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Reference Document - Stormwater Mangement Report & Letter Repsonse - MCU24 0094 · MCU24/0094
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REFERENCE DOCUMENT
MCU24/0094
NOOSA COUNCIL
8 APRIL 2025
Stormwater Management Report
Proposed Residential Development
33 Ross Crescent
Sunshine Beach
For: Susie Hamill
3 July 2024
Ref: S24-043
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Section 2
DO C UM E NT I NFO RM ATIO N
Project Name: Proposed Residential Development
Westera Partners Ref: S24-043
Westera Partners Contact:
Jared Hill Phone: 0437 335 403
Email: [email protected]
Certified for Issue by:
Jared Hill RPEQ 19891
3 July 2024
Document Control:
Revision Author Certified for Issue Date
A P. Baxter J. Hill RPEQ 19891 03.07.2024
This report has been prepared for Susie Hamill for the purpose of accompanying a development
application to Noosa Council. This report must only be used by Susie Hamill for this purpose and must
not be used or relied upon by any other person for any other purpose.
The assessment, conclusions or recommendations in this report are based on conditions encountered
and information received at the time of preparing the report and may not be relied upon as site
conditions or operations vary over time.
ii
Section 3
CO NT E NT S
1 INTRODUCTION ..................................................................................................................... 1
2 SITE DESCRIPTION ............................................................................................................... 1
2.1 Location and Land Use ............................................................................................................ 1
2.2 Lawful Point of Discharge ........................................................................................................ 2
2.3 Upstream Drainage Connection .............................................................................................. 2
2.4 Flooding ................................................................................................................................... 2
3 STORMWATER QUANTITY MANAGEMENT ........................................................................ 2
4 WATER QUALITY MANAGEMENT ....................................................................................... 2
4.1 Operational Phase ................................................................................................................... 2
4.2 Construction Phase ................................................................................................................. 3
4.2.1 Design Objectives .................................................................................................................... 3
4.2.2 Erosion and Sediment Control ................................................................................................. 5
4.2.3 Maintenance and Monitoring Requirements ............................................................................ 6
5 CONCLUSION ......................................................................................................................... 7
6 APPENDICES ..................................................................................................................... A-1
Appendix A – Erosion Hazard Assessment ........................................................................................ A-1
Appendix B – Preliminary Engineering Plans ..................................................................................... B-1
Appendix C – Site Survey .................................................................................................................. C-1
List Of Tables
Table 1 – Pollutants Typically Generated During the Construction Phase ................................... 3
Table 2 – SPP Appendix 2: Part 1 Construction Phase – Stormwater Management Design
Objectives ............................................................................................................................. 3
Table 3 – SPP Appendix 2: Part 2 Construction Phase – Stormwater Management Design
Objectives for Temporary Drainage Works .......................................................................... 5
Table 4 – SPP Appendix 2: Part 3 Construction Phase – Stormwater Management Design
Objectives for Emergency Spillways on Temporary Sediment Basins ................................. 5
Table 5 - ESC maintenance requirements. ................................................................................... 6
List of Figures
Figure 1 – Indicative site location (Nearmaps, 2024) .................................................................... 1
iii
Section 4
1 INT RO D UC TIO N
Westera Partners Pty Ltd has been commissioned by Susie Hamill to prepare a Stormwater
Management Report to accompany a development application for a proposed residential development.
The proposal involves demolishing the existing dwelling of 33 Ross Crescent and constructing a new
dwelling house, including an access driveway and ground-level features.
This report documents how stormwater runoff will be managed on site in accordance with Noosa
Council’s (NC’s) requirements.
2 SI T E D ES CR I PT IO N
2. 1 Loc at i on an d L and U se
The proposed development site is located at 33 Ross Cres, Sunshine Beach; also known as Lot 6 on
RP216711.
The proposed development area is approximately 3517.2m2, and an existing single dwelling currently
occupies the lot. The site has a nominal fall of approximately 25.0% from Ross Cres toward the coastal
bushland.
The site is bound by residential dwellings to the north, Ross Cres to the west, coastal bushland to the
east, and Alison Park (35 Ross Cres) to the south. Refer to Figure 1 for an indicative site location and
Appendix C for detailed site survey information.
Figure 1 – Indicative site location (Nearmaps, 2024)
1
Section 5
2. 2 Law fu l P oint of D is ch ar ge
Stormwater runoff from the lot is assumed to discharge to the coastal bushland, which interfaces with
the eastern boundary as sheet flow.
The proposed lawful point of discharge for the roof water, driveway, crossover, and impervious ground-
level areas shall be the soakage trenches installed on the lower ground level towards the northeast and
southeast corners of the site. It is proposed that the catchment areas discharging to each soakage
trench be balanced with roof water and runoff from the impervious areas directed to the soakage
trenches via the construction of new on-site drainage. Lower pervious areas of the lot will continue to
discharge to the eastern boundary as sheet flow as per existing site conditions. Refer to Appendix B for
further information regarding the proposed stormwater works for the development.
2. 3 Ups tr e am D r ain ag e C onne ct ion
The development site does not have any upslope properties unable to gravity drain to a lawful point of
discharge.
2. 4 Flood ing
The proposed development site is not impacted by any NC flood mapping and is therefore considered
to be flood free.
3 STO R M WAT E R Q UA N TIT Y M AN AG E ME NT
A detailed stormwater quantity analysis of the existing and developed site conditions has not been
undertaken. The proposal is for a residential dwelling on an existing residential lot, with the final
impervious area fraction generally in line with lumped C10 values for low-density residential lots. It is
also to be noted that the impervious area change as a result of the proposed development will not be
significant, and therefore, no detention is considered to be required.
4 W AT ER Q U AL IT Y M A NAG E M EN T
4. 1 O pe r at io na l Ph a se
The development is not required to meet the Queensland Government’s State Planning Policy (July
2017), although the site does exceed the 2,500m2 minimum site area, as the development is considered
exempt from the stormwater water quality design objectives. However stormwater quality management
must still be undertaken via the application of best management practices (BMPs) to ensure no adverse
impacts to the downstream environment.
Pollutants typically generated during the operational phase of the development include:
• Litter/gross pollutants;
• Sediment;
• Nutrients (N & P);
• Hydrocarbons (oils and grease); and
• Heavy metals.
Stormwater quality best management practices may be implemented for the development as follows:
• First flush diversion system for roof water diverting the roof water for irrigation purposes
• Rainwater storage tanks may be used to collect rainwater for landscape irrigation.
2
Section 6
Best management practices have been deemed sufficient for the site area and land use. Refer to
Appendix B for the stormwater management drawing.
4. 2 Con st ruc t io n Ph a se
Management of stormwater runoff during construction and the implementation of an erosion & sediment
control program is necessary to avoid impacts to receiving waters from pollutants typically generated
during the construction phase. Typical pollutants are described in Table 1 below:
Table 1 – Pollutants Typically Generated During the Construction Phase
Pollutant Sources
Litter (Gross Pollutants) Paper, construction packaging, food packaging, cement bags.
Sediment Unprotected exposed soils and stockpiles during earthworks and building.
Hydrocarbons Fuel and oil spills, leaks from construction equipment.
Toxic materials Cement slurry, asphalt prime, solvents, cleaning agents, wash waters.
pH altering substances Acid sulphate soils, cement slurry and wash waters.
In addition to the degradation of receiving waters, impacts of inadequate erosion and sediment control
downstream from the site include:
• traffic safety problems;
• blocked drains;
• local flooding problems;
• aesthetic pollution of drainage paths; and
• damage to local ecosystems.
4.2.1 De si gn O bj e ct i v es
Management of stormwater runoff during construction should be undertaken in accordance with
Appendix 2 of the SPP (July 2017). The SPP outlines the design objectives for construction phase
stormwater management. These are presented in Table 2, Table 3 and Table 4.
Table 2 – SPP Appendix 2: Part 1 Construction Phase – Stormwater Management Design Objectives
Issue Desired Outcomes
Drainage Control 1. Manage stormwater flows around or through areas of exposed soil to
avoid contamination.
2. Manage sheet flows in order to avoid or minimise the generation of rill or
gully erosion.
3. Provide stable concentrated flow paths to achieve the construction
phase stormwater management design objectives for temporary
drainage works (part 2).
3
Section 7
Issue Desired Outcomes
4. Provide emergency spillways for sediment basins to achieve the
construction phase stormwater management design objectives for
emergency spillways on temporary sediment basins (part 3).
Erosion Control 1. Stage clearing and construction works to minimise the area of exposed
soil at any one time.
2. Effectively cover or stabilise exposed soils prior to predicted rainfall.
3. Prior to completion of works for the development, and prior to removal
of sediment controls, all site surfaces must be effectively stabilised
using methods which will achieve effective short-term stabilisation.
Sediment Control 1. Direct runoff from exposed site soils to sediment controls that are
appropriate to the extent of disturbance and level of erosion risk.
2. All exposed areas greater than 2500 metres must be provided with
sediment controls which are designed, implemented and maintained
to a standard which would achieve at least 80% of the average annual
runoff volume of the contributing catchment treated (i.e. 80%
hydrological effectiveness) to 50mg/L Total Suspended Solids (TSS) or
less, and pH in the range (6.5–8.5).
Litter, Hydrocarbons and 1. Remove gross pollutants and litter.
other contaminants
2. Avoid the release of oil or visible sheen to released waters.
3. Dispose of waste containing contaminants at authorised facilities.
Waterway Stability and 1. Where measures are required to meet post-construction waterway
flood flow management stability objectives, these are either installed prior to land disturbance
and are integrated with erosion and sediment controls, or equivalent
alternative measures are implemented during construction.
2. Earthworks and the implementation of erosion and sediment controls
are undertaken in ways which ensure flooding characteristics
(including stormwater quantity characteristics) external to the
development site are not worsened during construction for all events up
to and including the 1 in 100 year ARI (1% AEP).
4
Section 8
Table 3 – SPP Appendix 2: Part 2 Construction Phase – Stormwater Management Design Objectives
for Temporary Drainage Works
Temporary Drainage Works Anticipated Operation Design Life and Minimum
Design Storm Event
<12 Months 12-24 Months >24 Months
Drainage Structure 1 in 2 year 1 in 5 year 1 in 10 year
ARI/39% AEP ARI/18% AEP ARI/10% AEP
Where located immediately up-slope of an 1 in 10 year ARI/10% AEP
occupied property that would be adversely
affected by the failure or overtopping of the
structure
Culvert Crossing 1 in 1 year ARI/63% AEP
Table 4 – SPP Appendix 2: Part 3 Construction Phase – Stormwater Management Design Objectives
for Emergency Spillways on Temporary Sediment Basins
Drainage Structure Anticipated Operation Design Life and Minimum
Design Storm Event
<3 Months 3-12 Months >12 Months
Emergency spillways on temporary 1 in 10 year 1 in 20 year 1 in 50 year
sediment basins ARI/10% AEP ARI/5% AEP ARI/2% AEP
Best practice erosion and sediment controls must be installed to minimise the discharge of sediment
laden runoff during construction and to achieve the objectives outlined in Tables 2-4. This is discussed
in the following section.
4.2.2 E ro sio n and Se dim en t Co ntr ol
Management of stormwater runoff during construction is necessary to avoid pollution of downstream
waterways from sediment and gross pollutant loading. Impacts of inadequate erosion and sediment
control downstream from the site include:
• traffic safety problems;
• blocked drains;
• local flooding problems;
• aesthetic pollution of drainage paths; and
• damage to local ecosystems.
Best practice erosion and sediment controls must be installed to minimise the discharge of sediment
laden runoff during construction. Erosion and sediment control plans shall be developed during detailed
design phase and must be continually maintained and amended as required to minimise environmental
harm.
5
Section 9
Erosion and sediment control plans are based on three sets of control measures:
• drainage control;
• erosion control; and
• sediment control.
These control measures must be maintained in an effective operational condition. Sediment disposal
from site is to occur to the satisfaction of Noosa Council. Defects in erosion and sediment control
devices, such as sediment fences, are to be inspected and documented. Upon Inspection, the
Contractor is to determine whether the device should be replaced or repaired. Documentation is to
include how the damage was caused and what measures can be implemented to reduce the possibility
of repeat occurrences. Any damage to either permanent or temporary water quality control structures
or devices is to be immediately rectified at the contractor’s expense.
The effectiveness of the erosion and sediment control devices can be monitored by visual audits. All
ESC measures are to be inspected:
• at least daily (when work is occurring on site) or weekly (when work is not occurring on site);
• within 24 hours of expected rain; and
• within 18 hours of a rainfall event (i.e. an event of sufficient intensity and duration to mobilise
sediment on site).
Drainage paths are to be inspected to ensure the sediment fences are not being bypassed as a result
of soil erosion.
Sediment laden runoff shall be prevented from entering neighbouring properties. This shall be achieved
by landscaping disturbed areas immediately and prior to a rainfall event.
The proposed development has scored a ‘22’ on the IECA erosion hazard assessment with one trigger
score value exceeded as a result of the site slope (refer Appendix A for details). Further details of
proposed on site erosion and sediment control measures will be required at the detailed design phase
of the development.
4.2.3 Ma int en an ce and M o nit o ri ng Re qui r em ent s
Periodic maintenance and monitoring of stormwater devices proposed in this report is crucial to ensure
effective operation and design life.
Inspect field inlet grates, pits and underground pipes for blockage or damage at least 6 monthly or after
significant rainfall event. The filter baskets shall be inspected and maintained preferably by the
manufacturer to avoid damage to units and to ensure adequate cleaning and record keeping. For the
first 12 months routine inspections of filter baskets shall be carried out monthly with routine clean out
at alternate months. Results of the initial 12 months maintenance program shall be used to determine
future maintenance intervals. Refer manufactures maintenance and monitoring methodology for
specific details.
Maintenance of ESC measures must occur in accordance with Table 5.
Table 5 - ESC maintenance requirements.
ESC Measure Maintenance Trigger Timeframe for Completion
of Maintenance
6
Section 10
Sediment basins When settled sediment exceeds Within 7 days of the
the volume of the sediment inspection.
storage zone
Other ESC measures The capacity of ESC measures By the end of the day.
falls below 75%.
Sediment accumulation on ESC devices is to be removed and disposed of to the satisfaction of Noosa
Council.
5 CO N CLU S IO N
This SWMP outlines how stormwater runoff from the site will be managed in order to not adversely
impact the receiving environment.
The proposed lawful point of discharge for the roofwater and impervious areas from the proposed
development shall be soakage trenches installed on the ground level towards the northeast and
southeast corners of the site. Stormwater detention is not considered to be required as the proposal is
for a residential dwelling on an existing lot. Roofwater runoff from the development site will need to be
collected on site and directed to the soakage trench to ensure no adverse impacts to neighbouring
properties as a result of the development.
The development site is considered to be flood free.
Stormwater treatment should be managed through the implementation of best management practices
on site. Based on the scale of the proposed development, and typical pollutants produced, these
measures are considered adequate.
By implementing the proposed stormwater management system, and providing adequate maintenance,
the downstream environment and neighbouring properties will not experience any adverse deterioration
of water quality as a result of the proposed development.
7
Section 11
Us WESTERA PARTNERS 6 APPENDICES Appendix A — Erosion Hazard Assessment
Section 12
Best Practice Erosion And Sediment Control Erosion Hazard Assessment Form
Erosion Hazard Assessment Form
Condition Points Score Trigger
value
AVERAGE SLOPE OF DISTURBANCE AREA [1]
• not more than 3% [3% 33H:1V] 0
• more than 3% but not more than 5% [5% = 20H:1V] 1
6 4
• more than 5% but not more than 10% [10% = 10H:1V] 2
• more than 10% but not more than 15% [15% 6.7H:1V] 4
• more than 15% 6
SOIL CLASSIFICATION GROUP (AS1726) [2]
• GW, GP, GM, GC 0
• SW, SP, OL, OH 1 3
• SM, SC, MH, CH 2
• ML, CL, or if imported fill is used, or if soils are untested 3
EMERSON (DISPERSION) CLASS NUMBER [3]
• Class 4, 6, 7, or 8 0
• Class 5 2 4 6
• Class 3, (default value if soils are untested) 4
• Class 1 or 2 6
DURATION OF SOIL DISTURBANCE [4]
• not more than 1 month 0
• more than 1 month but not more than 4 months 2 4 6
• more than 4 months but not more than 6 months 4
• more than 6 months 6
AREA OF DISTURBANCE [5]
• not more than 1000 m2 0
• more than 1000 m2 but not more than 5000 m2 1 1 4
• more than 5000 m2 but not more than 1 ha 2
• more than 1 ha but not more than 4 ha 4
• more than 4 ha 6
WATERWAY DISTURBANCE [6]
• No disturbance to a watercourse, open drain or channel 0
0 2
• Involves disturbance to a constructed open drain or channel 1
• Involves disturbance to a natural watercourse 2
REHABILITATION METHOD [7]
Percentage of area (relative to total disturbance) revegetated by seeding
without light mulching (i.e. worst-case revegetation method).
• not more than 1% 0 0
• more than 1% but not more than 5% 1
• more than 5% but not more than 10% 2
• more than 10% 4
RECEIVING WATERS [8]
• Saline waters only 0 0
• Freshwater body (e.g. creek or freshwater lake or river) 2
SUBSOIL EXPOSURE [9]
• No subsoil exposure except of service trenches 0 2
• Subsoils are likely to be exposed 2
EXTERNAL CATCHMENTS [10]
• No external catchment 0
1
• External catchment diverted around the soil disturbance 1
• External catchment not diverted around the soil disturbance 2
ROAD CONSTRUCTION [11]
• No road construction 0 0
• Involves road construction works 2
pH OF SOILS TO BE REVEGETATED [12]
• more than pH 5.5 but less than pH 8 0 1
• other pH values, or if soils are untested 1
Total Score [13] 22
IECA (Australasia) November 2008 Page 1
Section 13
Best Practice Erosion And Sediment Control Erosion Hazard Assessment Form
Explanatory notes
Requirements: Specific issues or actions required by the proponent.
Warnings: Issues that should be considered by the proponent.
Comments: General information relating to the topic.
[1] REQUIREMENTS:
For sites with an average slope of proposed land disturbance greater than 10%, a
preliminary ESCP must be submitted to the regulatory authority for approval
during planning negotiations.
Proponents must demonstrate that adequate erosion and sediment control
measures can be implemented on-site to effectively protect downstream
environmental values.
If site or financial constraints suggest that it is not reasonable or practicable for
the prescribed water quality objectives to be achieved for the proposal, then the
proponent must demonstrate that alternative designs or construction techniques
(e.g. pole homes, suspended slab) cannot reasonably be implemented on the
site.
WARNINGS:
Steep sites usually require more stringent drainage and erosion controls than
flatter grade sites.
COMMENTS:
The steeper the land, the greater the need for adequate drainage controls to
prevent soil and mulch from being washed from the site.
[2] REQUIREMENTS:
If the actual soil K-factor is known from soil testing, then the Score shall be
determined from Table 1.
If a preliminary ESCP is required during planning negotiations, then it must be
demonstrated that adequate space is available for the construction and operation
of any major sediment traps, including the provision for any sediment basins and
their associated embankments and spillways. It must also be demonstrated that
all reasonable and practicable measures can be taken to divert the maximum
quantity of sediment-laden runoff (up to the specified design storm) to these
sediment traps throughout the construction phase and until the contributing
catchment is adequately stabilised against erosion.
WARNINGS:
The higher the point score, the greater the need to protect the soil from raindrop
impact and thus the greater the need for effective erosion control measures. A
point score of 2 or greater will require a greater emphasis to be placed on
revegetation techniques that do not expose the soil to direct rainfall contact
during vegetation establishment, e.g. turfing and Hydromulching.
COMMENTS:
Table 2 provides an indication of soil conditions likely to be associated with a
particular Soil group based on a statistical analysis of soil testing across NSW.
This table provides only an initial estimate of the likely soil conditions.
IECA (Australasia) November 2008 Page 2
Section 14
Best Practice Erosion And Sediment Control Erosion Hazard Assessment Form
The left-hand-side of the table provides an indication of the type of sediment
basin that will be required (Type C, F or D). The right-hand-side of the table
provides an indication of the likely erodibility of the soil based on the Revised
Universal Soil Loss Equation (RUSLE) K-factor.
Table 3 provides some general comments on the erosion potential of the various
soil groups.
Table 1 – Score if soil K-factor is known
RUSLE soil erodibility K-factor
K < 0.02 0.02<K<0.04 0.04<K<0.06 K > 0.06
Score 0 1 2 3
Table 2 – Statistical analysis of NSW soil data [1]
Unified Likely sediment basin Probable soil erodibility K-factor (%) [2]
Soil classification (%)
Class Dry Wet Low Moderate High Very High
System
Type C Type F Type D K < 0.02 0.02<K<0.04 0.04<K<0.06 K > 0.06
GM 30 58 12 12 51 26 12
GC 42 33 25 13 71 17 0
SW 40 48 12 49 39 12 0
SP 53 32 15 76 18 5 1
SM 21 67 12 26 48 25 1
SC 26 50 24 16 64 18 2
ML 5 63 32 4 35 45 16
CL 9 51 39 12 56 19 13
OL 2 80 18 34 61 5 1
MH 12 41 48 15 19 41 25
CH 5 44 51 39 43 11 7
Notes: [1] Analysis of soil data presented in Landcom (2004).
[2] Soil erodibility based on Revised Universal Soil Loss Equation (RUSLE) K-factor.
Unified Soil Classification System (USCS)
GW Well graded gravels, gravel-sand mixtures, little or no fines
GP Poorly graded gravels, gravel-sand mixture, little or no fines
GM Silty gravels, poorly graded gravel-sand-silt mixtures
GC Clayey gravels, poorly graded gravel-sand-clay mixtures
SW Well graded sands, gravelly sands, little or no fines
SP Poorly graded sands, gravelly sands, little or no fines
SM Silty sands, poorly graded sand-silt mixtures
SC Clayey sands, poorly graded sand-clay mixtures
ML Inorganic silts & very fine sands, rock flour, silty or clayey fine sands with slight plasticity
CL Inorganic clays, low–medium plasticity, gravelly clays, sandy clays, silty clays, lean clays
OL Organic silts and organic silt-clays of low plasticity
MH Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts
CH Inorganic clays of high plasticity, fat clays
OH Organic clays of medium to high plasticity
IECA (Australasia) November 2008 Page 3
Section 15
Best Practice Erosion And Sediment Control Erosion Hazard Assessment Form
Table 3 – Typical properties of various soil groups [1]
Soil Groups Typical properties [2]
GW, GP • Low erodibility potential.
GM, GC • Low to medium erodibility potential.
• May create turbid runoff if disturbed as a result of the release of silt
and clay particles.
SW, SP • Low to medium erodibility potential.
SM, SC • Medium erodibility potential.
• May create turbid runoff if disturbed as a result of the release of silt
and clay particles.
MH, CH • Highly variable (low to high) erodibility potential.
• Will generally create turbid runoff if disturbed.
ML, CL • High erodibility potential.
• Tendency to be dispersive.
• May create some turbidity in runoff if disturbed.
Note: [1] After Soil Services & NSW DLWC (1998).
[2] Any soil can represent a high erosion risk if the binding clays or silts are unstable.
Table 4 provides general guidelines on the suitability of various soil groups to various
engineering applications.
Table 4 – Engineering suitability based on Unified Soil Classification [1]
Embankments
USC Fill Slope Untreated
Unified Soil Class Water Non
Group stability roads
retaining water
retaining
Well graded gravels GW Unsuitable Excellent Excellent Excellent Average
Poorly graded gravel GP Unsuitable Average Excellent Average Unsuitable
Silty gravels GM Unsuitable Average Good Average Average
Clayey gravels GC Suitable Average Good Average Excellent
Well graded sands SW Unsuitable Excellent Excellent Excellent Average
Poorly graded sands SP Unsuitable Average Good Average Unsuitable
Silty sands SM Suitable [2] Average Average Average Poor
Clayey sands SC Suitable Average Average Average Good
Inorganic silts ML Unsuitable Poor Average Poor Unsuitable
Inorganic clays CL Suitable [2] Good Average Good Poor
Organic silts OL Unsuitable Unsuitable Poor Unsuitable Unsuitable
Inorganic silts MH Unsuitable Poor Poor Poor Unsuitable
Inorganic clays CH Suitable [2] Average Unsuitable Average Unsuitable
Organic clays OH Unsuitable Unsuitable Unsuitable Unsuitable Unsuitable
Highly organic soils Pt Unsuitable Unsuitable Unsuitable Unsuitable Unsuitable
Notes: [1] Modified from Hazelton & Murphy (1992)
[2] Suitable only after modifications to soil such as compaction and/or erosion protection
IECA (Australasia) November 2008 Page 4
Section 16
Best Practice Erosion And Sediment Control Erosion Hazard Assessment Form
[3] If the soils have not been tested for Emerson Class, then adopt a score of 4.
REQUIREMENTS:
Works proposed on sites containing Emerson Class 1 or 2 soils have a very high
pollution potential and must submit a conceptual ESCP to the regulatory authority
for review and/or approval (as required by the authority) during planning
negotiations.
WARNINGS:
Class 3 and 5 soils disturbed by cut and fill operations or construction traffic are
highly likely to discolour stormwater (i.e. cause turbid runoff). Chemical
stabilisation will likely be required if these soils are placed immediately adjacent
to a retaining wall. Any disturbed Class 1, 2, 3 and 5 soils that are to be
revegetated must be covered with a non-dispersive topsoil as soon as possible
(unless otherwise agreed by the regulatory authority).
Class 1 and 2 soils are highly likely to discolour (pollute) stormwater if exposed to
rainfall or flowing water. Treatment of these soils with gypsum (or other suitable
substance) will most likely be required. These soils should not be placed directly
behind a retaining wall unless it has been adequately treated (stabilised) or
covered with a non-dispersible soil.
[4] The duration of disturbance refers to the total duration of soil exposure to rainfall
up until a time when there is at least 70% coverage of all areas of soil.
REQUIREMENTS:
All land developments with an expected soil disturbance period greater than 6
months must submit a conceptual ESCP to the regulatory authority for review
and/or approval (as required by the authority) during planning negotiations.
COMMENTS:
Construction periods greater than 3 months will generally experience at least
some significant storm events, independent of the time of year that the
construction (soil disturbance) occurs.
[5] REQUIREMENTS:
Development proposals with an expected soil disturbance in excess of 1ha must
submit a conceptual ESCP to the regulatory authority for review and/or approval
(as required by the regulatory authority) during planning negotiations.
The area of disturbance refers to the total area of soil exposed to rainfall or dust-
producing winds either as a result of:
(a) the removal of ground cover vegetation, mulch or sealed surfaces;
(b) past land management practices;
(c) natural conditions.
WARNINGS:
A Sediment Basin will usually be required if the disturbed area exceeds 0.25ha
(2500m2) within any sub-catchment (i.e. land flowing to one outlet point).
COMMENTS:
For soil disturbances greater than 0.25ha, the revegetation phase should be
staged to minimise the duration for which soils are exposed to wind, rain and
concentrated runoff.
IECA (Australasia) November 2008 Page 5
Section 17
Best Practice Erosion And Sediment Control Erosion Hazard Assessment Form
[6] REQUIREMENTS:
All developments that involve earthworks or construction within a natural
watercourse (whether that watercourse is in a natural or modified condition) must
submit a conceptual ESCP to the regulatory authority for review and/or approval
(as required by the regulatory authority) during planning negotiations.
Permits and/or licences may be required from the State Government, including
possible submission of the ESCP to the relevant Government department.
[7] REQUIREMENTS:
No areas of soil disturbance shall be left exposed to rainfall or dust-producing
winds at the end of a development without an adequate degree of protection
and/or an appropriate action plan for the establishment of at least 70% cover.
COMMENTS:
Grass seeding without the application of a light mulch cover is considered the
least favourable revegetation technique. A light mulch cover is required to
protect the soil from raindrop impact, excessive temperature fluctuations, and the
loss of essential soil moisture.
[8] COMMENTS:
All receiving waters can be adversely affected by unnatural quantities of
sediment-laden runoff. Freshwater ecosystems are generally more susceptible to
ecological harm resulting from the inflow of fine or dispersible clays than saline
water bodies. The further inland a land disturbance is, the greater the potential
for the released sediment to cause environmental harm as this sediment travels
towards the coast.
For the purpose of this clause it is assumed that all sediment-laden runoff will
eventually flow into saline waters. Thus, sediment-laden discharges that flow first
into freshwater are likely to adversely affect both fresh and saline water bodies
and are therefore considered potentially more damaging to the environment.
This clause does not imply that sediment-laden runoff will not cause harm to
saline waters.
[9] COMMENTS:
This clause refers to subsoils exposed during the construction phase either as a
result of past land practices or proposed construction activities. The exposure of
subsoils resulting from the excavation of minor service trenches should not be
considered.
[10] WARNINGS:
The greater the extent of external catchment, the greater the need to divert up-
slope stormwater runoff around any soil disturbance.
COMMENTS:
The ability to separate “clean” (i.e. external catchment) stormwater runoff from
“dirty” site runoff can have a significant effect on the size, efficiency and cost of
the temporary drainage, erosion, and sediment control measures.
IECA (Australasia) November 2008 Page 6
Section 18
Best Practice Erosion And Sediment Control Erosion Hazard Assessment Form
[11] REQUIREMENTS:
Permission must be obtained from the owner of a road reserve before placing
any erosion and sediment control measures within the road reserve.
WARNINGS:
Few sediment control techniques work efficiently when placed on a road and/or
around roadside stormwater inlets. Great care must be taken if sediment control
measures are located on a public roadway, specifically:
• safety issues relating to road users;
• the risk of causing flooding on the road or within private property.
The construction of roads (whether temporary or permanent) will usually modify
the flow path of stormwater runoff. This can affect how “dirty” site runoff is
directed to the sediment control measures.
COMMENTS:
“On-road” sediment control devices are at best viewed as secondary or
supplementary sediment control measures. Only in special cases and/or on very
small projects (e.g. kerb and channel replacement) might these controls be
considered as the “primary” sediment control measure.
[12] WARNINGS:
Soils with a pH less than 5.5 or greater than 8 will usually require treatment in
order to achieve satisfactory revegetation. Soils with a pH of less than 5
(whether naturally acidic or in acid sulfate soil areas) may also limit the choice of
chemical flocculants (e.g. Alum) for use in the flocculation of Sediment Basins.
[13] REQUIREMENTS:
A preliminary ESCP must be submitted to the local government for approval
during the planning phase for any development that obtains a total point score of
17 or greater or when any trigger value is scored or exceeded.
IECA (Australasia) November 2008 Page 7
Section 19
Us WESTERA PARTNERS Appendix B - Preliminary Engineering Plans B-1
Section 20
LEGEND
SWD
S
W
S
W S
TE
S
TE
S
S
TE
S
W S
TE
W
S
R
S
O
V W
S
S
W S
C
R
E
W
S
C
E
N
S
T
W
W
S
W
S
RO
SWD
W
S
SS
W
S
CR
W
ES S
CE
S
NT
W
S
W
S
W
STORMWATER
MANAGEMENT PLAN
DESIGNED BRISBANE SURVEYOR DATUM DRAWING STATUS
T 07 3852 4333
E [email protected]
PROJECT
DRAWN
GOLD COAST T 07 5571 1599
CHECKED
E [email protected] LOCATION DRAWING NUMBER
SUNSHINE COAST T 07 5391 3777 USE FIGURED DIMENSIONS ONLY. DO NOT SCALE, IF A DISCREPANCY ARISES
E [email protected] CHECK WITH THE PROJECT ENGINEER AND/OR SUPERVISING AUTHORITY. DO NOT
APPROVED
WORK FROM REDUCED SCALE DRAWINGS (A1-A3 SIZE PAPER). COPYRIGHT OF ALL
For and on behalf of
NORTHERN NSW T 02 6674 8047
DRAWINGS & WORKS EXECUTED FROM THEM IS VESTED IN WESTERA PARTNERS
TITLE
DATE E [email protected] SHEET NUMBER REVISION
WESTERA PARTNERS PTY. LTD. AND USE OF THERE FORE WITHOUT PERMISSION IS STRICTLY PROHIBITED! IT IS
www.westerapartners.com.au ABN 52 097 417 975 CENTRAL VICTORIA T 03 5441 0922 THE BUILDERS RESPONSIBILITY TO ENSURE ALL WORKS ARE CARRIED OUT WITH
No. DATE REVISIONS DES DRN CHK APD DOCUMENT CONTROL APPROVED E [email protected] DUE CARE AND DILIGENCE TO COMPLY WITH THE CONTRACT DOCUMENTS. CLIENT
Section 21
SECTION
ROSS
CRES
SECTION
DESIGNED BRISBANE SURVEYOR DATUM DRAWING STATUS
T 07 3852 4333
E [email protected]
PROJECT
DRAWN
GOLD COAST T 07 5571 1599
CHECKED
E [email protected] LOCATION DRAWING NUMBER
SUNSHINE COAST T 07 5391 3777 USE FIGURED DIMENSIONS ONLY. DO NOT SCALE, IF A DISCREPANCY ARISES
E [email protected] CHECK WITH THE PROJECT ENGINEER AND/OR SUPERVISING AUTHORITY. DO NOT
APPROVED
WORK FROM REDUCED SCALE DRAWINGS (A1-A3 SIZE PAPER). COPYRIGHT OF ALL
For and on behalf of
NORTHERN NSW T 02 6674 8047
DRAWINGS & WORKS EXECUTED FROM THEM IS VESTED IN WESTERA PARTNERS
TITLE
DATE E [email protected] SHEET NUMBER REVISION
WESTERA PARTNERS PTY. LTD. AND USE OF THERE FORE WITHOUT PERMISSION IS STRICTLY PROHIBITED! IT IS
www.westerapartners.com.au ABN 52 097 417 975 CENTRAL VICTORIA T 03 5441 0922 THE BUILDERS RESPONSIBILITY TO ENSURE ALL WORKS ARE CARRIED OUT WITH
No. DATE REVISIONS DES DRN CHK APD DOCUMENT CONTROL APPROVED E [email protected] DUE CARE AND DILIGENCE TO COMPLY WITH THE CONTRACT DOCUMENTS. CLIENT
Section 22
Us WESTERA PARTNERS Appendix C — Site Survey
Section 23
LEGEND
. 0 9.04
0
1
LIGHT POLE
19
OP ORIGINAL PEG
POWER POLE
50
FIRE HYDRANT 18 . 5
AJS SURVEYS
0
VALVE
. 00 RP216711 . 50 . 00
7
71
.2
.5
50
18
.
18
16
SEWER MANHOLE 17 17 0
19
.0 0
SURVEYING
.
ROOFWATER PIT
16 .5 0
16
.0 0
4
15
.4
.5
14
POWER BOX
15
14
Post & Wire Fence
7
.1 .17
.2
CP
19
18 18
97
TELSTRA PIT
5 09.37
.
3
19
18 . 0 0
4
.4
1
20
18 . 50
9
RETAINING WALL
.6
19 . 00
Concrete
9
GTP100987
18
0
.1
00
2
. 19
6
.6
0
.9
17 . 50
0
17
9
0
8
17
.1
50
2. 010. 0
STORMWATER MANHOLE T*S2/200
18 . 50
.5
1
21
0.
.
1
.6
1 219.63
19
7
17
. PLANNING . DEVELOPMENT
.3
9
5
.
3
5
0
17
.2
.1
GAS SUPPLY/GAS CYLINDER
.7
.2
.9 4
20
20
18
18 . 00
17 7.9
18
19
4
0
2
1
.6
9
7
.3
. 521
Block Retaining Wall
6
1
.3
81
.3
Rock
19
.00 .07
TEMPORARY BENCH MARK (TBM)
19
Ridge
17
Roof
17 4
.
8
ence
17
2
7
17 . 50
.6
9308 63|0 (approx)
.4
02
Timber F Concrete Roof
.3
5
2
17
17
3
Retaining
.2
1
2 2 . 5 22.40
.4
49 x)
Level 24.11
Section 24
2
Level 22.83
21
Stairs
50
.9
17
Level
2
PERMANENT SURVEY MARK
0
22
10
66
0
Wall Post & Wire Fence
0
8
15 . 0
. 5 024.24
17 . 00
2
.0
1 6 . 0 0 16.
o
1
7
0
ppr
2
.8
59
17
.1
16 . 50
.4
23.02
.4
.
24
2 22
.
24
17
.
17
8
14
0
(a
.4
1
3
GULLY GRATE
22
1
.7
15 . 50
.3
17
.1
10|0 Bench
0
14
15
14
15 . 00
9
8
.3
2
.6
14 . 50
T*S2/200
3.
.3
20
24
20
WATER METER
17
00
14 . 00
1
50
2
5
.8
.3
.9
12
50
2
17
Ridge
20
. 00
2
50
.4
39
5
13 . 00
20
.9
3 .. 5
SIGN
Garden
.
Roof
20
1 1 . 5. 0 0 11
Level
16 .
12 . 50
12 . 50
8
15 .
.
.3
50
42
Co
T*S2/200
17
12 . 00
Garden Level
14
7
Bank
.
24.69
.3
0
20
Timber
1
.7
25
13
20
7
Garden
The text continues on section 25.
Used in these records
Reference Document - Stormwater Mangement Report & Letter Repsonse - MCU24 0094Related documentApplication case desk ↗
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