March 2014
Prepared for
Suite 4, 162 Drummond Street, Oakleigh, 3166 | (03) 9569 9402 |
[email protected] | Certified to ISO 9001
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
CONTENTS PAGE 1.0 Introduction 3 2.0 Site Description 3 3.0
Engineering Issues 4
3.1 Roadworks 4
3.2 Stormwater drainage 5 Site minor drainage strategy proposal 6
Site major drainage system 8 Storm water quality issues 10
4.0 Recommended strategy 12 5.0 Conclusions 12 6.0 Disclaimer 12
ATTACHMENTS 1 APPENDIX A1 Wyndham North PSP boundaries plan 2
APPENDIX A2 Site locality Plan 3 APPENDIX B1 Site plan of
re-establishment and feature survey 4 APPENDIX B2 Preliminary
Conceptual Development Plan 5 APPENDIX C1 Road Hierarchy plan 6
APPENDIX C2 Road Topology plan (sections) 7 Appendix D Proposed MWC
scheme works plan 8 Appendix E Drainage advice from Spiire
Australia for AMEX land 9 Appendix F Drainage Strategy sub
catchment plan 10 Appendix G Drainage catchment characteristics 11
Appendix H Preliminary drainage calculations
Page 2 of 24
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
1.0` INTRODUCTION Taylors Stizza has been engaged to provide a
stormwater drainage management strategy associated with the
proposed development of a parcel of land located at 1121 Dohertys
Road Tarneit as a residential subdivision. This land is included
within the proposed Wyndham North PSP 1089 currently under
consideration by Melbourne Planning Authority (MPA). MPA has
advised a Section 96A Permit Application for development within
this PSP shall be accepted and this drainage strategy forms part of
the documentation requirements associated with the application.
PSP1089 is centred about the major intersection of Dohertys and
Tarneit Roads– general Melways Ref 359 D9. A copy of the MPA PSP
boundaries plan, including PSP1089 is attached as Appendix A1. This
report will essentially provide advice on
- key drainage management issues - stormwater runoff water quantity
and quality issues - compliance of the strategy with current best
practice management
objectives The Section 96A application relating to this site is for
the central portion referred to as Precinct A – refer to plan in
Appendix B2, Taylors Masterplan MP2 dated 19 August 2013. The
balance site, Precinct B will be the subject of a separate
application in future. This drainage strategy primarily considers
Precinct A but also includes peripheral calculations relating to
Precinct B that are pertinent. 2.0 SITE DESCRIPTION The subject
site comprises some 84.75 Ha in total and is located at the south
eastern corner of Dohertys and Tarneit Roads intersection.– a site
locality plan is attached as Appendix A2. The site comprises two
titles, namely
- the northern portion, Lot 1 on PS706302B comprising some 41.97 Ha
and encumbered by an electricity transmission easement in the north
western corner of some 64 m in width– road abuttal along Doherty
Road is approximately 801 m and road abuttal along Tarneit Road is
approximately 536 m.
Page 3 of 24
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
- The southern portion, Lot 5 on PS701126U comprising some 42.78 Ha
with road abuttal along Tarneit Road of some 533 m and depth of
approximately 801 m.
Site is generally flat for the most part and falls from Tarneit
Road on the west towards the north eastern corner in the case of
the northern portion and towards the south eastern corner in the
case of the southern portion with a slight ridge running west to
east approximately along the common title boundary. The site has
been cleared over time and is currently covered by grass. There are
no trees on site other than those around a homestead at the north
eastern corner of the northern parcel and along the eastern site
boundary to act as a wind row. The homestead and associated sheds
and other buildings shall ultimately be demolished as part of the
development of the site. The two roads abutting the site and
providing access are currently constructed as two lane two way
sealed roads to rural standards and are in reasonable condition.
Their ultimate configuration are intended as 34 m divided arterial
roads. A feature survey plan of the site is attached as Appendix
B1. 3.0 ENGINEERING AND INFRASTRUCTURE 3.1 ROADWORKS The
responsible authority for all road works is Wyndham City Council
with referral to Vicroads for arterial road construction. Dohertys
Road Dohertys Road to the east of Tarneit Road currently comprises
a two lane two way sealed road to rural standards. The existing
road at the eastern extremity of the site crosses Dry Creek (the
creek also crosses the road at two other locations further east), a
tributary of Skeleton Creek and is subject to periodic flooding.
The draft PSP indicates a diversion and realignment of Dohertys
Road into the subject site with future road upgrade to negate the
flooding problem and this has been reflected in the development
concept plan. The ultimate road classification of Dohertys Road is
anticipated to be a 4 lane divided arterial road with central
median within a 34 m wide road reservation. Development of the
subject site will necessitate upgrade of Dohertys Road to urban
standards, initially comprising the southern carriageway as a two
lane two way road until future traffic volumes warrant
duplication.
Page 4 of 24
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
Tarneit Road Tarneit Road abuttal of the project site is also
currently constructed as a sealed two lane two way road to rural
standards. The southern end of the subject site has recently
undergone some upgrade works within the road reserve associated
with the road crossing over the Regional Rail Link (RRL)
reservation further south between the southern boundary of the
southern parcel and Leakes Road. Tarneit Road overpass construction
has been completed and is functional. The ultimate road
classification of Tarneit Road is proposed as a 4 lane divided
arterial road with central median within a 34 m wide road
reservation. Development of the subject site will necessitate
upgrade of Tarneit Road to urban standards, initially comprising
the eastern carriageway as a two lane two way road until future
traffic volumes warrant duplication. Internal Roads Internal roads
within the development site shall be designed and constructed in
accordance with Wyndham City Council and MPA standards as
applicable. The cross sectional elements for each road shall be
generally as per the MPA’s Engineering Design and Construction
Manual in accordance with the road classification as designated by
the project’s traffic engineer, primarily ranging from access lanes
to an avenue and based on the anticipated traffic volumes along the
particular road (vehicles per day). A road hierarchy master plan
and Road Typology plan identifying type sections prepared by
Taylors are included as Appendices C1 and C2 respectively – these
sections were adopted to assess the overland flood carrying
capacity for each road type used to convey these flows. Roads will
need to be designed to accommodate both the minor and major
drainage networks with overland flows being contained within road
reserves (or dedicated drainage reserves where deemed necessary)
with appropriate freeboard being provide to abutting allotments.
Overland flow considerations shall be designed in accordance with
MWC safety criteria and or GAA standards with respect to freeboard.
3.2 STORMWATER DRAINAGE The responsible authority for main
drainage, floodplain and waterway management is Melbourne Water
Corporation (MWC).
Page 5 of 24
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
The subject principally site drains to three locations, the
northern section to Dry Creek to the north eastern corner of the
site, the middle section (essentially Precinct A) to Skeleton Creek
to the east and the southern section towards the south eastern
corner and ultimately to Skeleton Creek via Melbourne Water
Drainage scheme works which includes piped works to Derrimut Road
to the east and then via constructed waterway / low flow drain to
Skeleton Creek. MWC have recently provided a copy of the scheme
works proposals included for this site which is attached as
Appendix D. Recent discussions with Spiire Australia, acting for
Amex Corporation, the developers of the upstream land to the west
of Tarneit Road, has resulted in advice being given with regards to
their proposed drainage strategy which has impacts on the subject
site and significantly influences the drainage strategy proposals
for the site as assessed in this report. A copy of their advice is
contained under Appendix E. Minor Drainage Strategy proposal. Minor
drainage network for the catchment shall comply with Wyndham City
Council, MPA and MWC standards and essentially provide for a 5 year
Average Recurrence Interval (ARI) storm event. Given the Amex site
has been divided into three sub-catchments from a drainage
perspective and directed to separate outlets, there are impacts on
the subject site which has necessitated the consideration of six
sub- catchments in the assessment of the total site’s drainage
strategy, sub-catchments C1 through to C6. The minor drainage
proposal for the development site will comprise both Melbourne
Water Scheme drain extensions together with subdivision drainage.
Plans showing the proposed major internal minor drainage network
layout together with drainage sub-catchment boundaries are attached
as Appendix F. An analysis of the contributing external upstream
drainage catchment (as supplied by Spiire) and proposed subdivision
plan land use statistics has been undertaken to determine the post
development 5 year ARI weighted co-efficient of runoff in
conjunction with recommended fraction impervious values as
identified in Table 16 of GAA Engineering Design and Construction
Manual (April 2011) – refer to Appendix G for this analysis. A
preliminary catchment minor drainage design (5 year ARI post
development) has been prepared for the MWC scheme drains proposed
through the site. This was undertaken to get a sense of catchment
flows and likely drainage pipe sizes together with assessment of
overland flows through the site. Pipe grades adopted for the
analysis were based on existing surface levels at each node
location
Page 6 of 24
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
and not on any design levels – given the flat nature of the site,
generally a pipe slope of 1 in 250 was adopted for the analysis
(some sections were flatter) –refer to Appendix H for calculations.
The following sub catchment results at their respective outlets are
summarized from the analysis above:-
Sub- Catcment
dia - mm
C1+C2+C4 98.13 28.04 0.580 38.88 56.909 6.146 1800 C2 26.95 17.85
0.635 49.57 17.108 2.356 1200 C3 17.02 13.00 0.651 51.63 11.081
1.785 1050 C4 9.02 10.00 0.538 65.46 4.856 0.883 750 C5 31.00 28.20
0.586 38.75 18.178 1.967 1200 C6 13.41 11.25 0.656 62.05 8.797
1.516 1050
Site specific rainfall intensities were based on rainfall
co-efficients derived from ARR87 – Volume 2 for Wyndham City
Council. Catchments C1, C5 and C6 (from it’s outlet) contain a MWC
scheme drain. Drainage calculations are based on using Colebrooke
-White method with pipe roughness coefficients “k” of 0.6 mm for
non MWC drains (ie council drains) and 1.5 mm for MWC scheme pipes
– the drainage calculation sheet indicates the pipe roghness
co-efficient adopted for each drain in calculation of pipe
velocities and hence capacities. It should be pointed out that even
though the catchment areas are large, external Amex Corporation
contributions of 48.07 Ha and 25.44 Ha at sub-catchments C1 and C5
respectively create larger flows to be catered for throughout the
subject site as these upstream flows are not retarded back to
predevelopment flows. As an example, Amex drainage catchments
directed at sub-catchment C1 totalling 48.07 ha have the following
impacts on the subject site at Tarneit Road:-
- Undeveloped flows- tc = 34.5 min, c5= 0.25, I5 = 34.5 mm/hr ->
q5 und = 1.152 cumecs
- Developed flows – tc = 21.1 min, c5w= 0.53, I5 = 45.4 mm/hr ->
q5 dev = 3.222 cumecs
- Increased pipe flow through the developed site is thus 2.070
cumecs at the Tarneit Road end which must be catered for via larger
pipes (MWC drain)
- Impact on q100 between developed and undeveloped is 8.394 less
2.86 cumecs respectively or an increase of 5.534 cumecs.
This issue will require further discussions with both MWC and
Spiire to arrive at an equitable outcome.
Page 7 of 24
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
It is also worth noting that from past experiences with Wyndham
City Council, they do not permit the conveyance of gap flows across
major roads and their requirement has been to provide a Q100 drain
crossing of major roads, such as Tarneit Road in this case. These
Q100 pipes shall need to be given consideration by Spiire with
respect to sizing, configuration and crossing over large services (
both existing and proposed) and reverting to a Q5 pipeline on the
east side of Tarneit Road via a surcharge pit arrangement. Major
Drainage System Wyndham City Council is the responsible drainage
authority for all drainage matters within the site.
The design criteria for the conveyance of these flows (maximum
velocity, maximum ponded depths, extent and width of water flows
etc) shall be in accordance with council’s and or MWC’s
requirements. All flows from major storm events (100 year ARI)
shall be directed to the east and to Skeleton Creek with the
exception of catchment C6 which will be directed to Dry Creek to
the north eastern corner of the site and to the future waterway.
Overland flows (comprising gap flows between 100 year and 5 year
minor drainage flows) shall be conveyed along roadways that shall
be designed in accordance with MWC safety criteria and GAA
freeboard requirements. Safety criteria limits both the maximum
velocity to 1.5 m/sec and average velocity times average depth
ratio to 0.35 m/sec for flows along a roadway acting as a floodway.
Freeboard requirements for allotments abutting an overland flow
path are a minimum of 150 mm above the computed water level. For
the development, a functional design of the overland flow paths for
the 100 year ARI storm event has been prepared and is indicated on
the drainage catchment plan – internal roads are used to convey
these gap flows.
Page 8 of 24
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
A summary of Gap flow calculations at key internal drainage nodes
is presented in the table below
Catchment Drain Area C5w tc I5 I100 Q5 Q100 Qgap
ID Node Ha. min mm/hr mm/hr cumec cumec cumec
C1 G 41.38
C1 F 47.80
C1 E 54.88
C1 D 62.54 0.599 26.90 39.79 82.80 5.463
10.770 5.487
2.686 1.668
4.863 3.016
6.244 3.867
0.635 19.27 47.60 99.90 2.260
5.935 3.675 C5 is the weighted 5 year ARI coefficient of runoff for
the respective applicable catchment area and c100 has been adopted
as 1.25 * c5 Considering peak gap flow calculations above at
specific nodes, a review of the applicable road type sections and
adoption of a longitudinal slope of 1 in 250 (0.40%) results in the
following characteristics with respect to overland flows:
Node
E - D
D – C*
L - K
Page 9 of 24
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
* Nodes D-C calculations are based on a minimum required road
reservation width of 24.0 m with future Precinct B. ** Nodes K – J
are within a 13.0 m road abutting a future reserve – the flood
capacity of this road exceeds MWC’s safe flow criteria of vavg *
davg <= 0.35 – an alternate analysis is presented in the above
table recommending this as a 16 m local road which performs
adequately. The calculations were undertaken via the use of PC –
Convey V7.22 and assume an arbitrary crown RL of 100.00 for top
water level illustrative purposes. The gap flow is based on Q100 –
Q5 as calculated previously. The road capacities are adequate
although the magnitude of the gap flow makes them flow full – refer
to previous comments under the minor drainage system section
relating to the design flows through the site from upstream AMEX
catchments that are proposed to be discharged into the development
site without any retardation back to undeveloped conditions – this
has a significant impact on the development site and will need
further discussions with MWC. Alternatively, it may be prudent to
consider higher ARI’s to reduce the magnitude of the surface flows.
The road reserves have adequate flow conveyance capacities however
the required freeboard (150 mm) must be provided within the 2.0 m
setback in the frontage of abutting allotments as permitted under
GAA standards. Overland flows will discharge downstream at a number
of locations and adequate provisions will need to be made for these
flows – ultimately the discharge points are to Skeleton Creek and
appropriate rock lined chutes will need to be provided to ensure
bank stabilization is not compromised. Storm water quality issues
Stormwater discharges from the site are generally required, by MWC
to be treated in accordance with the principles established in
“Urban Stormwater: Best Practice Environmental Management
Guidelines” (Stormwater Committee Victoria, 1999) to attain the
following pollution reduction targets as a minimum
- 100% reduction in litter/gross pollutants - 80% reduction in
suspended solids loads - 45% reduction in Total Phosphorus loads -
45% reduction in Total Nitrogen loads
Melbourne Water encourages the use of WSUD initiatives such as
sediment ponds, wetlands, bio-filtration systems, grassed swales,
grey water re-use and rainwater tanks to be implemented in these
types of developments as a means of achieving these outcomes prior
to discharge into the drainage system, which in this case comprises
Skeleton Creek.
Page 10 of 24
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
Limited opportunities appear to exist within the general site for
implementation of effective water quality treatment measures in the
form of say bio-retention trenches/vegetated swales or the like. It
is not considered desirable to encumber the Active Open Space area
with water quality treatment facilities, although the opportunity
may exist to effect stormwater harvesting for irrigation purposes
with the future development of this site by council. In any event,
catchment wide water quality improvement measures either exist or
are proposed within Skeleton Creek drainage corridor and it is
therefore proposed the development site will meet it’s water
quality obligations via Stormwater Qualty Offset contributions as
allowed in the Skeleton Creek Drainage Scheme. As advised
previously, the scale of the upstream catchments and the site
topography dictates a number of drainage outlets to be provided -
there are essentially four minor drainage system catchments (Q5)
discharging Skeleton Creek. We have determined that some water
quality measures may be provided within the developed site to
achieve some quality outcomes via the use of the following
strategies in each of the catchments within the development site
–
- provision of rainwater tanks on each lot – allowed on the basis
of 200 sq.m
roof area connected to a 5000 L tank plumbed into the toilet and
laundry with daily domestic re-use of 120 l/day per lot
- provision of a pre treatment in line gross pollution trap at the
downstream end
of the drainage network via a diversion chamber diverting the
treatment flow of 3 month ARI (20% of Q5) with the balance design
flow directed to the creek or waterway outlet – the GPT will filter
litter (of size 20 mm or greater) and coarse sediments from the
treatment flow
- consideration to some capture and harvesting of stormwater for
irrigation
purposes within the active open space area that would form part of
future development of facilities within that site.
We note that we do not have any advice from Spiire regarding
proposals for stormwater quality measures likely to be introduced
(if any ) within the AMEX landholdings upstream
Page 11 of 24
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
4.0 Recommended Strategy The preceding sections of this report
indicate the following key measures are required for a sustainable
drainage management strategy for this development site:
a. Outfall drainage for the site shall be provided via discharge to
Skeleton Creek or Dry Creek to the north east
b. No retardation of developed flows back to pre development rural
flows is proposed for the development given it’s direct discharge
to the creek
c. Site topography dictates minor drainage system network based on
six sub catchments and the provision of four drainage outlets to
Skeleton Creek
d. 100 year ARI surface (gap) flows can be totally accommodated
within the site via roads acting as floodways – the calculated
flows can be accommodated in accordance with MWC safety criteria
and acceptable freeboard allowances as per GAA standards
e. The magnitude of the upstream drainage catchments draining at
full development levels (without retardation) has significant
impacts on the development site both in terms of the minor and
major systems – further discussions may be required with MWEC and
the upstream developer (AMEX) to assess whether an alternate
discharge scenario may be provided from the AMEX site
f. Water quality treatment facilities are not provided within the
development site as scheme wide water quality measures are either
existing or shall be provided within the Skeleton Creek drainage
corridor
5.0 Conclusions The preceding analysis provides advice and
recommendations to ensure that a feasible surface water management
strategy is achievable for the total development site that meets
the stated objectives of addressing stormwater runoff issues.
Whilst minimal on site water quality measures are proposed, water
quality objectives can be met via catchment wide existing or
proposed water quality proposals within the Skeleton Creek drainage
corridor. The analysis has been prepared on the basis of advice
from upstream consultants, MWC scheme proposals, GAA and Council
standards and is considered to provide a feasible solution. 6.0
Disclaimer This report is based on preliminary information obtained
from discussions with MWC, and consultants acting on behalf of AMEX
Corporation together with in house expertise in determining
drainage strategies for broad acre greenfield sites. All items are
subject to confirmation and review on receipt of further advice
from MPA / MWC and other key stakeholders pending outcomes of the
Wyndham North
Page 12 of 24
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
PSP 1091 exhibition process and formal applications for servicing
conditions at time of development. The drainage management
strategies identified in this report are thus subject to amendments
resulting from the detailed design phase which may also include the
use of other water sensitive design elements as deemed appropriate
to provide similar outcomes. This report has been prepared in good
faith specifically for The Corcoris Group and Taylors in support of
a planning permit application to the MPA under Section 96A of the
Planning and Environment Act 1987. This report is dated 18 March
2014.
Page 13 of 24
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
APPENDIX A1 WYNDHAM NORTH PSP BOUNDARIES PLAN
Page 14 of 24
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
APPENDIX A2 1121 DOHERTYS ROAD - SITE LOCALITY PLAN
Page 15 of 24
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
APPENDIX B1 PLAN OF RE-ESTABLISHMENT AND FEATURE SURVEY
Page 16 of 24
DOHERTYS ROAD
42.78ha
No.1121
MUNICIPALITY:Principal:
© This drawing remains the property of Taylors Development
Strategists - Do not reproduce unlawfully
Sheet:
Revision:
P:\2270\ACAD\SURVEY\DETAIL PLANS\2270 D1 DWG | 1
Lengths are in metres
1121 DOHERTYS ROAD AND LOT 5 TARNEIT ROAD TARNEIT 3029
TCG (RM) Pty Ltd WYNDHAM CITY COUNCIL
RLI & MTK
• •
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
APPENDIX B2 CONCEPTUAL DEVELOPMENT PLAN
Page 17 of 24
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
APPENDIX C1 ROAD HIERACHY PLAN
Page 18 of 24
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
APPENDIX C2 PROPOSED ROAD TYPE SECTIONS
Page 19 of 24
28 35 7.5
concrete strip concrete strip
p:\2270\acad\urban design\concept plans\cad\2. august revision
(mp2)\2270_concept mp02.dwg | 6. ROAD TYPOLOGY
NOT TO SCALE Job No.
Date.
2270 | MP 2 | ROAD TYPOLOGY 19/08/13 CNL AGT
PLAN NOTES • Plan is indicative only and has not yet had Council
feedback or approval. • Boundaries and areas shown are subject to
survey and design changes may
be required to consider onsite features, engineering &
consultants advice. • Layout & lot yield may change as a result
of strategic planning outcomes yet
to be finalized by the GAA and Council. • Further requirements may
be needed but not finalized until the appropriate
investigations have been reported, including but not limited to: -
Feature Survey, Flora and Fauna, Arboricultural Survey, -
Archaeological, Engineering Services, Traffic Engineering.
SOURCE DATA • Surrounding boundary and contour information derived
from supplied
VICMAP digital data.
ASSUMPTIONS • Assumed Road widening: Doherty's Rd: 14m, Tarneit Rd:
10m - TBC. • Road connections as shown require further
investigation
DRAFT
Road Function Connector
Cycling Lanes 1.7m
Parking Lanes 2 x 2.3m
Cycling Lanes 1.7m
Cycling Lanes N/A
Cycling Lanes N/A
Notes:
Parking Lanes 1 x 2.3m unmarked
Cycling Lanes N/A
Footpath Width 1.5m
Notes:
Parking Lanes N/A
Cycling Lanes N/A
Notes:
Avenue 1 28 Avenue 2 24.6 Street 2 24 Street 1 20.6 Local road 16
Reserve/Service Road 13 Laneway 6.5
KEY MAP
Avenue 2 Cross section as per Avenue 1 without on road bike
lanes
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
Page 20 of 24
APPENDIX D PROPOSED MWC SCHEME WORKS PLAN
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
APPENDIX E DRAINAGE ADVICE FROM SPIIRE AUSTRALIA RE AMEX
CORPORATION
Page 21 of 24
From: Leigh Holmes [
[email protected]] Sent: Friday, 24
January 2014 4:22 PM To: John Mitsios Cc: Elizabeth Hamila;
[email protected]; Leah Strauch Subject: FW: Amex North -
outfall locations Attachments: R01 012 Appendix - Catchment
Plan.pdf; R01 012 Appendix - Rational calcs.pdf; R01
012 Outfall options summary.pdf
Hi John, Further to our meeting this morning please find attached
documentation to underpin the AMEX drainage assumptions and assist
with your drainage strategy. I am sure you understand that these
calculations are still only preliminary and are subject to change
upon further detail design. If you need any further clarifications
please do not hesitate to contact myself or Liz
Leigh Holmes | Principal Consultant - Water Team Manager t +61 3
9993 7923 m +61 409 972 229 Level 4 | 469 La Trobe Street PO Box
16084 Melbourne VIC 8007 Australia
spiire.com.au client feedback survey
Please consider the environment before printing. The information
contained in this email communication may be confidential. You
should only disclose, re-transmit, copy, distribute, act in
reliance on or commercialise the information if you are authorised
to do so. Any views expressed in this email communication are those
of the individual sender, except where the sender specifically
states them to be the views of Spiire Australia Pty Ltd. Spiire
Australia Pty Ltd does not represent, warrant or guarantee that the
integrity of this communication has been maintained nor that the
communication is free of errors, virus or interference.
From: Leah Strauch
Sent: Friday, 24 January 2014 4:06 PM
To: Leigh Holmes
Subject: Amex North outfall locations
Hi Leigh, Please find attached:
1. Summary of rationale for multiple outfalls and table of flows 2.
PDF of rational calc worksheet 3. PDF of outfall catchments.
Cheers, Leah
Leah Strauch | Professional Engineer t +61 3 9993 7825 m Level 4 |
469 La Trobe Street PO Box 16084 Melbourne VIC 8007 Australia
spiire.com.au client feedback survey
Spiire Australia Pty Ltd ABN 55 050 029 635 T 61 3 9993 7888
spiire.com.au Level 3 469 La Trobe Street PO Box 16084 Melbourne
Victoria 8007 Australia
:\13\137869\R01 012 Outfall options summary.docx Page 1
Project Name Amex North Project No. 137869
Subject Drainage outfall locations Reference R01 012
1. Introduction
Spiire was engaged by Amex Corporation to provide a drainage
strategy for property 3 within the Truganina Development Services
Scheme. The conveyance of stormwater flows (underground and
overland) across the the DSS area requires thoughtful design due to
the linear nature of catchments and relatively flat grades towards
Skeleton Creek.
Spiire considered the impact and requirements on downstream
properties when developing the Amex property drainage
strategy.
2. MWC DSS Option
The original DSS included one discharge point/crossing from
property 3 into the Tarneit Road reserve. With one discharge point,
the Q100 flow at the crossing point is close to 11m3/s. As
previously outlined, it would be complex to convey this flow
through the catchment to Skeleton Creek in road reserves, and a
drainage corridor is not a preferred solution.
3. Presented Alternate Scheme Option
Spiire has therefore proposed three discharge points to Tarneit
Road:
• Outfall 1: Capturing an external catchment to the west and the
northern portion of the site above the transmission line easement,
and directing it northeast towards Skeleton Creek, most likely
along a drainage corridor. This effectively removes this area from
the DSS area.
• Outfall 2: Midway along the site. This outfall will be for
gap/overland flow only.
• Outfall 3: This outfall will be for the minor (piped) system for
the majority of the subject area, as well as the remaining
gap/overland flow.
4. Outfall Flows
The calculated piped (Q5), total (Q100) and overland (Qgap) flows
relevant to each outfall are presented below.
Q5 Q100 Qgap
Outfall 2 6.53 m3/s 4.44 m3/s
Outfall 3 3.21 m3/s 1.82 m3/s
60 83
.4 m
ut fa
ll op
tio ns
.x ls
P ag
e 1
of 1
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
APPENDIX F DRAINAGE SUBCATCHMENTS AND STRATEGY PLAN
Page 22 of 24
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
APPENDIX G DRAINAGE CATCHMENT CHARACTERISTICS
Page 23 of 24
Area c5 Area c5
Commercial Zone 2.550 0.800 Electricity Easement 2.300 Dohertys
Road realignment 1.000 0.700 Waterway area 1.150 0.000 Tarneit Road
widening 0.540 0.700 0.190 0.700 Dohertys Road widening 0.350 0.700
Open Space 0.660 0.870 Active open Space - AOS 10.910 0.400
residential lots 17.950 0.680 road connector 2.010 0.700 local
roads 8.450 0.600 balance area-lots / roads 35.810 0.650
Existing Tarneit Road 1.050 0.700 0.780 0.700 Existing Dohertys
Road 0.590 0.700
AMEX catchments 10.710 0.610 25.440 0.600 as advised by Spiire
37.360 0.520
Totals 89.640 71.030
Total area 160.670
Notes
Above values derived from GAA Standards - Tables T16 and T17
Residential 1 and 2 zones - average lot size 410sq.m <450
sq.m
fraction impervious 0.75 - adopt c5 as 0.68 local roads - fraction
impervious 0.65 average - adopt c5 as 0.60 major roads - fraction
impervious 0.75 - adopt c5 as 0.70 commercial - BIZ - fraction
impervious 0.90 - adopt c5 as 0.80
APPENDIX G
1121 DOHERTYS ROAD - TARNEIT
ZONE PRECINCT A PRECINCT B
Drainage Management Strategy PSP 189 – 1121 Dohertys Road Tarneit
Taylors Stizza Ref: 2332
Page 24 of 24
4 /1
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CONTENTS PAGE