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Attachment C - Stormwater report
Attached to the e-mail MCU14/0039 Response to information request Stormwater & Riparian reports email 2 of 3.
Stormwater Management Plan - 305 Lake Macdonald Drive Lot 1 on SP108094 CLIENT: D’VINERIPE STATUS: FINAL REPORT REPORT NUMBER: SC15-0070\R003370 ISSUE DATE: JUNE 2015 O2 ENVIRONMENTAL PTY LTD PO Box 199 Peregian Beach QLD 4573 ABN 79 136 340 924 www.o-2.com.au
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Important Note This report and all its components (including images, audio, video, text) is copyright. Apart from fair dealing for the purposes of private study, research, criticism or review as permitted under the Copyright Act 1968, no part may be reproduced, copied, transmitted in any form or by any means (electronic, mechanical or graphic) without the prior written permission of the O2 Environmental Pty Ltd. This report has been prepared for the sole use of the D’VINERIPE (herein, ‘the client’), for a specific site (herein ‘the site’, the specific purpose specified in Section 1 of this report (herein ‘the purpose’). This report is strictly limited for use by the client, to the purpose and site and may not be used for any other purposes. Third parties, excluding regulatory agencies assessing an application in relation to the purpose, may not rely on this report. O2 Environmental Pty Ltd waives all liability to any third party loss, damage, liability or claim arising out of or incidental to a third party publishing, using or relying on the facts, content, opinions or subject matter contained in this report. O2 Environmental Pty Ltd waives all responsibility for loss or damage where the accuracy and effectiveness of information provided by the Client or other third parties was inaccurate or not up to date and was relied upon, wholly or in part in reporting. Stormwater Management Plan – Lot 1 on SP108094, 305 Lake Macdonald Drive Page ii D’VINERIPE R003370
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O2 Environmental Pty Ltd t/as O2 ABN 79 136 340 924
Originating Office – Sunshine Coast
Unit 7, 8 Grebe St, Peregian Beach QLD 4573
PO Box 199 Peregian Beach QLD 4573
T 61 7 5448 3288 | F 61 7 5302 6680 | [email protected]
Version Register
Version Status Author Reviewer Change from Authorised for Release
Previous Version
Signature Date
- FINAL S Chamberlain K Robson n/a 26-6-15
RPEQ (15545) RPEQ (15954)
Transmission Register
Controlled copies of this document are issued to the persons/companies listed below. Any copy of this
report held by persons not listed in this register is deemed uncontrolled. Updated versions of this report if
issued will be released to all parties listed below via the email address listed.
Name Email Address
Byron Mason [email protected]
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Table of Contents
1. Introduction 6
1.1. Objective 6
2. Site Description 7
2.1. Land use 7
2.2. Topography 7
3. Land Use and Nutrient Loads 8
3.1. Historical Land Use 8
3.2. Proposed Land Use 8
4. MUSIC Modelling 10
4.1. Rainfall Data 10
4.2. Evapotranspiration Data 10
4.3. Regional Modelling 11
4.3.1. Model Objectives 11
4.3.2. Catchment Description 11
4.3.3. Rainfall Runoff Parameters 14
4.3.4. Pollutant Export Parameters 14
4.3.5. Regional MUSIC Model Layout 15
4.3.6. Modelling Results 15
4.4. Site Specific MUSIC Model 16
4.4.1. Model Objectives 16
4.4.2. Pollutant Export Parameters 16
4.4.3. Treatment Options 18
4.4.4. MUSIC Results 19
5. Flooding and Water Quantity Management 21
5.1. Introduction 21
5.2. Catchments 21
5.3. Rainfall Intensities 21
5.4. Hydrologic Modelling 22
5.4.1. Rainfall Losses 22
5.4.2. Roughness Coefficients 22
5.5. Peak Flow Rate 22
5.6. Regional Flooding 24
5.7. Mitigation Measures 25
6. Erosion and Sediment Control (ESC) 26
6.1. Erosion Risk Assessment 26
6.2. Erosion Control and Rehabilitation 27
6.3. Drainage Control 28
6.3.1. Design Standard 28
6.4. Sediment Control 28
6.4.1. Design Standard 28
6.5. Roles and Responsibilities 29
6.6. Corrective and Preventative Action 29
7. Summary and Recommendations 31
8. Reference List 33
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Figures
Figure 1 - Site Location 6
Figure 2 – Pre-Development Topography 7
Figure 3 – Hydroponic Tomato Setup 8
Figure 4 – Drip Irrigation System 8
Figure 5 - Catchment Plan. 11
Figure 6 - Land Use Mapping for Catchment (Source QLUMP). 12
Figure 7 - MUSIC Model Layout. 15
Figure 8 – Pre- vs Un-Mitigated Post-Development Hydrographs – 1% AEP Event. 23
Figure 9 – A Comparison of the Runoff Volumes for the Pre- (left) and Post-Development (right) Scenarios. 24
Figure 10 - 1% AEP Hydrographs - Site vs Regional. 25
Tables
Table 1 – Meteorological and Rainfall Runoff Data. 10
Table 2 – MUSIC Monthly Evapotranspiration Data (mm). 10
Table 3 – Summary of Landuse and Fraction Impervious. 13
Table 4 – Rainfall-runoff Parameters for MUSIC Source Nodes. 14
Table 5 – Pollutant Export Parameters for Urban, Industrial, Mining and Waste, Forest and Agriculture Source Nodes
(extracted from Table 3.9, Water by Design, 2010). 14
Table 6 – Results from MUSIC Modelling. 15
Table 7 – Pollutant export parameters for Roof source nodes (extracted from Table 3.8, Water by Design, 2010). 16
Table 8 – Water Quality Objectives. 16
Table 9 – Bioretention System Input Parameters 18
Table 10 – Media Filtration Input Parameters. 18
Table 11 – Infiltration System Input Parameters. 19
Table 12 – MUSIC Modelling Results – Receiving Node 20
Table 13 – IFD Data Applied to Hydrologic Assessment 21
Table 14 – Performance of Mitigation Measures – Peak Flow Rate at LPD 23
Table 15 – Erosion Risk Categories 26
Table 16 – Estimated Soil Loss and Risk Categorisation for Varied Slope Lengths and Grades 27
Table 17 – Stabilisation Materials 27
Table 18 – Sediment Control Standard based on Soil Loss Rate 28
Table 19 – Roles and Responsibilities 29
Appendices
Appendix A Site Layout (Martoo Drawing Number) A
Appendix B Assessment of Historic Nutrient Loads B
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1. Introduction O2 Environment + Engineering (O2) has been commissioned by D’VINERIPE to develop a Stormwater Management Plan (SMP) for the tomato farm located at Lot 1 on SP108094, 305 Lake Macdonald Drive, Qld. The purpose of this document is to clearly present the SMP specifically designed to address issues raised in Show Cause Notice COM14/0133, and Information Request 01569 issued by Noosa Council. The regional location of the project area is presented in Figure 1. 1.1. Objective The objective of this report is to address Points 8 and 9 of Show Cause Notice issued by Noosa Council on April 29, 2015 and Points 3 and 4 of Information Request (IR) issued by Noosa Council on June 25, 2014. The IR, application number: MCU14/0039, is in response to the proposal for a development permit for Material Change of Use – Cultivation Type 2 (Intensive Greenhouses). Figure 1 - Site Location Stormwater Management Plan – Lot 1 on SP108094, 305 Lake Macdonald Drive Page 6 D’VINERIPE R003370
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2. Site Description This section describes the current land use and topography within and adjacent to the Project area. 2.1. Land use The site is currently being used to produce hydroponically grown tomatoes, and contains a greenhouse with a roof area of approximately 2 ha (the subject of this application). The site layout is included as Appendix A. There are also two smaller sheds used for equipment and chemical storage located to the south of the greenhouse. The area surrounding the site is relatively undeveloped, providing a mixture of land uses. The land to the north and west is largely rural with few houses dominated by forests and vegetation. There appears to be a quarry or cement works to the immediate west of the site. There are private residences 1.2 km to the south and the town of Cooroy is located approximately 3.7 km to the south west. Lake Macdonald and associated rural residential housing lie immediately to the east. The line of residential dwellings extends north to south approximately 1.3 km. 2.2. Topography The site is generally flat and is bounded on the east and west sides by grassed areas and vegetated creeks. The topography decreases in elevation moving to the east and west of the site. The greenhouse is located at the high point on the site, at about 136 m Australian Height Datum (AHD). There is approximately a 1 m fall across the length of the site moving to the north towards the adjacent watercourse. The approximate slope of the northern drainage path is 0.3% – 0.5%. Refer to Figure 2 for the existing contours and indicative flow directions. Figure 2 – Pre-Development Topography Stormwater Management Plan – Lot 1 on SP108094, 305 Lake Macdonald Drive Page 7 D’VINERIPE R003370
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3. Land Use and Nutrient Loads
3.1. Historical Land Use
The site was previously approved and used as a turf farm for approximately 30 years where, due to the
activities large quantities of fertilizers and pesticides were employed. Calculations using data provided to
O2 Environment + Engineering by the client show Total Nitrogen and Phosphorus applied at the site (in the
form of fertilizer and pesticide) to be:
Total Nitrogen - 9.95 tonnes per year, and
Total Phosphorus - 3.34 tonnes per year
Further details in relation to the assumptions made and calculations undertaken to determine the nutrient
loads are contained in Appendix B.
3.2. Proposed Land Use
The proposed development seeks a Development Permit for a Material Change of Use for a Cultivation
Type 2 Intensive for crops within a 140 x 144 m greenhouse on the site. The greenhouse will be used to
grow tomatoes hydroponically. The current arrangement contains rows of tomato plants in “growbags”, as
shown in Figure 3. Watering of the plants is undertaken using a drip irrigation system as shown in Figure 4.
Irrigation is typically undertaken at a rate of approximately 4L/m² per day.
Each row of growbags and plants are located in lined trenches, with an ag. pipe collection system below the
growbags to collect any excess water. The ag. pipe conveys excess runoff to a 300mm diameter pipe which
conveys runoff out of the greenhouse to a sump, before returning it to the mixing tank for re-use in the
irrigation system. Therefore, the irrigation system is a closed loop system, with any water not utilised by
the plants being recycled. Therefore, there is no chance that unused effluent associated with the
greenhouse irrigation system can either leach down to groundwater then migrate to the adjoining creek
system.
Figure 3 – Hydroponic Tomato Setup Figure 4 – Drip Irrigation System
Based on the information provided by the operators of the greenhouse, current fertilizer and pesticide use
of the tomato farm are substantially less than the turf farm, being approximately:
Total Nitrogen - 3.84 tonnes per year, and
Total Phosphorus – 0.52 tonnes per year.
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In addition to the reduced nutrient loads now being applied at the site, the operators have the ability
to remove the nutrient rich irrigation water from the greenhouse. Irrigation can be halted, and the
runoff pumped back to the holding tank. Fresh water can then be used to flush the growbags and again
pumped back to a holding tank. This can be undertaken within a period of approximately 3 – 4 hours
and therefore allows the operators to extract the nutrient rich runoff in the event of a major flood
event.
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4. MUSIC Modelling
The Model for Urban Stormwater Improvement Conceptualisation (MUSIC) Version 6 was used in
combination with MUSIC Modelling Guidelines Version 1.0 (2010) to evaluate expected pollutant loads
Two models have been developed:
1. Regional MUSIC Model – used to assess the likely pollutant loads generated within the catchment,
and
2. Site Specific MUSIC Model – used to assess the pollutant loads from the greenhouse roof area and
the required treatment measures to achieve the South East Queensland water quality objectives.
4.1. Rainfall Data
Stormwater runoff is simulated using historical rainfall data. Data from Nambour DPI, station number
40282, has been used from 1989 - 1998 to represent the climatic period which the MUSIC model is based. A
summary of the meteorological parameters used to simulate climate behaviour are presented in Table 1.
Table 1 - Meteorological and Rainfall Runoff Data.
Input Data Used in Modelling
Rainfall station 40282 – Nambour DPI
Time step 6 minute
Modelling period 1/1/1989 -31/12/1998
Mean annual rainfall (mm) 1,527
Annual evapotranspiration (mm) 1,675
Rainfall runoff parameters Varies (refer Section 4.3.4 & Section 4.4.2)
Pollutant export parameters Varies (refer Section 4.3.4 & Section 4.4.2)
Rainfall runoff and pollutant export parameters included as model inputs are in line with the MUSIC
Modelling Guidelines Version 1.0 (2010).
4.2. Evapotranspiration Data
Nambour DPI evapotranspiration data was extracted from Table 3.1 of the MUSIC Modelling Guidelines
Version 1.0 (2010), as detailed in Table 2.
Table 2 - MUSIC Monthly Evapotranspiration Data (mm).
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
204 166 169 125 89 76 78 93 121 168 187 199
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4.3. Regional Modelling 4.3.1. Model Objectives An assessment of the total catchment conveying runoff to the watercourse that bounds the site has been undertaken to determine the likely pollutant loads generated within the catchment. 4.3.2. Catchment Description Mapping of the catchment reveals the total area contributing runoff to the waterway bounding the site is approximately 3600 ha, as illustrated by Figure 5. Further assessment of the catchment has been undertaken using the Queensland Land Use Mapping Program (QLUMP). QLUMP has updated land use mapping in the South-East Queensland Natural Resource Management Region to 2011 or later. Mapping has been compiled at the catchment level, to assess the land uses within the catchment and determine the areas associated with each designated land use. A copy of the QLUMP mapping extract for this catchment and associated land uses is included as Figure 6. Figure 5 - Catchment Plan. Stormwater Management Plan – Lot 1 on SP108094, 305 Lake Macdonald Drive Page 11 D’VINERIPE R003370
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Figure 6 - Land Use Mapping for Catchment (Source QLUMP). Stormwater Management Plan – Lot 1 on SP108094, 305 Lake Macdonald Drive Page 12 D’VINERIPE R003370
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Based on the land uses provided by QLUMP, the catchments have been classified as Agricultural, Forest,
Road, Urban or Mining and waste (user defined) to enable them to be modelled in MUSIC. A summary of
the catchment areas applied to the MUSIC Model is included as Table 3.
Table 3 - Summary of Landuse and Fraction Impervious.
No Area (ha) QLUMP Designation MUSIC Land use Fraction Impervious (%)
1 31 Cropping - Sugar Agriculture 0
Grazing native
2 942 Agriculture 0
vegetation
Intensive animal
3 58 production (horse and Agriculture 5
aquaculture)
4 13 Intensive horticulture Agriculture 0
Irrigated perennial
5 24 Agriculture 0
horticulture
Manufacturing and
6 30 Industrial 80
industrial
7 39 Mining Mining and Waste 10
8 85 Nature conservation Forest 0
9 112 Other minimal use Urban 5
10 2 Perennial horticulture Agriculture 0
11 31 Plantation forestry Forest 0
12 358 Production forestry Forest 0
13 2 Reservoir/dam Urban 0
14 1860 Residential Urban 60
15 65 Services Urban 90
Transport and
16 8 Road 50
communication
Waste treatment and
17 14 Mining and Waste 10
disposal
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4.3.3. Rainfall Runoff Parameters
The rainfall runoff export parameters have been adopted from Table 3.7 of the MUSIC Modelling Guidelines
Version 1.0, as summarised in Table 5.
Table 4 - Rainfall-runoff Parameters for MUSIC Source Nodes.
Parameter Forest Urban Transportation Industrial Agriculture
Rainfall threshold (mm) 1 1 1 1 1
Soil storage capacity (mm) 120 500 500 18 98
Initial storage (% capacity 10 10 10 10 10
Field capacity (mm) 80 200 200 80 80
Infiltration capacity 200 211 211 243 84
coefficient a
Infiltration capacity 1.0 5.0 5.0 0.6 3.3
exponent b
Initial depth (mm) 50 50 50 50 50
Daily recharge rate (%) 25 28 28 0.0 100
Daily baseflow rate (%) 3 27 27 31 22
Daily deep seepage rate (%) 0.0 0.0 0.0 0.0 0
4.3.4. Pollutant Export Parameters
The pollutant export parameters have been adopted from Table 3.9 of the MUSIC Modelling Guidelines
Version 1.0, as summarised in Table 5.
Table 5 - Pollutant Export Parameters for Urban, Industrial, Mining and Waste, Forest and Agriculture Source Nodes (extracted
from Table 3.9, Water by Design, 2010).
10 10 10
TSS log values TP log values TN log values
Land Use Flow Type
Mean St. dev. Mean St. dev. Mean St. dev.
Baseflow 1.00 0.34 -0.97 0.31 0.20 0.20
Urban
residential
Stormflow 2.18 0.39 -0.47 0.32 0.26 0.23
Baseflow 0.78 0.45 -1.11 0.48 0.14 0.20
Industrial
Stormflow 1.92 0.44 -0.59 0.36 0.25 0.32
Baseflow 1.03 0.55 -1.07 0.46 0.38 0.27
Mining and
Waste
Stormflow 3.72 0.34 -0.03 0.27 0.73 0.22
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10 10 10
TSS log values TP log values TN log values
Land Use Flow Type
Mean St. dev. Mean St. dev. Mean St. dev.
Baseflow 0.51 0.28 -1.79 0.28 -0.59 0.22
Forest
Stormflow 1.90 0.20 -1.10 0.22 -0.075 0.24
Baseflow 1.00 0.13 -1.155 0.13 -0.155 0.13
Agriculture
Stormflow 2.477 0.31 -0.495 0.30 0.29 0.26
Baseflow 1.00 0.34 -0.97 0.31 0.20 0.20
Road
Stormflow 2.43 0.39 0.30 0.31 0.26 0.23
4.3.5. Regional MUSIC Model Layout
The MUSIC model produced to analyse the proposed development is shown in Figure 7.
Figure 7 - MUSIC Model Layout.
4.3.6. Modelling Results
The results of the MUSIC analysis for the total catchment are reported in Table 6.
Table 6 – Results from MUSIC Modelling.
Pollutant Pollutant Load
Flow (ML/yr) 29,500
Total Suspended Solids (kg/yr) 8,420,000
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Pollutant Pollutant Load
Total Phosphorus (kg/yr) 11,600
Total Nitrogen (kg/yr) 60,500
Gross Pollutants (kg/yr) 491,000
These results show the average annual flow rate and pollutant loads generated by the (approximately)
3600 ha catchment based on the QLUMP mapping and assumptions described in previous sections of the
report. As detailed in Section 3.2, the tomato farm utilises approximately 3,840 kg/yr of TN and 512 kg/yr of
TP. This represents only 6.3% and 4.4% of the total TN and TP loads respectively. It is important to note that
these values for the tomato farm represent the total nutrient load for the hydroponic operation in a year.
The actual load in the irrigation system at any one time is far less than this and these calculations do not
take into consideration the uptake of nutrients by the plants. Furthermore, as previously discussed, the
operators can flush the system and remove the irrigation water from the greenhouse in the event of a
major storm event. Therefore, the likelihood of any of this water entering the adjacent waterway is
extremely low.
4.4. Site Specific MUSIC Model
4.4.1. Model Objectives
The objective of the MUSIC model is to accurately represent the site and facilitate stormwater quality
management. Stormwater quality management aims to protect the quality of receiving waters by limiting
the quantity of stormwater pollutants discharged to the receiving environment as a result of urban
development.
4.4.2. Pollutant Export Parameters
The pollutant export parameters have been adopted from Table 3.8 of the MUSIC Modelling Guidelines
Version 1.0, as summarised in Table 7.
Table 7 - Pollutant export parameters for Roof source nodes (extracted from Table 3.8, Water by Design, 2010).
10 10 10
Flow Type Pollutant Source TSS log values TP log values TN log values
Mean St. dev. Mean St. dev. Mean St. dev.
Baseflow Roof N/A N/A N/A N/A N/A N/A
Stormflow Roof 1.30 0.39 -0.89 0.31 0.26 0.23
The following water quality objectives have been adopted from the Queensland State Planning Policy’s
Water Quality Code.
Table 8 - Water Quality Objectives.
Minimum reductions in Mean Annual Loads from unmitigated catchment
Total Suspended Solids Total Phosphorus Total Nitrogen Gross Pollutants
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(TSS) (TP) (TN) > 5mm
80% 60% 45% 90%
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4.4.3. Treatment Options
MUSIC modelling has been undertaken to assess the treatment system requirements to achieve the above
water quality objectives. Three treatment systems have been modelled:
1. Bioretention system
2. Media filtration system
3. Infiltration system
4.4.3.1. Bioretention System
The size of the bioretention system is to be reflective of the total catchment area anticipated for treatment.
Evaluation suggests each basin should be constructed at approximately 2% of the contributing area. It has
been determined a bioretention system will be capable of achieving the load based reduction targets
identified in Section 4.4.2. The parameters utilised to analyse the bioretention system are presented in
Table 9.
Table 9 – Bioretention System Input Parameters
Catchment ID Bioretention System Parameters
2
Surface Area (m ) 454.8
Extended Detention Depth (m) 0.3
2
Filter Area (m ) 396.8
Saturated Hydraulic Conductivity (mm/hr) 200
Filter Depth (m) 0.5
4.4.3.2. Media Filtration System
An alternative to a bioretention system is the media filtration system. Runoff is directed to an underground
pit containing filtration media which removes suspended solids and nutrients from the water before
dispersing it into the soil. It has been determined a media filtration system will be capable of achieving a
comparable load based reduction to the same size bioretention system. The parameters utilised to analyse
the media filtration system are presented in Table 10
Table 10 – Media Filtration Input Parameters.
Catchment ID Media Filtration Parameters
Extended Detention Depth (m) 0.3
2
Filter Area (m ) 400
Saturated Hydraulic Conductivity (mm/hr) 200
Filter Depth (m) 0.5
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4.4.3.3. Infiltration System
A stormwater infiltration system holds runoff and allows it soak into the ground. The ponds are open
facilities with grass or sand bases. They can either drain rapidly or act as permanent ponds where water
levels rise and fall with stormwater flows. Generally, infiltration basins are managed like detention ponds
but with greater emphasis on maintaining the ability to infiltrate stormwater. The parameters utilised to
analyse the infiltration system are presented in Table 11.
Table 11 – Infiltration System Input Parameters.
Catchment ID Infiltration System Parameters
2
Pond Surface Area (m ) 450
Extended Detention Depth (m) 0.3
2
Filter Area (m ) 400
Saturated Hydraulic Conductivity (mm/hr) 200
Filter Depth (m) 0.5
4.4.4. MUSIC Results
The results of the MUSIC modelling are presented in Table 12. The bioretention system was sized to
achieve the Best Practice water quality objectives for urban developments. The media filtration system and
infiltration system have been modelled as the same size.
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Table 12 - MUSIC Modelling Results – Receiving Node Bioretention System Reduction (%) Objective (%) TSS 80.3 80 TP 75.9 60 TN 60.3 45 Gross Pollutants 100 90 Media Filtration System Reduction (%) Objective (%) TSS 79.3 80 TP 59.9 60 TN 36.1 45 Gross Pollutants 100 90 Infiltration System Reduction (%) Objective (%) TSS 23.7 80 TP 16.8 60 TN 13.4 45 Gross Pollutants 100 90 The results of this assessment indicate the bioretention system is capable of achieving the water quality objectives. The media filtration system achieves the load based reduction targets for TSS and TP (within +/- 1%). The TN reduction is slightly lower than the water quality objective, but the media filtration system still removes a considerable quantity of TN from the roof runoff and could be constructed for considerably less expense. Stormwater Management Plan – Lot 1 on SP108094, 305 Lake Macdonald Drive Page 20 D’VINERIPE R003370
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5. Flooding and Water Quantity Management 5.1. Introduction Hydrologic and hydraulic modelling has been undertaken of the site to establish the flow regime and peak discharges at the outlet of the site to the north. The modelling has been undertaken in XP-SWMM for both the pre and post development scenarios. The modelling undertaken for this SMP represents the site catchment only, and does not take into consideration the large catchment of which the site forms a part. 5.2. Catchments Due to the flat grades of the site and lack of defined flowpaths, the site has been considered as a single 33.2 ha catchment for the purposes of this modelling 5.3. Rainfall Intensities Intensity Frequency Duration (IFD) data for the site has been derived in accordance with Australian Rainfall and Runoff (ARR) though the use of the AUS-IFD software. The rainfall intensities generated for the site are shown below in Table 13. Table 13- IFD Data Applied to Hydrologic Assessment Duration I1 I2 I5 I10 I20 I50 I100 (mins) (mm/hr) (mm/hr) (mm/hr) (mm/hr) (mm/hr) (mm/hr) (mm/hr) 10 95 121 151 168 192 223 247 15 80 102 127 142 162 188 208 20 70 89 111 124 142 165 183 25 62 80 100 111 127 148 164 30 57 73 91 101 116 135 150 45 45.7 58 73 82 94 110 122 60 38.9 49.8 63 70 80 94 104 90 30.2 38.8 49.4 56 64 75 84 120 25.1 32.4 41.6 47.2 55 65 72 Stormwater Management Plan – Lot 1 on SP108094, 305 Lake Macdonald Drive Page 21 D’VINERIPE R003370
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5.4. Hydrologic Modelling
The XP-SWMM runoff-routing model been has used to estimate design flood discharges within the site. The
catchment node is defined by its pervious (undeveloped) and impervious (developed) area, fraction
impervious and average catchment slope. A fraction impervious of 0% has been applied to the
undeveloped portion and 100% to the developed portion. The net rainfall is routed through the network
after appropriate losses (initial and continuing) and roughness factors are applied, resulting in a surface
runoff hydrograph for each sub-catchment. Hydrologic modelling has been undertaken using the
Laurenson Runoff Routing Method.
5.4.1. Rainfall Losses
Initial Loss (IL) and Continuing Losses (CL) have been applied to the modelling, and again these values have
been varied for the developed (impervious) and developed (pervious) portions of the catchment. The
following loss rates have been applied:
Developed catchment IL = 1mm CL = 0mm/hr; and
Undeveloped catchment IL = 12mm CL = 2mm/hr
5.4.2. Roughness Coefficients
Manning’s roughness coefficients (n values) have been applied to represent the undeveloped and
developed portions of the catchment. XP-SWMM allows a range to be applied to represent the varied
degree of roughness that could be expected within the catchment. The following values have been applied:
Developed catchment n = 0.014 and
Undeveloped catchment n = 0.04.
5.5. Peak Flow Rate
The unsteady state, 1D hydrodynamic model XP-SWMM was used to analyse the peak flow rate of the site.
Flood levels, discharge and velocity can be extracted from the model as functions of time at required
locations.
The key objective of the hydraulic modelling was to demonstrate that the post development peak discharge
from the site for 63% AEP and 1% AEP storm event is less than or equal to the pre development peak
discharge.
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Figure 8 – Pre- vs Un-Mitigated Post-Development Hydrographs – 1% AEP Event.
The peak flow rate from the site for the pre-development case has been assessed and the design
hydrograph for the 1% AEP plotted as Figure 8. To assess the peak flow rate during the post-development,
unmitigated scenario, an additional 2.016 ha (i.e. 140 m x 144 m roof area) of the impervious area was
added to the model. A summary of the pre- and post-development peak discharge for the 1% and 63% AEP
events is included as Table 14.
Table 14 – Performance of Mitigation Measures – Peak Flow Rate at LPD
3 3
AEP Pre-Development (m /s) Post-Development – mitigated (m /s)
1% 5.24 5.24
63% 1.09 1.09
Results of this assessment demonstrate there is no increase in peak flow rate from the site due to the
construction of the greenhouse. We typically observe an increase in flow rate due to an increase in
impervious surfaces. However, due to the remainder of the site and the flat grades across the site, no
increase was observed in this scenario. It is noted from Figure 8 that the leading edge of the hydrograph
rises quicker in the post-development scenario. This can be attributed to the increase in impervious area.
Further assessment of the XP-SWMM modelling results reveals an increase in runoff volume does occur for
the post-development scenario, but does not translate to an increase in peak flow rate. A comparison of
the runoff volumes for the pre- and post-development scenarios is contained below in Figure 9, and
demonstrates an increase in runoff volume of approximately 540 m3 during the post development scenario.
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Figure 9 – A Comparison of the Runoff Volumes for the Pre- (left) and Post-Development (right) Scenarios. 5.6. Regional Flooding A hydrological model was developed by Hydrology & Water Management Consulting for the 1% AEP Duration Independent Storm (DIS) event. The hydrological model indicates a peak flow rate of approximately 470 m3/s is the critical design flow rate for the catchment at the site boundary. The design hydrograph was utilised by Water Technology in a flood model to determine the peak water levels and inundation extent for the site. The hydrographs of the 1% AEP design event for both the site and the catchment as a whole are shown in Figure 10. The peak flow rate from the farm site represents a little more than 1% of the peak flow in the whole catchment and therefore does not make a significant contribution. The 1% AEP DIS event hydrograph rises for approximately 8 hours before reaching the peak flow rate (and therefore peak water level at the site). Analysis of the site hydrology reveals the critical storm duration is the 180 minute storm. As illustrated by Figure 10, the critical hydrograph for the site has entered the receiving waters and left the site well before the peak flow rate associated with the larger catchment reaches the site. As a consequence, the increase in runoff volume associated with the greenhouse roof has no impact on the peak water level for flooding associated with the larger catchment. It is therefore considered that no adverse impacts associated with flooding will occur for neighbouring properties due to the construction of the greenhouse. Stormwater Management Plan – Lot 1 on SP108094, 305 Lake Macdonald Drive Page 24 D’VINERIPE R003370
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Figure 10 - 1% AEP Hydrographs - Site vs Regional. 5.7. Mitigation Measures Based on the findings discussed in Section 5.5 and 5.6, it is considered that no stormwater quality mitigation measures are required as the site demonstrates no increase in peak flow rate, and the insignificant increase in runoff volume occurs much sooner than the critical storm associated with the major flood event for the catchment. Stormwater Management Plan – Lot 1 on SP108094, 305 Lake Macdonald Drive Page 25 D’VINERIPE R003370
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6. Erosion and Sediment Control (ESC)
6.1. Erosion Risk Assessment
An erosion risk assessment has been conducted using the Revised Universal Soil Loss Equation (RUSLE). The
calculated soil loss is then used to determine the level of sediment control required, as well as stabilisation
and staging requirements. It must be noted that no soil sampling has been conducted on site, and as such,
a conservative erodibility (K) factor has been adopted based on soil mapping.
It has been assumed that no dispersive soils will be encountered on site. If at any time dispersive, or sodic
soils are encountered the client should contact the plan preparer for a review of the plans and procedures.
A = K x R x LS x P x C Equation 1 (IECA 2008)
Where:
A is the predicted soil loss per hectare per year
K is the soil erodibility factor
R is the rainfall erosivity factor
LS is the slope length/gradient factor
P is the erosion control practice factor
C is the ground cover and management factor
K = 0.055
R = 5923
LS = varies
C=1
P = 1.3
As a conservative approach, a K factor of 0.055 has been applied, and represents silty loam soils.
Rainfall erosivity has been calculated using the following equation:
R = 164.74 x 1.1177S x S0.6444
Where:
S is the 39% AEP 6 hour rainfall event (mm) (IECA, 2008)
The erosion risk categories are summarised in Table 15.
Slope length/gradient has been varied to assess how the erosion risk varies as the slope of the site varies,
as summarised in Table 16.
Table 15 – Erosion Risk Categories
Soil Loss (t/ha/yr) Erosion Risk Category
0 to 150 Very Low
150 to 225 Low
225 to 500 Moderate
500 to 1500 High
> 1500 Extreme
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Table 16 – Estimated Soil Loss and Risk Categorisation for Varied Slope Lengths and Grades
Based in the Erosion Risk Assessment undertaken, it is concluded that the site presents only a Very Low or
Low erosion risk, as slopes are typically less than 0.5%, increasing to approximately 2% in some areas
adjacent to the creek.
Based on these factors, soil loss for disturbed areas is estimated as less than 150 t/ha/year.
6.2. Erosion Control and Rehabilitation
Based on the erosion risk rating, the following best practice land clearing and rehabilitation controls should
be applied:
Land clearing limited to a maximum 8 weeks of work.
Disturbed soils surfaces stabilised with minimum 70% cover within 30 days of completion of works
within any area of a work site.
Unfinished earthworks are suitably stabilised if rainfall is reasonably possible, and disturbance is
expected to be suspended for a period exceeding 30 days.
During the site inspection, a number of disturbed areas were observed. These should be stabilised as soon
as possible, using turf or topsoil and hydromulch, or other vegetative cover.
However, should stabilisation not be achievable using permanent specifications, any of the temporary
controls presented in Table 17 may be utilised.
Table 17- Stabilisation Materials
Flat Land (<1 in 10) Mild Slopes (1 in 10 – 1 in 4)
Erosion Control Blankets Bonded Fibre matrix
Gravelling Compost Blankets
Mulching Erosion Control Blankets, Mats and Mesh
Revegetation Mulching well anchored
Rock Mulching Revegetation
Geofabric (temporary) Rock Mulching
Black plastic (temporary)
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6.3. Drainage Control
6.3.1. Design Standard
Based on the calculated soil loss, the following design standards apply to construction phase drainage and
erosion and sediment control:
Temporary drainage structures 39% AEP event (assuming design life < 12 months)
Roof runoff from the greenhouse is currently conveyed to a sediment basin via open drains. The operators
are in the process of installing a pipe drainage system to convey runoff to this location. However, no details
have been provided in relation to the design of these drains or the pipe drainage system.
6.4. Sediment Control
6.4.1. Design Standard
For any future construction activities, the following standards summarised in Table 18 apply to sediment
control.
Table 18 - Sediment Control Standard based on Soil Loss Rate
Area Limit Sediment Loss Rate Limit (t/ha/.yr)
(m²) Type 1 Type 2 Type 3
250 n/a n/a n/a
1,000 n/a n/a All cases
2,500 n/a > 75 75
> 2,500 > 150 150 75
Therefore, Type 2 and Type 3 controls are applicable for sediment control on the site. Examples of Type 2
and Type 3 controls that could be employed on site include:
Type 3:
o Sediment Fence,
Type 2:
o Filter Bag or Filter Tube,
o Filter Pond, and
o Filter Tube Dam.
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6.5. Roles and Responsibilities
Table 19 outlines the responsibilities of parties with respect to ESC during construction.
Table 19 - Roles and Responsibilities
Role Responsibility
Project Superintendent Overall responsibility of ESC implementation
Notify the Environmental Manager immediately of any non-compliance
with ESCP
Ensure the prompt implementation of measures to mitigate erosion and
sediment generation
Project Engineer Provide design information as required
Inspect ESC installation and maintenance
Inspect offsite impacts and management
Site Supervisor/Foremen Monitor daily rainfall
Notify Environmental Advisor/Consultant when runoff generating rainfall
occurs in the previous 24 hours
Maintain current records of rainfall, storage volumes, water quality,
treatment practices, discharge volumes (as appropriate)
Installation and maintenance of ESC
Environmental Advisor/Consultant Conduct in-situ monitoring (as required)
Collect and submit samples to laboratory (as required)
Collate results and prepare reports as required
Conduct site inspections and audits as required
Inspect ESC installation and maintenance
Inspect offsite impacts and management
Erosion and Sediment Control Auditor / Conduct site inspections and audits (as required)
Advisor (CPESC) Prepare audit reports (as required)
Provide advice regarding ESC site improvement (as required)
All Personnel Report any damage to ESC devices and any potential or actual
environmental harm in line with Duty to Notify under the requirements of
the Environmental Protection Act 1994
6.6. Corrective and Preventative Action
An environmental incident with respect to the ESCP is defined as any occurrence where sediment is
released from the site, whether controlled or uncontrolled, or where stormwater is released (controlled)
from site which does not meet the water quality requirements.
All incidents and non-conformances are to be reported, investigated and corrected in accordance with the
ESCP to ensure effective soil and water quality management practices at all times.
Best practice site management requires all ESC measures to be inspected by the Contractors nominated
representative at least daily when rain is occurring, within 24 hours prior to expected rainfall, and within 18
hours of a rainfall event of sufficient intensity and duration to cause onsite runoff (IECA, 2008). Such
inspections must check:
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Daily site inspections (during periods of runoff producing rainfall):
Any sign of increased turbidity around the current work areas
Evidence of litter or hydrocarbon sheens around the work area ; and
Any potential sources of contamination on banks or pontoons.
Weekly site inspections (even if work is not occurring on-site):
Occurrences of excessive sediment deposition (whether on-site or off-site);
Occurrences of construction materials, litter or sediment placed, deposited, washed or
blown from the site, including deposition by vehicular movements;
Litter and waste receptacles; and
Oil, fuel and chemical storage facilities.
Spillkits are well stocked and readily available
Prior to anticipated runoff producing rainfall:
All potential sources of contamination, including waste bins, skips and on platforms
Following runoff producing rainfall:
All potential discharge points from pontoons and banks.
Occurrences of excessive sediment deposition;
Occurrences of construction materials, litter or sediment placed, deposited, washed or
blown from the site
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7. Summary and Recommendations
This SMP has taken into consideration the historic and proposed land use of the site, and the hydrologic
and flooding behaviour. It also considers potential pollutant loads for the site and the catchment as a
whole. Based on these considerations, the following conclusions are made.
The previously approved turf farm operated for 30 years and applied considerably higher
quantities of nutrients (in the form of fertiliser) to the site. Based on the data available it is
expected the sediment and nutrient loads exiting the site will reduce considerably as a result of
the proposed change in land use due to decreased application of fertilisers.
While the irrigation water is high in nutrients, the hydroponic setup is a closed system. Due to the
lining of the trenches in which the plants and growbags are located, no irrigation water can enter
the soil profile. Furthermore, as the system is located inside the greenhouse, rainfall and overland
flows cannot convey nutrients associated with the hydroponics operations to the receiving
watercourse under normal conditions.
While the site is subject to inundation during major storm events, the likelihood of nutrient rich
irrigation water being conveyed to the receiving water is minimal. As indicated by the regional
hydrograph for the 1% AEP event, there is considerable time before the peak of the hydrographs
reaches the site. Therefore, operators at the site will be aware of the risk of flooding well in
advance of the site being inundated. A flood management plan has been developed to ensure the
operators are able to extract the irrigation water from the system and flush the growbags with
fresh water prior to inundation of the site. The irrigation is a closed loop system and the irrigation
water can be extracted and stored in a tank located above the water levels associated with the
major flood event.
The pollutant loads generated within the entire catchment, including neighbouring properties far
exceed those that would potentially leave the site during its operation as a tomato farm. The
results of this assessment indicate that the annual nutrient loads applied to the tomato crop
through the irrigation system represents only 6.3% and 4.4% of Total Nitrogen and Total
Phosphorus loads generated within the entire catchment. Given that TN and TP levels mentioned
are annual percentages, at any one time the nutrient loads in the irrigation system would be far
less than these levels, and considering that the irrigation water can be extracted from the system
in the event of a major flood event the potential for harm is minimal.
Hydrologic and hydraulic modelling of the site for the pre- and post-development scenarios
indicates the construction of the greenhouse results in no increase in peak flow rate from the site.
Therefore, no mitigation measures (i.e. detention basins or tanks) are required to maintain pre-
development peak flow rates from the site. The requirements of QUDM are therefore satisfied.
Results of the modelling indicate in the post-development scenario an additional 540m³ will be
generated during the critical duration (i.e. 180 minute) 1% AEP storm event.
To satisfy the requirements of the Queensland State Planning Policy’s Water Quality Code, Water
Sensitive Urban Design (WSUD) features would be required to capture and treat runoff from the
roof area of the greenhouse. Any runoff for the roof will be low in TSS loads, and the nutrients
contained will only be associated with atmospheric deposition.
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To achieve the relevant load based reduction targets, a bioretention system of 400m² filter area
would be required. Construction of this system would come at considerable cost to the client, and
would not greatly reduce the pollutant loads entering the waterway due to the quality of runoff
entering the bioretention system.
The following recommendations are made in relation to the site and operation of the tomato farm within
the proposed 140m x 144m greenhouse:
A media filtration system, as detailed in Section 4.4.3.2, should be provided to treat runoff from the
greenhouse roof area.
o While the media filtration system does not achieve the load based reduction target of 45%
removal of TN, it meets the load based reduction targets for TSS and TP, and is able to
remove a considerable portion of TN from runoff. It is considered the additional cost
associated with constructing a bioretention system cannot be justified by the potential
increase in TN load removal.
o The media filtration system will also facilitate infiltration of runoff into the soil profile. No
modelling has been undertaken to determine the volume of runoff that would be
infiltrated, and this would vary due to the groundwater levels at the site. However, it will
assist in returning the predevelopment hydrologic regime and reduce the volume of
additional runoff from the greenhouse roof that enters the creek system.
o Any overflows from the media filtration system should be conveyed to the creek in an open
drain to further increase the infiltration potential. Detailed design of the media filtration
system should be undertaken as part of any future works, and the spillway designed to
convey the relevant design storm event.
All exposed surfaces should be stabilised with either a vegetative cover (i.e. turf or topsoil and
hydromulch), or mulching. Ideally, access tracks around the site will also be stabilised using gravel
sheeting (refer Main Roads Specification Type 2.3).
Any future works for the site will require an ESCP to be developed for the project.
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8. Reference List
BOM. (2010). Rainfall IFD Data System. Retrieved 11 29, 2010, from Bureau of Meteorology:
http://www.bom.gov.au/hydro/has/cdirswebx/cdirswebx.shtml
Department of Natural Resources and Water. (2008). Queensland Urban Drainage Manual Second Edition.
Brisbane: Department of Natural Resources and Water.
Water by Design. (2010). MUSIC Modelling Guidelines Version 1.0. Brisbane, Queensland ISBN 978-0-
9806278-4-8: Waterways Partnership.
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Appendix A Site Layout (Martoo Drawing Number) Stormwater Management Plan – Lot 1 on SP108094, 305 Lake Macdonald Drive Page A D’VINERIPE R003370
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NOTE:
Aerial Photograph sourced from Near Map
Scale 1:4000 - Metres.
200 0 200 400
Sunshine Coast: R.P.D DEVELOPMENT PROJECT
13/6 Bottlebrush Ave SUMMARY
NOOSA HEADS
P.O.Box 1684 Lot 1 & 2 on SP108094
Noosa Heads QLD 4567 Total Site Area: SITE PLAN FOR STAGE 1 Scale: Date:
martoo
consulting
Ph: 07 5447 2550
Fax: 07 5455 3322
Gympie:
305 Lake Macdonald Drive,
COOROY
33.4 ha approx.
Applicant:
1:4000 (A3)
Drawn By:
23/06/2015
38 Nash Street
Como Glasshouse Pty Ltd LMc - MARTOO CONSULTING
pty ltd P.O. Box 391 Local Authority:
town planners + Gympie QLD 4570 NOOSA COUNCIL Detail: Reference No.:
Ph: 07 5482 7440
urban designers Fax: 07 5482 4952
Proposal Plan (Aerial) D-01569-06-A
+ surveyors
Page 36
Appendix B Assessment of Historic Nutrient Loads Stormwater Management Plan – Lot 1 on SP108094, 305 Lake Macdonald Drive Page B D’VINERIPE R003370
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Turf Farm
Fertilizers
D.A.P.
Chemical Formula Molecular Weight (g/mol) kg/yr mol/yr mol N mol P Atomic Weight N (g/mol) kg/yr N Atomic Weight P (g/mol) kg/yr P
(NH4)2HPO4 131.985 12000 90919.42 181838.8 90919.42266 14.0067 2546.962 30.974 2816.138
Crop King
kg/yr Percentage N Percentage P kg/yr N kg/yr P
12000 15 4.3 1800 516
Urea
Chemical Formula Molecular Weight (g/mol) kg/yr mol/yr mol N Atomic Weight N (g/mol) kg/yr N
CO(NH2)2 60.0128 12000 199957.3 399914.7 14.0067 5601.485017
Chemicals
Lorsban
Chemical Formula Molecular Weight (g/mol) kg/yr mol/yr mol N mol P Atomic Weight N (g/mol) kg/yr N Atomic Weight P (g/mol) kg/yr P
C9H11Cl3NO3PS 350.3 20 57.09392 57.09392 57.0939195 14.0067 0.799697 30.974 1.768427
Roundup (Glyphosate)
Chemical Formula Molecular Weight (g/mol) kg/yr mol/yr mol N mol P Atomic Weight N (g/mol) kg/yr N Atomic Weight P (g/mol) kg/yr P
C3H8NO5P 169 7.2 42.60355 42.60355 42.6035503 14.0067 0.596735 30.974 1.319602
Total N (kg/yr) Total P (kg/yr)
9950 3335
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Tomato Farm
Calcium nitrate
Chemical Formula Molecular Weight (g/mol) kg/yr mol/yr mol N Atomic Weight N (g/mol) kg/yr N
Ca(NO3)2 164.09 15969 97318.54 194637.1 14.0067 2726.22332
Potassium nitrate
Chemical Formula Molecular Weight (g/mol) kg/yr mol/yr mol N Atomic Weight N (g/mol) kg/yr N
KNO3 101.105 7939 78522.33 78522.33 14.0067 1099.838695
Iron Chelate
Chemical Formula Molecular Weight (g/mol) kg/yr mol/yr mol N Atomic Weight N (g/mol) kg/yr N
C10H12N2O8FeNa.3H2O 420.8484 182.5 433.6478 867.2957 14.0067 12.14795043
Potassium di hydrogen phosphate
Chemical Formula Molecular Weight (g/mol) kg/yr mol/yr mol P Atomic Weight P (g/mol) kg/yr P
KH2PO4 136.07 2281.25 16765.27 16765.27 30.974 519.2874072
Total N (kg/yr) Total P (kg/yr)
3838 519