280 garfield road east and 259 riverstone road – flood...
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280 Garfield Road East and 259 Riverstone Road – Flood Assessment
Reference: R.N20909.001.01.docx Date: October 2017 Final Report
A part of BMT in Energy and Environment
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280 Garfield Road East and 259 Riverstone Road – Flood Assessment
610 Princes Highway, Rockdale - Flood Impact Assessment 610 Princes Highway, Rockdale - Flood Impact Assessment
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BMT WBM Pty Ltd 126 Belford Street Broadmeadow NSW 2292 Australia PO Box 266 Broadmeadow NSW 2292 Tel: +61 2 4940 8882 Fax: +61 2 4940 8887 ABN 54 010 830 421 www.bmtwbm.com.au
Document: R.N20909.001.01.docx
Title: 280 Garfield Road East and 259 Riverstone Road – Flood Assessment
Project Manager: Daniel Williams
Author: Daniel Williams / Stephanie Lyons
Client: at&l
Client Contact: Dane Segail
Client Reference:
Synopsis: Flood Assessment for the proposed residential development of 280 Garfield Road East and 259 Riverstone Road, Riverstone. This report details the model development, establishment of existing flood conditions and the assessment of flood impacts associated with the proposed development.
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280 Garfield Road East and 259 Riverstone Road – Flood Assessment ivContents
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Contents
1 Introduction 1
1.1 Background 1
1.2 Study Area 1
1.3 Report Purpose 2
2 Model Development 5
2.1 Hydrologic Model 5
2.1.1 Design Rainfall 5
2.1.2 Subcatchment Delineation 6
2.2 Hydraulic Model 6
2.2.1 Model Topography 6
2.2.2 Extents and Layout 9
2.2.3 Hydraulic Roughness 9
2.2.4 Hydraulic Structures 10
2.2.5 Boundary Conditions 10
3 Existing Conditions and Constraints 11
3.1 Existing Conditions 11
4 Assessment of Proposed Development 13
4.1 Proposed Development Details 13
4.2 Flood Impacts 15
4.3 Flood Planning Considerations 18
5 Conclusion 20
6 References 21
Appendix A Masterplan Layout A-1
Appendix B Existing Scenario Results B-1
Appendix C Developed Scenario Results C-1
Appendix D Change in Peak Flood Level D-1
List of Figures
Figure 1-1 Study Locality 3
Figure 1-2 Study Catchment and Topography 4
Figure 3-1 1% AEP Peak Flood Results – Existing Scenario 12
Figure 4-1 Proposed Development Layout and Topography 14
280 Garfield Road East and 259 Riverstone Road – Flood Assessment vContents
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Figure 4-2 1% AEP Peak Flood Results - Developed Scenario 16
Figure 4-3 1% AEP Change in Peak Flood Level 17
Figure 4-4 1% AEP Flood Level along Channel (refer Figure 4-5) 18
Figure 4-5 1% AEP Peak Flood Levels - Developed Scenario 19
List of Tables
Table 2-1 Average Design Rainfall Intensities (mm/h) 5
Table 2-2 Adopted Hydrologic Model Roughness Values 6
Table 2-3 Adopted Model Roughness Parameters 9
280 Garfield Road East and 259 Riverstone Road – Flood Assessment 1Introduction
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1 Introduction
1.1 Background A new 550 lot residential development is proposed for a site at 280 Garfield Road East and 259
Riverstone Road. The site is located on the alignment of a tributary of First Ponds Creek within the
Riverstone East Precinct Growth Centre, within the Blacktown City Council LGA, as shown on
Figure 1-1. Sunglow Australia is planning and coordinating the proposed subdivision of the site.
BMT WBM has been engaged by at&l on behalf of Sunglow Australia to assist in the assessment of
flood requirements for the proposed development. The provided concept masterplan for the site
has been reproduced in Appendix A.
A Water Cycle Management Report was completed by Mott MacDonald for the broader Riverstone
East Priority Growth Area to assist in the planning of an indicative lot layout for the site. The scope
of works undertaken by Mott MacDonald involved hydrologic, hydraulic and water quality
assessment of the development, aiming to provide an integrated approach to flood risk and water
cycle management. The modelling indicated that the site is subject to inundation from the tributary
of First Ponds Creek.
This study will develop local hydrologic and hydraulic models for the development site, at a finer
resolution than that completed by Mott MacDonald. Increased model resolution will enable a more
detailed representation of flood behaviour at the site to be established. The modelling tools
developed for this study will be used to re-establish existing flood conditions at the site, from which
post-development flood conditions can be assessed.
1.2 Study Area The development site is situated within the catchment of First Ponds Creek. The northern extent of
the site is bound by Garfield Road East. To the south, the site is bound by Riverstone Road. The
catchment area upstream of Garfield Road East is just over 1.0 km2, as shown in Figure 1-2. The
catchment comprises of two tributary alignments of First Ponds Creek, both flowing to the north-
west. Typically, the study area is elevated between 30 - 50 m AHD, with terrain grades of around
5%. Maximum elations of around 65 - 67 m AHD are reached along the south-eastern catchment
boundary.
Existing landuse in the study area is predominantly cleared, with pockets of industrial development
and remnant vegetation. The main residential precinct of Riverstone is located west of the
catchment, between First Ponds Creek and the larger system of Eastern Creek.
Watercourses within the site are largely modified from their natural flow conditions. The main
watercourse alignment within the catchment is located outside of the study site and is intercepted
by a number of dams before draining under Garfield Road East. The smaller tributary located near
the south-western site boundary is conveyed under Riverstone Road. This tributary alignment is
also intercepted by a number of smaller dams.
280 Garfield Road East and 259 Riverstone Road – Flood Assessment 2Introduction
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1.3 Report Purpose This report documents the flood impact assessment in relation to the proposed development at the
280 Garfield Road East and 259 Riverstone Road subdivision. The flooding assessment incudes
consideration of the following:
existing design flood conditions (to be used as the baseline for impact assessment);
estimation of post-development flood conditions, to be informed by the proposed digital
elevation model (DEM) of the subdivision development and change in imperviousness of the
catchment; and
assessment of the impacts of the proposed development (specifically, performance of proposed
temporary detention basins and required flood planning levels).
280 Garfield Road East and 259 Riverstone Road – Flood Assessment 3Introduction
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Figure 1-1 Study Locality
280 Garfield Road East and 259 Riverstone Road – Flood Assessment 4Introduction
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Figure 1-2 Study Catchment and Topography
280 Garfield Road East and 259 Riverstone Road – Flood Assessment 5Model Development
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2 Model Development
The integrated flooding and water quality management modelling for the Riverstone East Priority
Growth Area was completed by Mott MacDonald for the NSW Department of Planning and
Environment in May 2016. The flood modelling involved the development of an XP-RAFTS
hydrologic model and a TUFLOW hydraulic model. This modelling has been accepted by
Blacktown Council and currently forms the basis for flood planning in the study area.
Due to the detailed nature of local hydraulic controls and the required model representation of the
proposed subdivision development, a more detailed TUFLOW model was developed specifically for
this assessment. The Riverstone East Priority Growth Area TUFLOW model adopted a 5 m 2-D
grid cell resolution, whereas the detailed model developed for this assessment has adopted a finer
2 m resolution. Additionally, a finer resolution XP-RAFTS hydrologic model was developed to
provide inflows at key locations to the TUFLOW model.
Design flood events were simulated for the 20% AEP, 10% AEP, 5% AEP, 2% AEP and 1% AEP
magnitudes.
2.1 Hydrologic Model The hydrologic model predicts the amount of runoff from rainfall and the attenuation of the flood
wave as it travels down the catchment. This process is dependent on catchment area, slope and
vegetation; variation in distribution, intensity and amount of rainfall; and antecedent conditions of
the catchment. Runoff-routing software XP-RAFTS was used to generate flow hydrographs for the
study catchment.
2.1.1 Design Rainfall
For design events, rainfall depths are usually determined by the estimation of intensity-frequency-
duration (IFD) design rainfall curves for the catchment. Standard procedures for derivation of these
curves are defined in AR&R (2001).
Table 2-1 shows design rainfall intensities for the study area for a range of design events.
Table 2-1 Average Design Rainfall Intensities (mm/h)
Duration (hrs)
Design Event
20% AEP 10% AEP 5% AEP 2% AEP 1% AEP
0.25 87.1 104 121 144 161
0.5 58.3 69.5 80.6 95.6 107
1 36.3 43.1 49.8 59.1 66.4
2 22.2 26.3 30.4 36.1 40.8
3 16.9 19.9 23.1 27.6 31.2
6 10.9 13.0 15.2 18.2 20.8
The recently released ARR update (2016) revised the recommended application of temporal
patterns for use in design flood estimation. For simplicity, this study has adopted the temporal
280 Garfield Road East and 259 Riverstone Road – Flood Assessment 6Model Development
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patterns and initial and continuing loss guidance in accordance with AR&R (2001). This is in
keeping with the approach adopted in the Riverstone East Priority Growth Area. For the First
Ponds Creek catchment, design temporal pattern Zone 1 and an initial loss of 10 mm and
continuing loss of 2.5 mm/h were selected for pervious areas, as is recommended for catchments
located in eastern NSW.
2.1.2 Subcatchment Delineation
The First Ponds Creek catchment area upstream of Garfield Road East was delineated into twelve
sub-catchments utilising the available LiDAR data. The Bransby-Williams approach was adopted to
determine lag times between each sub-catchment. Figure 2-1 and Figure 2-2 show the delineation
of sub-catchments for the existing and proposed development.
For the development scenario, urbanised sub-catchments were modelled using the second sub-
catchment approach, to represent the influence of the higher proportion of imperviousness in these
areas. Future urban areas were assumed to be 85% impervious and 15% pervious in accordance
with Blacktown City Council guidelines. For impervious areas, an initial loss of 2 mm and continuing
loss of 0 mm/h were applied.
The roughness values adopted in the hydrologic model are detailed in Table 2-2 and are in
accordance with those adopted in the Riverstone East Priority Growth Area XP-RAFTS model
developed by Mott MacDonald.
Table 2-2 Adopted Hydrologic Model Roughness Values
Material Description Model Roughness
(PERN)
Existing impervious areas
0.025
Existing pervious areas
0.04
Post-developed impervious areas
0.015
Post-developed pervious areas
0.035
Inflow hydrographs were determined for each sub-catchment using the XP-RAFTS software. A
range of storm durations were simulated with the XP-RAFTS software and it was found that the 90
minute rainfall event resulted in the critical flow condition at the site.
2.2 Hydraulic Model
2.2.1 Model Topography
The ability of the model to provide an accurate representation of the flow distribution on the
floodplain ultimately depends upon the quality of the underlying topographic model. For this study,
a 1 m by 1 m gridded Digital Elevation Model (DEM) was derived from the LiDAR survey datasets
captured for NSW LPI in 2011, as presented in Figure 1-2.
280 Garfield Road East and 259 Riverstone Road – Flood Assessment 7Model Development
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Figure 2-1 RAFTS Sub-catchment delineation (Existing)
280 Garfield Road East and 259 Riverstone Road – Flood Assessment 8Model Development
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Figure 2-2 RAFTS Sub-catchment delineation (Proposed Development)
280 Garfield Road East and 259 Riverstone Road – Flood Assessment 9Model Development
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Topographic survey data of the study site and some of the adjacent area was provided by at&l
(adjointopo_3d.dwg) and was used to define the model elevations where available.
In the study area, the dam embankments located along the tributary watercourse alignment are
significant topographical controls to flood behaviour. These embankments range from around 0.5 m
to 2.5 m above the typical dam surface water level. The largest of these embankments is located
approximately 170 m upstream of Garfield Road East and spans around 230 m across the entire
width of the floodplain. Adopting a model grid resolution of 2 m will ensure that the dam
embankment crests are captured from the input DEM to be represented within the hydraulic model.
2.2.2 Extents and Layout
Consideration needs to be given to the following elements in constructing the model:
topographical data coverage and resolution,
location of recorded data (e.g. levels/flows for calibration),
location of controlling features (e.g. dams, levees, bridges),
desired accuracy to meet the study’s objectives, and
computational limitations.
With consideration to the available survey information and local topographical and hydraulic
controls, a 2D model was developed covering the study area at a 2 m grid cell resolution. With a 2
m grid TUFLOW samples elevations at 1 m intervals, at grid cell sides, corners and centres, hence
fully utilising the resolution of the input DEM. A model resolution of 2 m is generally required to
adequately represent complex overland flow paths in urban environments, which will be of
relevance when representing the proposed subdivision development within the model.
2.2.3 Hydraulic Roughness
The development of the TUFLOW model requires the assignment of different hydraulic roughness
zones. These zones are delineated from aerial photography and cadastral data identifying different
land-uses (e.g. forest, cleared land, roads, urban areas, etc.) for modelling the variation in flow
resistance.
The hydraulic roughness is one of the principal calibration parameters within the hydraulic model
and has a major influence on flow routing and flood levels. The roughness values adopted for use
in this study have been based on available literature and previous experience in modelling
catchments of a similar nature and are presented in Table 2-3.
Table 2-3 Adopted Model Roughness Parameters
Land Use Manning’s ‘n’
Cleared / parkland areas 0.04
Dams and waterways 0.03
Urban blocks 0.10
Roads 0.02
280 Garfield Road East and 259 Riverstone Road – Flood Assessment 10Model Development
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Land Use Manning’s ‘n’
Car parks and industrial storage areas 0.03
In order to represent the hydraulic impact of buildings within the TUFLOW model, urban blocks
have been represented with a higher Manning’s roughness values. This represents the combined
flow impedance offered by buildings, gardens and fences. This provides a suitable representation
of the constriction of flood waters imposed by these features, whilst accounting for potential flood
storage volumes within or under the buildings themselves and within other urban areas such as
gardens.
2.2.4 Hydraulic Structures
The drainage culvert beneath Riverstone Road is the main existing hydraulic structure of note
within the study area extent. Incorporation of this structure in the model provides for flow
conveyance through the road embankment whilst simulating the hydraulic losses associated with
the structure and its influence on peak water levels within the study area.
The culvert has been modelled as a 1-D structure embedded within the 2-D domain. This enables
an accurate representation for structures smaller than the model grid resolution. This culvert has
been assumed to be a 450 mm diameter pipe. For the purposes of design flood modelling the
hydraulic structures have been modelled at full capacity, with no allowance for additional structure
blockage.
2.2.5 Boundary Conditions
The downstream model boundary has been represented as a constant water level and is located a
suitable distance downstream from the study site. This allows for the adopted model boundary
conditions to be resolved and not influence flood behaviour at the site.
Each dam within the catchment was modelled with a typical initial water level. This is the standard
approach to simulate a conservative scenario whereby the dam is full at the onset of a flood event.
Local hydrological inflows for sub-catchments located within the study area catchment were input
using runoff hydrographs from the XP-RAFTS hydrological model.
280 Garfield Road East and 259 Riverstone Road – Flood Assessment 11Existing Conditions and Constraints
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3 Existing Conditions and Constraints
3.1 Existing Conditions The establishment of existing design flood conditions provides for description of the:
general flood behaviour throughout the study area,
existing flooding conditions based on design flood events, and
constraints and limitations to potential development with respect to flooding regimes.
TUFLOW model results for the existing scenario are shown for the 20% AEP, 10% AEP, 5%, AEP,
2% AEP and 1% AEP design flood events in Appendix B and are used as a baseline for the
assessment of the proposed development in Section 4.
Under existing conditions the site is flooded along the alignment of the small tributary watercourse
located near the south-west boundary. At the 1% AEP design event, there is minor spill-over from
the dams, with overland flow paths typically less than 0.2 m in depth and with velocities of 0.2 – 0.6
m/s. Figure 3-1 presents the flow distribution across the floodplain for the 1 % AEP design event.
280 Garfield Road East and 259 Riverstone Road – Flood Assessment 12Existing Conditions and Constraints
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Figure 3-1 1% AEP Peak Flood Results – Existing Scenario
280 Garfield Road East and 259 Riverstone Road – Flood Assessment 13Assessment of Proposed Development
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4 Assessment of Proposed Development
Civil works (i.e. earthworks, buildings, altered channel alignments) within a floodplain can
potentially increase flood levels, re-distribute flows, increase inundation times and increase
velocities. These impacts need to be minimised, especially in populated areas and in areas of
agricultural or environmental significance.
4.1 Proposed Development Details The proposed subdivision development on the site consists of around 150 residential lots. BMT
WBM was provided with the proposed masterplan for the subdivision of the site (included as
Appendix A).
A number of key components were required to accurately model the potential flood impacts
associated with the proposed subdivision development, including:
increase in impervious area associated with urban development and the impact of flow regimes,
design levels for external surfaces, and
modification to existing watercourses including the inclusion of storage basins.
In order to simulate the impact of the proposed subdivision on existing flood flows in the study area,
the XP-RAFTS hydrological model was modified to represent the increase in impervious area
associated with the developed scenario. Alterations made to the XP-RAFTS model were described
in Section 2.1. Inflow hydrographs were determined for each sub-catchment using the developed
scenario XP-RAFTS model.
The proposed development involves significant cut and fill earthworks to be undertaken across the
site. The proposed finished ground levels and lot layout for the site are presented in Figure 4-1.
The design strings of proposed finished ground levels for the subdivision were provided by at&l
(17-10-24 DESIGN TIN_DWG.dwg). These were processed into a 1 m gridded DEM to be
incorporated into the TUFLOW model for the development scenario.
The proposed subdivision layout includes five detention basins within the study area. These have
been included to manage the increase in runoff and flow rates from the site due to the higher
proportion of impervious area associated with the developed scenario. Proposed basin locations
are included on Figure 4-1. The detention basins were sized by at&l using Blacktown City Council’s
deemed to comply OSD tool. The corresponding basin outlet details were incorporated into the
TUFLOW model.
Another key feature of the proposed topography of the site is the provision of an open channel
along the existing tributary alignment adjacent to Basin A in Figure 4-1. The channel widens to form
into a secondary storage structure with capacity of around 3000 m3. The secondary storage outlet
is a 525 mm diameter RCP. Upstream of the storage area, the channel is confined and is around
1.5 m deep and is roughly trapezoidal in shape. The design strings provided by at&l contain details
of the channel and secondary storage, and as such both are represented in the finished ground
level DEM.
280 Garfield Road East and 259 Riverstone Road – Flood Assessment 14Assessment of Proposed Development
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Figure 4-1 Proposed Development Layout and Topography
280 Garfield Road East and 259 Riverstone Road – Flood Assessment 15Assessment of Proposed Development
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The inflow hydrographs derived from the developed scenario XP-RAFTS model were applied to the
modified TUFLOW model (i.e. proposed finished ground level DEM to replace existing LiDAR input
DEM where appropriate) and the entire suite of design floods were simulated. TUFLOW model
results for the developed scenario are shown for the 20% AEP, 10% AEP, 5%, AEP, 2% AEP and
1% AEP design flood events in Appendix C.
The 1% AEP design peak flood conditions for the developed scenario is presented in Figure 4-2.
For the developed scenario, the previous overland flow path through the site is now simulated as
two distinct flow paths intercepted by Basin A and Basin B, respectively.
4.2 Flood Impacts Model results for the development scenario have been used to assess relative flood impacts of
developing the site. Afflux diagrams are presented for peak water level for the 20% AEP, 10%
AEP, 5% AEP, 2% AEP and 1% AEP design events in Appendix D. These diagrams show the
afflux (difference) between flood conditions resulting from developing the site and the existing
baseline flood conditions in the vicinity of the site. They are useful for presenting the magnitude
and extent of flood impacts as a result of developing the site.
Figure 4-3 presents the peak flood level impact for the 1 % AEP design event. Within the site, the
re-alignment of the tributary watercourse into a defined channel and storage system has
significantly limited the flood inundation extents at the 1% AEP event. Almost all of the previously
inundated areas on-site are removed as a result of the proposed development earthworks, seen as
the bright green extents in Figure 4-3.
Inclusion of detention storage at Basin A has resulted in reduced peak flows off the site. Previously,
flows from the upper catchment would exceed the capacity of the existing dam and flow in a north-
westerly direction toward Clarke Street (downstream of Basin B). These flows are now attenuated
and discharged offsite immediately downstream of Basin A. Consequently, a reduction in off-site
peak flood levels downstream of Basin B of around 0.1 – 0.2 m is simulated for the developed
scenario.
Minor off-site impacts can be seen downstream of Basin D at the model boundary. This is due to
the concentration of flow out of Basin D and into an engineered swale running parallel with Garfield
Road East. Previously the flow off the undeveloped catchment flowed freely across Garfield Road
East. It is noted that the significant reduction in flood inundation extent at this location is likely
favourable over minor increases within the road boundary. Furthermore, it is understood that
Garfield Road East will be upgraded, rendering the marginal increase in flood level only temporary.
280 Garfield Road East and 259 Riverstone Road – Flood Assessment 16Assessment of Proposed Development
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Figure 4-2 1% AEP Peak Flood Results - Developed Scenario
280 Garfield Road East and 259 Riverstone Road – Flood Assessment 17Assessment of Proposed Development
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Figure 4-3 1% AEP Change in Peak Flood Level
280 Garfield Road East and 259 Riverstone Road – Flood Assessment 18Assessment of Proposed Development
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4.3 Flood Planning Considerations The Blacktown City Council Development Control Plan (DCP) contains a number of controls in
relation to flood management of new subdivisions. Key controls of relevance to this site are:
no residential allotments are to be located at a level lower than the 1% Annual Exceedance
Probability (AEP) flood level plus a freeboard of 500 mm (i.e. within the ‘flood planning area’),
and
roads are generally to be located above the 1% AEP level.
Figure 4-5 shows the 1% AEP design flood condition at each basin location. A peak flood profile
along the defined channel in the south west corner of the site is also provided in Figure 4-4.
In regard to the planning controls detailed above, proposed roads on-site are located above the 1%
AEP design flood levels determined in this study. Residential allotments will be required to fulfil the
flood planning control requirements detailed in Council’s DCP i.e. they must be located above the
1% AEP design flood level plus 500 mm freeboard.
Figure 4-4 1% AEP Flood Level along Channel (refer Figure 4-5)
280 Garfield Road East and 259 Riverstone Road – Flood Assessment 19
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Figure 4-5 1% AEP Peak Flood Levels - Developed Scenario
280 Garfield Road East and 259 Riverstone Road – Flood Assessment 20Conclusion
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5 Conclusion
This Flood Assessment has included the development of a XP-RAFTS hydrologic model and a
TUFLOW hydraulic model for the First Ponds Creek catchment area upstream of Garfield Road
East. The models have been used to define existing flood conditions for a range of flood
magnitudes and form a baseline with which to assess potential flood impacts associated with the
proposed subdivision development.
The existing design flood conditions for the range of flood event magnitudes are represented in
Appendix B through a flood mapping series, incorporating peak flood extents, levels, depth and
velocity distribution. Developed scenario flood conditions for the range of flood events are
presented in Appendix C.
Overall, the developed flood conditions are largely compatible with existing conditions within the
site. The impacts of the proposed development are presented in terms of relative change from the
existing peak flood level distributions, and are presented in Appendix D.
The proposed subdivision development at 280 Garfield Road East and 259 Riverstone Road,
largely satisfies the flooding requirements in terms of manageable flood condition on-site.
Assessment of the proposed design surface level against design flood levels may need further
consideration in regard to fulfilling the flood management controls as outlined in the Blacktown City
Council DCP.
280 Garfield Road East and 259 Riverstone Road – Flood Assessment 21References
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6 References
at&l (-) Stage 1 DA Villa Rosa 280 Garfield Road and 259 Riverstone Road
Blacktown City Council (2016) Blacktown City Council Growth Center Precincts Development
Control Plan
Mott MacDonald (2016) Water Cycle Management Report Riverstone East
Sitios Urban Design (2017) 280 Garfield Road and 259 Riverstone Road Masterplan - Staging
280 Garfield Road East and 259 Riverstone Road – Flood Assessment A-1Masterplan Layout
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Appendix A Masterplan Layout
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ROAD (MC11)ROAD (MC11)
ROAD (MC12)
ROAD (MC11)
R
O
A
D
(
M
C
1
3
)
BASIN A
BASIN B
BASIN C
BASIN D
BASIN E
FU
TU
RE
R
IV
ER
ST
ON
E R
OA
D E
XT
EN
SIO
N (M
C201)
GA
RF
IE
LD
R
OA
D E
AS
T
LOT 7
DP 229296
LOT 5
DP 229296LOT 4
DP 229296
F
U
T
U
R
E
H
A
M
B
L
E
D
O
N
R
O
A
D
E
X
T
E
N
S
I
O
N
LOT 3
DP 229296
LOT 2
DP 229296
LOT 1
DP 229296
LOT 1
DP 30211
LOT 1
DP 1235169
E
LE
C
T
R
IC
A
L E
A
S
E
M
E
N
T
UNZONED
LAND
Issue
Description
Date
100mm on Original
Project
Title
Client
Project No. IssueDrawing No.
Grid
Checked
Designed
Drawn
Height
A1
Datum
Approved
Status
ScalesBar Scales
Civil Engineers and Project Managers
02 9923 1055
02 9439 1777
Level 7, 153 Walker Street
North Sydney NSW 2060
Tel:
Fax:
ABN 96 130 882 405
www.atl.net.au
THIS DRAWING CANNOT BE COPIED OR REPRODUCED IN ANY FORM
OR USED FOR ANY OTHER PURPOSE OTHER THAN THAT ORIGINALLY
INTENDED WITHOUT THE WRITTEN PERMISSION OF AT&L
Key Plan
F:\17-494 Garfield Road\Drgs\Civil\Final\1000_DA Stage 1 Package\C1003.dwg
C1003
GENERAL ARRANGEMENT
PLAN
FOR APPROVAL
NOT TO BE USED FOR CONSTRUCTION
JB
JB
DS
1 : 1250
AHD
MGA
17-494
VILLA ROSA
280 GARFIELD ROAD AND
259 RIVERSTONE ROAD
P2
280 Garfield Road East and 259 Riverstone Road – Flood Assessment B-1Existing Scenario Results
S:\WATER\PROJECTS\N20909_Riverstone\Docs\R.N20909.001.01.docx
Appendix B Existing Scenario Results
280 Garfield Road East and 259 Riverstone Road – Flood Assessment C-1Developed Scenario Results
S:\WATER\PROJECTS\N20909_Riverstone\Docs\R.N20909.001.01.docx
Appendix C Developed Scenario Results
280 Garfield Road East and 259 Riverstone Road – Flood Assessment D-1Change in Peak Flood Level
S:\WATER\PROJECTS\N20909_Riverstone\Docs\R.N20909.001.01.docx
Appendix D Change in Peak Flood Level
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