. Summary
This SMP has been developed for the proposed commercial development located at 215 David Low Way at
Peregian Beach. A treatment train has been devised to ensure the relevant water quality objectives can be
achieved for runoff exiting the site, and that pre development peak flow rates can be maintained.
Based on this assessment, the following conclusions have been made:
The relevant water quality objective for the site are load based reduction targets of:
o TSS 80%,
o TP 60%, and
o TN 45%.
These water quality objectives can be achieved by implementing a treatment train consisting of:
o 4 bioretention systems providing a total of 56m² of filter area (at 0.4m depth).
Detention of runoff will be required to ensure pre development peak flow rates from the site are
maintained. A minimum storage volume of 98.8m³ is required to achieve this objective.
To reduce the volume and frequency of runoff occurring, additional infiltration opportunities will
be investigated prior to Operational Works Approval. Options for increased filtration include the
use of leaky bases in the bioretention systems, stormwater pits and the proposed detention tank
system.
STORMWATER MANAGEMENT PLAN – PEREGIAN VILLAGE MARKET Page 18
Scanlon Property Group
R002616
Page 24
8. Reference List Department of State Development, Infrastructure and Planning (DSDIP) (2013). State Planning Policy, Department of State Development, Infrastructure and Planning, Brisbane. Ecological Engineering (2006). Girraween Stormwater Management Plan Version 1, Ecological Engineering. Facility for Advancing Water Bio-filtration (2008).Guidelines for Soil Filter Media in Bio-retention Systems (Version 2.01) – March 2008, Facility for Advancing Water Bio-filtration. Healthy Waterways (2006). Water Sensitive Urban Design – Technical Design Guidelines for South East Queensland (Version 1 June 2006). Moreton Bay Waterways and Catchment Partnership. Water by Design (2009). Construction and Establishment Guidelines: Swales, Bio-retention Systems and Wetlands, South East Queensland Healthy Waterways Partnership, Brisbane. Water by Design (2009).Concept Design Guidelines for Water Sensitive Urban Design Version 1, South East Queensland Healthy Waterways Partnership, Brisbane. DERM (2010). Urban Stormwater Quality Planning Guidelines 2010.Department of Environment and Resource Management. DNRW (2007). Queensland Urban Drainage Manual, Volume 1, Second Edition. Department of Natural Resources and Water. STORMWATER MANAGEMENT PLAN – PEREGIAN VILLAGE MARKET Page 19 Scanlon Property Group R002616
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Appendix A Operational Control Concept Plan STORMWATER MANAGEMENT PLAN – PEREGIAN VILLAGE MARKET Page A Scanlon Property Group R002616
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; | LEGEND 200 ——-_ FLOW DIRECTION \ | —s— PIPED DRAINAGE | | | [)_ BIORETENTION SYSTEM DETENTION TANK DETENTION TANK - 100m? STORMTRAP OR SIMILAR PRODUCT ‘ \ 250 FACILITATE SHEET FLOW TOWARDS BIORETENTION SYSTEMS, AS INDICATED. 3.00 BIORETENTION SYSTEM DESIGN PARAMETERS EXTENDED DETENTION \ 2 LD. FILTER AREA (m?) |FILTER DEPTH (m) DEPTH (mm) ) BIO 1a & BIO 1b ' (COMBINED) 20 0.40 0.15 / BIO2 10 0.40 0.15 ‘ BIO3 16 0.40 0.15 BIO 4a & BIO 4b (COMBINED) 10 0.40 0.15 www.o-2.com.au 0 4 8 42 16 20m DRAWN BN CLIENT TITLE ENVIRONMENT+ DESIGNED | BN SCANLON PROPERTY GROUP OPERATIONAL CONTROL ENGINEERING I, ®) SCALE 1:400 APPROVED | SC PROJECT CONCEPT PLAN ACN: 198.360 824 | ABN: 7B 1288810926 AQ rrescate snows omtanscpesvana s CALE DATE 25/11/13 SEU HO ne > covenant © coos ance PUD STORM WATER MANAGEMENT PLAN 7 8 Grebe Sirest Ground Floor, 48 Whart St RPEQ NO. NIA DRAWING NO. XK “GaN EE “0 toate "Tey | DATE | REVISION DETAILS APPROVED Resseguurnmescmee cromagumeeaascomwcseowers GRIDER P Wa |” PEREGIAN VILLAGE MARKET $C13-0128-004 Thursday, 12 December 2013 2:30:28 PM
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