Manzeene Village, Lara
Manzeene Ave, Lara
Site Stormwater Management Plan Report
15 April 2013
Prepared by SPIIRE Australia
Manzeene Ave
Site Stormwater Management Report
This report has been prepared from the office of SPIIRE
10 Moorabool Street, Geelong, Victoria, 3220
PO Box3042, Geelong, Victoria, 3220 T5249 6888
Acknowledgements and Recognition
Issue Date / Revision No / Author / Checked / Approved20th June 2012 / DRAFT / M. Cairney / J. Koehler / L. Holmes / L. Holmes
6th December 2012 / DRAFT REV A / M. Cairney / J. Koehler/ N. Green / L. Holmes / L. Holmes
16th April 2013 / REV B / N. Green / J. Koehler
© SPIIRE
The information contained in this document is intended solely for the use of the client identified on the report cover for the purpose for which it has been prepared and no representation is made or is to be implied as being made to any third party. Other than for the exclusive use of our client, no part of this report may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying or otherwise, without the prior written permission of SPIIRE.
Manzeene Ave
Site Stormwater Management Report
Contents
1Introduction
1.1Background
2Existing Site Conditions
3Clause 56.07-04
4Methodology
5Denise Court and Cameron Crescent Catchments Hydrologic / Hydraulic Analysis
5.1Flow Estimates and Rorb Models
5.1.1Pre-developed Flows
5.1.2Functional Retarding Basin Sizing (RORB Method)
5.2Functional Design Elements
5.2.1Existing Drainage Constraints
5.2.2Extreme Storm Events
5.2.3Water Quality Provision within Retarding Basins
5.2.4Retarding Basin Reserve Areas
5.2.5Internal Flow Conveyance Requirements
5.2.6Interface with Existing Lots to East of Site
5.2.7Alternate Interfacing Option
5.3Retarding Basin Outfall Drainage System
5.3.1Easement Widening
5.3.2Patullos Road Swale
5.42d modelling of system
5.5Summary of 2d Modelling for Denise Court and Cameron Crescent
6Kees Road Catchment Hydrologic / Hydraulic Analysis
6.1Existing Conditions RORB Model
6.2Developed Conditions RORB Model
6.2.1Internal Kees Road RORB Model
6.3Functional Design Elements
6.3.1Kees Road Drainage Swale
6.3.2Internal Drainage Reserve
6.3.3Proposed Underground Drainage to Hovells Creek
6.3.4Major Gap Flows over Kees Road
6.42d Modelling
6.4.1Detrimental Impacts Realised
7Stormwater Quality Strategy
7.1Guidelines for Treatment
7.2MUSIC Analysis
7.2.1Treatment Option - Combination of Raingardens and wetlands
7.3WSUD Recommendations
7.4Drainage/WSUD Layout
8Conclusion & Recommendations
APPENDIX A: Denise Court and Cameron Crescent Rational Method Calculations and RORB Calibration
APPENDIXB: Functional Design Drainage Strategy Plans
APPENDIX C: HECRAS analysis of 16m wide Road Reserve at 1 in 500 Sawtooth Grading
APPENDIX D: BMT WBM Flood Mapping and Discussion
APPENDIXE: RORB Catchment Plans
APPENDIXF: Property Titles Between Kees Road and Hovell Creek
APPENDIXG: Kees Road Catchment Rational Calcs and Calibration of Best Fit Comparison of 1%AEP Flows
APPENDIXH: City of Greater Geelong Internal Referral Comments to Draft Revision A Stormwater Management Report
APPENDIXI: Lara Structure Plan – Surface Water Management Strategy Report
List of Figures
Figure 1: Site Location
Figure 2: Manzeene Avenue Property catchments
Figure 3: Proposed flow paths for Denise Court and Cameron Crescent catchments
Figure 4: Significant flow locations for Manzeene Avenue property
Figure 5: Indicative size of ‘theoretical’ RB as per LWGA SWMS report
Figure 6: MUSIC model schematic
List of Tables
Table 1 : RORB parameters for Denise Court and Cameron Crescent Catchments
Table 2: Pre-Developed Flows for Range of Annual Exceedance Probabilities
Table 3 : Volume required to detain storm events up to and including 1% AEP
Table 4 : Retarded Outflows from Retarding Basins
Table 5 : Volume required to detain storm events up to and including 1% AEP (RORB and Tuflow)
Table 6 : Retarded Outflows from Retarding Basins
Table 7: 100 Year ARI Peak Flows
Table 8: Best Practice Objectives for Environmental Management of Stormwater
Table 9: Treatment measures
Table 10: Overall Pollutant Reductions
Manzeene Ave
Site Stormwater Management Report
1Introduction
Spiire Australia Pty Ltd have been engaged by Manzeene Avenue Development Trust Pty Ltd to develop a stormwater management plan for the Manzeene Village sitein order to support a re-zoning and development plan application for the subject land. An initial investigation was carried out in June 2012 and has been refined following discussions with City of Greater Geelong (CoGG). After discussion with CoGG, BMT WBM was engaged to facilitate tuflow modelling of the Spiire Functional Design.
The site is approximately 58 hectares in size. It is bounded by O’Hallorans Road to thewest, Patullos Road to the south,land used for residentialpurposes and Kees Road to the east and north as shown inFigure 1 below.
The land is relatively flat,with the southern half of the site space sloping from west to the east, and with a ridge half way along Mazeene Avenue and the land to the north of the ridge sloping to the north east.
The purpose of this report is to to develop a Site Stormwater Management Plan (SSMP) for the Manzeene Villagesite whichis in accordance with City of Greater Geelong’s (CoGG) SSMP requirements including in accordance with Clause 56.07-04 of the Victorian Planning Provisions and hence supports the lands rezoning. This report willprovide guidance for achieving best practice drainage and waterway management while integrating water sensitive urban design into the development works.
This Site Stormwater Management Plan has been finalised following further detailed modelling and consultation with Council.
1.1Background
The current Greater GeelongPlanning Scheme has the subject site zoned as Rural Living Zone (UGZ). The rezoning is planned to be to Residential 1 and Business 1 Zone.
Previous work in the area
A high level drainage strategy has been previously prepared for Area 4 of the Lara Structure Plan (LSP) by Neil M Craigie Pty Ltd (NMC), this report was updated to the Lara West Growth Area Surface Water Management Strategy report (LWGA SWMS report) on 9th June 2012 by Neil Craigie Pty Ltd.
The NMC report will dictate much of the drainage requirements for the northern part of the site as it sets the flow regime coming into the Manzeene Village Site from the upstream catchment as part of the Lara West development.
BMT WBM has also previously undertaken flood modelling and mapping in the area that informed Neil Craigie’s report.
This stormwater management report is a refinement of the Draft Issue (June 2012) and Draft Revision A (December 2012) issue, both which presented options and recommendations for the implementation of stormwater management for the site.
Following the June 2012 report, CoGG requested further detail to support the drainage strategy. This includes the inclusion of 2d modelling and functional plans showing the infrastructure required. These are included in this report.
Following the December 2012 report, CoGG responded with internal referral comments dated 28 February 2013. These comments have been addressed in the report and found in Appendix H.
This Report refines the SSMP and has informed the development plan to ensure the development plan has been produced to make allowance for the drainage assets required.
2Existing Site Conditions
The site is made up of three distinct catchments (refer toFigure 2):
Figure 2: Manzeene Avenue Property catchments
- The southern most catchment referred to as Denise Court is a trapped low point that falls to the rear of existing allotments in Denise Court; the catchment is 14.1ha in size.
- The middle catchment referred to asCameron Crescent is a trapped low point that falls to the rear of existing allotments in Cameron Crescent and is 13.8ha in size1. It is understood that there is an under ground pipe drain that is available at the rear of the allotment (this pipe’s capacity has not been investigated at this stage due to lack of information regarding the pipe). It is understood that this pipe will not be available as the point of discharge for the Cameron Crescent catchment,due to existing flooding impacts within existing lots on Cameron Crescent, and the outlet will be provided at Patullos Road.
- The northern catchment - is around 30.1ha and makes up a small proportion of the overall 1020ha catchment upstream of Kees Road. Refer to the LWGA SWMS report, Appendix I). Thesite and external catchment areaform part of the Hovell Creek catchment.The site and external catchment areais presently used for mainly agricultural purposes, cropping and grazing, with a small portion of it used as low density residential. The existing overland flow (as per the LWGA SWMS report) through the site is 39.2m3/s.
BMT WBM flood mapping of the area (Appendix D)suggests much of the subject site is inundated under existing conditions, with significant sections of upstream catchments contributing flow to the Manzeene Village Site. The LWGA SWMS adopts O’Halloran’s Road as a future catchment boundary for storm events up to and including 1 in 100 year ARI flow events for the Denise Court catchment and the Cameron Crescent catchment (refer Figure 3 below from the LWGA SWMS report). The depth of inundation in the Kees Road catchment and upstream of it, is low and hence opportunities to minimise the inundation through constructed drainage reservesare significant.
Figure 3: Proposed flow paths for Denise Court and Cameron Crescent catchments
Source: Lara West Growth Area Surface Water Management Strategy report
3Clause 56.07-04
Clause 56.07-04 is the section of Clause 56 that relates to drainage matters, the main objectives of this clause are:
-To minimise damage to properties and inconvenience to residents from urban runoff.
-To ensure that streets operate adequately during major storm events and provides for public safety.
-To mimimise increases in stormwater run-off and protect environmental values and physical charateristics of recieving water from degradation by urban runoff.
To achieve the above the stormwater managment plan must:
-Incorporate authority requirements and standards.
-Meet Best Practice Environmental Management Guidelines.
-Ensure that flows downstream of the subdivision site are restricted to predevelopment levels unless increased flows are approved by the relevant drainage authority and there are no detrimental impacts.
4Methodology
To demonstrate that this Site Stormwater Management Plan meets the requirements of CoGG, including Clause 56.07-04 the following methodology was adopted:
- Undertake rational and RORB flow estimates for the Denise Court and Cameron Crescent catchments to understand pre-developed flows and retarding basin volumes required.
- Review Rorb Model for the overall Kees Road catchment and assess need for retardation within the catchment within Manzeene Village.
- Undertake MUSIC modelling of catchments to determine functional sizing of water quality infrastructure required.
- Undertake functional design of retarding basins and drainage infrastructure to incorporate retardation requirements, water treatment measures, provision for access and maintenance and integration with Urban Design.
- BMT WBM to undertake 2d modelling of functional designs using Tuflow to assess flooding impacts of the following scenarios as agreed with CoGG:
Existing conditions –Broad scale model
Existing conditions – cut down model
Developed Conditions – broad scale model (Lara west not developed)
Developed Conditions – cut down model (Lara West Developed)
- Review of Tuflow results to assess any detrimental impact and flooding improvements as a result of implementing the functional designs.
Spiire, together with BMT WBM have completed the above work to allow for the full development of a Site Stormwater Management Plan Report to support the rezoning of the Manzeene Village Site.
During later design stages, the sizing of drainage infrastructure including retarding basins, floodways and drainage will be refined and checked using Tuflow to ensure no additional detrimental impacts are realised during the detailed design.. This is a detailed aspect of the design and should not affect the rezoning of the land.
5Denise Court and Cameron Crescent Catchments Hydrologic / Hydraulic Analysis
5.1Flow Estimates and Rorb Models
To ascertain flow estmates for developed and pre-developed scenarios for the Denise Court and Cameron Crescent catchments, rational calulations and Rorb models produced for each catchment.
The premace of this phase is to allow for the functional sizing of retarding basins and drainage infrastructure that would later have flooding impacts checked via 2d modelling of the functional design.
Rorb models for the developed un-retarded Denise Court and Cameron Crescent catchemnts was created and calibration undertaken as shown in Appendix A.
This results in parameters as Table 1.
Table 1: RORB parameters for Denise Court and Cameron Crescent Catchments
Rorb Parameter / Cameron Crescent / Denise Courtm / 0.8 / 0.8
kc / 0.4 / 0.39
IL / 15 / 15
RoC / 0.6 / 0.6
Un-retarded flow estimates for the Denise Court and Cameron Crescent using the above parameters was 3.9 and 3.7m3/sec respectively.
In addition, developed, unretarded rational calcs as in Appendix A were produced. These calculations were based on CoGG guidelines at the time (June 2012). The developed, unretarded flows for Denise Court and Cameron Crescent catchments are 3.8 and 3.7m3/s respectively which correlates to the Rorb flows as previous, as such the Rorb models were then utilised to determine predeveloped flows and functional retarding basin volumes required for each of the catchments.
5.1.1Pre-developed Flows
Existing peak flows have been estimated using RORB by revising the calibrated Rorb model to have ‘natural’ reaches and sub area fraction impervious values of 0.1.
In addition to the 1% AEP storm event, Spiire have provided interem events to allow for an understanding of the pre-developed flows upto and including the 1% AEP.
Pre-developed rational calculations for the Denise Court and Cameron Crescent have been done for the 1%AEP event as showin in Appendix A. The pre-developed rational calcs for the 1%AEP event are lower than thwhat has been produced by Rorb, however, given that Council preference is for Rorb to be used to estimate pre—developed flows from a site, the calibrated Rorb model flows have been adopted to set the retardation target for the Denise Court and Cameron Crescent catchments.
As previously discussed, these flows will set a guideline for the retardation requirement for the site. Should detrimental impact be realised via the WBM modelling beyond the site boundaries, the retardation will increase beyond these flows shown.
The Existing flows for the Denise Court and Cameron Cresent catchments are as follows as modelled in RORB:
Table 2: Pre-Developed Flows for Range of Annual Exceedance Probabilities
AEP / Cameron Crescent / Denise Court% AEP / RORB flows (m3/s) / RORB flows (m3/s)
20% AEP / 0.32 / 0.33
10% AEP / 0.37 / 0.38
5% AEP / 0.44 / 0.44
2% AEP / 0.60 / 0.6
1% AEP / 0.74 / 0.75
Note: Catchment west of O’Hallorans road has been excluded, hence figures above will be conservative.
5.1.2Functional Retarding Basin Sizing (RORB Method)
To understand functional sizing of the Denise Court and Cameron Crescent retarding basins, Spiire adopteda RORB model approach to determine the retarding basin volume required to detain developed flowsto pre development levels for each of the Denise Court and Cameron Crescent catchments, for storm events up to and including the 1%AEP storm event.
Spiire utilised the RORB results to create 3D functional designs that were then inputted into the WBM BMT tuflow models.The RORB and Tuflow results were then compared.
Table 3shows the storage volumes sized in Rorbfor each retarding basin to best match the pre-developed flows dericved from the pre-develop Rorb model.
Table 3 : Volume required to detainstorm events up to and including 1% AEP
Cameron Crescent / Denise CourtRetardation Detention Volume (RORB) / 3070 m3 (RL 13.0) / 3141 m3(RL 13.0)
Table 4 shows the retarded flows from the retarding basins to at or below the pre-developed flows as modelled in RORB.
Table 4: Retarded Outflows from Retarding Basins
AEP / Cameron Crescent / Denise Court% AEP / RORB flows m3/s / RORB flows m3/s
50% AEP / 0.21 / 0.21
20% AEP / 0.30 / 0.30
10% AEP / 0.35 / 0.35
5% AEP / 0.42 / 0.42
2% AEP / 0.52 / 0.51
1% AEP / 0.61 / 0.62
It can be seen that from the above analysis, the flows out of the retarding basins, when modelled in Rorb are at or lower than pre developed levels up to and including the 1%AEP event.
The 3d functional design for each basin has been done based on these volumes and sets the basis for the BMT WBM 2d modelling.
The BMT WBM 2d modelling considers impacts external to the site to ascertain what flooding impacts occur as a result of the Manzeene Village development. The Tuflow models are inclusive of the functionally designed drainage elements including the proposed retarding basins, drainage reserves and outfall drainage pipes. The functional design plans are shown in Appendix B and have been developed with consideration to the following sections.
The Rorb modelling analysis has allowed for the functional sizing of the retarding basins and major drainage infrastructure. This functional design has then been analysed by BMT WBM using Tuflow to establish refined flood levels and impacts from implementation of the functional design.
5.2Functional Design Elements
5.2.1Existing Drainage Constraints
The existing drainage constraints are:
-CoGG have confirmed that the point of discharge for the Denise Court and Cameron Crescent catchments is to be to Patullos Road, not to existing drainage within the existing streets directly to the east.
-CoGG have indicated that Patullos Road is likely to be duplicated within the future. The outfall swale on Patullos Road has considered this and made an allowance of 23.6m for a 4 lane divided road including parking as per CoGG direction 29 January 2013. This is shown in the functional drawings.