DIT:Planning Reform Submissions

From: Sent: Friday, 18 December 2020 6:15 PM To: DIT:Planning Reform Submissions Subject: Water Sensitive SA submission - Code Phase 3 I 4 November 2020 amendment Attachments: WSSA_Planning and Design Code Revision _submission FINAL_Letter and Submission_ 18Dec20.pdf - ■ Dear Mr Lennon

Please find attached the submission from W ater Sensitive SA in response to the consultation on the Code (Phase 3) amendment 4 November 2020.

Regards

Me llissa

Mellissa Bradley ager Water Sensitive SA · 142

--e~s1 1vesa.com LIVFRBLE - WRTER WRTER SENSITIVE ■■ SENSITIVE SR COMMUNITIES.

1 ■■ WRTER ■■ SENSITIVE SR

18 December 2020

Mr Michael Lennon Planning Commission [email protected]

Dear Mr Lennon

Planning and Design Code – Phase 3 submission, 4 November 2020 amendments

Water Sensitive SA is pleased to submit this response to the Planning and Design Code- Phase 3.

Water Sensitive SA has devoted considerable resources over the past three years to understand the changing urban form, the associated implications for communities and the environment and to develop suitable solutions at a range of scales to meet the strategic targets of the 30 Year Plan for Greater Adelaide. The focus of this submission is on the urban greening and stormwater management aspects of the Code.

The recent amendments to the deemed-to-satisfy stormwater policy for small-scale development (Part 3 – Stormwater Management Overlay) will improve peak flow management performance of small-scale developments, which is an important step forward. This improvement did however come at the expense of the other performance criteria for water conservation and stormwater quality water quality management. We appreciate this is a balance act and offer in this submission the outcomes of modelling that attempts to find optimal lot scale solutions for stormwater management for your consideration.

Attached is our detailed submission comprising:

▪ Policy and guideline recommendations ▪ Appendix A –Evidence base for recommendations

We would welcome the opportunity to work with DPTI to assist in any refinement of policy and guidelines that support the Code. Water Sensitive SA can offer assistance with the development of design guidelines for built form typologies and allotment scale solutions.

If you require any clarification of the comments raised as part of this submission, please contact the Program Manager, Mellissa Bradley at [email protected] or 0431 828 980.

Yours sincerely

Keith Downard Chair, Water Sensitive SA Steering Committee

LIV ERB LE WRTER SENSITIVE COMMUNITIES. WATER SENSITIVE SA – Comment on Code amendments 4 November 2020

Submission to the Planning Commission on the Planning and Development Code – Phase 3 (the Code) November 2020 Revision

OVERVIEW Urban infill provides governments and communities with the opportunity to regenerate our suburbs. Without suitable amendments to the Code and associated guideline development, there is a risk that poor quality infill will continue to degrade our suburbs.

This submission provides the quantitative evidence of the water performance of differing rainwater harvesting, tank size and use options, site coverage and urban greening at the lot and scale, to inform the stormwater management and canopy cover policies within the Planning and Design Code Phase 3 November 2020 Update.

Combined rainwater harvesting and reuse via retention and stormwater detention is provided in the policy as the means of meeting the performance objectives for small-scale development in the deemed-to-satisfy solutions in Part 3 – Stormwater Management Overlay. Incentives are provided to increase overall site permeability via discounting of minimum tank sizes, which is strongly supported as a means of demonstrating the importance of reduced site coverage.

To ensure small-scale infill gives back to the local area and does not distract from streetscape amenity, modest changes to housing footprint (site coverage and layout) and design are required to accommodate greater dwelling density while retaining green space and permeability of outdoor spaces, and support greening, thereby contributing to stormwater management objectives. The deemed-to-satisfy criteria target absolute minimum standards and are expected to fall short of community expectations and state level targets for urban greening and stormwater management.

Recommendation 1 - All allotments < 200m2 shall include a detention component as per the findings of BDO EconSearch (2020a) OPTIONS ANALYSIS: Costs and Benefits of Stormwater Management Options for Minor Infill Development in the Planning and Design Code. A Report to the Attorney-General’s Department, September 2020 and an analysis using the Water Sensitive SA Insite Water tool analysis.

The inclusion of the detention component for all small-scale infill is needed, not just for those sites of 200m2 or greater, to sustain an acceptable level of service of local flood protection for the minor drainage system. This is consistent with the outcomes of the:

▪ BDO EconSearch report: BDO EconSearch (2020a) OPTIONS ANALYSIS: Costs and Benefits of Stormwater Management Options for Minor Infill Development in the Planning and Design Code. A Report to the Attorney-General’s Department, September 2020 (BDO EconSearch Options Analysis Stormwater Report) and ▪ Water Sensitive SA InSite Water Analysis (Refer to Appendix A Evidence for policy recommendations for more information that clearly states the cumulative impacts of infill development on peak flows are substantial and that onsite detention is a cost-effective method to manage these impacts.

Suggested amendments to the Code (Phase 3) – Part 3 Stormwater Management Overlay are provided in red in Table 1. WATER SENSITIVE SA- Comment on Code amendments 4 November 2020

Table 1 Alternative deemed-to-satisfy solution to replace Code Phase 3 Part C - Stormwater Management Overlay

PO 1.1 DTS/DPF 1.1

Residential development is Residential development comprising detached, semi-detached or row designed to capture and re- dwellings, or less than 5 group dwell ings or dwellings w ithin a residential use stormw ater to: flat building:

1. maximise 1. includes rainwater tank storage: conservation of 1. connected to at least 80% of the roof area w ater resources 2. connected to either all toilets, laundry cold water outlets 2. manage peak or hot water service for sites less than 200m2 stormw ater runoff flows and volume to 3. connected to ~ all toilets and either the laundry cold ensure the carrying water outlets or hot water service for sites of 200m2 or capacities of greater downstream 4. with a minimum total capacity in accordance w ith Table 1 systems are not overloaded 5. where detention is required, includes a 20-25 mm diameter slow release orifice at the bottom of the 3. manage stormwater runoff quality. detention component of the tank 2. incorporates dwelling roof area comprising at least 80% of the site's impervious area

Table 1: Ra inwater Tank

Site size Minimum Minimum detention volume 2 (m ) retention (Litres) volume (Litres) <200 2000 NM,1000 200-400 2000 Site perviousness <30%: 1000 Site perviousness =30%: N/ A >401 4000 Site perviousness <35%: 1000 Site perviousness =35%: N/ A

Recommendation 2 - Prior to the release of the Code (Phase 3), develop a guideline to support better choices for deemed-to-satisfy solutions for stormwater management for small-scale development

Appendix A.1 provides an analysis of the performance of a range of allotment sizes, tank sizes and connected uses. Key take-home messages to be drawn from this work are:

• The deemed-to-satisfy solution for allotments < 200m2 should be amended to be l000L retention + 1,000L detention storage, instead of 2,000L retention only.

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▪ For a combined 1000 L detention and 1000 L retention tank the ranking in order of decreasing performance across all criteria is hot water service, laundry, all toilets, and a single toilet. ▪ One toilet alone provides minimal benefit due to the high efficiencies of modern toilets and associated limited rainwater use (draw down on the tank).

Recommendation 3 – DO NOT delete the rainwater tank requirements from the National Construction Code

The rainwater tank requirements within the National Construction Code (SA Amendment) (NCC) need to be retained, with minor amendments, if the deemed-to-satisfy pathway proposed in Part 3 of the Code has any chance of effective implementation.

The recommended minor amendments to the NCC with respect to rainwater tanks is that the NCC should be silent on the size of the rainwater tank and the type of rainwater use connections (e.g. toilet, laundry cold tap or hot water service. Rather, it should define how the connections should be made. The Code (Phase 3) should specify the tank size and rainwater use connections.

Recommendation 4 – Require compliance certificate prior to occupation for stormwater management that is inspected and deemed-to-satisfy the Code

Further to Recommendation 3, the certificate of occupancy must include the installation of the rainwater (combined detention and retention) tank and connection to approved uses. The absence of this requirement both:

▪ undermines the entire Stormwater Management Policy in Part 3 Overlays, and ▪ brings into question why the Attorney-General’s Department would invest in the BDO EconSearch Options Analysis Stormwater Report to determine the most cost-effective solutions for stormwater management at the city scale, if there is no intention to bring into effect the same enforcement controls for rainwater tanks that are applicable to every other component of built form that constitutes development.

Recommendation 5 – Prior to the release of the final Code (Phase 3), develop a guideline for housing typologies that better deliver upon performance objectives for design of urban development

Greater support is needed for developers/development applicants looking to offer improved design quality over and above the minimum standards within the deemed-to-satisfy requirements of the Code.

The CRC for Water Sensitive Cities has developed two resources that will support a housing design quality:

 Water sensitive outcomes for infill development: Infill performance evaluation framework  Infill typologies catalogue that together can provide the basis of design quality guidance to deliver the type of development envisaged by the Desired Outcomes and Performance Objectives within the Code for stormwater runoff, infiltration, evapotranspiration and urban heat, thus improving liveability, resilience and water security.

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WATER SENSITIVE SA – Comment on Code amendments 4 November 2020

Recommendation 6 – Prior to the release of the Code (Phase 3), develop a guideline to support the establishment of green cover and tree canopy in Zones excluded from the Urban Tree Canopy Overlay.

The policies proposed within the Code (Phase 3) Part 3 Tree Canopy Overlay are insufficient to achieve a 20% increase in urban green cover by 2045 as per the 30-Year Plan for Greater Adelaide, and in fact will decrease urban tree canopy area.

Further, with Urban Tree Canopy Overlay not being applicable to the:

▪ Neighbourhood Zone, in addition to the ▪ Master Planned Neighbourhood Zone we have grave concerns for the resultant urban heat impacts for these suburbs, particularly given many are considered vulnerable for their social disadvantage to the north of Adelaide.

The default position in these zones should not be no trees on private land. Guidelines are needed to support developers to meet the Desired Outcomes and Performance Outcomes for landscape, urban green cover and canopy cover in the Neighbourhood Zone, in addition to the Master Planned Neighbourhood Zone.

Recommendation 7 – Offset schemes

It would be desirable to integrate the offsite schemes for urban stormwater and trees as there are cross-subsidies (contributions to dual objectives) that would increase the benefits to the South Australian community, and enable support for the land costs identified in the BDO EconSearch Options Analysis Stormwater Report.

Prior to the establishment of an offset scheme for stormwater management or urban green cover, extensive consultation with local government and industry is required to ensure establishment of:

▪ Clear objectives for the scheme ▪ Analysis of viability of offsite solutions, particularly in terms of land availability, and clear management plans defining the location and nature of offsets. For example, offsite detention must be in same catchment and upstream of critical points for flooding. ▪ The full costs of offsets, including purchase of land where necessary should be transparent and incorporated into any offset scheme. This will enable developers to make rational decisions on their choice between on-site and off-site measures and provide equity such that there is not a cost-shift to the wider rate-paying community ▪ The amount of stormwater and green canopy measures that can be offset should be considered in the context of the locality and as such restriction may apply in particular local government areas or precincts, i.e. offsets are a privilege not a right. ▪ Offsets should be voluntary.

Recommendation 7.1 – Stormwater Management Offset scheme – The development of any stormwater offset scheme must involve detailed consultation with local government and industry, while drawing upon learnings from similar interstate projects.

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WATER SENSITIVE SA – Comment on Code amendments 4 November 2020

A number of stormwater offset schemes exist, both in South Australia and interstate, that could be a valuable reference for the development of any South Australian scheme, including City of Onkaparinga in South Australia; and City of Kingston and City of Moonee Valley in Victoria.

Other matters to consider when establishing a stormwater offset scheme include: ▪ What values is the offset scheme aiming to protect? E.g protecting is a receiving environment (creek/ waterway/ coast) (i.e. not the allotment) ▪ Provided the water quality treatment occurs upstream of the receiving environment – it doesn’t really matter where it happens (i.e. on-site or downstream) ▪ There is benefit in having stormwater management treatment systems in the public domain, due to economies of scale and fulfilling maintenance requirements ▪ That said, it is possible that only some stormwater impacts can be best managed offsite (e.g water quality) and any scheme may potentially recommend a partial onsite solution (e.g peak flow, volume management), as per the Moonee Valley City Council’s WSUD voluntary contribution scheme described in a CRC for Water Sensitive Cities case study ▪ Costs are developed to ensure council’s are not unfairly burdened with who of lifecycle costs.

Recommendation 7.2 – Canopy Cover Offset – The development of any canopy cover offset scheme must involve detailed consultation with local government and industry, while drawing upon learnings from both interstate and international case studies

Overview

During the consultation on the 4 November 2020 Code Policy amendment, a canopy cover offset was raised and a nominal contribution of $300 was stated.

This amount is grossly inadequate and merely represents the cost to supply and install a tree. It does not consider:

(a) The cost – labour, plant hire (water truck), passive infiltration (e.g. via kerb inlets and stormwater pits) or irrigation systems – of keeping the new plants watered for a minimum of two years during the plant establishment phase (b) Maintenance of the tree (periodic pruning, sweeping of leaves/gum nuts, etc.) (c) The value of the land take for the tree, including establishment, and mature height and canopy.

Any offset scheme must cover the full costs, including costs listed above.

It is recommended that any offset scheme consider offset criteria, including but not limited to:

▪ Offsite tree plantings to be as close as practicable (within 200 m) of the development site ▪ Offset costs to cover land purchase where required ▪ Where possible, tree canopy offsets shall be delivered conjunctively with stormwater offsets to achieve multiple benefits.

Commentary

The BDO EcoSearch (2020b) OPTIONS ANALYSIS: Costs and benefits of urban tree canopy for minor infill development in the Planning and Design Code (BDO EconSearch Options Analysis Tree Canopy Report) is a welcome first step towards understanding the costs and benefits of tree canopy policy.

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WATER SENSITIVE SA – Comment on Code amendments 4 November 2020

Consultation on this document has yet to be sought by the Planning Commission and it is recommended that prior to the establishment of any offset scheme, that industry, local government, state government and community are given the opportunity to provide comment on the Options Analysis Tree Canopy report.

Water Sensitive SA is willing and able to offer detailed feedback on this report and its implications for urban green cover policy and offset schemes. In the interim, we offer a few brief statements in regard to the proposed Tree Canopy Offset scheme:

▪ A robust tree canopy offset scheme must take into account the cost of purchase of land

We are concerned to note on pages 22-23 of the BDO EconSearch Options Analysis Tree Canopy Report that the offset costing method does not account for land purchase on the assumption that public land is available in close proximity to the infill development site and can be made over to tree planting. However, under the heading “Spatial Issues” (page 22) there is a statement that “the evidence is that there is not enough space on public land to keep up with the loss of trees and green cover due to infill development on private land”. A robust offset scheme must take into account the cost of purchase of land for the purpose of effecting the scheme.

A fair method is essential for achieving the green canopy goals of the 30-Year Plan while addressing cumulative impacts of incremental infill development. This suggests that provision for acquisition of land for canopy should apply to all new developments that rely on offsets, rather than waiting until there is no plantable public space left in near proximity and suddenly charging 100% land acquisition costs for shortfall in tree canopy area of a development. The sooner this is applied the better to allow accumulation of funds for land purchase and reduce the future unit costs of green offsets.

▪ No account in the policies and options analysis has been given for the time lag in canopy establishment

None of the pricing methods appear to compensate for the loss of canopy over the time taken for a planted replacement tree to achieve the same size as the tree removed. For larger trees, this may take decades. Replanting a larger number of trees could be a way of compensating for this long- lasting reduction in tree canopy area. A scaling factor relating to the time to achieve canopy replacement as a fraction of average time for housing stock redevelopment would be more plausible to achieve plan objectives.

▪ Local market-based studies of the influence of trees on housing prices

Section 3.3.4, page 3 of the BDO EconSearch Options Analysis Tree Canopy Report – the analysis relies on benefit transfer from Perth studies, which may be deemed as not suitably relevant to the Adelaide context. There have been hedonic real estate valuation studies done in Adelaide that considered proximity to trees, which should provide more statistically robust figures (Darla Hatton MacDonald, CSIRO, and students e.g. Segaran, R.R. (2015). https://digital.library.adelaide.edu.au/dspace/bitstream/2440/84696/8/02whole.pdf.

Recommendation 8 – Prior to the release of the Code (Phase 3), develop a guideline to support tree species selection suitable for context

It is also noted from page 10, Figure 6, Options Analysis BDO EconSearch Options Analysis Tree Canopy Report shows large areas of the north-western suburbs have very low tree density. This area also has a shallow saline water table (Pavelic et al. 1992) and even if trees are planted, only those with shallow roots that are salt tolerant are likely to survive. Hence, account needs to be taken of

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WATER SENSITIVE SA – Comment on Code amendments 4 November 2020

the native vegetation that was initially in place in the Adelaide metropolitan area that present a challenge to broad urban green cover targets.

There is very little mutual recognition of impacts of trees (positive and negative) on stormwater systems, and no consideration of watering requirements for trees and how these could be addressed through stormwater system design. Provision for stormwater infiltration for tree watering on the block and in offset plantings in public spaces is warranted to ensure tree survival and health and to minimise the impost on the mains water supply of tree watering that could otherwise be met by stormwater infiltration. Such watering should also be accounted for in footing design and in stormwater system design.

Recommendation 9 – Promote Designing for a cool city: Guidelines for passively irrigated landscapes as a means of supporting the health of trees, particularly during establishment phase

Allotment sizes within riparian zones

Recommendation 10: We recommend that provisions be made within the Code to preclude allotments within the ‘riparian’ zone from subdivision in accordance with the proposed minimum lot sizes.

(Riparian defines any land that adjoins natural creek lines, eg including Brownhill Creek.) Further that any further developments/structures on such land are not permitted to encroach closer to creek lines.

The amendment is sought as creeks are currently, and in future will continue to be, relied upon for passing stormwater flows, and have significant natural heritage value. Prevention of subdivision of land adjacent creeks will limit further investment of assets in flood prone land and importantly will avoid the impossibility of reclaiming riparian land along urban creeks to green corridors. This has been highly successful in land beside the Torrens River and Little Para River and would have great value if replicated along all urban natural creek lines for conservation, recreation, tree canopy preservation, heat island mitigation and enabling communities to be connected by foot and cycle. Without this provision, such significant community-wide opportunities would be lost.

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WATER SENSITIVE SA – Comment on Code amendments 4 November 2020

APPENDIX A – Evidence for policy recommendations

A.1 Allotment scale stormwater management policy analysis

(i) Need for measurable performance-based policy for small scale (< 5 allotments) infill

The performance outcomes in the Code (Phase 3) Part 3 Stormwater Management Overlay are not measurable and hence stating that the deemed-to-satisfy solutions are adequate is arbitrary.

We have therefore adopted the performance outcomes for 5 to 19 allotments for stormwater runoff peak flow management (criteria 2) and stormwater runoff quality (criteria 3). There is no South Australian government performance outcome for the conservation of water resources. We have therefore conservatively taken the lowest value when benchmarking against other capital cities, being 25% potable water reduction. Note: In comparison, potable water reduction targets in Melbourne is 25% and Sydney 40%. The performance criteria upon which the deemed-to-satisfy criteria has been tested are stated below.

Table 2 Performance benchmarks for small-scale (<5 allotments) in the absence of measurable targets in the Code.

Performance Outcome Benchmark Source

Residential development is designed to capture and re-use stormwater to:

1. Maximise 25% saving of potable water (through replacement No State level conservation of with alternative water, e.g. rainwater and water- performance-based water resources efficient appliances) policy. However, InSite Water Tool Note: Minimum Target > 25%, Best Practice > 40%, offers a conservative approach compared with Melbourne 25%, and Sydney 40% potable water saving.

2. Manage peak Development includes stormwater management P&D Code stormwater systems that: Part 4 runoff flows and (a) maintain a pre-development peak flow rate from volume to Design in Urban Areas the site, based upon a 0.35 runoff coefficient for ensure the the 5% AEP 30-minute storm, unless a lower carrying DTS/DPF 42.3 performance measure is specified in an approved capacities of catchment-based Stormwater Management Plan Council engineering downstream requirement systems are not (b) maintains the stormwater runoff time to peak to (although variations overloaded match that of the pre-development do exist across LGAs)

(c) manages up to and including the 1% AEP flood event to avoid flooding of buildings

Development includes stormwater management systems to maintain pre-development total annual

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WATER SENSITIVE SA – Comment on Code amendments 4 November 2020

Performance Outcome Benchmark Source

runoff increase to no more than 10% as a result of Insite Water, development. Principles Australian Rainfall and Runoff.

Residential development is designed to capture and re-use stormwater to: 3. Manage Development includes stormwater management P&D Code stormwater systems designed to achieve the following pollutant Part 4 runoff quality1 reduction outcomes: Design in Urban Areas (a) 80 per cent reduction in average annual total suspended solids DTS/DPF 42.1 (b) 60 per cent reduction in average annual total phosphorus and (c) 45 per cent reduction in average annual total Water sensitive urban nitrogen design – Creating (d) 90 per cent reduction of litter/gross pollutants more liveable and compared to untreated stormwater runoff water sensitive cities (e) no visible oils/grease for flows up to the 4 EY in South Australia (Exceedances per year).

Volume reduction is based on volume runoff for all impervious areas. This is based on a predetermined (see flow reduction section) or user selected storm intensity and duration.

Volume reduction (lot scale) is set as a percentage of total impervious area runoff volume retained by the water tank and any infiltration devices. The volume reduction targets is that annual average volume should be the same as the pre development level. An allowance of 10% over pre- development levels is allowed to account for uncertainties. This target has been established within the Insite Water Tool based-upon best practice stormwater management practices within Australian Rainfall and Runoff (2016)

(ii) Analysis of deemed-to-satisfy policy against measurable performance criteria in (i)

The following summary of the assessment of the performance of the proposed deemed-to-satisfy solutions for stormwater management indicates how solutions other than those in the Code Part 3 Stormwater Overlay for allotment scale (< 5 dwellings) stormwater policy will provide a greater net benefit to the householder and the wider community.

1 A ‘STORMWATER’ score is also given as a target for stormwater runoff quality in InSite Water. The target is to remove 45% of nitrogen, which achieves 100 ‘STORMWATER’ points. Removal rates less than the 45% target receive a proportion reduction in the score out of 100.

Nitrogen is difficult to remove because it is soluble in water, and generally requires tertiary treatment to reduce its levels in stormwater runoff, or nitrogen can be reduced proportional to the percentage of stormwater runoff re-used via rainwater tanks or infiltration systems. Nitrogen is a good proxy for removal of other pollutants as it is generally the most difficult pollutant to remove. If the total nitrogen reduction target is achieved, it is deemed to be a good indicator that other pollutant targets have been achieved.

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WATER SENSITIVE SA – Comment on Code amendments 4 November 2020

The analysis in Tables 3 to 5 tests the proposed (4 November 2020) Part 3 Stormwater Management Overlay policy, the December 2019 policy and some variations to rainwater tank size and use combinations, through application of the InSite Water Tool, which applies the performance criteria detailed in Table 2.

Scenario 1 – 201-300m2 allotment and 3000 litre rainwater tank retention/detention combinations Scenario 2 – Allotment up to 200m2 and 2000 litre retention tank. Scenario 3 – Allotment up to 200m2 and a combined 1,000 litre retention and 1,000 litre detention tank

Scenario 3 was modelled to demonstrate the benefits of introducing a detention component to the rainwater tank deemed-to-satisfy solution for very small allotments, without increasing the overall tank size. Given the reduction in retention tank volume (1,000L only), creation of a connection to more than one use was not considered viable and hence not modelled in this scenario. It must be acknowledged that the proposed deemed-to-satisfy requirement for detention (peak flow management) represents a “one size fits most” policy solution. In some circumstances the 1kL requirement suggested is too small by a factor between 3 and 8 that is currently required by some Adelaide metropolitan councils, given the DTS detention storage proposed is currently only about 20% of the required Council volume. This reinforces the need for inclusion of a detention component as part of any deemed-to-satisfy solution for stormwater management that involves small rainwater tank storages.

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WATER SENSITIVE SA- Comment on Code amendments 4 November 2020

Table 3 Scenario 1: 201-300m2 allotment and 3000 litre rainwater tank combinations. Summary of scenario testing of adequacy of the deemed-to­ satisfy criteria for stormwater management in Code (Phase 3) - Part 3 Stormwater Management overlay.

Scenario 1-201-300m2 allotment, 20% landscaped December 2019 Policy November 2020 Policy - 2000L retention + November 2020 Policy - 2000L retention + lO00L 3000L retention only tank, connected to 1000 L detention tank connected to one toilet + detention tank connected to one toilet + NON­ - All toilets + laundry laundry COMPLIANCE WITH SECOND CONNECTION (laundry or HWS) Quality Volume Flow Efficiency Quality Volume Flow Efficiency Quality Volume Flow Efficiency Target Score = (< 100/4 Management Target Score = (< 100/4 Management Ta rget Score = (< 10% Management uI.U z or > 1000/4 increase) or > 100% increase) o r> 100% increase) <( t::l ::i: I- > PASS PASS PASS FAIL PASS FAIL FAIL a: V') j::: ozu 119 -5.la 27.2" 200Lextra 26.2" 200Lextra 22.8% u. - I.U a: <( ~ I.U I!) a:, water savi1111 detention water savi1111 detention water saving a. <( 0 required required

Water tank performance over time Water tank performance over time Water tank performance over time

0z - Tank Balance - T3nk 8;:il311¢e <( 3,000 -' u::-' ""z f ::c a. ::i­ l <( -' I:~ ~ l 200 <400 :~ iMJ!~200 200 400 ,oo ~ 1"MililllL1T•me =Wffk.s ffi e; Twe • weeks Trme • weeks

Rainwater Tan k Reliability(%)\ Ra inwater Tank Overflow(%) Rainwater Tank Reliability(%)\ Ra inwater Tank Overflow(%) Ra inwater Ta nk Relia bility(%)\ Ra inwater Tank Overflow(%)

39 16.3 58.1 37.7 90.3 65

The tank size and connections meet three of the four One toilet connected plus laundry only passes the water This solution fails the stormwater runoff quality and volume z criterion, however they fail flow management which efficiency target targets and is approaching the flow management and water 0 vi provides the greatest community benefit, according to the efficiency targets. ::> BOO EconSearch (2020a) Options Analysis Stormwater -'u z report, described in Appendix A.3 8 POLICY NOT RECOMMENDED POLI CY NOT RECOMMENDED POLI CY NOT RECOMMENDED

Page I 11 WATER SENSITIVE SA- Comment on Code amendments 4 November 2020

Table 4 Scenario 2: Allotment up to 200m2 and 2000 litre retention tank. Summary of scenario testing of adequacy of the deemed-to-satisfy criteria for stormwater management in Code {Phase 3) - Part 3 Stormwater Management overlay.

Scenario 2 - <200m2 allot ment, 15% landscaped December 2019 Policy November 2020 Policy - 2000L tank, connected November 2020 Policy - 2000L tank, connected 2000L retention only tank, connected to all to one toilet + laundry to one toilet+ NON-COMPLIANCE WITH SECOND toilets + laundry CONNECTION

Quality Volume Flow Efficiency Quality Volume Flow Efficiency Quality Volume Flow Efficiency Target Score = (< 10% Management Target Score = (< 100/4 Management Target Score = (< 10% Management or > 1000/4 increase) or > 100% increase) or>100% increase) PASS PASS PASS PASS PASS PASS Smre117" 3.1" increase 27. l " savil'l8 114" 6.9" increase 26.8%

Water tank performance over t ime ::, Water tank performance over time Water tank performance over time -'a: V, 0 - Tri Balanot z - Tank Sa!anee <( 2.000 -' u::-' !2.000:s 1.000 mrrrm· ""z 'l f I! ::c 0 ....,..__ _._ _ ..__....~ __,_ __...;_ _ _.__ __,_ 0.. <( 200 400 a: (!) l·~ ~Mi~hl200 •oo •oo n,.,.=~ffks Tm:-., = wttk$ 200 Tlme • weeM Rainwater Tank Reliability(%)\ Rainwater Tank Overflow(%) Rainwater Tank Reliability(%)\ Rainwater Tank Overflow (%) Rainwater Tank Reliability(%)\ Rainwater Tank Overflow(%)

38.3 17.7 45.3 20.2 93.9 63.6

The tank size and connections meet three of the four The tank size and connections perform marginally poorer One toilet connected w ithout compliance measures to criterion, however they fail flow management which than the December 2019 policy for most performance ensure the second use is connected fails to deliver upon any provides the greatest community benefit. objectives, however flow management performance is the of the objectives. z same, a fail requiring an extra 700L detention storage. The graph indicates that the tank w ill regularly spill, causing 0 vi 64% of all rainwater falling on the roof to spill to Councils ::> drainage network. Detention is required in addition to a -'u z multiple connections (retention and use) 8 POLICY NOT RECOMMENDED POLI CY NOT RECOMMENDED POLI CY NOT RECOMMENDED

Page I 12 WATER SENSITIVE SA- Comment on Code amendments 4 November 2020

Table 5 Scenario 3: Allotment up to 200m2 and a combined 1,000 litre retention and 1,000 litre detention tank. Summary of scenario testing of adequacy of the deemed-to-satisfy criteria for stormwater management in Code (Phase 3) - Part 3 Stormwater Management overlay.

Scenario 3 - <200m2 allotment, 15% landscaped Alternative to December 2020 policy Alternative t o December 2020 policy Alternative t o December 2020 policy l000L retention + lO00L detention tank, l000L retention + lO00L detention tank, l000L retention + lO00L detention tank, connected HWS only connected laundry only connected one toilet only

VI Quality Volume Flow Efficiency Quality Volume Flow Efficiency Quality Volume Flow Efficiency "-' > Target Score = (< 10% Management Target Score = (< 100/4 Management Ta rget Score = (< 10% Management "-'u 6"-' or > 1000/4 increase) or> 100% increase) or> 100% increase) ~ Cl FAIL (NEAR FAIL FAIL PASS FAIL PASS FAIL FAIL ::E 0 a: t:;; PASS) 22.9% 100L extra 25.9 lO0L extra 25.1 100L detention 22.6% o z Score 99% detent ion detent ion ~ <( "-' I!) required required

Water tank performance over t ime Water tank performance over time Water tank performance over time 3' ;;:: VI - Tank. Balanoe - Tank Balance 0 1.000 z 1.000 <( -' u:-' ""z f 1'~ fjmffl ::c 0.. 200 400 200 400 <( 200 400 ~illW~nme •weeks ~ uM~~ r~ • WHka a: Time: weeks

Rainwater Tank Reliability(%) Rainwater Tank Overflow(%) Rainwater Tank Reliability(%)\ Rainwater Tank Overflow(%) Rainwater Ta nk Reliability(%)\ Rainwater Tank Overflow(%)

21.3 30.8 44 39.4 84.9 67.2 Hot water services have the greatest daily demand when Connecting to laundry only provides a greater demand (draw One toilet connected to a l OOOL combined retention/ compared with laundry or toilets and hence perform best down) on t he tank, meeting the water efficiency target. detention tank performs poorly for stormwater runoff overall across the four criteria. While the results for water quality and volume management quality outcomes and the rainwater use, in combination While t he detention storage of 1000L fails the performance are better than for t he toilets only scenario, this scenario w ith water efficient devices, falls short of the 25% target for criterion for flow management, a mere extra 100L of storage does not meet the require performance targets water conservation. z Q would provide a pass result . VI ::i POLICY PROVI DES AN APPROXIMATION FOR ALL POLI CY PROVIDES AN APPROXIMATION FOR ALL POLI CY IS NOT RECOMMENDED -'u z PERFORMANCE MEASU RES, HOWEVER RELIABILTY FOR THE PERFORMANCE M EASURES PLUS GOOD RELIABILITY OF 0 u INTENDED USE IS 21% SUP PLY FOR THE INTENDED USE {44%).

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A.2 Precinct Scale Salisbury East Case Study – business as usual versus water sensitive development

The CRC for Water Sensitive Cities 2020 study of Salisbury case study final report – water sensitive outcomes for infill development provides an assessment of greyfield development scenarios for an urban precinct.

The purpose of the study was to:

(i) understand the context-specific water-related and urban heat impacts of urban infill futures for the Salisbury East precinct, and (ii) test how water sensitive design typologies, architectural space quality and water servicing variables can improve the performance of the urban precinct in terms of liveability, water security and resilience.

This study demonstrates that the cumulative impacts of a business-as-usual approach to development are significant and the importance of effective site-scale solutions for stormwater management and urban greening should be acknowledged within planning policy to ensure that each and every development contributes to State high-level urban greening and WSUD targets.

Key findings

At a precinct scale the benefits of a water sensitive approach accrue and are significant. Housing typologies that reduce site coverage, reduce hard paved surfaces, increased canopy cover, and harvest and reuse of rainwater will result in :

1. The proportion of rainfall converted to runoff reduced by 11% 2. The fraction of total case study area with deep root zone increased by 11% 3. The proportion of additional water stored in the soil 5% (or 30ML/annum) 4. The fraction of outdoor areas that are less than 42oC UTCI on an extreme heat day increased by 15%. 5. The fraction of Fraction of total case study area with deep root zone increased by 8% compared with business-as-usual approach to housing design.

Description of the precinct

The study considered a suburban precinct of approximately 130 hectares and 1,900 residents (2019) in the City of Salisbury (Greater Adelaide, South Australia), refer to Figure 1.

The site is bounded by Main North Road, Saints Road, Brian Street, Commercial Road, Park Terrace and the Little Para River. It is representative of a small-scale, low-to-medium density infill development on scattered sites that are predominantly residential with individual privately owned lots and a public housing site, along with some industrial, commercial and vacant land.

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WATER SENSITIVE SA – Comment on Code amendments 4 November 2020

Figure 1 – Salisbury East infill precinct study area.

Future infill scenarios

The study considered several future infill development scenarios for the Salisbury East Precinct to accommodate a future population of 5,000 people. The scenarios of relevance to the Planning and Design Code policy are:

▪ Future infill development without water sensitive interventions (BAU – business-as-usual) ▪ Future infill development with water sensitive interventions (WS-Con – water sensitive conservative)

Table 6 Comparison of BAU versus Water sensitive (conservative) Scenarios

BAU scenario Water sensitive scenario Paved areas Driveways and footpaths were Driveways and footpaths were assumed to be 70% effective assumed to be 70% effective impervious. impervious. Canopy cover Limited canopy cover Vegetated private yards Rainwater storage1 No significant harvesting 2,000L retention tank for each dwelling Total rainwater storage 0 3 capacity (ML) Proportion of gardens of 50% 100% residential dwellings irrigated Indoor water demand Provided by potable water Toilets and laundry cold tap demand provided by rainwater

The case study used the infill evaluation framework and the steps followed is as follows:

(i) creating site plans for residential lots using the Infill typologies catalogue as a template for existing development (EX), business-as-usual (BAU) and WS- Conservative (WS_Con) scenario.

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WATER SENSITIVE SA – Comment on Code amendments 4 November 2020

(ii) once the site-plans are analysed using SUWMBA tool and the site plans with the desired performance is applied to all the potential redevelopment sites in the precinct of 130ha.

(iii) water servicing assumptions for all three scenarios is developed.

(iv) the precinct is evaluated in three different aspects namely, urban water flows using Aquacycle, urban heat using the UMEP model and architectural and outdoor place quality is assessed using a qualitative rating scheme.

Key findings

The benefits of implementing urban green cover, tree cover and stormwater management at the allotment scale can at times seem small, however when these benefits are scaled-up to the precinct scale, the cumulative benefits to the community become clear. A comparison of the Salisbury East precinct key performance measures for a business-as-usual versus greener, water sensitive approach are provided in Table 7. This again reinforces that urban greening and stormwater management solutions should be adopted at the allotment scale, on conjunction with streetscape and catchment scales if we are serious about reaching the targets within the 30-Year Plan.

Table 7 Comparison of key performance measures at the precinct scale

Existing (2019), BAU, population WS-Con, population 1900 5000 population 5000 people WATER PERFORMANCE (HYDROLOGY AND WATER DEMAND AND SUPPLY) Precipitation fraction 42% 50% 39% converted to runoff Total water storage in the soil 31 25 30 (ML) Per capita demand for 251 166 141 imported water (L/day) Fraction of total case study area with deep root zone 24% 9% 17% (Residential zoned area only) URBAN HEAT Fraction of outdoor areas that are less than 42oC UTCI on an 23% 17% 32% extreme heat day

A.3 Catchment scale

The following comment relates to findings of the BDO EconSearch (2020a) OPTIONS ANALYSIS: Costs and Benefits of Stormwater Management Options for Minor Infill Development in the Planning and Design Code. A Report to the Attorney-General’s Department, September 2020.

The project objective was to analyse the cost-effectiveness of the proposed Planning and Design Code policies for minor infill, in relation to stormwater management and rainwater tanks.

The key conclusions that can be drawn from both the Water Sensitive SA InSite Water modelling and UniSA modelling are that:

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WATER SENSITIVE SA – Comment on Code amendments 4 November 2020

 The effectiveness of retention systems in reducing peak flow is dependent on emptying rate (how quickly the household uses the water captured in the tank), with higher rates leading to greater reductions in peak flow  Retention systems alone are unlikely to produce sufficient reductions in peak flow to match pre-development rates unless very high rates of usage, typically considerably greater than all internal household uses, can be applied  Provision of onsite detention, combined with onsite retention, can produce substantial reductions in peak flows.

Based on the above, BDO Econsearch suggest that:

 Proposals to plumb retention tanks into more household uses should be supported, to increase household reuse and contribute to peak flow management  The draft Code policy should be modified to include some detention storage, to provide more reliable contributions to peak flow management.

The November 2020 Code amendments do not appear to be consistent with the Attorney Generals Department’s own report that recommends onsite stormwater management solutions include a detention component. This conclusion is reflected in Recommendation 1.

The 1kL requirement suggested by BDO Econsearch (2020a) is smaller than the 3 to 8 kL that is currently required by some Adelaide metropolitan councils and performance (flood resilience) in these local government areas will fall once the Code is adopted.

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WATER SENSITIVE SA – Comment on Code amendments 4 November 2020

REFERENCES

BDO EconSearch (2020a). OPTIONS ANALYSIS: Costs and Benefits of Stormwater Management Options for Minor Infill Development in the Planning and Design Code. A Report to the Attorney- General’s Department.

BDO EconSearch (2020b). OPTIONS ANALYSIS: Costs and benefits of urban tree canopy for minor infill development in the Planning and Design Code. A Report to the Attorney-General’s Department.

London, G., Bertram, N., Sainsbury., O. and Todorovic, T. (2020). Infill Typologies Catalogue. Melbourne, Australia: Cooperative Research Centre for Water Sensitive Cities.

Pavelic, P., Gerges, N.Z., Dillon, P.J., and Armstrong, D. (1992). The potential for storage and re-use of Adelaide stormwater runoff using the upper Quaternary groundwater system. Centre for Groundwater Studies Report No. 40.

Renouf M.A., Kenway S.J., Bertram N., London G., Todorovic T., Sainsbury O., Nice K., Moravej M., Sochacka B. (2020). Water Sensitive Outcomes for Infill Development: Infill Performance Evaluation Framework. Melbourne, Australia: Cooperative Research Centre for Water Sensitive Cities.

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