742 CITY PLANNING COMMITTEE MEETING 30 AUGUST ......2017/08/30 · Cut/fill batters and earth-retaining structures AS4678: 2002: Earth-retaining structure, Amendment 1 – 2003 and

(d) traffic control devices Pedestrian crossings;

(e) cul-de-sac;

(f) bridges (minimum Category V5 at abutments and minimum Category P3 on deck);

(g) night time accident locations;

(h) a higher category is appropriate where there are land uses such as retailing or entertainment;

(i) frequently used night time bus stops; or

(j) areas or routes where pedestrian and cyclist volumes are deemed high by the City.

Energex tariff 2.6.4Street lighting poles and luminaries are to be standard Energex equipment, which will be supplied and maintained by Energex at Standard Rate 2 Tariff. The installation of Rate 3 Tariff street lighting will only be considered in special circumstances and will require the City’s approval.

Luminaries 2.6.5Luminary types, (e.g. LED, compact fluorescent, high pressure sodium, metal hydride), are subject to Energex guidelines. Use the most economical lamps type available (and acceptable) to Energex as follows:

(1) Category V1 to V5– HPS 100 watt or greater aeroscreen lamps or equivalent aeroscreen LED lamps.

(2) Category P1 to P3– HPS 70 watt lamps or LED equivalent lamps.

(3) Category P4 and P5– LED 14 watt lamps (standard stock item or nostalgia light 15 watt lamps).

Pole location 2.6.6Street lighting poles are to be located opposite common allotment boundaries to minimise potential interference with vehicle access and glare complaints from residents. Poles are not to be located opposite boundaries of battle-`axe allotments due to a higher potential for vehicle collision.

Pole location is required to avoid likely vehicle conflict points to minimise the risk of damage to both poles and vehicles and injury to vehicle occupants. Consideration is given to potential paths of vehicles accidentally leaving the carriageway, and also to the swept path of oversize vehicles that may need to leave the carriageway to manoeuvre, (e.g. at cul-de-sac turning areas, speed control devices, bends and intersections).

Where poles are in vulnerable locations, (e.g. in small islands or roundabouts), consideration is given to the use of slip base or frangible type poles.

Roundabouts 2.6.7The preferred option for the street lighting of roundabouts is for the light poles to be located on the approach side of each intersecting street, without poles in the central median island. Lighting poles should be located as far as practical from the intersection. If the road pavement cannot be lit from the outside then central island lights may be considered provided the poles are cantilever (pivot arm) type or similar design such that Energex will accept the installation under Rate 2 Tariff.

Where central island lighting is proposed, detailed design information (i.e. civil, landscaping and lighting design) is to be submitted.

2.7 Bikeways In new development areas, a network of off-road routes in parks and on-road and off-road bikeways on all major traffic routes and collector roads are provided. Bikeways are designed in accordance with Table 2.16: Bike facilities. Table 2.16: Bike facilities

Type of facility Document for compliance

iSPOT:#64095264 - Draft for Council's consideration Page 26 of 251

742nd Council Meeting 5 September 2017 City Planning Committee Meeting 30 August 2017

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Type of facility Document for compliance

On-road bikeway Austroads Guide to Road Design 2009 Part 6A: Pedestrian and Cyclist Paths; AS1742.9 -2000: Manual of uniform traffic control devices Bicycle facilities; and Department of Transport and Main Roads Manual of Uniform Traffic Control

Devices (MUTCD).

Off-road bikeway Austroads Guide to Road Design 2009 Part 6A: Pedestrian and Cyclist Paths; AS1742.9 -2000: Manual of uniform traffic control devices Bicycle facilities; Department of Transport and Main Roads Manual of Uniform Traffic Control

Devices (MUTCD), Part 9: Bicycle facilities; and AS1428.1-2009 Design for access and mobility.

Other Bicycle parking is provided in accordance with the Transport Code – Table 9.4.13.11; and

End of trip facilities are provided in accordance with AS2890.3-2015 Parking facilities - Bicycle parking facilities.



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3 Change to ground level standards

3.1 Application This chapter assists with satisfying the assessment benchmarks in City Plan that relate to the City’s change to ground level standards as outlined in Table 3.1 Application – Change to ground level standards. Table 3.1: Application – Change to ground level standards

Section or table in the code Assessment benchmark reference Section in chapter

Overlay codes

Landslide hazard overlay code

Table 8.2.11-2: Landslide hazard overlay code – for assessable development

Cut and fill work AO3.1

Section 3.8



Section 3.6



Section 3.6

Development codes – use codes

Change to ground level and creation of new waterways code

Table 9.4.1-1: Change to ground level and creation of new waterways code – for assessable development

Geotechnical fill AO7

Section 3.5

Batters and retaining walls Section 3.6



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Section or table in the code Assessment benchmark reference Section in chapter AO9 Section 3.7

General development provisions code

Table 9.4.4-1: General development provisions code – for accepted development subject to requirements

Earthworks and treatment of retaining walls RO4

Section 3.6 Section 3.7

Table 9.4.4-2: General development provisions code – for assessable development

Earthworks and treatment of retaining walls AO9

Section 3.6 Section 3.7

3.3 Design principles The design, construction and maintenance of earthworks are guided by five (5) design principles. These principles aim to ensure:

(1) the application of sound geotechnical and ecological practices;

(2) no land instability, contamination or adverse ecological impacts are established, including the disturbance of acid sulfate soils;

(3) the visual character, privacy, amenity and landscape values of a site, its immediate neighbouring properties and the surrounding area are not unduly diminished;

(4) the natural hydrologic behaviour of local stormwater and drainage catchments (upstream, downstream and on adjoining property) is not adversely affected; and

(5) retaining structures are fit for purpose and do not impact on existing utility services and infrastructure.

3.4 Chapter reference table The following table is intended to be used as a reference point to assist the applicant to quickly identify what standard, specification and/ or guidance applies to the change to ground level activities. Table 3.2: Chapter reference table – Standards for change to ground level

Element (A-Z)

Relevant standard, specification and/or guidance

Section in chapter

Clearing, grubbing and preparation works for filling and excavation Works

Section 3.13

Cut/fill batters and earth-retaining structures AS4678: 2002: Earth-retaining structure, Amendment 1 – 2003 and Amendment 2 – 2008.

Section 3.6

Earthworks AS1289:2000 Methods for testing sols for engineering purposes – general requirements and list of methods.

AS3798 Guidelines on earthworks for commercial and residential developments clause 4.3 and clause 4.4.

Section 3.5

Final earthworks presentation Section 3.14

Ocean beaches Section 3.8

Stormwater treatment systems in public land Section 3.8

Topsoiling and grassing Section 3.15

Treatment of adjoining properties Section 3.11

Treatment of dams/ponds and embankments Section 3.12



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Element (A-Z)

Relevant standard, specification and/or guidance

Section in chapter

Waterfront development Section 3.10

3.5 Earthworks

3.5.1 Compressible soils (1) Existing areas, which have compressed soils and are intended to be developed for urban use

(including roads and parks) will need to be preloaded (or other approved methods) in order to achieve a suitable level of consolidation and stability.

(2) Identify on the design engineering drawings, areas to be preloaded (where other approved

method will be utilised). Submit certification by the consulting engineer and test results to the City prior to formal acceptance of the works on maintenance. For standard requirements and methods refer to AS1289:2000 Methods for testing sols for engineering purposes – general requirements and list of methods.

3.5.2 Materials for filling and ground conditions

3.5.2.1 Suitable materials

(1) Structural fill material is in accordance with AS3798 Guidelines on earthworks for commercial and residential developments clause 4.4 including inorganic, non-perishable material suitably graded and capable of compaction to the documented density to support commercial and/or residential developments and associated infrastructure.

(2) Certification by a RPEQ shall be submitted demonstrating compliance test results (certificates) for all imported fill material, prior to delivering material to site.

(3) The abovementioned geotechnical documentation is to demonstrate the suitability for use of:

(a) clays of high plasticity which may be reactive and need to be selectively placed within the filling and under strict moisture and density control;

(b) material which, after compaction, contains large particles and may lead to difficulties in the excavation of trenches for footings or services or driving of piles or drilling of piers;

(c) over-wet materials, as may be encountered in low lying areas;

(d) single-sized or gap-graded gravels or rock fill which will not break down upon compaction, leaving voids into which finer material may subsequently migrate;

(e) saline, chemically-aggressive, or polluted soils;

(f) carbonate soils where acid disposal may occur;

(g) acid sulphate soils; and

(h) areas of known, or suspect, low slope stability.

3.5.1.2 Unsuitable materials (1) The following materials are considered unsuitable as structural fill in accordance with AS3798

Guidelines on earthworks for commercial and residential developments clause 4.3 and the following:

(a) materials from swamps, marshes or bogs, or containing peat, logs, stumps and perishable material;

(b) materials susceptible to spontaneous combustion;

(c) materials contaminated through past site usage or containing noxious weeds and other matter which may adversely affect the local environment, except where these are treated in an appropriate manner;



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(d) materials that contain substances that can be dissolved or leached out, or which undergo volume change or loss of strength when disturbed and exposed to moisture, unless conforming to the requirements of reuse of excavated material;

(e) silts or silt-like materials, unless conforming to the requirements of reuse of excavated material;

(f) materials containing wood, metal, plastic, boulders or other deleterious material;

(g) building rubble including concrete, asphalt and other materials except where broken down or otherwise treated and proved to be suitable for use;

(h) abandoned public utility plant and any associated material;

(a) material which is not capable of being compacted in accordance with the contract;

(b) material forming the foundation for a structure which has an allowable bearing pressure less than that nominated;

(c) material forming the foundation for an embankment which has an insitu California Bearing Ratio (CBR) less than 3; and

(d) material with a sulphur content exceeding 0.5 % within 500 millimetre of cement bound elements (for example concrete structures or masonry) unless such elements are protected by impermeable membranes or equivalent means.

(2) Particular materials, other than those prone to dissolving or which undergo physical or chemical

changes or exposure to moisture and contaminated soils including noxious, hazardous and deleterious materials, may be confined to non-critical areas as designated and approved by the City.

(3) Contaminants within materials shall be dealt with appropriately in accordance with the relevant

Acts, local laws or regulations having applicable jurisdiction over any development.

3.5.1.3 When using suitable material excavated from site, or imported material (1) In the top 300mm layer of the formation, the maximum allowable stone size is 75mm.

(2) Below the top 300mm of the formation, the maximum allowable stone size is 2/3 of the allowable layer thickness (layer thickness in conformance with MRTS04 – General Earthworks Table 15.3-A Layer Thickness for Compaction).

(3) The best material available is to be used to form the upper 500mm of fill embankments.

3.6 Cut/fill batters and earth-retaining structures

3.6.1 Batters (1) The preferred standards for batters are set out in Table 3.3: Batters – preferred standards

below::

Table 3.3: Batters – preferred standards Location Preferred standards

Batters within road reserves (a) In accordance with Chapter 10 – Standard drawings. The City will consider an alternative proposal if submitted with a supporting geotechnical report.

(b) To have a maximum slope of 1:4 in accordance with Chapter 10 - Standard drawings. Stabilisation through vegetation planting is to commence immediately following completion of bulk earthworks. Drainage of the batters is to prevent damage occurring and be in an approved form.

(c) The City may request a full geotechnical engineering report (prepared by a qualified and experienced geotechnical engineer) certifying the stability of the cut/fill batter.

(d) The preferred batter treatments to roads are set out in City Plan –



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Location Preferred standards Landscape work.

Batters within private property (a) It is preferred that batters have a maximum slope of 1:2. Stabilisation through vegetation planting is to commence immediately following completion of bulk earthworks. Batters are not to straddle allotment boundaries or extend into existing or proposed parkland and/or bushland reserve. Batters steeper than 1:2 are to be retained.

(b) All platforms resulting from cut/fill operations are to comply with standard requirements for drainage of allotments to the street at an absolute minimum slope of 1:150.

(c) Benching is to be undertaking where any proposed freestanding batter height exceeds 2.5m. The minimum width of benching is to be 1m with a minimum slope of 1:100 towards the lower face. The benching is to be vegetated to prevent erosion.

(d) The maximum height of any freestanding cut/fill batter with benching is to be 5m.

(e) The preferred batter treatments to landscaped areas are set out in City Plan – Landscape work.

Batters within public open space (1) It is preferred that batters have a maximum slope of 1:6. Stabilisation through vegetation planting is to commence immediately following completion of bulk earthworks.

(2) Batters are either turfed or vegetated depending on park category and the need for surveillance.

(3) Any slope in excess of 1:6 is to be revegetated or otherwise planted. (4) Batters with a height difference of greater than 2m are to be avoided,

where practical. Where batters of a size larger than 30m² are dedicated within public open space, these batters are to be planted with at least two (2) plants per square metre. Planting extends a minimum of 2m from both the top and toe of the batter.

(5) Batters are topsoiled to a minimum of 100mm and stabilised by one or more approved treatments, being mulch, eco-blanket or jute-matting.

(6) The preferred batter treatments to landscaped areas are set out in – Landscape work.

Batters to waterways such as lakes, canals, rivers or streams

(1) The maximum constructed batter slope above the high water mark that falls towards a lake, canal, river, stream or other waterway is 1:4.5.

(2) The batter slope is to continue to the building line, which is to be at or above the 1:100 year flood level. The remainder of the property must fall to the street frontage. Typical details are shown in Chapter 10 - Standard drawings. The location of quay lines, waterway regulation lines, building setbacks lines and revetment regulation heights is to be shown on the design and construction drawings for the City’s approval.

3.6.2 Retaining structures The preferred standards applicable to retaining structures are as follows:

3.6.2.1 General (1) Retaining structures:

(a) are designed in accordance with AS4678:2002 – Earth-retaining structure. Amendment 1 – 2003 and Amendment 2 – 2008.

(b) design dead loads are to include a full hydrostatic load acting behind the structure, including when proper drainage of seepage is provided;

(c) are designed to provide a neat architectural and aesthetic appearance. The City’s preferred construction material is concrete, masonry and/ or steel;

(d) are to drain stormwater discharge to a Lawful point of discharge; and



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(e) do not impose loadings on any adjoining structures, including underground utility services, that will adversely affect the structure (this also applies to footings).

3.6.2.2 Road reserves

Retaining structures are not permitted within the road reserve.

3.6.2.3 Private property

3.6.2.3.1 Residential activities

(1) Retaining walls (including footings and drainage) are setback 200mm from the property boundary;

(2) Retaining walls have a maximum overall height of 3m; and

(3) For retaining structures over 1.5m, a two (2) tiered retaining structure is designed in accordance with the Table 3.3: Design requirements for a two (2) tiered retaining wall.

Table 3.3: Design requirements for two (2) tiered retaining wall

Construction material

Lower tier (maximum)

Horizontal setback between tiers

(minimum)

Upper tier (maximum)

Overall height (maximum)

Boulder retaining wall

1.5m 1.5m 2m 3m

Masonry or concrete wall

1.5m 1m 2m 3m

Figure 3.3 typical example of a two (2) tiered retaining wall for residential lots



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3.6.2.3.2 Industrial and business activities

(1) Retaining walls are designed as follows:

(a) have a maximum overall height of 5m; and

(b) setback in accordance with Table 3.4 – Retaining wall setbacks for industrial and commercial uses.

Table 3.4 – Retaining wall setbacks for industrial and business activities

Scenario Setback for retaining wall (including footings and associated drainage)

Where the site adjoins industrial or business activities

Inside property boundary

Where the site adjoins residential, open space or road reserve

Retaining wall ≤ 1.5m in height to be setback a minimum distance of 200mm from the property boundary

Retaining wall > 1.5m in height to be setback at least the equivalent height of the retaining wall from the property boundary.

3.6.2.3.2 Public open space

(1) The City will assess the need for any structures in public open space and only grant its approval where: (a) retaining structures minimise maintenance requirements; (b) public safety is not compromised; and (c) the usability of the public open space is enhanced.

(2) If any retaining structures are to be constructed in public open space they are:

(a) constructed of solid masonry (not rock or dry walling);

(b) free of hollows or cracks in which vermin or snakes may dwell;

(c) designed in accordance with AS4678: 2002: Earth-retaining structure;

(d) buffered by landscape planting;

(e) reflective of the theme or character of the surrounding landscape; and

(f) for multiple or tiered retaining structures, they do not exceed 1.8m high within a 30m wide horizontal plane.

(3) The high side of the road is to be retained within private lots, where a change in level adjacent to a public open space is required. The difference in levels adjacent to the public open space is to be no more than 500mm. The residual difference in levels are to be dispersed across the road reserve (nature strips and centre median), which, if in excess of 1:6 must be vegetated.

(4) All retaining structures that are to be transferred as an asset to the City are to have a design life to the structure as set out in AS4678:2002 Earth-retaining structures. An RPEQ must certify all walls.

3.8 Retaining walls in stormwater treatment systems on public land Retaining walls are not the City’s preferred design outcome within stormwater treatment systems and where there is an urban design change that can be made to remove the walls (by creating more space for the stormwater system) then the City will not approve a retaining wall.

For further information on Stormwater treatment systems in public land refer to Chapter 4 – Stormwater drainage and water sensitive urban design standards.



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3.10 Waterfront development (1) Where retaining structures (revetments - either concrete walls or rock walls) associated with

waterfront development are required, they are to be designed by a RPEQ. Certification of structural detail and stability is to be provided to the City;

(2) The performance and stability of any retaining structures is to be assessed for a wide range of possible waterway changes within the next 60 years; and

(3) The design of retaining structures associated with waterfront development is to address the following: (a) top of wall no lower than RL 1.2m AHD; (b) minimum foreshore erosion/accretion envelope of 1m in Gold Coast tidal waters; (c) changes to water quality; (d) natural meandering process; (e) sea level rise; (f) increased boating traffic; (g) increased tidal volume upstream due to future development; (h) increased flows due to developed catchments; and (i) changes in sediment transport availability.

3.11 Treatment of adjoining properties (1) Where earthworks/retaining structures are adjacent to existing residential or commercial

developments cross-sections are to be provided showing the batter or retaining wall in relation to the adjoining boundary use.

(2) The toe of any fill batter or top of any cut batter is to be a minimum 300mm clear of the boundary line with the adjoining property.

(3) The effects on the drainage of adjoining properties from any cut or fill works is to be considered and is demonstrated on the engineering drawings that no ponding or nuisance from stormwater runoff will be caused.

3.12 Treatment of dams/ponds and embankments (1) All works involving construction of, or alterations to dams, is to be in accordance with Table 3.5:

Preferred standards for dams and ponds and supported by engineering drawings and a cover letter/report prepared by a RPEQ.

(2) Embankments are to be constructed of earthen materials and designed in accordance with the requirements of the Queensland Department of Environment and Heritage and QUDM.

(3) A construction bond for the works shall be lodged (as agreed) with the City in accordance with Chapter 8 - Procedures.

Table 3.5: Preferred Standards for dams and ponds

Component Preferred Standards

Dams and embankments (general)

(a) embankments and associated outlet structures are not built any closer than 3m from a common property boundary;

(b) all dams must incorporate a spillway at the top of the embankment allowing free surface flow (a pipe outlet may also be incorporated), to ensure that the location of the outflow is controlled for all flow rates;

(c) no change occurs to the location of flows from the subject site. Spillways and outlets must be built in the same location as the natural location of overland flow;

(d) spillways are to be designed with an allowance for a freeboard between water level and top of the embankment, ensuring the embankment is not breached , with an increased risk of erosion of the embankment;

(e) the hydrology, flow rates, spillway sizing and level, and upstream ground levels are to be analysed to ensure the water surface does not intrude



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Component Preferred Standards onto upstream properties;

(f) the spillway face and associated works is to be designed to prevent scour and erosion;

(g) the embankments are to be designed and constructed to ensure geotechnical stability, in accordance with a geotechnical report prepared by a suitably qualified and experienced geotechnical engineer;

(h) any proposal to dredge out dams for maintenance or enlarging capacity is to have regard to water quality requirements;

(i) the relevant Australian Standards and State Government requirements and procedures are to be complied with at all times; and

(j) in the treatment of dams/ponds, the earthworks design is to address issues related to artificial wetlands such as wildlife habitats and nutrient sink..

Where dams and/or ponds are removed and backfilled

(a) dewater dams and remove any spoil of an unsuitable material from the site to a location approved by the City;

(b) undertake works to level the dam wall to its original ground level or what is deemed to be a soundly based representation of that level;

(c) ensure the integrity of the drainage lines to and from the dam including the provision of an alternative drainage path to replace the drainage path previously provided by the dam; and

(d) to backfill the dam with selected fill which meet Section 3.5.2 and is compacted in layers to the requirements set out Chapter 9 - Specifications.

3.13 Clearing, grubbing and preparation works for filling and excavation Works (1) Clearing grubbing and other preparatory works is to be undertaken in accordance with the

following:

(a) an approved Erosion and Sediment Control Management Plan. It is the applicant’s responsibility to manage the construction process such that Department of Environment and Heritage Protection guidelines are adhered to at all times;

(b) any approved management plan and associated documents (for example vegetation management, stormwater management, open space management, bushfire management or construction management);

(c) current approved conditions and engineering drawings;

(d) Chapter 9 - Specifications; and

(e) demolition works to be carried out with the appropriate approvals and in accordance with relevant workplace health and safety regulations.

3.14 Final earthworks presentation (1) Prior to grassing of all disturbed areas, ensure that the finished earthwork levels are in

accordance with the approved engineering drawings. The minimum grade is to be:

(a) 1:150 in clay soils; and

(b) 1:200 in sands.

In addition to the above grading requirements, appropriate measures are to be implemented to comply with the City Plan - Healthy waters code and Change to ground level and creation of new waterways code.



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3.15 Topsoiling and grassing

3.15.1 Topsoil (1) Topsoil is to be provided to all disturbed areas, including allotments and verges, to a 100mm

minimum compacted thickness which complies with the Chapter 9 - Specifications.

3.15.2 Grassing (1) Grass seeding is provided following the placing and spreading of topsoil to disturbed areas on

allotments. (2) Turfing to disturbed areas is provided on verges and overland flow paths such as swales. The turf

is to be established and maintained, and achieves a ground cover in the selected species of greater than 90% of the turf area.

(3) Where stormwater drainage overland flow paths, swales and the like are constructed, the minimum grassing requirement is cover turf or an equivalent treatment approved by the City.



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4 Stormwater drainage and water sensitive urban design standards

4.1 Application This chapter assists with satisfying the assessment benchmarks in City Plan that relate to the City’s stormwater and water sensitive urban design (WSUD) standards as outlined in the Table 4.1: Application – Stormwater drainage and water sensitive urban design standards.

Table 4.1: Application – Stormwater drainage and water sensitive urban design standards.

Section or table in the code Assessment benchmark reference Section in chapter

Overlay codes

Landslide hazard overlay code

Table 8.2.11-2 – Landslide hazard overlay code – for assessable development

Stormwater drainage AO2.2

Section 4.4



Section 4.4

Other development codes

Change to ground level and creation of new waterways code

Table 9.4.1-1 – Change to ground level and creation of new waterways code – for assessable development

Stormwater drainage AO2.1

Section 4.4.9

General development provisions code

Table 9.4.4-2 – General development provisions code – for assessable

Stormwater drainage AO10

Section 4.4



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development

Healthy waters code

Table 9.4.5-2 – Healthy waters code – for assessable development

Stormwater quality AO1.1

Section 4.5.3

Stormwater quality AO1.2

Section 4.5.3

Stormwater quantity AO2

Section 4.5.3

4.2 Design principles The design, construction, operation and maintenance of stormwater drainage and WSUD infrastructure are guided by eleven (11) design principles. These principles aim to ensure the stormwater drainage and WSUD infrastructure:

(1) Implements the principles of total water-cycle management;

(2) minimises disturbance to existing landforms, surface drainage, watercourses and groundwater;

(3) maintains waterway/ waterbody health, biodiversity and ecosystem function;

(4) maintains the natural hydraulic behaviour of catchments;

(5) safely conveys stormwater runoff through urban areas;

(6) promotes the protection of overland flow paths;

(7) mitigates the occurrence, severity and duration of flood events;

(8) protects receiving water quality by limiting the quantity of key pollutants discharged in stormwater from the development;

(9) is integrated carefully into the urban and natural landscape;

(10) contributes to the green space values within the City and promotes co-location of assets; and

(11) includes no-worsening measures to meet the above principles.

4.3 Chapter reference table The following tables - Table 4.2: Chapter reference table – Stormwater drainage and Table 4.3: Chapter reference table – Water sensitive urban design are intended to be used as a reference point to assist the applicant with quickly identifying what standard, specification and/or guidance applies to the specific element of stormwater drainage and WSUD.

Table 4.2: Chapter reference table – Stormwater drainage

Element (A-Z)

Relevant standard, specification and/or guidance Section in chapter

Stormwater drainage

Coefficient of discharge Section 4.4.7

Culvert design Queensland Urban Drainage Manual (QUDM) Austroads Guide to Road Design – Part 5:

Drainage Design (Part 5B) IPWEAQ Standard drawing DS-082

Section 4.4.24

Design storms – major/ minor drainage Section 4.4.10

Discharge to tidal and other waterways QUDM Section 4.4.23

Downstream drainage requirements QUDM Section 4.4.5

Drainline location Section 4.4.17

Integration with existing drainage QUDM Section 4.4.4



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Element (A-Z)


Stormwater drainage

Extent of stormwater drainage works QUDM Section 4.4.1

Freeboard at inlets and junctions Section 4.4.22

Gully and field inlet types IPWEAQ Standard Drawings for Kerb Inlets, Drawings No. DS-060 to DS-063 and DS-068 (Standard Gully Inlet)

IPWEAQ Standard Drawings for Field Inlets, Drawings No. DS-050 for Type 1 and 2 and DS-069 Dome top cover (Standard Field Inlet)

QUDM

Section 4.4.11

Hydraulic calculations QUDM Section 4.4.19

Hydrologic methods QUDM Section 4.4.7

Intensity – frequency – duration data Australian Rainfall and Runoff 2016 (ARR 2016) Section 4.4.3

Intersections Section 4.4.13

Manholes (access chambers) QUDM Section 4.4.14

Manhole tops Section 4.4.15

Minor and major drainage system design criteria

QUDM Section 4.4.2

Overland flow QUDM Section 4.4.9

Pipe and material standards and structural design of pipelines and manholes

DTMR Specification MRTS26; AS3725:2007 – Design for Installation of Buried

Concrete Pipes; AS15972:2013 Precast reinforced concrete box

culverts Part 2: Large culverts; AS/NZS3600 Concrete Structures; and AS1597.1 Precast reinforced concrete box culverts

Part 1: Small culverts

Section 4.4.18

Pipe capacity Section 4.4.21

Reduction in pipe size QUDM Section 4.4.16

Standards for drainage reserves in public open space

Section 4.4.6

Start hydraulic grade level QUDM Section 4.4.20

Standard inlet times QUDM

Section 4.4.12

Swale/table drains Section 4.4.24

Table 4.3: Chapter reference table – WSUD – erosion and sediment control, stormwater quality, stormwater quantity and lakes

Element (A-Z)


WSUD – erosion and sediment control, stormwater quality, stormwater quantity and lakes

Asset handover Section 4.5.17

Bioretention systems Water by Design Technical Design Guidelines; IPWEAQ standard drawing RS-051; and QUDM

Section 4.5.12



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Element (A-Z)


WSUD – erosion and sediment control, stormwater quality, stormwater quantity and lakes

Compliance methods Environmental Protection Act Best practice erosion an sediment control (IECA) AS4970-2009 Protection of trees on development

sites WSUD : developing design objective for urban

development in South East Queensland (Healthy waterways partnership, November 2007)

Section 4.5.6

Construction and establishment Section 4.5.16

Design guideline Healthy Land and Water – Water by Design Guideline

QUDM

Section 4.5.9

Design objectives Healthy Land and Water – Water by Design Guidelines

QUDM

Section 4.5.4

Development triggers Section 4.5.3

Development application process and submission requirements

Section 4.5.5

Frequent flow Water by design Stormwater Harvesting Guideline Section 4.5.7

General design details Water by Design Technical Design Guidelines Section 4.5.13

Lakes Section 4.5.15

Modelling MUSIC modelling guidelines (Water by Design) Section 4.5.8

Plant selection Section 4.5.18

Proprietary design Music modelling guidelines (Water by Design) Section 4.5.10

Swales Water by Design Technical Design Guidelines Section 4.5.11

Waterway design QUDM Section 4.5.14

4.4 Stormwater drainage Queensland Urban Drainage Manual (QUDM) provides the basis for the design of stormwater drainage, except as specifically varied by this policy. Where there is an inconsistency between QUDM and this chapter, this chapter takes precedence.

Extent of stormwater drainage works 4.4.1Developers are to meet the full cost of providing an appropriate stormwater drainage system, with capacity sufficient for the design runoff from all upstream catchments (when such catchments are fully developed) to pass through the development.

The drainage system is designed to minimise impacts to all upstream and downstream properties and demonstrates that such discharge would, in no way, adversely affect any land, drainage systems or any watercourses (refer to QUDM).

Where a stormwater management plan is required, the City requires stormwater drainage drawings that demonstrate the following:

(1) feasibility and function of the proposed drainage system(s) within the site;

(2) its compliance with any relevant Stormwater Drainage Study (SDS); and

(3) its connection to the lawful point of discharge.

The minimum stormwater drainage works to be constructed by the developer, are detailed in the following sections.



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4.4.1.1 Urban areas The requirements for residential, industrial and commercial areas are:

(1) a minor drainage system, including:

(a) kerb and channel on both sides of all roads;

(b) gully pits at locations such that the flow in the kerb and channel does not exceed the requirements and specified limits in QUDM;

(c) roof and allotment drainage systems discharge to the street or piped drainage system. Lots that front waterways (including canals) are to discharge to the street unless the City determines otherwise. If discharge to a waterway is approved by the City, discharge pits are to be installed within private property;

(d) inter-allotment drainage connecting more than two (2) properties will only be considered where there is no viable alternative available, and will be determined in accordance with the principles outlined in QUDM. Under these circumstances, an easement, designed in accordance with Section 4.4.5.3, will be required to be provided in favour of the City; and

(e) piped drainage from all gully pits and other inlets is to discharge at the boundary of the development at a lawful point of discharge approved by the City. Outlets are not permitted within private property. Where the piped system traverses private property, an easement in favour of the City is provided in accordance with Section 4.4.5.3.

(2) a major drainage system including an overland flow system for runoff in excess of the capacity of the pipe system, is designed to ensure the design flow is carried through the development clear of allotments (i.e. through roads or drainage reserves).

(3) safety screens are provided in accordance with QUDM, unless otherwise determined by the City.

4.4.1.2 Rural residential areas The minor and major drainage system is to consist of open watercourses within allotments and fully-piped drainage within road reserves, with:

(1) kerb and channel on both sides of all roads;

(2) gully pits at locations such that the flow in the kerb and channel does not exceed the requirements and specified limits in QUDM;

(3) piped drainage from all gully pits and other inlets, is to discharge into defined natural watercourses or at a lawful point of discharge approved by the City. Outlets are not permitted within private property, unless topographically constrained and are approved by the City. Where outlets are approved by City in private property, appropriate scour protection is to be provided and an easement in favour of the City is provided in accordance with Section 4.4.5.3;

(4) stabilised overland flow paths/watercourses, where scour and erosion protection works are required;

(5) reinforced pipe or precast concrete pipes (including drainage aprons) are to be located at road crossings of all natural watercourses and extend to the limits of the road reserve. Cross drainage design is to take into account the possible debris load from the catchment and accommodate blockage factors (see Section 4.4.23). Where the extent of drainage works traverses land, that is not owned by the City, easements are to be provided in accordance with Section 4.4.5.3, on either side of the road reserve to allow the necessary scour protection works and future maintenance works to be undertaken (see Section 4.4.5.3). The provision of precast reinforced concrete pipes is the City’s preferred option. Masonry block construction is not permitted;

(6) the drainage system maintains the natural bed of the waterway and provides for fish passage; and

(7) safety screens in accordance with QUDM, unless otherwise determined by the City.

4.4.1.3 Rural areas The minor and major drainage system is to consist of open watercourses, with the following:

(1) gravel shoulders, without kerb and channel, on all roads;



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(2) reinforced pipe or precast concrete box culvert structures (including drainage aprons), bridges or concrete causeways are to be located at road crossings of all natural watercourses, and extend to the limits of the road formation. Cross drainage design is to take into account the possible debris load from the catchment and accommodate blockage factors in accordance with Section 4.4.23. Where the extent of drainage works traverses land, that is not owned by the City, easements are to be provided in accordance with Section 4.4.5.3, on either side of the road reserve to allow necessary scour protection works and future maintenance works to be undertaken. Depth of flow indicators and delineator posts are to be used to better define the areas of more frequent inundation. The provision of reinforced concrete pipes is the City's preferred option. Masonry block construction is not permitted;

(3) earth table drains and catch drains are located in road reserves. Where required for scour and protection works, the drains are to be stone pitched or concrete lined ;

(4) rural access pipe crossings for entry to all allotments in accordance with IPWEAQ Standard Drawing RS-056;

(5) the drainage system maintains the natural bed of the waterway and provides for fish passage; and

(6) safety screens in accordance with QUDM, unless otherwise determined by the City.

Minor and major drainage system design criteria 4.4.2The minor and major drainage systems are defined by the requirements and principles set out in QUDM.

(1) For a major drainage system:

(a) major underground piped drainage systems (as defined in QUDM), which carry flows in excess of the capacity of the minor drainage system, are not permitted unless approval is obtained from the City. Examples of where the City would consider major drainage systems are as follows:

i. if an overland flow path is either impractical or unacceptable (e.g. the overland flow path is obstructed), a major underground piped drainage system is to be provided where approval is provided by the City; or

ii. in addition to QUDM requirements, where major underground piped drainage is required, inlet capacities are designed for 100 year ARI flows with a 50% blockage factor.

(b) building over natural flow paths will not be permitted.

(2) Flow depth and width limitations are in accordance with the principles outlined in QUDM.

(3) Minimum pipe size requirements (excluding roof and allotment drainage) are as follows:

(a) drainage infrastructure, which is to be owned and maintained by the City, is 375mm diameter;

(b) drainage systems within private property where the drainage system conveys stormwater from any external public property(e.g. roads and parks) is:

i. a minimum of 600mm diameter for pipes discharging to open watercourses, or

ii. the size of the downstream drainage network that has been approved as the lawful point of discharge.

Intensity – frequency – duration data 4.4.3

Refer to Australian Rainfall and Runoff 2016 (ARR 2016) to determine Intensity – frequency – duration data.

Integration with existing drainage 4.4.4The following section is to be read in conjunction with QUDM:

The design of the proposed drainage system (both major and minor) and earthworks for the development is to ensure the following:

(1) existing upstream drainage is not adversely affected; and



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(2) existing downstream drainage system is capable of adequately catering for the discharge of any additional flow produced as a result of the development. If the downstream system is not capable of carrying the increased discharge, indicate what measures are proposed to ensure the downstream system is capable of carrying the increased discharge. Such measures are to include, but not be limited to, investigation of upgrading the existing downstream system, onsite detention and regional detention facilities.

Downstream drainage requirements 4.4.5

4.4.5.1 General At the time of the relevant approval, the City will determine if one or more of the following is required:

(1) all downstream drainage paths have easements/reserves as appropriate in favour of the City (see Section 4.4.5.3);

(2) provide written approval from all property owners, that they accept flow from the development site to a lawful point of discharge. (For the lawful point of discharge, refer to QUDM and additional requirements nominated in Section 4.4.5.2);

(3) hydraulic calculations, derived from computer modelling, indicating that post development stormwater flows do not adversely affect downstream properties, increase flood heights or create nuisance to any property in the catchment; and

(4) maintenance requirements of drainage infrastructure that allows for safe access for all inspection and maintenance activities; with anticipated maintenance activities to be listed at the time of design.

4.4.5.2 Lawful point of discharge In addition to the above requirements, the City will determine which of the following are required as a lawful point of discharge:

(1) to concrete kerb and channel, gullies, natural watercourse or existing enclosed stormwater drainage system abutting the development, provided the system has the capacity required. Obtain approval from the City for any connection to the City infrastructure. Calculations are to incorporate the design runoff from all upstream catchments (when such catchments are fully developed);

(2) to the road reserve, provided the concentration of stormwater does not adversely affect the drainage capacity of the road and/or adjoining properties;

(3) through adjoining private properties, providing it is managed by easements between the property owners. The minimum width of the easement is to be 3m; and/ or

(4) to an existing enclosed drainage system higher than the development from a drainage pit within a site by pumping. Direct discharge to kerb and channel is not permitted, instead discharge is to be to an approved access or gully pit. Pumping will only be considered on merit when all other alternatives have been exhausted. The pumping infrastructure will remain the asset of the site owner, and will not form part of the City’s drainage scheme. The applicant is to clearly demonstrate, in this instance, that the alteration to catchment boundaries will not cause a worsening of any kind to existing drainage systems, property or public safety.

In addition, all pumped stormwater systems are to be designed to manage overflows in case of malfunction or flow rates in excess of design capacity by:

(a) demonstrating that in the event of malfunction, there is no adverse impact to neighbouring properties, e.g. overflows leave the site in a safe manner and do not inundate habitable or non-habitable areas within and external to the site; and

(b) ensuring the owner of the pump system is responsible for all costs associated with installation, operation and maintenance and is liable for all damages as a result of system malfunction. The pumping infrastructure will remain the asset of the site owner, and will not form part of the City’s drainage scheme.

A lawful point of discharge is not permitted within private property, unless otherwise approved by the City. Where approved, this is to be in accordance with Sections 4.4.5.1 and 4.4.5.3.

4.4.5.3 Drainage easements Stormwater drainage is preferably located as follows:



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(1) in dedicated drainage reserves; or

(2) on public land, with direct access from public land.

Where the above circumstances arenot achievable and an alternative outcome is proposed, the easement requirements specified in QUDM are modified to the extent that:

(1) easements in favour of the City are required to be provided over any pipe that is to be a Council owned and maintained asset that is located in private land;

(2) a minimum easement width of 3m for single pipes up to and including 900mm diameter. For pipes larger than 900mm in diameter, multi-cell pipes or box culverts, the minimum easements widths are in accordance with QUDM;

(3) easements in favour of the City are required over cross drainage outlets from road reserves for maintenance purposes where that land is not owned by the City. Easements are to be a minimum length of 5m ;

(4) easements over open drains or channels must be wide enough to incorporate berms along the top of the channel (refer to QUDM);

(5) easements over piped drainage or drainage outlets within private property are to encompass the length of the drainage system and overland flow path to provide access from public land for maintenance purposes and protection of the overland flow path;

(6) overland flow path easements provide for passage of stormwater flows along the easement and prohibit the erection of structures, the alteration of surface levels, and any activity within the easement which may obstruct the flow of storm runoff (e.g. debris retentive fences, landscaping, walls, filling). The easement must be the full design flow width and vegetated or paved to prevent potential scouring;

(7) access easements are to be provided to enable the City to have access from a surveyed road to a drainage easement;

(8) easements are to be of such width, length and location to enable necessary works (e.g. construction, maintenance and site inspection) to be carried out; and

(9) building works over or near stormwater drains must be assessed against the Queensland Development Code (QDC).

Standards for drainage reserves in public open space 4.4.6Drainage standards areto consider the nature of the intended function and constraints of the land including:

(1) preserving the recreation function of the open space;

(2) general open space areas with a need for access by pedestrians and cyclists;

(3) passive areas with a need for public access;

(4) active areas in tourist significant areas; and

(5) natural watercourses with ecological significance.

The City will consider the following in its determination of drainage standards for particular open space areas:

(1) major flood capacity;

(2) convenience flood capacity – minor event in terms of interval event and the time to drain ponded sites;

(3) maintenance costs, e.g. batter slopes;

(4) safety, e.g. maximum velocity 2 m/sec;

(5) stability factors, e.g. resistance to scour, slip; and/or

(6) ecological considerations, e.g. preserving valuable areas, provide fish passage, and appropriate planting in waterway areas, minimum impact on existing riparian/aquatic ecosystems.

(7) the stormwater outlet is not to impact on use of the park land or access to adjacent land. The City may require developers to extend pipes through public open space until it can be discharged to an approved drain, waterway and stormwater management system.



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Hydrologic methods 4.4.7Hydrologic methods are to be determined in accordance with the principles set out in QUDM.

Coefficient of discharge 4.4.8 Table 4.4: Runoff coefficient vs. development category below sets out the runoff coefficients vs. development categories as a variation to the requirements of QUDM.

Table 4.4: Runoff coefficient vs. development category

Zones C10

Slope < 1%

1% Slope < 5%

Slope 5%

Neighbourhood centre, Mixed use, Extractive industry, Waterfront and marine industry and low, Medium and high impact industry.

0.95 0.95 0.95

Urban zones

High density residential Medium density residential Centre Neighbourhood centre Emerging community (including roads)

High density

0.90 0.90 0.90

0.80 0.85 0.85

Low density residential Emerging community (average lot size)

Low density

< 600m² 0.80 0.85 0.90

> 600m² < 1000m² 0.75 0.80 0.85

> 1000m² < 4000m² 0.65 0.70 0.75

Rural and Rural residential zones

Rural Rural residential

Bare rock 0.82 0.88 0.94

Rocky clayey soil 0.68 0.78 0.90

Open forest/grassed/crops 0.47 0.62 0.80

Average grassed/timbered 0.39 0.52 0.70

Heavily timbered 0.30 0.40 0.58

Bare sand 0.15 0.25 0.40

Open space and Community facilities zones

Community facilities Conservation Sport and recreation Open space

0.55 0.65 0.75

Overland flow 4.4.9In addition to the requirements of QUDM, the time adopted for travel in a large pervious area, such as a major park or urban forest is to recognise the limits of the overland flow phenomenon. It is a matter of field observation that sheet flow rarely progresses more than 50m before entering a runnel or rill, with travel in the latter mode falling into the natural channel category.

The City's preferred option is to use the Kinematic Wave Equation for the determination of overland sheet flow times. This equation takes into account that for the more intense and higher return periods, the run-off occurs more rapidly.



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Design storms – major/minor drainage 4.4.10Table 4.5: Table of recommended design average recurrence intervals – major and minor drainage system below modifies QUDM requirements.

Table 4.5: Table of recommended design average recurrence intervals – major and minor drainage system

Drainage system ARI (years) AEP (%)

Major drainage system

100 1

Minor drainage system

Zones

Residential zones

LDR1 (up to 12.5 dwellings per net hectare) 2 39

LDR2 (up to 16.6 dwellings per net hectare) 2 39

RD1 (up to 25 dwellings per net hectare) 2 39

RD2 (up to 33 dwellings per net hectare) 2 39

RD3 (up to 40 dwellings per net hectare) 2 39 RD4 (up to 50 dwellings per net hectare) 2 39 RD4A (up to 66 dwellings per net hectare) 10 9.5 RD5 (up to 200 bedrooms per net hectare) 10 9.5

RD6 (up to 300 bedrooms per net hectare) 10 9.5 RD7 (up to 400 bedrooms per net hectare) 10 9.5 RD8 (up to 769 bedrooms per net hectare) 10 9.5

Centre zone 10 9.5 Neighbourhood centre zone 102 9.52

Open space zone 1 63 low, medium and high impact industry zones 2 39 Waterfront and marine industry zone 2 39

Major tourism zone 10 9.5

Community facilities zone 10 9.5

Innovation zone code 10 9.5

Mixed use zone 102 9.52

Southport PDA 10 9.5 Conservation zone Emerging community zone Sport and recreation zone Extractive industry zone Limited development (constrained land) zone

See note 3

Roads

Minor and major roads



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Drainage system ARI (years) AEP (%)

Minor road Longitudinal drainage system Refer to relevant development

category

Cross drainage system (culverts, bridges)

10 9.5

Major road – major traffic routes

Longitudinal drainage system 10 9.5

Cross drainage system (culverts, bridges)

50 2

Notes: (1) The design ARI for the minor drainage system in a major road shall be that indicated for the major road, not that for the

development category of the adjacent area. (2) Seek the City’s advice on design storms for this development category. Lower design storms may be approved based

on the standards of service for the surrounding area. (3) Where design storms have not been defined in the table above, seek the City’s advice. (4) The terms used in this table are described in the Glossary and/or QUDM. (5) The City may require higher recurrence intervals based on particular locality considerations that include:

(a) ability to accommodate the major event (QUDM); (b) Transport and Main Roads flood requirements; (c) afflux considerations; (d) future strategic planning considerations; (e) counter disaster planning consideration; (f) connections with a history of interruption in flash flooding events; (g) safety considerations in flood events; and (h) the ability to access isolated or single entry communities.

(6) The City may accept lower recurrence intervals where the upgrading of sections of the road are not feasible in isolation and the development has provided compensatory elements that will assist the improvement of the road system.

Gully and field inlet types 4.4.11In addition to the inlet types nominated in QUDM and the Chapter 10 – Standard drawings, the City will allow alternative inlet systems where approved by the City, noting that these systems are to comply with the City’s stormwater drainage specification.

Chapter 10 – Standard drawings provides inlet capacity charts for the standard inlet types as follows:

4.4.11.1 Standard gully inlet A standard gully inlet is provided in accordance with IPWEA Standard Drawings for Kerb Inlets, Drawings No DS-060 to DS-063 and DS-068.

The City has completed full scale hydraulic testing (in conjunction with other Authorities) for lip-in-line gully configurations. The inlet capture charts shown on Chapter 10 – Standard drawings provide inlet capacity rates for a kerb-in-line pit. The charts have been produced for barrier and roll top kerb profiles for on grade and sag configurations. Appropriate reduction factors in accordance with QUDM have been included and are to be applied to the on-grade capacity charts for the lip-in-line gully pit configuration.

A reduction factor is not to be applied to the sag capacity charts. As a result of the hydraulic testing program, modified freeboard requirements are to be used for the lip-in-line gully pit. Refer to Section 4.4.23.

4.4.11.2 Pre-cast stormwater inlet system The pre-cast stormwater drainway inlet system as detailed in Section 4.4.17.5 can be used as an alternative pre-cast gully manhole inlet configuration, where preferred.

QUDM is to be referenced for inlet capacity charts.

The use of cast in situ gully manholes may be approved where demonstrated to the City’s satisfaction that approved proprietary products cannot be utilised.



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4.4.11.3 Standard field inlet A standard field inlet is provided in accordance with IPWEA Standard Drawings for Field Inlets, Drawings No DS-050 for Type 1 and 2 and DS-069 Dome top cover.

Field inlet design is to be in accordance with QUDM. The allowable depth of ponding depends on location, 0.25m being an average maximum.

Standard inlet times 4.4.12The use of standard inlet times does not apply in the City. Alternative methods outlined in QUDM are recommended. The minimum time of concentration is five (5) minutes.

Intersections 4.4.13The City will only approve anti-ponding gully inlets within kerb turnouts where it can be demonstrated that this is the best design option available under the particular circumstances (Refer to Chapter 2 – Transport network standards)

Manholes (access chambers) 4.4.14The design of manholes is to be in accordance with QUDM.

In addition to the requirements of QUDM, install manholes directly upstream of revetment walls as shown on Chapter 10 – Standard drawings.

Pre-cast manholes from the City’s ‘Approved product list for stormwater drainage’ may be used provided they are installed in accordance with the manufacturer’s specifications. The diameter of the manhole access opening and cover to converter slab is to conform to the City’s standards.

Manhole tops 4.4.15Where drainage manholes are located in flood prone areas or where the design hydraulic grade line is above the top of the manhole, provide bolt down manhole tops as directed and/or approved by the City.

Reduction in pipe size 4.4.16Where a pipe size reduction is allowed in QUDM, the manhole outlet is to be bell-mouthed to the same size as the upstream pipe diameter, through the wall of the manhole, to the downstream pipe.

Drainline location 4.4.17The City’s standard drainline location is detailed in the sections below:

4.4.17.1 Cast in situ gully inlet For cast in situ gully inlet design, refer IPWEAQ Standard Drawing Nos. DS-060 and DS-063.

The City will permit gully-to-gully piped systems where pipes are connected between gully pits instead of manholes with both the inlet and outlet pipes connected to the gully pit walls provided the following criteria are met:

(1) maximum gully to gully connection pipe diameter is 600mm diameter;

(2) gullies are constructed in accordance with the Chapter 10 – Standard drawings; (3) acute angles in connecting pipes are avoided to minimise head losses;

(4) interferences with other utility services and guardrails on the footpath are avoided;

(5) the main drainage line (spine) of the gully system is constructed on one side of the road only. The number of gully-to-gully connections is unlimited unless specified otherwise in this policy. Connect any gullies on the opposite side of the road directly (as close to 90° as possible) across the road;

(6) a maximum of three (3) gully to gully to manhole connections is allowed on the non-spine side of the drainage system prior to connecting across the road; and

(7) once the maximum requirements of the gully-to-gully system have been reached, the gullies are to be connected to a conventional herringbone drainage pattern.



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4.4.17.2 Pre-cast stormwater inlet system Pre-cast stormwater drainway inlet/gully manhole systems are accepted for general use.

The standard alignment for drainlines, other than gully-to-gully connections, is 2m measured towards the road centreline from the nominal face of kerb. For standard width access streets, as shown on Chapter 10 - Standard drawings, the drainline alignment is to be on the centreline of the street. The pipework layout is, in most cases, to be the conventional herringbone layout.

Pipe and material standards and structural design of pipelines and manholes 4.4.18When designing drainage systems in locations that will be subjected to a saltwater environment and/or aggressive ground water conditions, liaise with the relevant suppliers for an appropriate product designed to comply with the current Australian Standard and to meet the specific site conditions.

Fibre reinforced pipes are to be in accordance with the DTMR Specification MRTS26.

4.4.18.1 Pipes Pipes and pipe laying are to comply with the requirements of QUDM except in reference to flush jointed pipes. Flush jointed pipes will not be accepted in the City. Spigot and socket and rubber ring jointed pipes are required for all sizes of pipe. Reinforced concrete pipes are the City’s preferred option.

4.4.18.2 Box sections It is the City’s preference that construction of box sections is from precast reinforced concrete box culvert sections only. Precast base slabs are not to be used in the City. Box culverts are only to be used where it has been demonstrated that:

(1) unrestricted access for maintenance and replacement purposes can be achieved; or

(2) design constraints prevent the use of pipes. Viable constraints to be considered are:

(a) slope or cover constraints;

(b) fauna movement requirements;

(c) waterway area restrictions; and/or

(d) cost/benefit analysis.

4.4.18.3 Pressure applications The City does not accept pressurised or pumped systems for drainage assets that are to be contributed to the City.

4.4.18.4 Structural design The structural design of drainage pipelines is to be carried out in accordance with the following:

(1) AS3725:2007 – Design for Installation of Buried Concrete Pipes;

(2) AS1597.2-2013 Precast reinforced concrete box culverts Part 2: Large culverts; and

(3) AS/NZS3600 Concrete Structures and AS1597.1 Precast reinforced concrete box culverts Part 1: Small culverts.

Note: Large and small culverts are defined in Chapter 11 – Glossary.

Box culvert sections, that are under fill, with a depth greater than 2m, require the base slabs to be structurally designed and certified by an RPEQ.

The strength class for concrete drainage pipes is to be determined using the appropriate environmental conditions, loading factors (construction and traffic) and be in accordance with AS3725:2007 Design for Installation of Buried Concrete Pipes. Construction loads are to be nominated on the construction drawings.

A minimum of class 3 is to be adopted where sufficient evidence cannot be provided for the use of a lower class. Pipes are to be of a suitable material for the site specific environmental conditions in accordance with AS/NZS 3600-2001 Concrete Structures, Exposure Classification and be a minimum of B2.

Engineering drawings submitted for approval are to show the following information for each drainage line:

(1) type and class of pipe;



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(2) installation and bedding details; and

(3) construction method (backfill layer thickness, compaction equipment).

Hydraulic calculations 4.4.19The hydraulic gradeline calculations are to take into consideration the impact of a gross pollutant structure where one is identified as a requirement in the SDS, SMP or as required by the City.

Start hydraulic grade 4.4.20

For start hydraulic grade refer to QUDM.

Pipe capacity 4.4.21Calculations for stormwater pipe capacity flowing full may be based on Colebrook-White equation using K = 0.6 minimum.

Freeboard at inlets and junctions 4.4.22Notwithstanding the requirements of QUDM regarding minimum freeboard recommendations for gully inlets and manholes, Table 4.6: Gully inlet freeboard (mm) below provides the City’s requirements for gully inlets on grade. All other freeboard requirements for gully inlet in sag, field inlet and manhole or junction structure shall be in accordance with QUDM.

Table 4.6: Gully inlet freeboard (mm)

Longitudinal road grade Lintel

S M + L

≤ 3% 150 150

> 3% 150 350

S = Small lintel 2.4m M = Medium lintel 3.6m L= Large lintel 4.8m

Note: Freeboard is measured from lowest side of channel invert.

Discharge to tidal and other waterways 4.4.23An appropriate allowance for storm surge and impacts of climate change is to be provided when establishing tailwater levels for outfalls to tidal and non-tidal waters. For particular requirements associated with design and protection of tidal and non-tidal outlets (refer to QUDM). Notwithstanding these requirements of QUDM, the lowest invert level of the drainage system at the outlet shall not be lower than mean low water spring tide (MLWS) or the standing water level of the receiving waterway, lake or watercourse.

For stormwater drainage, outfall level requirement from stormwater management system refer to Section 4.5.10.6. Drainage outlets should not be permanently submerged.

Consultants should liaise with the City prior to commencing detail design.

Specific consideration is to be given to design and protection for locations of outlets where discharge is directed over surfaces that have not previously been subjected to concentrated flows and where significant scour and erosion may result.

Drainage works which require physical alterations to a natural watercourse and/or its flow regime require Department of Environment and Heritage Protection (DEHP) approval in accordance with the Water Act 2000.

Open drains and watercourses, either natural or manmade, are protected from scour and erosion as directed or approved by the City, in accordance with QUDM and Section 4.5.10.6. Note: All construction within the tidal zone requires approval under the Planning Act 2016, Transport Infrastructure Act 1994

and Coastal Protection and Management Act 1995.



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Swale/table drains 4.4.24Swales are not permitted in place of kerb and channel in urban areas.

Swales are not permitted in the replacement of conventional stormwater drainage in a rural residential zone where there is no kerb and channel. In these instances, table drains are required to manage the road run-off, with the preferable option being a v-drain.

To prevent erosion and to minimise maintenance, table drains are to be free draining with scour protection as required.

Refer to Section 4.5.8 for details of swale construction where swales have been approved.

Culvert Design 4.4.25This section imposes additional requirements to those of Chapter 2 – Transport network standards.

In addition to principles outlined in QUDM, Austroads Guide to Road Design - Part 5: Drainage Design (Part 5B) and IPWEAQ Standard drawing DS-082, the following is required:

(1) Culverts under roads are to be designed to accept the full flow for the minor system (ARI shown), ensuring that the 100 year ARI backwater does not enter properties upstream. If upstream properties are at a relatively low elevation, it may be necessary to install culverts of capacity greater than that for the minor system ARI design storm to ensure flooding of upstream properties does not occur. In addition, the upstream and downstream face of the causeway embankment may need scour protection where overtopping is likely to occur. All road crossings are to be designed to meet the above criteria with allowance for debris blockage as follows:

(a) 50% blockage on culverts is provided up to and including 2400mm wide;

(b) 30% blockage on culverts is provided over 2400mm span;

(c) 100% blockage of guardrails is provided;

(d) Debris deflectors are provided in cases where the blockage potential is high; and

(e) ARR 2016 is checked for higher blockage percentages and applied where appropriate.

(2) The design is to cater for 1% AEP (i.e. 100yr ARI) flow without worsening of flooding to private property by utilising formalised secondary flow paths. The design ensures that a 1% AEP flow under a 100% blockage scenario does not re-route overland from its normal watercourse alignment.

All major culverts require Level 2 inspection reports and maintenance manuals to be supplied as part of the as-constructed requirements (refer to Chapter 9 – Specifications).

4.5 Water sensitive urban design

Introduction 4.5.1

The City has grown rapidly over the last few decades and accompanying this growth is development pressure and an increased population. These factors place stress on our natural water systems and receiving waterways and leads to degradation of our most prized assets, our beaches and waterways.

In response to these pressures, the City has fostered and encouraged the use of more sustainable and integrated urban water management across the city over the last decade. This is through a number of measures including adopting the principles of water sensitive urban design (WSUD) for new development.

An integral element of WSUD is the design and construction of stormwater management systems as part of any development. These devices minimise the impact on waterways by removing pollutants and reducing the change in stormwater flows. The City requires all development manages its stormwater runoff appropriately for the protection of receiving waters and environments.

Purpose 4.5.2The purpose of this section is to outline the City’s requirements for stormwater quality management for any development and to protect the values and quality of all waterways in the City.

This section deals with the following aspects of stormwater management:

(1) erosion and sediment control during construction and building;



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(2) stormwater quality management

(3) waterway stability management;

(4) frequent flow; and

(5) integration of stormwater management infrastructure into development, built form and landscape.

This section also outlines the development triggers, stormwater design objective, compliance methods, design, construction and asset transfer requirements by the City for stormwater management infrastructure. It provides standard approaches to design and delivery of stormwater management infrastructure thus offering a degree of certainty to developer applicants, the city and the community. It does not disqualify innovative solutions but the onus is on the applicant to demonstrate the facts and circumstances to support the solution.

Where the requirements in this policy differ from information contained within the external documents, this policy is to take precedence.

4.5.2.1 External documents A number of external documents provide contemporary and comprehensive policy and guidance in relation to the management of stormwater. Table 4.7: External documents and application outlines the guidelines which are to be referred to during the respective stages of design development.

Table 4.7: External documents and application

External guideline (A-Z)

Phase of development Planning and

concept feasibility

Design development (development application)

Detailed design

(operational works

application)

Construction Establishment Operation and maintenance

Best Practice Erosion and Sediment Control (IECA)

Living waterways booklet Queensland Urban Drainage Manual

Standard Drawings (IPWEAQ) Water by Design - Concept Design Guideline for Water Sensitive Urban Design1

Water by Design - Construction and Establishment Guidelines: Swales, Bioretention Systems and Wetlands1

Water by Design - Deemed to Comply Solutions– Stormwater Quality Management¹ (including Worked Examples)

Water by Design - MUSIC Modelling Guideline1

Water by Design - Rectifying Vegetated Stormwater Assets¹

Water by Design – Stormwater Harvesting Guideline1

Water by Design – Transferring Ownership of Vegetated Stormwater Assets¹

Water by Design – Maintaining Vegetated Stormwater Assets¹

Water Sensitive Urban Design -Technical Design Guidelines for South East Queensland1

Notes:



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External guideline (A-Z)

Phase of development Planning and

concept feasibility

Design development (development application)

Detailed design

(operational works

application)

Construction Establishment Operation and maintenance

¹These guidelines are available from http://hlw.org.au/

Development triggers 4.5.3Development that meets or exceeds the triggers set out in Table 4.8: Development triggers for stormwater quality management is required to manage stormwater in accordance with the design objectives listed in Section 4.5.4. Development that is less than the triggers is required to meet the requirements of the Queensland Development Code (QDC).

The design and submission of the stormwater quality management strategy are to occur in accordance with the remainder of this guideline (and the guidelines referenced by this guideline). Table 4.8: Development triggers for stormwater quality management

Development type Stormwater quality management triggers1

Erosion and sediment control (construction phase)

Stormwater quality management, waterway stability management, frequent flow management4

Material change of use and Preliminary approvals

All development involving preconstruction, construction or building works

(a) greater than 850m2 of land (b) 3 or more dwellings (attached or detached)3 (c) includes newly constructed road (previously unformed road)

exceeding 30m in total length (d) includes 200m2 or more uncovered new or refurbished car

park area including parking bays and circulation driveways

Reconfiguring a lot All development involving preconstruction, construction or building works

(a) greater than 850m2 of land and results in an increased number of allotments

(b) 3 or more allotments result in 3 or more dwellings (attached or detached)3

(c) includes newly constructed road (previously unformed road) exceeding 30m in total length

(d) includes 200m2 or more uncovered new or refurbished car park area including parking bays and circulation driveways

Operational works All development involving preconstruction, construction or building works

(a) greater than 850m2 of land and results in an creation of new allotments

Note: 1. Stormwater management is not required for development in the Rural zone. 2. Development which involves the material change of use of an existing building without any construction or building

works does not trigger the requirement for stormwater management. 3. For development in the Rural residential zone, where the ‘residential’ development results in less than 15%

imperviousness (including roads and ground level impervious), then the stormwater quality objectives focus on road and parking areas only, with tanks and management of tank overflows required for buildings.

Design objectives 4.5.4This section outlines the stormwater management design objectives. .These design objectives are the minimum standard for new development, where local waterway or drainage design objectives have not been adopted by the City. Where local design objectives have been adopted for a particular catchment (i.e. master drainage strategy, catchment management plan or equivalent), these local specific objectives override the relevant objectives outlined in the following sections. It is the responsibility of the applicant to consult with the City regarding the existence of overriding local waterway or drainage design objectives.

4.5.4.1 Erosion and sediment control (construction phase)



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Table 4.9 Erosion and sediment control (construction phase)

Intent Ensure construction activities for the development avoid adverse impacts on stormwater quality and downstream water environments.

Standard / Objective Do not release prescribed water contaminants (as defined in the Environmental Protection Act 1994) from the development site, or cause likely release, should rainfall occur, unless all reasonable and practicable measures are taken to prevent or minimise the release and concentration of contamination. This will require minimising soil exposure, and undertaking erosion control, drainage control and sediment control in accordance with the following: (1) Section 4.5.5.4 of this policy; (2) relevant healthy waterways guidelines and documents; (3) Urban Stormwater Planning Guideline (Queensland State Government); and (4) Best Practice Erosion and Sediment Control (IECA).

Application All new development which requires stormwater management where involving (or likely to involve), but not limited to, the following: (1) vegetation clearing; (2) earthworks; (3) civil construction; (4) installation of services; (5) building works; (6) rehabilitation; (7) revegetation; and (8) landscaping.

4.5.4.2 Stormwater quality objectives (operational phase)

Table 4.10: Stormwater quality objectives

Intent Protect receiving water quality by limiting the quantity (loads) of stormwater pollutants discharged into receiving waters from development.

Standard / Objective Achieve the following minimum reduction in mean annual loads from unmitigated development: (1) gross pollutants (>5mm) – 90% reduction in mean annual load; (2) total suspended solids (TSS) – 80% reduction in mean annual load; (3) total phosphorous (TP) – 60% reduction in mean annual load; and (4) total nitrogen (TN) – 45% reduction in mean annual load.

Application All new development which requires stormwater management.

4.5.4.3 Stormwater quantity objectives

Table 4.11: Stormwater quantity objectives

Intent Ensure all runoff from developed catchments is managed to ensure that property and infrastructure upstream or downstream is protected from impacts of flooding, piped or overland flows in accordance with QUDM and City Plan.

Standard / Objective All runoff from developed catchments is managed to ensure that property and infrastructure upstream or downstream is protected from impacts of flooding and meets with the following: (1) development does not adversely impact on land, drainage system or watercourse; (2) the flood behaviour of the whole catchment must not change as a result of the

development; and (3) at the boundary of the development site or at nominated locations downstream of the

development the following is achieved: (a) no increase in peak flood flow rate for all events up to and including the 1% AEP (i.e.

100 year ARI) event; (b) no increased in peak flood velocities; (c) no increase in flood level for all events up to and including the 1% AEP (i.e. 100 year

ARI) event; (d) no material change in rate of flood rise; and



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(e) stormwater outfall or discharge is located to avoid conflict with existing usage of downstream land or impact on existing waterway or drainage.

Application All new development which requires stormwater management.

4.5.4.4 Waterway stability objectives

Table 4.12 Waterway stability objectives

Intent Prevent in-stream erosion downstream of urban development by controlling the rate (or magnitude) and duration of sediment transporting flows.

Standard / Objective Limit the post-development peak 1-year Average Recurrence Interval (ARI) event discharge within the receiving waterway to the pre-development peak 1-year ARI event discharge.

Application Applicable to new development which requires stormwater management and: (1) drains to an unlined channel or non-tidal waterway within the site or downstream of the

site which is not significantly degraded; or (2) drains to a tidal waterway withi

Documents

742 CITY PLANNING COMMITTEE MEETING 30 AUGUST ......2017/08/30 · Cut/fill batters and earth-retaining structures AS4678: 2002: Earth-retaining structure, Amendment 1 – 2003 and