Once the location of the landscape drainage has been decided, based on the Environment and Liveability Strategy (ELS) and Recreation Parks Plan (RPP) guidance, consider the appropriate embellishment level to suit the selected site.
Overarching design considerations:
Design in accordance with IPWEA (Institute of Public Work Engineering Australia) standard drawings and QUDM (Queensland Urban Drainage Manual).
Design to the site conditions to direct and channel the overland flow.
Accommodate all roof and surface water runoff, originating in the site or flowing through the site.
Existing overland flow paths are to be preserved.
Overland flow paths should be located in road reserves, parks, or other council controlled land, and should not traverse private property unless an easement has been arranged.
Location of surface and subsurface drainage should be clearly indicated on design drawings, including the nominal depth and width.
Location of outlets and cleanouts should also be indicated on design drawings.
See Table 1: Landscape drainage recommendations for further guidance.
Note: LIM Landscape drainage requires professional interpretation and judgement to ensure drainage measures are appropriately adapted for local conditions and local data.
Landscape drainage is designed to provide water free surfaces for safe park and open space activities, in average weather conditions. The design should prevent water-logging of parks and dangerous water build-up in storm events.
Landscape drainage may be a buried or a surface solution, or a combination of both. Prefabricated culverts and piped systems are made from concrete, steel, aluminium, high density polyvinyl chloride (PVC) and other synthetic materials. Products such as rock and gravel provide a natural surface drainage look.
Design to handle peak loads as specified by an accredited engineer.
Urban waterways and stormwater drainage systems can represent a significant safety risk during storms and times of flood. The design of drainage systems which require safety fencing is discouraged and should only be used if required to meet the risk, in accordance with the QUDM.
Product design for drainage components is to be as per Australian Standards for concrete/steel/plastics and composite materials.
Products should be designed for use in stormwater drainage applications and be suitable for buried applications.
Screens for inlets are available in cast iron, ductile iron (more flexible than cast iron), mild steel (subject to rust unless galvanised) and stainless steel.
Avoid using metal grates and pit lids where bare feet may come into contact with heated surfaces such as within pathways.
Drainage surface products must comply with Australian Standards for slip resistance.
Select products appropriate to location and environmental conditions.
The recommended drainage types include sub-surface drainage, field inlet and overflow gully, grated trench drain, open flow channel (swales), and culvert with overpass. These systems are essential for managing water flow and ensuring effective access across various landscapes.
Table 1: Landscape drainage recommendations
Drainage type
Recommended use
Sub-surface (or sub-soil) drainage
to drain sub-surface groundwater or seepage
at locations of high water table
at isolated springs
at salt affected areas.
Field inlet and overflow gully
at inlets situated within an overland flow path
at outlets leading to an overland flow path
distribute along an overland flow path
provide for overland flow path in the event of field inlet failure.
Grated trench drain
to achieve a dry and equal access path of travel over a trench drain.
Open flow channel (swales)
used on flat land soils with low to medium infiltration capacity
For inlets within or outlets to an overland flow path, the design should be in accordance with QUDM.
50% blockage factor for a screen dome and elevated horizontal grate. 80% blockage factor for flush mounted grates. Details can be found in QUDM.
Grate size and design to be specified by a suitably qualified engineer, with regard to hydraulic requirements.
An abrasive surface treatment can be applied to a pre-galvanised grate to create a slip resistant finish. Select slip resistant grates such as SlipNOT (or equivalent) where the grate is traversed by pedestrians.
Designed with positive fall to stormwater outlets.
A grated cover is required to minimise risk of children accessing drains.
Avoid using metal grates and pit lids where bare feet may come into contact with heated grate/lid materials, or apply a heat resistant, pedestrian grade anti-slip coating.
Minimise use when possible due to high maintenance requirement.
Where a trench drain crosses perpendicular to a path of travel, select grates which are designed to prevent ‘tramlining’ of bicycle wheels, wheelchairs and prams.
Select slip resistant trench grates such as Slip NOT (or equivalent).
Avoid using metal grates where bare feet may come into contact with heated grate/lid materials, or apply a heat resistant, pedestrian grade anti-slip coating.
For pedestrian paths select small gap grates designed to resist the possibility of high heeled shoes being caught between the bars.
Grates are selected by trench pit size (the internal measurement of the trench drain).
Force applied to drainage grates is measured in kilonewtons (kN is 1 kilogram of mass at the rate of 1 metre per second squared). This is the international standardised unit of forces and is part of the international system of units (SI).
Select grates with a suitable load classification for the required application.
Install a grated trench drain adjacent to amenities buildings to capture and direct waste water from cleaning services away from pathways and garden beds as cleaning products may harm plants.
See Table 2: Drainage grates load rating requirements for further guidance.
Table 2: Drainage grates load rating requirements
Grate class and load
Recommended use
End user
A
(10 kN)
Paths for pedestrians and pedal cyclists
B
(80 kN)
Paths for pedestrians, light tractor vehicles and livestock
C
(150 kN)
Malls and pedestrian areas open to slow moving commercial vehicles
For open flow channels and swales, the design should be in accordance with QUDM.
Used to minimise piped stormwater drainage systems.
Velocities should be kept low within swales to avoid scouring. They are designed to ensure that the depth-velocity limit of 400 mm2/s is not exceeded for all flows up to the major flow event.
Where drainage swales are turfed (preferred option), a maximum of 1:4 slope (1:6 or shallower is preferred) for mowing with a 2.0 m wide deck mower.
Vegetated swales can be turf (preferred), sedges and tufted grasses.
Rock lined swales are NOT preferred and must be approved by asset custodian. If installed, consider the following:
Any loose rock lined drain should include a low planted buffer area both sides of the drain. Buffer planting separates loose rocks and turfed areas to prevent rocks becoming missiles when grass cutting or lawn mowing equipment is being used.
Where there is a high potential for vandalism (such as removal of rocks from a rock lined drain), the rocks must be embedded in concrete or sealed in place using a suitable adhesive product.
Any loose dry creek bed rocks within 50 m of play ground equipment or safety surfacing, must have the rocks secured into concrete, as loose rocks:
can be used as projectiles
contaminate safety surfacing
can be used to damage equipment
have to be hand removed from turfed areas as they become a projectile when mowed.
Infrastructure designed to improve or protect downstream systems from pollutants by reducing the amount of pollutants entering creeks, rivers and bays.
This infrastructure may:
be required when it is impossible to prevent pollutants from entering the stormwater network
incur significant construction costs and on-going maintenance costs
require ongoing inspection, monitoring, clean-out and waste disposal procedures
require specialist input to ensure an appropriate stormwater management treatment train is designed.
See the following guidelines for further guidance:
Brisbane City Council's Urban Management Division Part C Water Quality Management Guidelines.
Effective drainage construction ensures a lasting, maintenance free facility. The following are a series of water management design options to redirect surface and sub-surface water.
Surface water runoff is the result of rainfall, ground water springs, rivers, lakes, wetlands and seepage.
Trails may intercept surface water and direct it along the trail surface. Structures to control surface water are required at appropriate intervals along the trail, depending on rainfall pattern, trail surface material and local grade.
The aim is to catch and redirect water away from the trail surface and to keep water velocity low to protect the trail surface from erosion.
The trail can be shaped (crowned at the centre) to direct surface water off the trail.
Cross fall can be used on any hardened, stable trail and is ideal for erosion resistant soils. Grades should be minor to moderate.
Open side drains may be used to catch water to drain the trail.
These options can be used alone or in combination with sub-surface drainage solutions to address water management.
See Figure 2: Typical – surface water – pedestrian trails.
Figure 2: Typical – surface water – pedestrian trails
The following diagrams illustrate a range of drainage options which may be used to redirect sub-surface water or a combination of surface and sub-surface water runoff for paths/trails construction.
See Figure 5: Typical sections – sub-surface water – drainage management options.
Grade dips are used to remove water at frequent intervals along a path/trail. Turnouts are short sections of extra width trail comprised of rock lined drain, installed to prevent scouring. Grade dips and turnouts should have the following characteristics:
Designed into the path/trail at regular intervals, dictated by path/trail grade and natural soil type.
Path/trail surface is out-sloped at the low point of the grade dip to divert water from the path/trail.
Path/trail grades should be minor to moderate where grade dips and turnouts are used.
Grade dips located on side slopes.
Install rock lined turnouts to assist with dispersal of runoff.
See the following table and figures for further guidance:
Table 3: Recommended spacing for grade dips and turnouts.
A culvert is a hydraulic structure which may carry flood waters, drainage flows and natural streams.
Culverts may be round, elliptical or box shaped.
Materials may be concrete, galvanised steel, aluminium or high density polyethylene (HDPE).
Are used to pass water under a path/trail in moderate to high water volume areas where bridges are not warranted.
The minimum recommended culvert size in all areas is 300 mm.
Ensure the culvert is aquatic organism compatible (fish friendly) if necessary.
Ensure fauna passage is considered in the culvert design.
Where an underpass crosses a wide road, install surface grills (designed for traffic loading) midway to allow light and airflow for fauna.
Consult Queensland Urban Drainage Manual (QUDM) by Queensland Government Natural Resources and Water.
Culvert design is the result of hydraulic analysis of considerations such as topography, average rainfall intervals (ARI) and catchment area.
Australian Rainfall and Runoff (ARR) is a design guide for flood estimation and hydraulic calculation.
Culverts are designed to carry flood waters and prevent blockage.
When designing culverts at sites used for stock crossing, consider the volume, frequency and type of stock which need to cross as well as any water which may pass through the culvert.
Culverts are to be bedded and backfilled as per Transport and Main Roads (DTMR) Installation, Bedding and Filling/Backfilling Against/Over Culverts – standard drawing UMS 311 Bedding methods for rigid and flexible drainage pipes.
Headwall and apron design is to be as per DTMR Construction of reinforced concrete wingwalls and aprons for pipe diameter up to 2400, drawings MR 1304, 1305, 1306.
Consult a suitably qualified hydrologist for hydraulic analysis.
A screened inlet may be required, to minimise risk of access.
A barrier and fence may be required at culvert ends. Site specific analysis is necessary.
For barrier and fence requirements see AS 2156.2 – Walking tracks Part 2: Infrastructure design.
Urban waterways and stormwater drainage systems can represent a significant safety risk during storms and flood. Risk may be associated with a person deliberately entering a drain or waterway, or as a result of an accidental slip or fall. This risk can be managed successfully through the use of inlet screens to prevent entry of people into a pipe or culvert.
See the following for further guidance:
Figure 7: Typical section – culvert crossing
Figure 8: Typical – culvert crossing with fish and fauna passage.
At a stream crossing with wider, shallower sections
With the aim to provide solid footing at a consistent depth from one stream bank to another
Place stepping stones on the upstream side of a crossing
Ensure rocks are large enough to provide stable footing
Do not block passage for fish or other aquatic organisms
Do not block stream flow
Queensland Department of Natural Resources and Mines (DNRM) Riverine Protection Permit may be required for permission to undertake such activities in a watercourse.
See the following for further guidance:
Figure 9: Typical waterway crossing with stepping stones.
Self-assessable codes by Department of Natural Resources and Mines (DNRM).
Figure 9: Typical waterway crossing with stepping stones
Perpendicular to the waterway to preserve the waterway hydraulic regime
Must comprise erosion proof material (stone or concrete)
Have both ends of the causeway ‘keyed’ into the banks
Allow normal stream flow to pass under the causeway
Allow flood waters to flow over the causeway
Are suitable for watercourses where intensive use is not anticipated
Are suitable for wide shallow streams where it is too expensive to construct a bridge
State Government Department of Natural Resources and Mines (DNRM) Riverine Protection Permit may be required for permission to undertake such activities in a watercourse
May fall within self-assessable codes for waterway barrier works by Department of Natural Resources and Mines (DNRM).
See Figure 10: Typical elevation – causeway water crossing.
Figure 10: Typical elevation – causeway water crossing
Water bars are diagonal channel deflectors installed across a path/trail surface.
Water bars are used to divert surface water which would otherwise flow down the trail reaching destructive energy levels.
As running water has enormous energy, the amount of sediment a flow can carry increases as the fifth power of velocity (the surface speed at which the water moves).
Sediment laden water has the characteristics of liquid sandpaper however a well-placed water bar will deflect the kinetic energy that gravity gives to water.
Volumes of water flowing down a path/trail can be reduced by constructing a series of water bars at regular intervals and at an angle of at least 10 degrees from perpendicular.
There are three main types of water bar:
a drain (shallow trench)
a ridge (mound)
a barrier.
Sediment accumulates on the uphill side of a water bar and requires cleaning to preserve effectiveness
Water bars may be constructed of:
stabilised soil bermed (mounded) to resemble a speed hump
timber
stone
compacted road base.
Do not construct water bars where they may divert flow onto unstable slopes, unprotected erodible materials or fills or onto environmentally sensitive areas.
Consider water bar spacing determined by trail grade and site specific conditions.
Water bars may make access along the path/trail difficult for people with limited mobility.
See the following table and figure for further guidance:
Table 4: Water bar material options
Figure 13: Water bars.
Table 4: Water bar material options
Material
Consideration
Timber
ACQ hardwood (or equivalent)
Class 1 suitable for in ground and moisture
typical section 200 x 50 mm or 75 mm
50–75 mm above surface on the water catchment side
90–100 mm footing
round off edges to prevent trip hazards.
Stone
natural look
maximised life span.
Compacted road base
construct to a height 150–200 mm
does not interfere with maintenance vehicle access.
Whoa boy is the common name for a small trafficable water diversion bank constructed by earth moving machinery or by hand. Whoa boys may be found on outback roads, four wheel drive path/trails and walking trails.
The function of a whoa boy is to divert water flowing down a road or path/trail, back onto undisturbed land. Whoa boys may also be designed as a speed deterrent to slow traffic in environmentally sensitive areas.
Whoa boy design and construction is as follows:
Shape an earth bank with a platform on the upslope side of a path/trail/road
Design a whoa boy to ensure that no rain water will flow down the path/trail/road
Design a whoa boy to ensure natural cross flow of water is maintained and is not diverted down the path/ trail/road
Construct a platform which ensures that any water flowing across the slope does not cause soil erosion
Gentle slopes require banks to be approximately 300 mm higher than the surrounding natural surface level
Slopes steeper than 2.5% require banks approximately 500 mm higher than the surrounding natural surface level
Wet down the whoa boy and compact the bank by rolling.
Whoa boy spacing
Spacing of whoa boys is determined by slope, natural watercourses and stable vegetated areas.
Maximum required spacing of whoa boys on an open road is 120 m, when the slope is 1% and cross slope is 1.5%.
Where there is a natural watercourse such as a creek crossing the road, place the whoa boy on the down slope side. This will ensure natural water flow is maintained.
Whoa boy outlet
Where water is diverted from a road/trail using a whoa boy, the outlet area must be stable and vegetated to prevent erosion.
Whoa boy spacing will therefore be determined by the occurrence of a suitably vegetated area.
A swale drain is a shallow channel designed to convey stormwater and is usually lined with turf or natural vegetation. The objective of a swale drain is to minimise the use of piped stormwater drainage systems and ensure overland flow paths are retained in the catchment helping to minimise risks during peak rainfall events. Key swale considerations include:
Swales slow down stormwater flows
Swales are suitable for side grades between 1% and 4%
Longitudinal grades should typically be between 1% and 4%
Swales which are too flat can become waterlogged or become stagnant ponds
Typically designed for small scale contributing catchment areas of 1 to 2 ha
Any loose rock lined drain should include a low planted buffer area both sides of the drain. Buffer planting separates loose rocks and turfed areas to prevent rocks becoming missiles when grass cutting or lawn mowing equipment is being used
Rock lined drains should include a low planted buffer area both sides of the drain. Buffer planting separates loose rocks and turfed areas to prevent rocks becoming missiles when grass cutting or lawn mowing equipment is being used.
The following safety measures should be undertaken when designing a rock lined drain:
Rock size is primarily dependent on the local flow velocity, rock shape, density and grading, and bank slope
Crushed (angular) rock is generally more stable than rounded rock
Water worn rounded rock from the local area is preferred for aesthetic reasons however a 36% increase in rock size is recommended for rounded rock
Rock should be proportioned so that neither the breadth nor the thickness of a single rock is less than one third its length
Typical thickness of rock layer should be sufficient to allow at least two overlapping layers of nominal rock size
Rock should be durable and resistant to weathering
Consult a suitably qualified engineer to determine the most appropriate rock size, type and installation treatment, to manage site drainage
Where there is a high potential for vandalism such as removal of rocks from a rock lined drain, the rocks should be embedded in concrete or sealed in place using a suitable adhesive product
Suitable only for low sediment flow environments
Used in constructed channels where ecological considerations are low
Most successful on mild gradients and channels up to 1:20.
See the following figures for further guidance:
Figure 16: Typical section – rock lined drain with planted safety buffer zone
Figure 16: Typical section – rock lined drain with planted safety buffer zone
Figure 17: Typical section – concrete lined drain with embedded rock
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Sunshine Coast Open Space Landscape Infrastructure Manual (LIM) DISCLAIMER
Disclaimer
Information contained in this document may change without notice and you should use the current material available from Council’s website and not rely on material previously printed or stored by you.
All figures and diagrams are intended to be used as an aid to design and include Council’s preferred elements but they are not intended to be prescriptive and may need to be varied as dictated by site specific factors. While Council has exercised reasonable care in preparing this document, it does not warrant or represent that it is accurate or complete. The Council will not accept responsibility for any loss, damage, cost or expense that you may incur as a result of the use of or reliance upon any material contained in this document.
This document is produced to convey general information and is not intended to constitute advice whether professional or legal. Any reference to legislation in this document is not an interpretation of the law. It is to be used as a guide only. Consult relevant authority websites for current documents, revisions and amendments.
Where a particular product or supplier is profiled in this document, Council is NOT nominating this product or supplier as the selected choice. Product/supplier information has been provided to allow users to source products which contain the correct elements required for Council embellishments. Each product profiled states ‘or equivalent’ which means that different products may be supplied provided they satisfy the identified performance criteria, recommended standards, equal access guidance and product specifications.
Product design, manufacture and installation requires appropriately qualified people to provide site specific solutions to ensure the embellishment is appropriately adapted to local conditions and data.
This document does not override requirements stipulated in a development approval. Project specific variations may be appropriate as a result of site, environmental or other constraints. Any variations to these standards must be approved in writing by council prior to commencement of variation works. Components of this document may be used within a contract document but users should undertake their own investigations to confirm the information is suitable for this purpose.
Drawings contained in this document are NOT FOR CONSTRUCTION.
Details in this document are deemed to be the minimum standard and the user may wish to apply a higher standard subject to approval by council.
Acknowledgements
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