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Storm Water management plan · MCU12/0133.03
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Noosa Council documents
Noosa Flexi-Learning
Centre
Site Based Stormwater Management Plan
8th August 2012
BUILDING STRUCTURES
LAND AND INFRASTRUCTURE DEVELOPMENT
ENVIRONMENTAL PLANNING
INTEGRATED WATER MANAGEMENT
SPECIAL STRUCTURES
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Noosa Flexi Learning Centre Stormwater Management Plan
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DOCUMENT CONTROL SHEET
BLIGH TANNER PTY LTD Document:
ABN 32 061 537 666 Noosa Flexi-Learning Centre Site Based
Stormwater Management Plan, 8th August
LEVEL 9, 269 WICKHAM STREET
2012
PO BOX 612
Bligh Tanner Job Number:
FORTITUDE VALLEY
2012.167.600
QUEENSLAND 4006 AUSTRALIA
TELEPHONE +61 7 3251 8555 Project Engineer:
FACSIMILE +61 7 3251 8599 Alan Hoban
[email protected] Client:
www.blightanner.com.au Fulton Trotter (for the Edmund Rice
Foundation)
Client Contact:
Mark Kalinowski
Climate change
Unless expressly stated otherwise, historical climate data has been used in, or underpins, the analyses that are
presented in this report. The historical climate is not necessarily a valid indicator of future climate, which may
contain prolonged periods that are wetter or drier than the historical record used for this analysis. There is
significant variability in estimates of how climate, and in particular, rainfall, will be impacted by various levels of
greenhouse gas accumulation in the atmosphere. Rainfall has a much greater spatial variability than temperature
and some areas are likely to become wetter whilst other areas become drier. Further to this there may be
changes in the seasonality and intensity of rainfall. Such changes in climate could affect the conclusions and
recommendations of this report.
Inherent natural variability in soils and plants
Where particular types of soils are recommended, such recommendations are based on information provided by
soils suppliers, laboratories and published industry guidelines. There can be inconsistencies in the behaviour of
soils under field conditions compared to laboratory conditions, and, for both natural and blended soils, many soils
are non-homogenous and properties and behaviour can be vary. Where particular plant species have been
recommended, such recommendations are based on botanical knowledge and observations of similar species
growing in similar, but not identical conditions. Plants can be sensitive to subtle changes in climate, hydrology,
soil and surrounding ecological conditions. Further to this, plant health is often closely linked to the level of
maintenance provided. No warranty or guarantee, whether explicit or implied is made with respect to the suitability
or performance of soils or plant species recommended in this report.
© Bligh Tanner Pty Ltd August 2012
Version Author Reviewed Approved Date
Version 1 Alan Hoban Chris Tanner Chris Tanner 8/8/2012
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TABLE OF CONTENTS
EXECUTIVE SUMMARY ...................................................................................................... IV
GLOSSARY .......................................................................................................................... V
1 INTRODUCTION ............................................................................................................. 1
1.1 Locality Plan ............................................................................................................ 2
1.2 Site Characteristics................................................................................................. 2
1.3 Proposed Land Uses .............................................................................................. 3
1.4 Location Conditions ............................................................................................... 3
1.5 Rainfall zone ............................................................................................................ 3
1.6 Soil Category ........................................................................................................... 3
2 DESIGN OBJECTIVES ................................................................................................... 5
2.1 Stormwater Treatment Objectives ......................................................................... 5
2.2 Hydrologic Objectives ............................................................................................ 6
2.3 Water Savings Targets ........................................................................................... 6
2.4 Construction Phase Objectives ............................................................................. 7
Erosion Hazard Assessment ........................................................................................... 7
3 STRATEGY DESCRIPTION AND PLAN ........................................................................ 8
3.1 Erosion and Sediment Control Strategy................................................................ 9
3.2 Stormwater Treatment Strategy ............................................................................. 9
4 STORMWATER QUALITY ASSESSMENT................................................................... 11
5 HYDROLOGIC ASSESSMENT ..................................................................................... 14
5.1 Flooding of the site ............................................................................................... 14
5.2 Flooding impacts downstream of the site ........................................................... 14
5.3 Frequent flow impacts downstream of the site ................................................... 16
6 IMPLEMENTATION ...................................................................................................... 17
6.1 Construction.......................................................................................................... 17
7 CONCLUSION .............................................................................................................. 18
8 REFERENCES .............................................................................................................. 19
List of Figures
Figure 1 Locality Plan showing the site in relation to relevant receiving environments ........... 2
Figure 2 Site plan showing relevant features of the stormwater strategy .............................. 10
Figure 3 MUSIC model schematic........................................................................................ 12
Figure 4: Comparison of runoff volumes and pollutant loads, which shows that the mitigated
pollutant loads are close to existing levels and well below a conventional ‘best-practice’
approach (note logarithmic scale). Actual values are presented in Table 6. ........................ 12
Figure 5 Catchment boundary and overland flow paths ....................................................... 14
Figure 6 Comparison of pre and post developed peak flows (without mitigation). The increase
in peak flow for the Q100 is about 140 litres per second. ..................................................... 15
Figure 7: Comparison of pre and post development flow frequency showing that the
proposed development avoids increasing the wetness of the downstream ecosystem......... 16
List of Tables
Table 1 Key site information.................................................................................................. 1
Table 2: Soil Properties estimated using the Atlas of Australian Soils .................................... 3
Table 3 How the proposal responds to the Noosa Plan.......................................................... 5
Table 4 Values used in erosion hazard estimation ................................................................. 7
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Table 5 Estimation of non-potable demands from rainwater tanks ......................................... 9
Table 6: Comparison of runoff volumes and pollutant loads ................................................. 13
Table 7 Rational method estimates of peak flows ................................................................ 15
Table B8 Meteorological and rainfall runoff data reporting table ............................................. 2
Table B9 Catchment definition reporting table ....................................................................... 2
Table B10 Rainwater tank node reporting table ..................................................................... 2
Table B11 Infiltration node reporting table.............................................................................. 3
Table B12 Porous pavement node reporting table ................................................................. 3
Table B13 Stormwater quality modelling results reporting table ............................................. 4
Attachments
Attachment A – MUSIC Modelling
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EXECUTIVE SUMMARY
The Noosa Flexi-Learning Centre aims to create a welcoming and distinctly un-institutional
learning environment for disenfranchised and disengaged youth in the Noosa Region. The
design response is to create a beach-house style environment which minimises its impact on
the site, as well as on the planet’s resources.
The young people that will use the centre are approaching life with few privileges. By
creating a learning environment that embodies great sustainability features, the design team
hopes to provide accelerated opportunities for them to understand and interact with the types
of environmental knowledge that we believe will be important to the world they are inheriting.
Such learning opportunities can help build their pride, self-confidence and a sense of
purpose.
The stormwater management strategy helps create such a place by:
• Preserving the natural hydrology across most of the site by building lightweight
structures on piers, and minimizing soil compaction during construction
• Harvesting rainwater and using a prominent elevated rainwater tank that both
symbolizes the responsible use of water and reduces the electricity needed for
pumping.
This report complies with the format for site-based stormwater management plans as set out
in the Urban Stormwater Planning Guidelines (DERM 2010) as referenced under the State
Planning Policy 4/10 Healthy Waters.
The site is low risk from an erosion and sediment control perspective, and accordingly a
minor erosion and sediment control plan will be provided as part of the operational works
application. Moving away from slab-on-ground construction significantly reduces earthworks
and hence the risk of sediment moving off the site during construction.
The stormwater quality management strategy is compliant with the requirements of the SEQ
Regional Plan Implementation Guideline No. 7—as referenced in the Noosa Plan.
Significantly, because the ground-level impervious area is kept at 10% of the site area, the
stormwater quality objective is satisfied by capturing and managing the first 10 mm of runoff.
For major storm events, runoff will continue to discharge across the front boundary of the site
as sheet flow. The design of the site, with limited ground level impervious surfaces, has a
minor impact on peak flows. A small area of depressed landscape at the front of the lot can
provide the 1 m³ of flood detention needed to avoid any increase in peak flows leaving the
site.
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GLOSSARY
Term Definition
ARI Average Recurrence Interval
A system that collects and infiltrates urban stormwater through a prescribed filter
Bioretention system
media covered with vegetation to reduce the concentration of stormwater pollutants
Area of land that collects rainfall and contributes to surface water (streams, rivers,
Catchment
wetlands) or to groundwater
GPT Gross Pollutant Trap
groundwater Sub-surface water in the soil or rock structure
Ha Hectare
Hydraulic conductivity The rate at which water can move through a permeable medium.
A impermeable surface where the majority of rainfall becomes runoff by limiting the
Impervious
infiltration of water into the underlying soils
Infiltration The movement of water from the ground surface into the underlying soil profile
kL kilolitre (1,000L)
Water quality modelling software; Model for Urban Stormwater Improvement
MUSIC
Conceptualisation
An important nutrient found in high concentrations in recycled waters, originating from
Nitrogen human and domestic wastes. A useful plant nutrient that can also cause off-site
problems of eutrophication in lakes, rivers and estuaries.
An important nutrient found in high concentrations in recycled waters, originating
Phosphorus principally from detergents but also from other domestic wastes. A useful plant nutrient
that can also cause off-site problems of eutrophication in water bodies
Pollutant Substance that damages the quality of the environment
QUDM Queensland Urban Drainage Manual
A water body that may receive runoff from the catchment under consideration, and has
Receiving water
some environmental value or beneficial use.
Surface overland flow of water resulting from rainfall or irrigation exceeding the
Runoff
infiltration capacity of the soil
Site Based Stormwater Management Plan. A SBSMP shall identify potential on and off
site impacts associated with stormwater for a proposed development. The SBSMP
SBSMP
shall also identify a range of stormwater management strategies and actions for water
quality, water quantity, and environmental issues.
Stormwater runoff All surface water runoff from rainfall, predominantly in urban catchments
A series of stormwater treatment measures located in a catchment to provide a staged
Treatment train
approach to removal of stormwater pollutants from runoff.
Water Sensitive Urban Design. WSUD Provides a strategy for the conservation and
WSUD
management of water resources through better management of stormwater.
Water quality The chemical, physical and biological condition of water
Water Quality Modelling An important technique used to make predictions about the quality of waterways.
Water Quality Objectives. Measurable goals for the quality of receiving waters to
WQO
ensure the Environmental Values are upheld.
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1 INTRODUCTION
This stormwater management plan has been prepared in accordance with the requirements
for Site Based Stormwater Management Plans as outlined in the Urban Stormwater Planning
Guidelines (DERM 2010) as referenced under the State Planning Policy 4/10 Healthy
Waters.
It described the stormwater strategy for the site and considers erosion and sediment control,
stormwater management (water quality and hydrology), and flooding, and has been prepared
to support a Development Application for the site. Key details about the site are listed in
Table 1 below.
The Noosa Flexi-Learning Centre aims to create a welcoming and distinctly un-institutional
learning environment for disenfranchised and disengaged youth in the Noosa Region. The
design response is to create a beach-house style environment which minimises its impact on
the site, as well as on the planet’s resources.
The young people that will use the centre are approaching life with few privileges. By
creating a learning environment that embodies great sustainability features, the design team
hopes to provide accelerated opportunities for them to understand and interact with the types
of environmental knowledge that we believe will be important to the world they are inheriting.
Such learning opportunities can help build their pride, self-confidence and a sense of
purpose.
The stormwater management strategy helps create such a place by:
• Preserving the natural hydrology across most of the site by building on piers, and
minimizing soil compaction during construction.
• Harvesting rainwater and using a prominent elevated rainwater tank that both
symbolizes the responsible use of water and reduces the electricity needed for
pumping.
Table 1 Key site information
Submission date August 2012
Developer’s name Edmund Rice Education and the Flexible
Learning Centre Network
Principal Consultant Fulton Trotter Architects
Consultant’s name Bligh Tanner Consulting Engineers
Current and proposed land use of The site is currently vacant. The
development site proposed use is for a Flexible Learning
Centre.
Description of site location The site is on Girraween Crt, Sunshine
Beach Qld, opposite the Sunshine Beach
High School and adjacent to Tennis
Noosa. The site has recently been
subdivided from the parent Lot 3 on
RP887636 (at the time of writing the plan
hasn’t been sealed).
Coordinates 26°24’25”S
153°06’06”
Reference to associated documents. Fulton trotter Architectural Drawings
DA-01 to DA-06
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1.1 Locality Plan
The site location is shown in Figure 1 below.
Noosa Flexi-
Learning
Centre
Noosa Heads
Sunshine Beach
Coastal waters and
the Coral Sea
Sensitive to
changes in water
quality
Sunrise Beach
Noosa National
Park/Girraween
Nature Reserve:
Environmentally
sensitive healthland
which is particularly
sensitive to increased
wetting near
stormwater outfalls
and high nutrient
levels, leading to weed
infestations and
Burgess Creek
changes in the
vegetation community Increases in peak
flows could
exacerbate erosion
Castaways
Beach
Figure 1 Locality Plan showing the site in relation to relevant receiving environments
1.2 Site Characteristics
The site is approximately 0.5 hectares. It is on free-draining sandy soils (as described in
Section 1.6).
The rear, northern end of the site is at RL 34.1 m grading to RL 32.5 m at the southern
boundary, a grade of about 1.6%. A raised mount to the south east of the site rises to RL35
M. The lowest point of the site is at the south western corner, at RL 32.27 m.
It is currently vegetated with endemic dunal species, including Banksia spp. and
Xanthorrhoea spp.
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Girraween Court has existing stormwater drains and kerb and channel. The stormwater pit in
front of the site has an invert at RL 31.27, about 1 metre below the lowest surface level on
the site.
At the end of the existing stormwater drain is a bioretention/infiltration system which was
inspected and had adequate plant coverage and no evidence of impeded infiltration.
1.3 Proposed Land Uses
The site is proposed to be used as Flexible Learning Centre, which seeks to respond to the
needs of young people disenfranchised and disengaged from education.
It will consist of a series of small buildings that create a learning environment for about 80
young people and about 10 staff.
1.4 Location Conditions
The site is located upstream of the environmentally sensitive Noosa National Park and the
Girraween Nature reserve, which Burgess Creek passes through. The stormwater
management priorities for this area are set out in the Girraween Stormwater Management
Plan (Ecological Engineering 2006) as follows:
1. Reinstate the natural hydrology of the catchment
2. Repair channel incision at existing stormwater outfalls and remove invasive aquatic
weeds
3. Treat urban stormwater to current best practice standards
1.5 Rainfall zone
The nearest rainfall gauge is Noosaville (Bureau of Meteorology Station ID 040995). This
rainfall station commenced in 2009, and so does not provide a sufficient period of record for
stormwater quality modelling. Accordingly the Cooroy Composite gauge (ID 40059) has
been used for long term simulations in accordance with the MUSIC Modelling Guidelines
Version 1.0 (Water by Design 2010).
1.6 Soil Category
For the purposes of this stormwater management plan, soils have been categorised by a
field inspection and from the Atlas of Australian Soils (accessed via the Australian Soil
Resource Information System). Full soil tests will be undertaken as part of a geotechnical
investigation as part of the detailed design and included with the operational works
application.
The site is characterised by fine, free draining sands with modest organic material and
limited fines (consistent with the dunal vegetation present on site). The Soils are in zone
Ca10. The five dominant principle profile forms for this zone, and their typical properties, are
outlined in Table 2 below.
Table 2: Soil Properties estimated using the Atlas of Australian Soils
Principal Median A horizon Texture Median A Horizon kSat
profile forms (Northcote class) (log10) (mm/hr)
Uc2.2 1 (Uniform Coarse) 9 +/-2
Uc2.3 1 (Uniform Coarse) 9 +/-2
Uc1.22 1 (Uniform Coarse) 9 +/-2
O 3 (Uniform Fine) 9 +/-2
Gn2.94 2 (Uniform Medium) 7 +/-2
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Based on this assessment there is a very high likelihood that the site soils do not present a
constraint to the propsed stormwater management strategy.
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2 DESIGN OBJECTIVES
This chapter outlines the relevant stormwater management design objectives for site.
2.1 Stormwater Treatment Objectives
Stormwater quality is to be managed in accordance with the Noosa Plan Water Sensitive
Urban Design Code (Table 14-61).
Table 3 How the proposal responds to the Noosa Plan
Specific Outcome Probable Solutions Proposed Approach
Water reuse S1.1 Development complies Minimise ground-level
O1 Development uses a with the water quality standards impervious areas (i.e. slab on
combination of detention and in Table 2 of the SEQ Regional ground construction) to less
retention systems to capture Plan Implementation Guideline than 25% of the site area.
run-off from areas on the site; No. 7 for Water Sensitive Urban
AND Design; Capture and manage the first 10
O2 Water storage devices must S2.1 No solution provided mm of runoff from impervious
have sufficient capacity having S3.1 Captured water is plumbed areas, including:
regard to local rainfall pattern to be available for all external • capturing roofwater for non-
and the catchment area of roof uses including gardening, potable uses
or other hard standing surface; irrigation, ponds, filling • infiltrating excess water into
AND swimming pools and outdoor
O3 Captured water is utilised for cleaning, as well as all ground the soils to preserve the
all non-potable uses on site; floor toilet cisterns and washing regional hydrology.
AND machine cold taps;
O4 On-site detention does not S3.2 Where the captured water
adversely impact on water is used for toilet flushing and/or
requirements downstream of the laundry use, an automatic or
site where the water is required manual interchange device that
to sustain the ecology and allows alternate use of captured
hydrology of downstream water or the reticulated water
systems (environmental flows); supply is installed to ensure that
AND there is a continual supply of
O5 Within the Shire Business water for sanitary flushing and
Centre site, as shown on Map laundry use.
SBC, on-site detention S4.1 No solution provided
measures are contained within S5.1 No solution provided
the developed areas of the site,
clear of drainage lines and
Open Space Precincts.
Run-off treatment S6.1 & S7.1 Development Capture and manage first 10
O6 Run-off that leaves the site complies with the water quality mm of runoff from impervious
is treated so as not to adversely standards in Table 2 of the SEQ surfaces as per Table 2 of the
impact on the ecology and Regional Plan Implementation SEQ Regional Plan
hydrology of downstream Guideline No. 7 for Water Implementation Guideline No. 7
environmental flows; Sensitive Urban Design. for Water Sensitive Urban
AND Design
O7 Within the Shire Business
Centre site, as shown on Map
SBC—
a) run-off treatment occurs
within the site ; and b) drainage
lines are only used for final
polishing of run-off.
Town water supply S8.1 A suitable backflow
connections prevention device is installed to
O8 Backflow devices or similar protect the potable water within
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systems ensure water reuse the reticulated water supply in
facilities have no impact on the accordance with AS/NZS
quality of the town mains water. 3500:2003 Plumbing and
Drainage.
Use of natural treatments and S9.1 & S10.1 Development The need for natural treatment
systems complies with the water quality systems will be minimised by
O9 Natural treatment strategies, standards in Table 2 of the SEQ preserving the natural hydrology
including grass swales and bio- Regional Plan Implementation of the site, thereby minimising
retention systems, vegetated Guideline No. 7 any increase in surface runoff.
filtration strips and gross
pollutant traps, are used
wherever practicable;
AND
O10 Within the Shire Business
Centre, as shown on Map
SBC— where necessary,
drainage lines are ecologically
enhanced to ensure that the
water quality polishing functions
are of high standard.
As per Table 2 of the SEQ Regional Plan Implementation Guideline No. 7, development that
is less than 25% impervious is excluded from load-based objectives but is required to
capture and manage the first 10 mm of runoff per day from impervious areas.
The rationale for this, according to the SEQ Regional Plan Implementation Guideline No. 7 is
“Since the load-based reductions are relative to the average pollutant loads in
untreated runoff, a higher standard is effectively imposed on low-pollutant-generating
development, by requiring pollutants to be removed to unachievable levels.
Accordingly, development resulting in no more than six dwellings or 25%
imperviousness or less can be addressed through simpler ‘deemed to comply’
solutions
2.2 Hydrologic Objectives
The hydrologic objective for this site is to preserve the natural hydrologic regime of the
catchment by avoiding any increase in the volume of surface runoff leaving the site.
This would thereby satisfy the Frequent Flow Management Objective outlined in Table 4 of
the SEQ Regional Plan Implementation Guideline No. 7, which states that the first 10 m of
runoff should be captured and managed (where the total impervious surface is 0% to 40%)
management of captured stormwater may include infiltration to native soils (where adverse
impacts will not arise).
2.3 Water Savings Targets
The proposed centre is a Class 9 Commercial Building (under the Building Code of
Australia), and therefore the Queensland Development Code Mandatory Part 4.3 Alternative
Water Sources – Commercial Buildings applies.
Accordingly, the centre must have an alternate water source which provides water for
suitable uses.
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The most appropriate acceptable solution for this site is to have rainwater tanks, sized at
1500L per required pedestal (Acceptable Solution A3), which is connected to each required
pedestal, external use, and washing machine cold water taps (Acceptable Solution A2).
2.4 Construction Phase Objectives
Stormwater run-off from land development and infrastructure development sites has a high
potential to cause water contamination and/or environmental harm. This is regulated under
the EP Act 1994.
Under S440ZG it is an offence to unlawfully deposit a prescribed water contaminant to
waters. Prescribed contaminants are listed in Schedule 9 of the Environmental Protection
Regulation 2008 (EP Reg), and include: ashes, clay, gravel, sediment, stones and similar
organic or inorganic matter, as well as building and construction materials and waste.
Under S 319 persons in Queensland carrying out activities which may cause environmental
harm must comply with the ’general environmental duty’ (GED). This requires that all
reasonable and practicable measures must be adopted to prevent and minimise
environmental harm. Although not being able to demonstrate compliance against GED is not
an offence, demonstrating that all reasonable and practicable measures have been adopted
is a defence for offences such as water contamination. For instance, under chapter 10,
s493A of the EP Act, where a person deposits a prescribed water contaminant to waters or
causes unlawful environmental harm, it is a defence to demonstrate compliance with the
GED. Demonstrating that all reasonable and practicable measures have been conceived and
implemented should encompass:
• thorough and ongoing site assessments
• consideration of, and adaptation for site specific erosion risk factors including
topography, soil type, climate and season
• design, installation, operation, management, maintenance and monitoring of control
measures as identified in the erosion and sediment control plan.
Erosion Hazard Assessment
This site is considered low risk based on the following erosion hazard assessment:
• Predicted Annual Soil loss (tonnes) = A x B x T
• Where A = R.K.LS.C.P (as per the Revised Universal Soil Loss Equation).
Table 4 Values used in erosion hazard estimation
Factor Description Adopted value
R Rainfall erosivity factor 5700 (i 2y 6hr = 15.8 mm/hr)
K Soil erodibility factor 0.04 (loam)
LS Topographic factor 0.2 (100 m @ 1%)
C Cover and management 1 (no cover)
P Practice 1.3 (no management)
B Area of disturbance 0.5 ha
T Predicted duration 0.5 yrs
Predicted unmitigated soil loss = 59 t/ha/yr x 0.5 ha x 0.5 yrs = 15 tonnes
As this is significantly less than 150 tonnes, this development is considered low risk,
and accordingly a minor erosion and sediment control plan will be provided as part of
the operational works application, as per Sunshine Coast Regional Council’s Manual
for Erosion and Sediment Control V1.2 (Nov 2008).
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3 STRATEGY DESCRIPTION AND PLAN
The overall intent of the stormwater strategy is to mimic the natural hydrology of the site by
minimising the level of disturbance to the existing ground conditions.
Key features of the strategy include:
1. Maintaining ground-level permeability across 90% of the site:
a. Only 3% of the site (177 m²) will be slab-on-ground construction (for the Music
building (due to soundproofing needs) and part of the Create building (due to
the raised ground levels in that area). The majority of structures will be built on
raised piers (consistent with a Noosa beach-house feel) to largely preserve
ground level infiltration characteristics. The pier-construction technique will
preserve large areas of shallow tree roots, which will assist in maintaining the
natural infiltration rate of the soils and retaining natural biological nutrient
removal capacity.
b. 7% of the site is carpark, and this will use permeable pavement to reduce
runoff from small rainfall events.
2. 68% of the site free is free of structures (buildings/carparks) which will minimise
change to pollutant generation or infiltration properties. This area includes significant
retention of existing vegetation, as well as revegetation with existing species.
3. Roof runoff will be captured in rainwater tanks that are designed to suit the non-
potable water demands at the Flexi-Learning Centre. 25% of the site is covered in
roofs and about 60% of roof areas will drain to rainwater tanks, and about 60% of this
water is able to be reused. The overflow from these tanks will be diverted to
infiltration trenches. The balance of roof areas will drain directly infiltration trenches,
rather to via rainwater tanks, because the relatively low non-potable water demands
at the Centre do not justify harvesting water from every roof.
4. The mean annual volume of surface runoff leaving the site is expected to be about
20% less than existing levels (due to rainwater harvesting and infiltration).
5. Runoff from the site will enter the stormwater drainage system along Girraween Crt,
which drains through an existing bioretention/infiltration system at the end of the court
before reaching the Noosa National Park/Girraween Nature Reserve and Burgess
Creek. Whilst this existing bioretention system is not specifically needed to treat
runoff from the site (and probably isn’t designed to do so), it does provide an
additional layer of protection to the receiving environment (given the nature of the
intended use, there are unlikely to be any activities on the site that would generate
atypical pollutant loads).
6. The small increase in impervious areas means there is only a small increase in peak
flows under major storm conditions. The very small amount of flood detention
required (about 1 m3) will be easily accommodated within the site design at the
detailed design stage (as part of infiltration systems, additional landscape
depressions or additional airspace in rainwater tanks).
7. Overland flow paths will be similar to existing conditions, and under major storm
events water will sheet flow across the south-western boundary of the site on to
Girraween Crt and then flow west towards Burgess Creek.
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3.1 Erosion and Sediment Control Strategy
Due to the site having a low erosion risk, a minor erosion and sediment control plan will be
submitted as part of the operational works application. A preliminary erosion and sediment
control strategy is outlined below:
Given the flat sandy nature of the site, and that soil disturbance will be minimised because
most structures will be built on raised stumps rather than slab-on-ground, the erosion and
sediment control strategy is expected to be quite straightforward and involve a combination
of:
• Careful staging of works and tightly controlled work-methods to minimize soil
disturbance (this is critical as the permeability of the soils needs to be maintained
post-construction)
• Temporary downpipes to minimize erosion
• Sediment fences
• Controlled vehicle access points
No sediment basins are planned.
3.2 Stormwater Treatment Strategy
The stormwater treatment strategy is closely linked to the architectural design for the site, in
particular, keeping the building footprints small and retaining large areas of greenspace, and
building on piers to maintain the ground level permeability of the site.
Roofwater will be harvested and used all non-potable uses. Estimating demands for a centre
of this nature is difficult, as attendance is highly variable, and there are atypical water uses
compared to conventional schools. For example clothes washing facilities are provided for
young people who may be homeless, and some of the learning activities could, from time to
time, be high water users.
Non potable demands estimates are outlined in Table 5 below.
Table 5 Estimation of non-potable demands from rainwater tanks
Use Rate Comment/Source
Toilets 10.5 l/p/day 50% of the demand for a high efficiency
toilet or houses (Water y Design 2010)
Washing 2.6 l/p/day 10% of the demand for a high efficiency
Machine washing machine (Water by Design 2010)
Occupancy 80 people
Total internal 0.94 kL/day
use
Irrigation rate 700 mm/yr for the Water by Design 2010
turfed area
Irrigation Area 640 m² Turfed area as per site plan
Total external 384 kL/yr
use
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CARPARK WITH CONTINGENCY LOCATION
AREAS TO BE PROTECTED REVEGETATED AREAS USING
PERMEABLE WHERE THE LANDSCAPE
DURING CONSTRUCTION EXISTING/RELOCATED PLANTS
PAVEMENT COULD BE DEPRESSED FOR
(INCLUDING UNDERSTOREY FLOOD DETENTION (1 M3) OR
PLANTING) BIORETENTION
ROOF AREA
DRAINING
`
DIRECTLY TO
INFILTRATION
ROOF AREA
DRAINING TO
RAINWATER
TANKS, WITH
OVERFLOW TO
INFILTRATION
CATCHMENT
EXTENT FOR SLAB-ON-GROUND
OVERLAND FLOWS CONSTRUCTION
Figure 2 Site plan showing relevant features of the stormwater strategy
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4 STORMWATER QUALITY ASSESSMENT
Modelling has been undertaken in accordance with Water by Design (2010) MUSIC
Modelling Guidelines Version 1.0 with the exception of the following:
• Forested parameters have been used to reflect the landscape areas—apart from the
turfed areas—in the post-development case, as there is no significant change to pre-
developed conditions.
Whilst the design objectives for the site (as outlined in Section 2.1) allow for the infiltration of
stormwater and do not explicitly require stormwater quality to be managed, given the
sensitivity of the receiving environment it is prudent to consider these impacts.
It is difficult to accurately estimate the impacts of the development on groundwater quality for
several reasons:
• The capacity of the in-situ soils to process stormwater pollutants, particularly the
denitrifying capacity of the soils and root zone, is difficult to estimate, and MUSIC
does not account for the potential retention or transformation of nutrients in natural
soils.
• The site’s sandy soils are far more permeable than the soils used to develop the
recommended rainfall runoff parameters outlined in the SEQ MUSIC Modeling
Guidelines (Water by Design 2010), and local calibration data are not available.
Permeable area parameters have a significant bearing on model results when
impervious areas are low (Water by Design 2010). For example, using a
recommended rainfall runoff parameters for a forested site results in an annual
volumetric runoff coefficient of 32% which is well above what would be reasonably
expected for this site a value of . Adjustments to these parameters in the absence of
calibration data would be somewhat arbitrary as they are calibration parameters and
not directly related to physical soil characteristics.
Notwithstanding the above limitations, using MUSIC in accordance with the recommended
guidelines produces the results shown in Figure 4 and Table 6 below.
A schematic of the MUSIC model configuration is presented in Figure 3.
Note that the architectural design of the site plays a key role in mitigating stormwater
impacts. If the site were to be developed as a conventional commercial development, and
the stormwater runoff was treated to current best practice standards using bioretention
systems, the runoff volumes and pollutant loads would be higher than those from the Noosa
Flexi Learning Centre even if there were no rainwater tanks or infiltration systems. In other
words the site, by virtue of the low impact design of the site, it will likely perform better than a
conventional ‘best-practice’ development.
This result highlights the logic of exempting development with low levels of imperviousness
from the stormwater quality load-based objectives.
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Figure 3 MUSIC model schematic
10000
1000 Existing
Conventional commercial
100 development
Conventional commercial with
best practice bioretention
10
Noosa Flexi
1 Noosa Flexi with tanks
Noosa Flexi with tanks +
0.1 infiltration
Flow (ML/yr) Total Total Total
Suspended Phosphorus Nitrogen
Solids (kg/yr) (kg/yr) (kg/yr)
Figure 4: Comparison of runoff volumes and pollutant loads, which shows that the mitigated
pollutant loads are close to existing levels and well below a conventional ‘best-practice’
approach (note logarithmic scale). Actual values are presented in Table 6.
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Table 6: Comparison of runoff volumes and pollutant loads
Conventional Noosa
commercial Flexi Noosa Flexi
Conventional with best Noosa School School with
commercial practice* Flexi with tanks +
Existing development bioretention School tanks infiltration
Flow (ML/yr) 2.9 7.8 7.6 4.6 3.9 2.0
Total Suspended Solids (kg/yr) 160 1300 270 330 300 150
Total Phosphorus (kg/yr) 0.19 3.0 1.2 0.8 0.65 0.22
Total Nitrogen (kg/yr) 2.1 25 14 7.3 5.5 1.9
* sized to reduce pollutant loads by 80% (TSS) 60% (TP) and 45% (TN)
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5 HYDROLOGIC ASSESSMENT
5.1 Flooding of the site
The site is located at the top of a dune system with a very small external catchment (0.3 ha)
and on sandy, free draining soils. The site is therefore not prone to flooding. The site is well
clear of Council’s estimated food extent for the 100 year average recurrence interval (ARI)
flood1.
Under major storm events, runoff will flow across the site as sheet flow, as shown in Figure 5
below.
The central turfed area is intended for active recreation, and so it will be slightly raised to
assist with drainage so that the students can use this area sooner after it rains.
CATCHMENT
BOUNDARY
OVERLAND FLOW
Figure 5 Catchment boundary and overland flow paths
5.2 Flooding impacts downstream of the site
For the purposes of flood assessments, a 0.3 ha external catchment has been included (from
land immediately to the north of the site, and part of the adjoining lot to the east of the site,
refer Figure 5).
An initial sizing of flood detention has been undertaken using the initial sizing method
outlined in QUDM (2007) Section 5.05.1. For the developed case, the ground level fraction
1
Sunshine Coast Regional Council Estimated Flood Extent – 100 Year Average Recurrence Interval: Freshwater
Flooding And Storm Tide, Current Climate Conditions
http://www.sunshinecoast.qld.gov.au/addfiles/documents/floodmaps/ari_map_north.pdf last printed 24/03/2011
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impervious has been conservatively adopted at 20% (the actual ground level impervious
area, including the full area of the carpark, is about 10%).
Table 7 Rational method estimates of peak flows
Predeveloped Developed
Area 0.8 ha 0.8 ha
Frequency factor (Fy) 1.2 1.2
Fraction Impervious (Fi) 0% 20%*
C10 0.53 0.74
Time of concentration 10 minutes 10 minutes
I (mm/hr) 250 250
Peak Flows
Q2 (m3/s) 0.1 0.2
Q10 (m3/s) 0.2 0.3
Q100 (m3/s) 0.4 0.5
*
0.60
Predevelopment
0.50
Post-development
Peak discharge (m³/s)
0.40
0.30
0.20
0.10
-
2 10 100
Average Recurrence Interval (yrs)
Figure 6 Comparison of pre and post developed peak flows (without mitigation). The
increase in peak flow for the Q100 is about 140 litres per second.
The increase in the Q100 flow as a result of the development, in absolute terms, is about 140
litres per second.
The detention size, in accordance with initial sizing method outlined in chapter 5.05 of
QUDM, has been estimated at 1 m³ (being the average of QUDM equations 5.01, 5.02, 5.03
and 5.04).
This flood detention is particularly small and could be considered immaterial particularly in
light of
• the limited infrastructure between the site and the receiving environment (being
raised classrooms and sporting facilities)
• the small increase in peak flow is unlikely to have a significant impact on the erosivity
of flows in Burgess Creek given it has a far larger catchment
Nonetheless the small volume will be easily provided for as follows (in order of preference):
• in the infiltration depressions beneath the buildings
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• In the front of the site there is an area of landscape that will be revegetated, and this
area could be easily depressed to create 1 m³ of shallow flood detention (0.1m depth
over 10 m²)
• As additional airspace within rainwater tanks.
Further guidance will be sought from Council at Operational Works to confirm this
requirement. In any case, the proposed development layout is compatible with attenuating
flooding impacts downstream.
5.3 Frequent flow impacts downstream of the site
According to the Girraween Stormwater Management Plan (Ecological Engineering 2006),
the increased frequency of surface runoff is considered to be the primary threat to the wet
heath vegetation of that ecosystem.
The strategy to minimise impervious areas and to harvest and infiltrate stormwater is
consistent with preserving the hydrology of this receiving environment.
Pre and post development flow frequency curves are presented in Figure 7 below. It shows
that the strategy is effective in avoiding any increase in runoff for all rainfall events within the
simulation period (1973 – 1983). Exact replication of pre-developed flows is the ideal
outcome, and the results show modest reduction in flows. The following points are noted:
• The results are generated from MUSIC in the absence of any calibration data to
reflect the sandy soils of the site (nonetheless, the relative impact between pre and
post development would probably not change greatly)
• The reduction is modest (it is only apparent when plotted on a logarithmic scale)
• A reduction is preferable to an increase (the wet heath is at risk from losing its drying
phase), and there is already surplus wetting already occurring from other parts of the
catchment, so a small reduction from this site is desirable.
100
10
Daily flow (m³/day)
1
0.1 pre
post
0.01
0.001
0% 20% 40% 60% 80% 100%
Cumulative frequency
Figure 7: Comparison of pre and post development flow frequency showing that the
proposed development avoids increasing the wetness of the downstream ecosystem.
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6 IMPLEMENTATION
The strategy avoids the creation of vegetated stormwater assets which makes it easier to
implement (i.e. it removes the need for detailed staging of works, construction hold points,
coordination of erosion and sediment control measures, and establishment periods), and
there are no assets being created that will be handed over to Council. The implementation of
this stormwater strategy is therefore relatively straightforward. The key implementation
challenge is managing construction activities as outlined below.
6.1 Construction
Construction activities will need to be carefully managed as follows:
• Retain as much natural vegetation as possible using appropriate fencing
• Minimise disturbance and compaction of soils by having dedicated access routes
through the site for construction vehicles
• Minimise the generation of fines from construction activites that may impede
infiltration (eg cement, sanding).
Specific management approaches will include pre-start meetings, hold points, and the use of
detailed work-method statements to ensure construction methods are compatible with
maintaining the natural hydrology of the site. These approaches will be integrated with the
erosion and sediment control plan.
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7 CONCLUSION
The proposed stormwater management strategy for the Noosa Flexi Learning Centre will
satisfy the requirements for the site for:
• Stormwater quality
• Hydrology (frequent flows)
• Flood mitigation
• Erosion and sediment control.
The strategy is simple and feasible, and is closely linked to the architectural design of the
site.
It addresses the specific environmental requirements of the high value receiving
environment, and is consistent with the aspiration to create a special place for
disenfranchised young people.
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8 REFERENCES
CSIRO (2000) Estimation of Soil Properties Using the Atlas of Australian Soils. Technical
report 11/00, February 2000.
Department of Environment and Resource Management (2007), Queensland Urban
Drainage Manual
Department of Environment and Resource Management (2010) Urban Stormwater Quality
Planning Guidelines Dec 2010
Department of Infrastructure and Planning (2009) South East Queensland Regional Plan
2009 – 2031 Implementation Guideline No. 7 Water Sensitive Urban Design.
Ecological Engineering (2006) Girraween Stormwater Management Plan, Version 1, 22nd Dec
2006. Report prepared for Noosa Council.
Sunshine Coast Regional Council (2008) Manual for Erosion and Sediment Control V1.2 Nov
2008.
Water by Design (2010) MUSIC Modelling Guidelines Version 1.0 - Healthy Waterways
Limited.
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ATTACHMENTS
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Attachment A – MUSIC Modelling
The following reporting tables outline the key parameters used in the MUSIC Modelling for
this project. The table format is adopted from the Water by Design (2010) MUSIC Modelling
Guidelines V1.0. In accordance with that guideline, where recommended rainfall-runoff and
pollutant generation parameters are adopted, they aren’t reported.
Interested parties can review the model files to verify model parameters.
Table B8 Meteorological and rainfall runoff data reporting table
Input Data used in modelling
Rainfall station Cooroy Composite 40059
Time step 6 minute
Modelling period 1/1/1973 – 13/12/1983 (11 years)
Mean annual rainfall (mm/yr) 1595 mm
Evapotranspiration (mm/yr) 1627 mm
Rainfall runoff parameters Predevelopment: Forested
Post development: Urban Residential (except for natural
landscaped areas which use Forested parameters)
Pollutant export parameters Predevelopment: Forested
Post Development: Urban Residential (except for natural
landscaped areas which use Forested parameters)
Table B9 Catchment definition reporting table
Catchment ID Area (m²) Land use Total impervious (%)
1 (reference to catchment Total area of sub- Residential, Total impervious portion of
plan) catchment commercial, catchment as measured
industrial etc. off development plans
Carpark 370 Residential 100%
Buildings Residential
Knowledge 170 Residential 100%*
Amenities 70 Residential 100%*
Create 318 Residential 100%*
Retreat 210 Residential 100%*
Sound 139 Residential 100%*
Allied/Support/Eat/Gather 497 Residential 100%*
Landscape 3226 Forest 0%
Turf 600 0%
TOTAL 5600
*Note this is roof area, not ground level impervious area
Table B10 Rainwater tank node reporting table
Rainwater tanks
Catchment ID Treatment node 1
Volume below overflow pipe (kL). If greater than 1 tank 20 kL
specify number of tanks, volume per tank and total e.g.
10 tanks x 5 kL = 50 kL
Depth above overflow (m) 0.1
If tanks are lumped, is depth below overflow the same as n/a
a single tank and overflow pipe scaled accordingly
2
Surface area (m ). 10
Overflow pipe diameter (mm). For lumped tanks this 150
must be equivalent to the diameter of the overflow pipe
of a single tank multiplied by the square root of the
number of tanks
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Stored water used for irrigation and other purposes (Y/N) Y
PET
PET – Rain
Indoor connections e.g. toilet, laundry etc. 0.94
Indoor demand (kL/day) 0.94
Outdoor demand (kL/yr) 384
Daily demand (kL/day) 0.94
Monthly distribution of annual demand (kL/day)
Confirmation that K and C* remain default? (Y/N) Y
Table B11 Infiltration node reporting table
Infiltration System
Catchment ID Treatment node 1 Treatment node 2
(etc.)
Water quality objectives (WQO’s) must be achieved prior (note the discussion on design objectives in
to stormwater entering an infiltration system i.e. Chapter 2)
infiltration systems cannot be use to demonstrate
compliance with WQO’s. Has compliance been achieved
prior to using this node? (Y/N)
Is the exfiltration rate justified Yes
Notwithstanding construction controls, the
Can the hydraulic conductivity of the in-situ soils be guaranteed even
hydraulic conductivity of sand is relatively
during earthworks?
insensitive to compaction.
If “no” was answered to any of the above questions this node cannot be used.
2
Pond surface area (m ) 200 200
Extended detention depth (m) 0.1 0.1
2
Filter area (m ) 200 200
Unlined filter media perimeter (m) 400 400
Depth of infiltration media (m) 0.3 0.3
Exfiltration rate (mm/hr) 180 180
Overflow weir width (m) 50 50
Evaporative loss as % of PET 25 25
Confirmation that K and C* remain default? (Y/N) y y
Table B12 Porous pavement node reporting table
Porous Pavements
Catchment ID Treatment node 1
Is direct rainfall modelled as a separate source node with Y
a 100% impervious fraction? (Y/N)?
Is the biofilter filter area set to represent the opening It is assumed at
area of the permeable paving or void ratio of porous 25% of total
pavement (not the total surface area)? (Y/N). This should carpark area
be estimated from the product specifications.
Is the extended detention depth set to 0 m? Y
Is the filter depth set to represent the treatment area only (should not Y
include the depth of the drainage layer)
Is the vegetation property set to “unvegetated”? n/a
2
Surface area (m ) 92.5
Has the filter area been calculated appropriately (Y / N / Y
N/A)
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Extended detention depth (m) 0m
2
Filter area (m ) 92.5 m²
Unlined filter media perimeter (m) n/a
Saturated hydraulic conductivity (mm/hour). This should 180 mm/hr
be modelled once at 50 mm/hr and once at 200mm/hr.
Report as “50/200”
Filter depth (m) 0.2
Overflow weir width (m) 20 m
Exfiltration rate (mm/hr) 180 mm/hr
If an exfiltration rate has been used, have node water n/a
balance losses been used in calculation of treatment
train effectiveness? (Y / N / N/A)
If exfiltration rate has been used, is the exfiltration rate Y
justified (Y / N / N/A)
Confirmation that K and C* remain default? (Y/N) Y
Table B13 Stormwater quality modelling results reporting table
Catchm Pollutant Inflows Outflow Reduction Reduction Water
ent ID (kg/yr) s (kg/yr) (kg/yr) achieved Quality
(%) Objective
(%)
TOTAL TSS 330 145 185 56% n/a
TP 0.79 0.22 0.58 73% n/a
TN 7.3 1.9 5.5 74% n/a
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MUSIC MRT File
Source nodes
Location,Ground Level
(Forest),Support/Eat/Gather/Allied,Knowledge,Sound,Retreat,Create,Amenities,Landscape
(forest),Turf,Direct rainfall on carpark
ID,1,3,4,8,9,10,11,13,14,15
Node
Type,UrbanSourceNode,UrbanSourceNode,UrbanSourceNode,UrbanSourceNode,UrbanSo
urceNode,UrbanSourceNode,UrbanSourceNode,UrbanSourceNode,UrbanSourceNode,Urba
nSourceNode
Total Area (ha),0.56,0.05,0.017,0.014,0.021,0.032,0.007,0.323,0.06,0.037
Area Impervious (ha),0,0.05,0.017,0.014,0.021,0.032,0.007,0,0,0.037
Area Pervious (ha),0.56,0,0,0,0,0,0,0.323,0.06,0
Field Capacity (mm),80,200,200,200,200,200,200,80,200,200
Pervious Area Infiltration Capacity coefficient - a,200,211,211,211,211,211,211,200,211,211
Pervious Area Infiltration Capacity exponent - b,1,5,5,5,5,5,5,1,5,5
Impervious Area Rainfall Threshold (mm/day),1,1,1,1,1,1,1,1,1,1
Pervious Area Soil Storage Capacity (mm),120,500,500,500,500,500,500,120,500,500
Pervious Area Soil Initial Storage (% of Capacity),10,10,10,10,10,10,10,10,10,10
Groundwater Initial Depth (mm),50,50,50,50,50,50,50,50,50,50
Groundwater Daily Recharge Rate (%),25,28,28,28,28,28,28,25,28,28
Groundwater Daily Baseflow Rate (%),3,27,27,27,27,27,27,3,27,27
Groundwater Daily Deep Seepage Rate (%),0,0,0,0,0,0,0,0,0,0
Stormflow Total Suspended Solids Mean (log mg/L),1.9,1.3,1.3,1.3,1.3,1.3,1.3,1.9,2.18,2.18
Stormflow Total Suspended Solids Standard Deviation (log
mg/L),0.2,0.39,0.39,0.39,0.39,0.39,0.39,0.2,0.39,0.39
Stormflow Total Suspended Solids Estimation
Method,Stochastic,Stochastic,Stochastic,Stochastic,Stochastic,Stochastic,Stochastic,Stocha
stic,Stochastic,Stochastic
Stormflow Total Suspended Solids Serial Correlation,0,0,0,0,0,0,0,0,0,0
Stormflow Total Phosphorus Mean (log mg/L),-1.1,-0.89,-0.89,-0.89,-0.89,-0.89,-0.89,-1.1,-
0.47,-0.47
Stormflow Total Phosphorus Standard Deviation (log
mg/L),0.22,0.31,0.31,0.31,0.31,0.31,0.31,0.22,0.31,0.31
Stormflow Total Phosphorus Estimation
Method,Stochastic,Stochastic,Stochastic,Stochastic,Stochastic,Stochastic,Stochastic,Stocha
stic,Stochastic,Stochastic
Stormflow Total Phosphorus Serial Correlation,0,0,0,0,0,0,0,0,0,0
Stormflow Total Nitrogen Mean (log mg/L),-0.075,0.26,0.26,0.26,0.26,0.26,0.26,-
0.075,0.26,0.26
Stormflow Total Nitrogen Standard Deviation (log
mg/L),0.24,0.23,0.23,0.23,0.23,0.23,0.23,0.24,0.23,0.23
Stormflow Total Nitrogen Estimation
Method,Stochastic,Stochastic,Stochastic,Stochastic,Stochastic,Stochastic,Stochastic,Stocha
stic,Stochastic,Stochastic
Stormflow Total Nitrogen Serial Correlation,0,0,0,0,0,0,0,0,0,0
Baseflow Total Suspended Solids Mean (log mg/L),0.51,0,0,0,0,0,0,0.51,1,1
Baseflow Total Suspended Solids Standard Deviation (log
mg/L),0.28,0,0,0,0,0,0,0.28,0.34,0.34
Baseflow Total Suspended Solids Estimation
Method,Stochastic,Stochastic,Stochastic,Stochastic,Stochastic,Stochastic,Stochastic,Stocha
stic,Stochastic,Stochastic
Baseflow Total Suspended Solids Serial Correlation,0,0,0,0,0,0,0,0,0,0
Baseflow Total Phosphorus Mean (log mg/L),-1.79,0,0,0,0,0,0,-1.79,-0.97,-0.97
Baseflow Total Phosphorus Standard Deviation (log mg/L),0.28,0,0,0,0,0,0,0.28,0.31,0.31
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Baseflow Total Phosphorus Estimation
Method,Stochastic,Stochastic,Stochastic,Stochastic,Stochastic,Stochastic,Stochastic,Stocha
stic,Stochastic,Stochastic
Baseflow Total Phosphorus Serial Correlation,0,0,0,0,0,0,0,0,0,0
Baseflow Total Nitrogen Mean (log mg/L),-0.59,0,0,0,0,0,0,-0.59,0.2,0.2
Baseflow Total Nitrogen Standard Deviation (log mg/L),0.22,0,0,0,0,0,0,0.22,0.2,0.2
Baseflow Total Nitrogen Estimation
Method,Stochastic,Stochastic,Stochastic,Stochastic,Stochastic,Stochastic,Stochastic,Stocha
stic,Stochastic,Stochastic
Baseflow Total Nitrogen Serial Correlation,0,0,0,0,0,0,0,0,0,0
OUT - Mean Annual Flow
(ML/yr),2.90,0.733,0.249,0.205,0.308,0.469,0.103,1.67,0.339,0.542
OUT - TSS Mean Annual Load (kg/yr),164,22.2,7.51,6.15,9.12,13.8,3.07,95.1,51.3,123
OUT - TP Mean Annual Load (kg/yr),0.188,0.121,41.5E-3,34.3E-3,51.8E-3,76.2E-3,16.8E-
3,0.107,0.111,0.236
OUT - TN Mean Annual Load
(kg/yr),2.09,1.54,0.522,0.432,0.642,0.985,0.213,1.22,0.661,1.14
OUT - Gross Pollutant Mean Annual Load
(kg/yr),0.00,16.9,5.76,4.75,7.12,10.8,2.37,0.00,0.00,12.5
Rain In
(ML/yr),8.91062,0.79559,0.270501,0.222765,0.334148,0.509179,0.111383,5.13951,0.95470
8,0.588737
ET Loss
(ML/yr),5.96828,0.0629535,0.0214045,0.0176266,0.0264403,0.0402895,0.00881327,3.4424
3,0.613075,0.046585
Deep Seepage Loss (ML/yr),0,0,0,0,0,0,0,0,0,0
Baseflow Out (ML/yr),1.09342,0,0,0,0,0,0,0.630668,0.127057,0
Imp. Stormflow Out
(ML/yr),0,0.732638,0.249097,0.205139,0.307708,0.468889,0.102569,0,0,0.542153
Perv. Stormflow Out (ML/yr),1.80969,0,0,0,0,0,0,1.0438,0.211814,0
Total Stormflow Out
(ML/yr),1.80969,0.732638,0.249097,0.205139,0.307708,0.468889,0.102569,1.0438,0.21181
4,0.542153
Total Outflow
(ML/yr),2.90311,0.732638,0.249097,0.205139,0.307708,0.468889,0.102569,1.67447,0.3388
71,0.542153
Change in Soil Storage (ML/yr),0.0392376,0,0,0,0,0,0,0.0226317,0.00276027,0
TSS Baseflow Out (ML/yr),4.34491,0,0,0,0,0,0,2.50974,1.72122,0
TSS Total Stormflow Out
(ML/yr),159.931,22.1814,7.50561,6.15266,9.12086,13.7974,3.0686,92.5662,49.5435,122.60
3
TSS Total Outflow
(ML/yr),164.276,22.1814,7.50561,6.15266,9.12086,13.7974,3.0686,95.076,51.2648,122.603
TP Baseflow Out (ML/yr),0.0218037,0,0,0,0,0,0,0.0125755,0.0175416,0
TP Total Stormflow Out
(ML/yr),0.166549,0.120962,0.0415425,0.0343147,0.0518497,0.0761971,0.0167506,0.09443
63,0.0933642,0.235955
TP Total Outflow
(ML/yr),0.188353,0.120962,0.0415425,0.0343147,0.0518497,0.0761971,0.0167506,0.10701
2,0.110906,0.235955
TN Baseflow Out (ML/yr),0.320177,0,0,0,0,0,0,0.184142,0.223599,0
TN Total Stormflow Out
(ML/yr),1.76716,1.54178,0.521941,0.431928,0.641761,0.985447,0.213405,1.03847,0.43762
4,1.135
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Noosa Council documents
Bligh Tanner Consulting Engineers
Noosa Flexi Learning Centre Stormwater Management Plan
August 2012
TN Total Outflow
(ML/yr),2.08733,1.54178,0.521941,0.431928,0.641761,0.985447,0.213405,1.22261,0.66122
3,1.135
GP Total Outflow (ML/yr),0,16.9487,5.76257,4.74564,7.11847,10.8472,2.37282,0,0,12.5421
No Imported Data Source nodes
USTM treatment nodes
Location,Tanks,Infiltration,Infiltration,Permeable Paving
ID,5,6,7,16
Node
Type,RainWaterTankNode,InfiltrationSystemNodeV4,InfiltrationSystemNodeV4,MediaFiltrati
onNode
Lo-flow bypass rate (cum/sec),0,0,0,0
Hi-flow bypass rate (cum/sec),100,100,100,100
Inlet pond volume,0, , ,
Area (sqm),10,200,200,92.5
Extended detention depth (m),0.1,0.1,0.1,0
Permanent Pool Volume (cubic metres),20, , ,
Proportion vegetated,0, , ,
Equivalent Pipe Diameter (mm),150, , ,
Overflow weir width (m),10,50,50,20
Notional Detention Time (hrs),16.8E-3, , ,
Orifice Discharge Coefficient,0.6, , ,
Weir Coefficient,1.7,1.7,1.7,1.7
Number of CSTR Cells,2,1,1,3
Total Suspended Solids - k (m/yr),400,400,400,8000
Total Suspended Solids - C* (mg/L),12,12,12,20
Total Suspended Solids - C** (mg/L),12,12,12,
Total Phosphorus - k (m/yr),300,300,300,6000
Total Phosphorus - C* (mg/L),0.13,0.09,0.09,0.13
Total Phosphorus - C** (mg/L),0.13,0.09,0.09,
Total Nitrogen - k (m/yr),40,40,40,500
Total Nitrogen - C* (mg/L),1.4,1,1,1.4
Total Nitrogen - C** (mg/L),1.4,1,1,
Threshold Hydraulic Loading for C** (m/yr),3500,3500,3500,
Horizontal Flow Coefficient, ,3,3,
Extraction for Re-use,On,Off,Off,Off
Annual Re-use Demand - scaled by daily PET (ML),0, , ,
Annual Re-use Demand - scaled by daily PET - Rain (ML),0.384, , ,
Constant Daily Re-use Demand (kL),0.94, , ,
User-defined Annual Re-use Demand (ML),0, , ,
Percentage of User-defined Annual Re-use Demand Jan,8.33333333333333, , ,
Percentage of User-defined Annual Re-use Demand Feb,8.33333333333333, , ,
Percentage of User-defined Annual Re-use Demand Mar,8.33333333333333, , ,
Percentage of User-defined Annual Re-use Demand Apr,8.33333333333333, , ,
Percentage of User-defined Annual Re-use Demand May,8.33333333333333, , ,
Percentage of User-defined Annual Re-use Demand Jun,8.33333333333333, , ,
Percentage of User-defined Annual Re-use Demand Jul,8.33333333333333, , ,
Percentage of User-defined Annual Re-use Demand Aug,8.33333333333333, , ,
Percentage of User-defined Annual Re-use Demand Sep,8.33333333333333, , ,
Percentage of User-defined Annual Re-use Demand Oct,8.33333333333333, , ,
Percentage of User-defined Annual Re-use Demand Nov,8.33333333333333, , ,
Percentage of User-defined Annual Re-use Demand Dec,8.33333333333333, , ,
User-defined Re-use File, , , ,
Filter area (sqm), ,200,200,92.5
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Noosa Council documents
Bligh Tanner Consulting Engineers
Noosa Flexi Learning Centre Stormwater Management Plan
August 2012
Filter perimeter (m), ,400,400,
Filter depth (m), ,0.3,0.3,0.2
Filter Median Particle Diameter (mm), , , ,1
Saturated Hydraulic Conductivity (mm/hr), , , ,180
Infiltration Media Porosity, ,0.35,0.35,0.3
Length (m), , , ,
Bed slope, , , ,
Base Width (m), , , ,
Top width (m), , , ,
Vegetation height (m), , , ,
Vegetation Type, , , ,
Total Nitrogen Content in Filter (mg/kg), , , ,
Orthophosphate Content in Filter (mg/kg), , , ,
Is Base Lined?, , , ,
Is Underdrain Present?, , , ,
Is Submerged Zone Present?, , , ,
Submerged Zone Depth (m), , , ,
B for Media Soil Texture,-9999,-9999,-9999,-9999
Proportion of upstream impervious area treated, , , ,
Exfiltration Rate (mm/hr),0,180,180,180
Evap Loss as proportion of PET,0,0.25,0.25,
Depth in metres below the drain pipe, , , ,0
TSS A Coefficient, , , ,0.52
TSS B Coefficient, , , ,-0.39
TP A Coefficient, , , ,1.28
TP B Coefficient, , , ,-0.19
TN A Coefficient, , , ,1.67
TN B Coefficient, , , ,-0.09
Sfc, , , ,
S*, , , ,
Sw, , , ,
Sh, , , ,
Emax (m/day), , , ,
Ew (m/day), , , ,
IN - Mean Annual Flow (ML/yr),1.25,0.821,0.801,0.542
IN - TSS Mean Annual Load (kg/yr),37.5,24.4,19.9,123
IN - TP Mean Annual Load (kg/yr),0.207,0.134,0.126,0.236
IN - TN Mean Annual Load (kg/yr),2.62,1.72,1.65,1.14
IN - Gross Pollutant Mean Annual Load (kg/yr),28.8,19.0,0.00,12.5
OUT - Mean Annual Flow (ML/yr),0.801,0.00,0.00,6.59E-3
OUT - TSS Mean Annual Load (kg/yr),19.9,0.00,0.00,0.251
OUT - TP Mean Annual Load (kg/yr),0.126,0.00,0.00,1.02E-3
OUT - TN Mean Annual Load (kg/yr),1.65,0.00,0.00,9.44E-3
OUT - Gross Pollutant Mean Annual Load (kg/yr),0.00,0.00,0.00,0.00
Flow In (ML/yr),1.24558,0.820557,0.800885,0.542229
ET Loss (ML/yr),0,0,0,0
Infiltration Loss (ML/yr),0,0.820545,0.800875,0.535277
Low Flow Bypass Out (ML/yr),0,0,0,0
High Flow Bypass Out (ML/yr),0,0,0,0
Orifice / Filter Out (ML/yr),0.788226,0,0,0.00644382
Weir Out (ML/yr),0.0126625,0,0,0.000146364
Transfer Function Out (ML/yr),0,0,0,0
Reuse Supplied (ML/yr),0.443419,0,0,0
Reuse Requested (ML/yr),0.724222,0,0,0
% Reuse Demand Met,61.227,0,0,0
% Load Reduction,35.7014,100,100,98.7846
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Noosa Council documents
Bligh Tanner Consulting Engineers
Noosa Flexi Learning Centre Stormwater Management Plan
August 2012
TSS Flow In (kg/yr),37.4551,24.3717,19.9417,122.603
TSS ET Loss (kg/yr),0,0,0,0
TSS Infiltration Loss (kg/yr),0,12.6527,13.0389,10.7399
TSS Low Flow Bypass Out (kg/yr),0,0,0,0
TSS High Flow Bypass Out (kg/yr),0,0,0,0
TSS Orifice / Filter Out (kg/yr),19.606,0,0,0.244347
TSS Weir Out (kg/yr),0.335678,0,0,0.006478
TSS Transfer Function Out (kg/yr),0,0,0,0
TSS Reuse Supplied (kg/yr),6.52001,0,0,0
TSS Reuse Requested (kg/yr),0,0,0,0
TSS % Reuse Demand Met,0,0,0,0
TSS % Load Reduction,46.7584,100,100,99.7954
TP Flow In (kg/yr),0.207126,0.13449,0.125607,0.235956
TP ET Loss (kg/yr),0,0,0,0
TP Infiltration Loss (kg/yr),0,0.0878825,0.0923026,0.0696649
TP Low Flow Bypass Out (kg/yr),0,0,0,0
TP High Flow Bypass Out (kg/yr),0,0,0,0
TP Orifice / Filter Out (kg/yr),0.123547,0,0,0.000999727
TP Weir Out (kg/yr),0.00206,0,0,2.11818E-5
TP Transfer Function Out (kg/yr),0,0,0,0
TP Reuse Supplied (kg/yr),0.0609768,0,0,0
TP Reuse Requested (kg/yr),0,0,0,0
TP % Reuse Demand Met,0,0,0,0
TP % Load Reduction,39.3571,100,100,99.5673
TN Flow In (kg/yr),2.61547,1.7208,1.64523,1.135
TN ET Loss (kg/yr),0,0,0,0
TN Infiltration Loss (kg/yr),0,1.40174,1.44888,0.790341
TN Low Flow Bypass Out (kg/yr),0,0,0,0
TN High Flow Bypass Out (kg/yr),0,0,0,0
TN Orifice / Filter Out (kg/yr),1.61898,0,0,0.00909755
TN Weir Out (kg/yr),0.0262464,0,0,0.000343
TN Transfer Function Out (kg/yr),0,0,0,0
TN Reuse Supplied (kg/yr),0.833146,0,0,0
TN Reuse Requested (kg/yr),0,0,0,0
TN % Reuse Demand Met,0,0,0,0
TN % Load Reduction,37.0962,100,100,99.1682
GP Flow In (kg/yr),28.8132,18.9831,0,12.5424
GP ET Loss (kg/yr),0,0,0,0
GP Infiltration Loss (kg/yr),0,0,0,0
GP Low Flow Bypass Out (kg/yr),0,0,0,0
GP High Flow Bypass Out (kg/yr),0,0,0,0
GP Orifice / Filter Out (kg/yr),0,0,0,0
GP Weir Out (kg/yr),0,0,0,0
GP Transfer Function Out (kg/yr),0,0,0,0
GP Reuse Supplied (kg/yr),0,0,0,0
GP Reuse Requested (kg/yr),0,0,0,0
GP % Reuse Demand Met,0,0,0,0
GP % Load Reduction,100,100,100,100
No Generic treatment nodes
Other nodes
Location,Pre-Development Node,Post-Development Node
ID,2,12
Node Type,PreDevelopmentNode,PostDevelopmentNode
IN - Mean Annual Flow (ML/yr),2.90,2.02
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Noosa Council documents
Bligh Tanner Consulting Engineers
Noosa Flexi Learning Centre Stormwater Management Plan
August 2012
IN - TSS Mean Annual Load (kg/yr),164,147
IN - TP Mean Annual Load (kg/yr),0.188,0.219
IN - TN Mean Annual Load (kg/yr),2.09,1.89
IN - Gross Pollutant Mean Annual Load (kg/yr),0.00,0.00
OUT - Mean Annual Flow (ML/yr),0.00,0.00
OUT - TSS Mean Annual Load (kg/yr),0.00,0.00
OUT - TP Mean Annual Load (kg/yr),0.00,0.00
OUT - TN Mean Annual Load (kg/yr),0.00,0.00
OUT - Gross Pollutant Mean Annual Load (kg/yr),0.00,0.00
Links
Location,Drainage Link,Drainage Link,Drainage Link,Drainage Link,Drainage Link,Drainage
Link,Drainage Link,Drainage Link,Drainage Link,Drainage Link,Drainage Link,Drainage
Link,Drainage Link,Drainage Link
Source node ID,1,3,4,5,10,9,8,11,7,6,13,14,15,16
Target node ID,2,5,6,7,6,5,5,6,12,12,12,12,16,12
Muskingum-Cunge Routing,Not Routed,Not Routed,Not Routed,Not Routed,Not Routed,Not
Routed,Not Routed,Not Routed,Not Routed,Not Routed,Not Routed,Not Routed,Not
Routed,Not Routed
Muskingum K, , , , , , , , , , , , , ,
Muskingum theta, , , , , , , , , , , , , ,
IN - Mean Annual Flow
(ML/yr),2.90,0.733,0.249,0.801,0.469,0.308,0.205,0.103,0.00,0.00,1.67,0.339,0.542,6.59E-3
IN - TSS Mean Annual Load
(kg/yr),164,22.2,7.51,19.9,13.8,9.12,6.15,3.07,0.00,0.00,95.1,51.3,123,0.251
IN - TP Mean Annual Load (kg/yr),0.188,0.121,41.5E-3,0.126,76.2E-3,51.8E-3,34.3E-
3,16.8E-3,0.00,0.00,0.107,0.111,0.236,1.02E-3
IN - TN Mean Annual Load
(kg/yr),2.09,1.54,0.522,1.65,0.985,0.642,0.432,0.213,0.00,0.00,1.22,0.661,1.14,9.44E-3
IN - Gross Pollutant Mean Annual Load
(kg/yr),0.00,16.9,5.76,0.00,10.8,7.12,4.75,2.37,0.00,0.00,0.00,0.00,12.5,0.00
OUT - Mean Annual Flow
(ML/yr),2.90,0.733,0.249,0.801,0.469,0.308,0.205,0.103,0.00,0.00,1.67,0.339,0.542,6.59E-3
OUT - TSS Mean Annual Load
(kg/yr),164,22.2,7.51,19.9,13.8,9.12,6.15,3.07,0.00,0.00,95.1,51.3,123,0.251
OUT - TP Mean Annual Load (kg/yr),0.188,0.121,41.5E-3,0.126,76.2E-3,51.8E-3,34.3E-
3,16.8E-3,0.00,0.00,0.107,0.111,0.236,1.02E-3
OUT - TN Mean Annual Load
(kg/yr),2.09,1.54,0.522,1.65,0.985,0.642,0.432,0.213,0.00,0.00,1.22,0.661,1.14,9.44E-3
OUT - Gross Pollutant Mean Annual Load
(kg/yr),0.00,16.9,5.76,0.00,10.8,7.12,4.75,2.37,0.00,0.00,0.00,0.00,12.5,0.00
Print Date: 2 March 2020, 2:19 PM
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