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Stormwater Management Report
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STORMWATER MANAGEMENT REPORT ______________________________________________________________________________ CLIENT: HASS HOLDINGS Pty Ltd ATF Quasar Trust JOB No: 18-0165 REPORT No: 18-0165A SITE: LOT 5 TAYLOR COURT, COOROY. QLD. 4563 JULY 6, 2018 HR DESIGN CROMAR WINNING CONSULTING ENGINEERS PTY LTD T/A SUITE 35, 13 NORVAL COURT, MAROOCHYDORE QLD 4558
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CONTENTS
Table of Contents
1 INTRODUCTION ......................................................................................................................................................... 2
2 SITE DESCRIPTION ..................................................................................................................................................... 3
3 PROPOSED DEVELOPMENT ....................................................................................................................................... 4
4 SITE ACCESS ............................................................................................................................................................... 4
5 SEWERAGE RETICULATION ........................................................................................................................................ 4
6 WATER SUPPLY .......................................................................................................................................................... 4
7 STORMWATER QUANTITY MANAGEMENT ............................................................................................................... 5
7.1 Discharge Goals ................................................................................................................................................. 5
7.2 Legal Point of Discharge .................................................................................................................................... 5
7.3 Non-worsening of Peak Discharge .................................................................................................................... 6
8 STORMWATER QUALITY MANAGEMENT .................................................................................................................. 7
8.1 Proposed Stormwater Treatment Train ............................................................................................................ 7
8.2 MUSIC Model Results ........................................................................................................................................ 8
8.3 Maintenance ..................................................................................................................................................... 9
9 STORMWATER MANAGEMENT DURING CONSTRUCTION ........................................................................................ 9
10 EROSION & SEDIMENT CONTROL............................................................................................................................ 10
11 DUST & AIRBORNE PARTICAL CONTROL ................................................................................................................. 11
12 ON SITE SOLID WASTE MANAGEMENT ................................................................................................................... 12
13 AMENDMENT OF THE STORMWATER MANAGEMENT PLAN ................................................................................. 13
14 REPORT OWNERSHIP ............................................................................................................................................... 13
15 REFERENCES ............................................................................................................................................................ 13
______________________________________________________________________________________________
APPENDIX A Engineering drawings
HR DESIGN Reference No: 18-0165A i
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Cromar Winning Consulting Engineers Pty LTD T/A
ABN 30 169 626 957
Office: Suite 35, 13 Norval Court, Maroochydore QLD 4558
Postal: PO Box 7117, Sippy Downs, QLD 4556
Phone: (07) 5444 5578
Email: [email protected]
W eb: www.hrdesigngroup.com.au
1 INTRODUCTION
At the request of Hass Holdings Pty Ltd ATF Quasar Trust, HR Design has been commissioned to prepare civil
engineering works and stormwater management strategies for a proposed industrial development located at Lot 5 on
SP197517 Taylor Court, Cooroy.
This report has been prepared to support the development application to the Noosa Shire Council (NSC) to approve
the construction of a thirty-nine (39) tenancy industrial complex, comprised of three (3) buildings and associated
hardstand and landscaping areas over the following parcels of land:
Property Address: 5 Taylor Court,
Cooroy. QLD. 4563
Property Description: Lot 5 on SP197517
Client: Hass Holdings Pty Ltd ATF Quasar Trust
Local Authority: Noosa Shire Council
Registered Area: 1.054 ha
The purpose of this report is to address the management of stormwater quantity and quality to ensure that the
proposed development complies with all necessary state and local government policies.
In addition, this report intends to assess the likely impact of the proposed development in relation to stormwater
quantity and quality, and the adequacy of the existing stormwater infrastructure to accommodate the proposed
development.
HR DESIGN Reference No: 18-0165A Page 2 of 14
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2 SITE DESCRIPTION
The proposed development will be situated within an existing industrial development at Taylor Court, Cooroy. The
property is located within the Noosa Shire Council Local Government Area and approximately 2km from the Cooroy
Town Centre.
The site has an area of approximately 1.054 ha and is bounded by Taylor Court to the east, vacant allotments to the
North and South and an existing drainage easement to the west.
The site grades from north east to south west. Full details of the site topography and existing features are shown on
the detailed site survey by ‘Bennet & Bennet’ surveyors. A general locality plan is presented in Figure 1 below.
Figure 1 - Site Locality Image
HR DESIGN Reference No: 18-0165A Page 3 of 14
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3 PROPOSED DEVELOPMENT The proposed development will consist of three (3) industrial buildings being constructed of tilt-up concrete panels, together with hardstand and car parking areas. Landscaped areas will be provided throughout the development. One WSUD devices in the form of a bio-swale and a bio-retention basin sized to treat the development runoff will be constructed to the southern and western boundaries of the allotment. 4 SITE ACCESS Access to and exit from the site and will be via new crossovers to Taylor Court. These crossovers are designed in accordance with IPWEAQ standard drawing SEQ RS-051. Turning path diagrams for the design vehicles, (19m articulated vehicle), are shown on the attached engineering drawings 18-0165 Sheet C07. All access driveways, carparks and associated hardstand areas will be constructed of reinforced concrete. 5 SEWERAGE RETICULATION An existing gravity sewer main exists within the allotment at levels sufficient to command the proposed development. 6 WATER SUPPLY The proposed development will be readily serviced by an existing water main located within Taylor Court, adjacent to the eastern boundary. HR DESIGN Reference No: 18-0165A Page 4 of 14
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7 STORMWATER QUANTITY MANAGEMENT
7.1 Discharge Goals
The following goals are to be achieved as part of the management of stormwater quantity:
• The quantity of storm discharged from the site is to have non-worsening effect on the existing stormwater
system.
7.2 Legal Point of Discharge
The legal point of discharge for this site is the existing drainage infrastructure located in the south-west corner of the
allotment. This infrastructure includes a 525∅ RCP discharging directly into the existing drainage easement located
adjacent to the western and southern boundaries.
Figure 2 - Legal Point of Discharge (source NSC mapping)
HR DESIGN Reference No: 18-0165A Page 5 of 14
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7.3 Non-worsening of Peak Discharge
Using the ‘Rational Method’ as per QUDM, the pre-developed and post-developed site runoff calculations are listed in
the following table:
Table 1 - Catchment Details
t c (min) 5 ARI 10 years 20 years 50 years 100 years
1
I 10 (mm/hr) 70.2 AEP 10% 5% 2% 1%
i
C y (=F y .C 10 ) <1 I y (mm/hr) 215 245 285 316
i
Q y =(C y . I y .A)/3600 (l/s) Fy 1 1.05 1.15 1.2
Catchment Area (m 2 ) fi C 10 Cy Q y (l/s) Cy Q y (l/s) Cy Q y (l/s) Cy Q y (l/s)
Pre Development 10540 0 0.7 0.7 440.6 0.735 527.2 0.805 671.7 0.84 777.1
Post Development 10540 0.9 0.88 0.88 553.9 0.924 662.8 1 834.4 1 925.2
Post development discharge increase Q 10% (post) 113.3 Q 5% (post) 135.6 Q 2% (post) 162.7 Q 1% (post) 148.0
Referring to the stormwater infrastructure design drawings, by Leddy Sergiacomi & Associates Pty Ltd (Ref. No.
3
45113-C22), the existing 525∅ RCP has been designed to convey an expected stormwater discharge of 0.8m /s.
Table 1 shows that the developed site, if left unmitigated, is likely to result in an increase of up to 162.7L/s during the
Q 2% storm event and up to 148L/s during the Q 1% storm event. To mitigate any potential impact that this increase in
peak discharge runoff may have to the existing drainage infrastructure during the Q 2% and Q 1% storm events, on-site
detention and harvest & re-use tanks are proposed to be installed to collect all roof water from each building.
Roof water not detained for re-use will be discharged through restricted office plates, sized accordingly to reduce flows
to predevelopment levels
The proposed stormwater pipe network for the subject site is shown on the attached engineering drawings 18-0165
Sheets C03 & C04.
HR DESIGN Reference No: 18-0165A Page 6 of 14
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8 STORMWATER QUALITY MANAGEMENT
The Water Sensitive Urban Design Technical Design Guidelines for South East Queensland recommends the
following minimum reductions in the annual pollutant loads leaving a development site compared to the developed
unmitigated case:
• ≥90% reduction in Total Suspended Solids Load (TSS);
• ≥60% reduction in Total Phosphorus Load (TP);
• ≥45% reduction in Total Nitrogen Load (TN);
• ≥100% reduction in Gross Pollutant Load (GP).
8.1 Proposed Stormwater Treatment Train
All site stormwater runoff from the site is proposed to pass through a bio-retention basin adjacent to the southern
boundary of the allotment prior to discharging through the existing drainage infrastructure.
The efficiency of the proposed treatment train has been identified using the Model for Urban Stormwater Improvement
Conceptualisation (MUSIC V6.2) developed by Monash University.
A schematic layout of the treatment train, as input into the MUSIC model, is shown in Figure 3 below.
Figure 3 - MUSIC Version 6.2 Schematic Layout
HR DESIGN Reference No: 18-0165A Page 7 of 14
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The Rainfall Runof Parameters for the source catchment nodes have been taken from Table 3.7 of Water By Design’s
– MUSIC Modelling Guidelines, Version 1.0 (2010) and are shown in Table 2 below.
Table 2 – Rainfall Runoff Parameters
Rainfall threshold (mm/day) 1
Pervious Area Properties
Soil storage capacity (mm) 18
Initial storage (% of capacity) 10
Field capacity (mm) 80
Infiltration capacity coefficient – a 243
Infiltration capacity exponent - b 0.6
Groundwater Properties
Initial depth (mm) 50
Daily recharge rate (%) 0
Daily baseflow (%) 31
Daily deep seepage rate (%) 0
The pollutant load concentrations for the source catchment has been taken from Water By Design’s – MUSIC
Modelling Guidelines, Version 1.0 (2010) using the concentrations recommended for industrial areas.
The model was run for an average rainfall recorded at Caloundra Rainfall Station 40040, between the years 2000-
2010 and using a 6 minute time step. The mean annual rainfall for Caloundra area is 1543mm.
8.2 MUSIC Model Results
The proposed treatment train modelled with MUSIC, includes the following water quality treatment measures:
A bio-retention basin will be constructed within landscaped areas to the south-east corner of the site adjacent the
2 2
existing bushland. The bio-retention basin is to have a total area of 74.7m and a filter media area of 39m and is to
accept runoff for all roofs, hardstand and majority of landscaped areas prior to discharging into the existing drainage
infrastructure. The basin has been modelled with an extended detention depth of 200mm, a hydraulic conductivity of
200mm/hr and a filter media depth of 400mm.
The results are shown in Table 3 below:
Table 3 - Treatment Train Effectiveness
These results indicate that the water quality objectives have been achieved based on the proposed treatment train for
all pollutants in the stormwater discharge.
HR DESIGN Reference No: 18-0165A Page 8 of 14
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8.3 Maintenance
Access to the proposed bio-retention basin may be gained from the internal hardstand area. A recommended
maintenance schedule for water quality treatment train is outlined in Table 4 below:
Table 4 - Treatment Train Maintenance Shcedule
Device Task Labour Plant Min. Max Failure Mode
Frequency Frequency
per Annum
Bio-retention Inspection Maintenance - 12 - Grass
Areas staff (1 exceeds
person) 300mm in
height.
Mowing Maintenance Whipper 12 As required Ponding in
staff (1 snipper/Mower excess of
person) 24hrs.
Accumulation
Cleaning Maintenance Shovel & 4 As required of sediment or
staff (2 Truck gross
persons) pollutants
Outlet Inspection Maintenance - 4 As required Excessive
staff (1 During rainfall ponding.
person) events. Downstream
scouring.
Rectification Environmental As required Discoloured
Consultant discharge.
Unacceptable
odurs.
9 STORMWATER MANAGEMENT DURING CONSTRUCTION
Stormwater Quantity
• The stormwater disposal system shall be installed as soon as is practicable to allow for good and
safe work environment practice.
Stormwater Quality
• Rubbish and the suspended solids will be adequately catered for by the erosion and sediment
control plan.
• Oils and greases by volume from plant and equipment will be removed by the contractor and
disposed in a satisfactory manner as specified by the EPA.
• Nutrients (ie fertilises etc will only be applied at the rates as specified by the manufacturers for the
specified use.
HR DESIGN Reference No: 18-0165A Page 9 of 14
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10 EROSION & SEDIMENT CONTROL
Person Responsible Contractor’s Site Manager
Operational Policy To prevent the displacement of sediment and soil across and
offsite during storm events
Performance criteria No visual indication of erosion on stages under construction,
including evidence of rilling (an indicator of sheet erosion).
Implementation 1. Erosion and sedimentation devices shall be installed prior
to commencement of work in each stage in accordance
Strategy with the approved engineering plans and to the
reasonable satisfaction of the NSC.
2. Temporary erosion measures (eg silt fences) are to be
employed onsite during construction where reasonably
deemed necessary by the NSC from the assessment of
the slope and soil type. Such measures should be in
accordance with the recommendations in the IE Aust.
Qld. Soil and sediment Control Guidelines.
3. Stockpiled soil should be stored/bunded in a manner to
prevent soil being washed offsite (where necessary)
4. Outside the construction area, existing surface water
conditions shall be maintained.
Monitoring Carryout visual inspections daily and after rainfall events (>25mm
in 24hrs) to ensure that erosion measures are in place and
operational to suit the activity being under taken.
Auditing Visual inspections to be carried out monthly and after rainfall
events to verify that control measures are in place and properly
maintained.
Reporting Reporting only required if insufficient sediment and erosion
measures are identified.
Identification of 1. Signs of erosion on site
2. Damaged or failed erosion control devices.
incident or failure 3. Build-up of sediment.
Corrective Action Apply remedial measures to improve sediment & erosion
measures (ie silt fences, shake down area)
HR DESIGN Reference No: 18-0165A Page 10 of 14
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11 DUST & AIRBORNE PARTICAL CONTROL
Person Responsible Contractor’s Site Manager
Operational Policy To achieve acceptable air quality standards through the control of
the movement of dust offsite from the site works.
Performance criteria The target level of complaints by nearby residents is no more than
one in every seven day period. Ambient air quality should not
deteriorate by more than 30% over a period of seven consecutive
days. Dust deposition at any nearby residence should not exceed
100mg/m2/day.
Implementation The minimisation of the movement of dust offsite will be achieved
through the following onsite practices.
Strategy
1. All permanent bunds and reshaped areas will be
revegetated within ten days after completion of earthworks.
(including service trenches)
2. Stockpiling onsite will be minimised where possible.
3. A water cart will be bought to site if required or watering via
the site water supply will be conducted during high-risk
times such as high winds and low rainfall and after the
receipt of a complaint.
4. Dusty activities to cease if wind speed exceeds 10m/sec.
5. Contractor’s staff to be trained to implement dust
minimisation measures.
Monitoring Dust inspections will be carried out to verify that dust mitigation
measures are being implemented. Dust monitoring will be
conducted upon receipt of complaints by residents. If dust
monitoring is to take place, the following will occur,
-Temporary dust deposition gauges will monitor the movement of
dust offsite at the nearest residences adjacent to the site in the
predominant wind direction.
Auditing Management to review the complaints register weekly and
corrective action taken.
Reporting The contractor is to notify NSC & EPA of a possible environmental
nuisance on receipt of 3 or more dust complaints in any 24hr.
Reports are to be provided to NSC upon request
Identification of Any dust related complaints by residents will indicate a failure of
dust control measures.
incident or failure
Corrective Action Locate the source of the dust and apply the following-
1. Apply water sprays to the vegetation
2. Cover or water exposed areas
3. If dust persists, cease the dust creating activities.
All dust complaints to be addressed in consultation with NSC.
HR DESIGN Reference No: 18-0165A Page 11 of 14
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12 ON SITE SOLID WASTE MANAGEMENT
Person Responsible Contractor’s Site Manager
Operational Policy To prevent the creation of unacceptable visual amenity due to the
storage of onsite solid wastes.
Performance criteria The target level of complaints by nearby residents is no more
than one in every seven day period. Regular monitoring of
volumes of waste generated/stored.
Implementation An onsite storage bin is to be provided to the receiving of
construction wastes.
Strategy
These wastes are to be stored in a manner that prevents leaching
of unwanted materials into the stormwater system downstream
from the site. If a material that is disposed off into the bin that has
potential for hazardous leaching it is not to be disposed of via the
site waste bin. It is to be removed immediately to the council
waste depot or in accordance with EPA standards and guidelines.
When a complaint is received the complaint is to be assessed
and the offending waste bin removed/emptied.
Monitoring Solid waste bin inspections will be carried out to verify that waste
levels in the bins and type of waste are acceptable.
Monitoring will be conducted upon receipt of complaints by
residents.
If the bins are full they are to be taken away by the waste bin
contractor.
Auditing Management to review the complaints register weekly and
corrective action taken.
Reporting The contractor is to notify NSC of a possible nuisance on receipt
of 3 or more solid waste storage complaints in any 24hr period.
Reports are to be provided to NSC upon request
Identification of Any waste related complaints by residents will indicate a failure of
waste control measures.
incident or failure
Corrective Action Apply the following-
1. If the bin is full – have it emptied/replaced
2. Waste that has not been placed in the bin must be
relocated to inside the bin.
HR DESIGN Reference No: 18-0165A Page 12 of 14
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13 AMENDMENT OF THE STORMWATER MANAGEMENT PLAN
Amendments may only be implemented with the consent of the preparing engineer (HR Design). Any amendments
without permission shall be the sole responsibility of the person making the amendment.
14 REPORT OWNERSHIP
This report has been prepared for the client/s listed at the beginning of the report. Use of this report by any other party
is prohibited without the express written permission of HR Design. HR Design retains the ownership of this report until
such time that all outstanding fees and monies have been received at the office of HR Design.
15 REFERENCES
1. Noosa Shire Council, Plan – 2006
2. Noosa Shire Council, Infrastructure Mapping
3. Queensland Urban Drainage Manual (QUDM), 2013
4. Australian Government – Bureau of Meteorology.
5. Queensland Department of Primary Industries (DPI)
6. WSUD technical design Guidelines Southeast Queensland Version 1- June 2006
7. Water By Design’s – MUSIC Modelling Guidelines, Version 1.0 (2010)
8. MUSIC version 6.2 modelling software by eWater
Yours sincerely, Certified by,
Benjamin J. Winning BEngTech (Civil), TMIEAust Barry R. Cromar BEng (Civil), MIEAust CPEng RPEQ NER
Dated: 6 July, 2018. Dated: 6 July, 2018.
HR DESIGN Reference No: 18-0165A Page 13 of 14
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APPENDIX A
Engineering Drawings
HR DESIGN Reference No: 18-0165A Appendix
[OCR of page images]
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APPENDIX A
Engineering Drawings
HR DESIGN Reference No: 18-0165A Appendix